mm: sync vmalloc address space page tables in alloc_vm_area()
[linux-2.6.git] / mm / memory.c
1 /*
2  *  linux/mm/memory.c
3  *
4  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
5  */
6
7 /*
8  * demand-loading started 01.12.91 - seems it is high on the list of
9  * things wanted, and it should be easy to implement. - Linus
10  */
11
12 /*
13  * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14  * pages started 02.12.91, seems to work. - Linus.
15  *
16  * Tested sharing by executing about 30 /bin/sh: under the old kernel it
17  * would have taken more than the 6M I have free, but it worked well as
18  * far as I could see.
19  *
20  * Also corrected some "invalidate()"s - I wasn't doing enough of them.
21  */
22
23 /*
24  * Real VM (paging to/from disk) started 18.12.91. Much more work and
25  * thought has to go into this. Oh, well..
26  * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
27  *              Found it. Everything seems to work now.
28  * 20.12.91  -  Ok, making the swap-device changeable like the root.
29  */
30
31 /*
32  * 05.04.94  -  Multi-page memory management added for v1.1.
33  *              Idea by Alex Bligh (alex@cconcepts.co.uk)
34  *
35  * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
36  *              (Gerhard.Wichert@pdb.siemens.de)
37  *
38  * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
39  */
40
41 #include <linux/kernel_stat.h>
42 #include <linux/mm.h>
43 #include <linux/hugetlb.h>
44 #include <linux/mman.h>
45 #include <linux/swap.h>
46 #include <linux/highmem.h>
47 #include <linux/pagemap.h>
48 #include <linux/ksm.h>
49 #include <linux/rmap.h>
50 #include <linux/module.h>
51 #include <linux/delayacct.h>
52 #include <linux/init.h>
53 #include <linux/writeback.h>
54 #include <linux/memcontrol.h>
55 #include <linux/mmu_notifier.h>
56 #include <linux/kallsyms.h>
57 #include <linux/swapops.h>
58 #include <linux/elf.h>
59 #include <linux/gfp.h>
60
61 #include <asm/io.h>
62 #include <asm/pgalloc.h>
63 #include <asm/uaccess.h>
64 #include <asm/tlb.h>
65 #include <asm/tlbflush.h>
66 #include <asm/pgtable.h>
67
68 #include "internal.h"
69
70 #ifndef CONFIG_NEED_MULTIPLE_NODES
71 /* use the per-pgdat data instead for discontigmem - mbligh */
72 unsigned long max_mapnr;
73 struct page *mem_map;
74
75 EXPORT_SYMBOL(max_mapnr);
76 EXPORT_SYMBOL(mem_map);
77 #endif
78
79 unsigned long num_physpages;
80 /*
81  * A number of key systems in x86 including ioremap() rely on the assumption
82  * that high_memory defines the upper bound on direct map memory, then end
83  * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
84  * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
85  * and ZONE_HIGHMEM.
86  */
87 void * high_memory;
88
89 EXPORT_SYMBOL(num_physpages);
90 EXPORT_SYMBOL(high_memory);
91
92 /*
93  * Randomize the address space (stacks, mmaps, brk, etc.).
94  *
95  * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
96  *   as ancient (libc5 based) binaries can segfault. )
97  */
98 int randomize_va_space __read_mostly =
99 #ifdef CONFIG_COMPAT_BRK
100                                         1;
101 #else
102                                         2;
103 #endif
104
105 static int __init disable_randmaps(char *s)
106 {
107         randomize_va_space = 0;
108         return 1;
109 }
110 __setup("norandmaps", disable_randmaps);
111
112 unsigned long zero_pfn __read_mostly;
113 unsigned long highest_memmap_pfn __read_mostly;
114
115 /*
116  * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
117  */
118 static int __init init_zero_pfn(void)
119 {
120         zero_pfn = page_to_pfn(ZERO_PAGE(0));
121         return 0;
122 }
123 core_initcall(init_zero_pfn);
124
125
126 #if defined(SPLIT_RSS_COUNTING)
127
128 static void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm)
129 {
130         int i;
131
132         for (i = 0; i < NR_MM_COUNTERS; i++) {
133                 if (task->rss_stat.count[i]) {
134                         add_mm_counter(mm, i, task->rss_stat.count[i]);
135                         task->rss_stat.count[i] = 0;
136                 }
137         }
138         task->rss_stat.events = 0;
139 }
140
141 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
142 {
143         struct task_struct *task = current;
144
145         if (likely(task->mm == mm))
146                 task->rss_stat.count[member] += val;
147         else
148                 add_mm_counter(mm, member, val);
149 }
150 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
151 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
152
153 /* sync counter once per 64 page faults */
154 #define TASK_RSS_EVENTS_THRESH  (64)
155 static void check_sync_rss_stat(struct task_struct *task)
156 {
157         if (unlikely(task != current))
158                 return;
159         if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
160                 __sync_task_rss_stat(task, task->mm);
161 }
162
163 unsigned long get_mm_counter(struct mm_struct *mm, int member)
164 {
165         long val = 0;
166
167         /*
168          * Don't use task->mm here...for avoiding to use task_get_mm()..
169          * The caller must guarantee task->mm is not invalid.
170          */
171         val = atomic_long_read(&mm->rss_stat.count[member]);
172         /*
173          * counter is updated in asynchronous manner and may go to minus.
174          * But it's never be expected number for users.
175          */
176         if (val < 0)
177                 return 0;
178         return (unsigned long)val;
179 }
180
181 void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
182 {
183         __sync_task_rss_stat(task, mm);
184 }
185 #else /* SPLIT_RSS_COUNTING */
186
187 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
188 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
189
190 static void check_sync_rss_stat(struct task_struct *task)
191 {
192 }
193
194 #endif /* SPLIT_RSS_COUNTING */
195
196 #ifdef HAVE_GENERIC_MMU_GATHER
197
198 static int tlb_next_batch(struct mmu_gather *tlb)
199 {
200         struct mmu_gather_batch *batch;
201
202         batch = tlb->active;
203         if (batch->next) {
204                 tlb->active = batch->next;
205                 return 1;
206         }
207
208         batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
209         if (!batch)
210                 return 0;
211
212         batch->next = NULL;
213         batch->nr   = 0;
214         batch->max  = MAX_GATHER_BATCH;
215
216         tlb->active->next = batch;
217         tlb->active = batch;
218
219         return 1;
220 }
221
222 /* tlb_gather_mmu
223  *      Called to initialize an (on-stack) mmu_gather structure for page-table
224  *      tear-down from @mm. The @fullmm argument is used when @mm is without
225  *      users and we're going to destroy the full address space (exit/execve).
226  */
227 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm)
228 {
229         tlb->mm = mm;
230
231         tlb->fullmm     = fullmm;
232         tlb->need_flush = 0;
233         tlb->fast_mode  = (num_possible_cpus() == 1);
234         tlb->local.next = NULL;
235         tlb->local.nr   = 0;
236         tlb->local.max  = ARRAY_SIZE(tlb->__pages);
237         tlb->active     = &tlb->local;
238
239 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
240         tlb->batch = NULL;
241 #endif
242 }
243
244 void tlb_flush_mmu(struct mmu_gather *tlb)
245 {
246         struct mmu_gather_batch *batch;
247
248         if (!tlb->need_flush)
249                 return;
250         tlb->need_flush = 0;
251         tlb_flush(tlb);
252 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
253         tlb_table_flush(tlb);
254 #endif
255
256         if (tlb_fast_mode(tlb))
257                 return;
258
259         for (batch = &tlb->local; batch; batch = batch->next) {
260                 free_pages_and_swap_cache(batch->pages, batch->nr);
261                 batch->nr = 0;
262         }
263         tlb->active = &tlb->local;
264 }
265
266 /* tlb_finish_mmu
267  *      Called at the end of the shootdown operation to free up any resources
268  *      that were required.
269  */
270 void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
271 {
272         struct mmu_gather_batch *batch, *next;
273
274         tlb_flush_mmu(tlb);
275
276         /* keep the page table cache within bounds */
277         check_pgt_cache();
278
279         for (batch = tlb->local.next; batch; batch = next) {
280                 next = batch->next;
281                 free_pages((unsigned long)batch, 0);
282         }
283         tlb->local.next = NULL;
284 }
285
286 /* __tlb_remove_page
287  *      Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
288  *      handling the additional races in SMP caused by other CPUs caching valid
289  *      mappings in their TLBs. Returns the number of free page slots left.
290  *      When out of page slots we must call tlb_flush_mmu().
291  */
292 int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
293 {
294         struct mmu_gather_batch *batch;
295
296         tlb->need_flush = 1;
297
298         if (tlb_fast_mode(tlb)) {
299                 free_page_and_swap_cache(page);
300                 return 1; /* avoid calling tlb_flush_mmu() */
301         }
302
303         batch = tlb->active;
304         batch->pages[batch->nr++] = page;
305         if (batch->nr == batch->max) {
306                 if (!tlb_next_batch(tlb))
307                         return 0;
308                 batch = tlb->active;
309         }
310         VM_BUG_ON(batch->nr > batch->max);
311
312         return batch->max - batch->nr;
313 }
314
315 #endif /* HAVE_GENERIC_MMU_GATHER */
316
317 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
318
319 /*
320  * See the comment near struct mmu_table_batch.
321  */
322
323 static void tlb_remove_table_smp_sync(void *arg)
324 {
325         /* Simply deliver the interrupt */
326 }
327
328 static void tlb_remove_table_one(void *table)
329 {
330         /*
331          * This isn't an RCU grace period and hence the page-tables cannot be
332          * assumed to be actually RCU-freed.
333          *
334          * It is however sufficient for software page-table walkers that rely on
335          * IRQ disabling. See the comment near struct mmu_table_batch.
336          */
337         smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
338         __tlb_remove_table(table);
339 }
340
341 static void tlb_remove_table_rcu(struct rcu_head *head)
342 {
343         struct mmu_table_batch *batch;
344         int i;
345
346         batch = container_of(head, struct mmu_table_batch, rcu);
347
348         for (i = 0; i < batch->nr; i++)
349                 __tlb_remove_table(batch->tables[i]);
350
351         free_page((unsigned long)batch);
352 }
353
354 void tlb_table_flush(struct mmu_gather *tlb)
355 {
356         struct mmu_table_batch **batch = &tlb->batch;
357
358         if (*batch) {
359                 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
360                 *batch = NULL;
361         }
362 }
363
364 void tlb_remove_table(struct mmu_gather *tlb, void *table)
365 {
366         struct mmu_table_batch **batch = &tlb->batch;
367
368         tlb->need_flush = 1;
369
370         /*
371          * When there's less then two users of this mm there cannot be a
372          * concurrent page-table walk.
373          */
374         if (atomic_read(&tlb->mm->mm_users) < 2) {
375                 __tlb_remove_table(table);
376                 return;
377         }
378
379         if (*batch == NULL) {
380                 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
381                 if (*batch == NULL) {
382                         tlb_remove_table_one(table);
383                         return;
384                 }
385                 (*batch)->nr = 0;
386         }
387         (*batch)->tables[(*batch)->nr++] = table;
388         if ((*batch)->nr == MAX_TABLE_BATCH)
389                 tlb_table_flush(tlb);
390 }
391
392 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */
393
394 /*
395  * If a p?d_bad entry is found while walking page tables, report
396  * the error, before resetting entry to p?d_none.  Usually (but
397  * very seldom) called out from the p?d_none_or_clear_bad macros.
398  */
399
400 void pgd_clear_bad(pgd_t *pgd)
401 {
402         pgd_ERROR(*pgd);
403         pgd_clear(pgd);
404 }
405
406 void pud_clear_bad(pud_t *pud)
407 {
408         pud_ERROR(*pud);
409         pud_clear(pud);
410 }
411
412 void pmd_clear_bad(pmd_t *pmd)
413 {
414         pmd_ERROR(*pmd);
415         pmd_clear(pmd);
416 }
417
418 /*
419  * Note: this doesn't free the actual pages themselves. That
420  * has been handled earlier when unmapping all the memory regions.
421  */
422 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
423                            unsigned long addr)
424 {
425         pgtable_t token = pmd_pgtable(*pmd);
426         pmd_clear(pmd);
427         pte_free_tlb(tlb, token, addr);
428         tlb->mm->nr_ptes--;
429 }
430
431 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
432                                 unsigned long addr, unsigned long end,
433                                 unsigned long floor, unsigned long ceiling)
434 {
435         pmd_t *pmd;
436         unsigned long next;
437         unsigned long start;
438
439         start = addr;
440         pmd = pmd_offset(pud, addr);
441         do {
442                 next = pmd_addr_end(addr, end);
443                 if (pmd_none_or_clear_bad(pmd))
444                         continue;
445                 free_pte_range(tlb, pmd, addr);
446         } while (pmd++, addr = next, addr != end);
447
448         start &= PUD_MASK;
449         if (start < floor)
450                 return;
451         if (ceiling) {
452                 ceiling &= PUD_MASK;
453                 if (!ceiling)
454                         return;
455         }
456         if (end - 1 > ceiling - 1)
457                 return;
458
459         pmd = pmd_offset(pud, start);
460         pud_clear(pud);
461         pmd_free_tlb(tlb, pmd, start);
462 }
463
464 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
465                                 unsigned long addr, unsigned long end,
466                                 unsigned long floor, unsigned long ceiling)
467 {
468         pud_t *pud;
469         unsigned long next;
470         unsigned long start;
471
472         start = addr;
473         pud = pud_offset(pgd, addr);
474         do {
475                 next = pud_addr_end(addr, end);
476                 if (pud_none_or_clear_bad(pud))
477                         continue;
478                 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
479         } while (pud++, addr = next, addr != end);
480
481         start &= PGDIR_MASK;
482         if (start < floor)
483                 return;
484         if (ceiling) {
485                 ceiling &= PGDIR_MASK;
486                 if (!ceiling)
487                         return;
488         }
489         if (end - 1 > ceiling - 1)
490                 return;
491
492         pud = pud_offset(pgd, start);
493         pgd_clear(pgd);
494         pud_free_tlb(tlb, pud, start);
495 }
496
497 /*
498  * This function frees user-level page tables of a process.
499  *
500  * Must be called with pagetable lock held.
501  */
502 void free_pgd_range(struct mmu_gather *tlb,
503                         unsigned long addr, unsigned long end,
504                         unsigned long floor, unsigned long ceiling)
505 {
506         pgd_t *pgd;
507         unsigned long next;
508
509         /*
510          * The next few lines have given us lots of grief...
511          *
512          * Why are we testing PMD* at this top level?  Because often
513          * there will be no work to do at all, and we'd prefer not to
514          * go all the way down to the bottom just to discover that.
515          *
516          * Why all these "- 1"s?  Because 0 represents both the bottom
517          * of the address space and the top of it (using -1 for the
518          * top wouldn't help much: the masks would do the wrong thing).
519          * The rule is that addr 0 and floor 0 refer to the bottom of
520          * the address space, but end 0 and ceiling 0 refer to the top
521          * Comparisons need to use "end - 1" and "ceiling - 1" (though
522          * that end 0 case should be mythical).
523          *
524          * Wherever addr is brought up or ceiling brought down, we must
525          * be careful to reject "the opposite 0" before it confuses the
526          * subsequent tests.  But what about where end is brought down
527          * by PMD_SIZE below? no, end can't go down to 0 there.
528          *
529          * Whereas we round start (addr) and ceiling down, by different
530          * masks at different levels, in order to test whether a table
531          * now has no other vmas using it, so can be freed, we don't
532          * bother to round floor or end up - the tests don't need that.
533          */
534
535         addr &= PMD_MASK;
536         if (addr < floor) {
537                 addr += PMD_SIZE;
538                 if (!addr)
539                         return;
540         }
541         if (ceiling) {
542                 ceiling &= PMD_MASK;
543                 if (!ceiling)
544                         return;
545         }
546         if (end - 1 > ceiling - 1)
547                 end -= PMD_SIZE;
548         if (addr > end - 1)
549                 return;
550
551         pgd = pgd_offset(tlb->mm, addr);
552         do {
553                 next = pgd_addr_end(addr, end);
554                 if (pgd_none_or_clear_bad(pgd))
555                         continue;
556                 free_pud_range(tlb, pgd, addr, next, floor, ceiling);
557         } while (pgd++, addr = next, addr != end);
558 }
559
560 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
561                 unsigned long floor, unsigned long ceiling)
562 {
563         while (vma) {
564                 struct vm_area_struct *next = vma->vm_next;
565                 unsigned long addr = vma->vm_start;
566
567                 /*
568                  * Hide vma from rmap and truncate_pagecache before freeing
569                  * pgtables
570                  */
571                 unlink_anon_vmas(vma);
572                 unlink_file_vma(vma);
573
574                 if (is_vm_hugetlb_page(vma)) {
575                         hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
576                                 floor, next? next->vm_start: ceiling);
577                 } else {
578                         /*
579                          * Optimization: gather nearby vmas into one call down
580                          */
581                         while (next && next->vm_start <= vma->vm_end + PMD_SIZE
582                                && !is_vm_hugetlb_page(next)) {
583                                 vma = next;
584                                 next = vma->vm_next;
585                                 unlink_anon_vmas(vma);
586                                 unlink_file_vma(vma);
587                         }
588                         free_pgd_range(tlb, addr, vma->vm_end,
589                                 floor, next? next->vm_start: ceiling);
590                 }
591                 vma = next;
592         }
593 }
594
595 int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
596                 pmd_t *pmd, unsigned long address)
597 {
598         pgtable_t new = pte_alloc_one(mm, address);
599         int wait_split_huge_page;
600         if (!new)
601                 return -ENOMEM;
602
603         /*
604          * Ensure all pte setup (eg. pte page lock and page clearing) are
605          * visible before the pte is made visible to other CPUs by being
606          * put into page tables.
607          *
608          * The other side of the story is the pointer chasing in the page
609          * table walking code (when walking the page table without locking;
610          * ie. most of the time). Fortunately, these data accesses consist
611          * of a chain of data-dependent loads, meaning most CPUs (alpha
612          * being the notable exception) will already guarantee loads are
613          * seen in-order. See the alpha page table accessors for the
614          * smp_read_barrier_depends() barriers in page table walking code.
615          */
616         smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
617
618         spin_lock(&mm->page_table_lock);
619         wait_split_huge_page = 0;
620         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
621                 mm->nr_ptes++;
622                 pmd_populate(mm, pmd, new);
623                 new = NULL;
624         } else if (unlikely(pmd_trans_splitting(*pmd)))
625                 wait_split_huge_page = 1;
626         spin_unlock(&mm->page_table_lock);
627         if (new)
628                 pte_free(mm, new);
629         if (wait_split_huge_page)
630                 wait_split_huge_page(vma->anon_vma, pmd);
631         return 0;
632 }
633
634 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
635 {
636         pte_t *new = pte_alloc_one_kernel(&init_mm, address);
637         if (!new)
638                 return -ENOMEM;
639
640         smp_wmb(); /* See comment in __pte_alloc */
641
642         spin_lock(&init_mm.page_table_lock);
643         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
644                 pmd_populate_kernel(&init_mm, pmd, new);
645                 new = NULL;
646         } else
647                 VM_BUG_ON(pmd_trans_splitting(*pmd));
648         spin_unlock(&init_mm.page_table_lock);
649         if (new)
650                 pte_free_kernel(&init_mm, new);
651         return 0;
652 }
653
654 static inline void init_rss_vec(int *rss)
655 {
656         memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
657 }
658
659 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
660 {
661         int i;
662
663         if (current->mm == mm)
664                 sync_mm_rss(current, mm);
665         for (i = 0; i < NR_MM_COUNTERS; i++)
666                 if (rss[i])
667                         add_mm_counter(mm, i, rss[i]);
668 }
669
670 /*
671  * This function is called to print an error when a bad pte
672  * is found. For example, we might have a PFN-mapped pte in
673  * a region that doesn't allow it.
674  *
675  * The calling function must still handle the error.
676  */
677 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
678                           pte_t pte, struct page *page)
679 {
680         pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
681         pud_t *pud = pud_offset(pgd, addr);
682         pmd_t *pmd = pmd_offset(pud, addr);
683         struct address_space *mapping;
684         pgoff_t index;
685         static unsigned long resume;
686         static unsigned long nr_shown;
687         static unsigned long nr_unshown;
688
689         /*
690          * Allow a burst of 60 reports, then keep quiet for that minute;
691          * or allow a steady drip of one report per second.
692          */
693         if (nr_shown == 60) {
694                 if (time_before(jiffies, resume)) {
695                         nr_unshown++;
696                         return;
697                 }
698                 if (nr_unshown) {
699                         printk(KERN_ALERT
700                                 "BUG: Bad page map: %lu messages suppressed\n",
701                                 nr_unshown);
702                         nr_unshown = 0;
703                 }
704                 nr_shown = 0;
705         }
706         if (nr_shown++ == 0)
707                 resume = jiffies + 60 * HZ;
708
709         mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
710         index = linear_page_index(vma, addr);
711
712         printk(KERN_ALERT
713                 "BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
714                 current->comm,
715                 (long long)pte_val(pte), (long long)pmd_val(*pmd));
716         if (page)
717                 dump_page(page);
718         printk(KERN_ALERT
719                 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
720                 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
721         /*
722          * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
723          */
724         if (vma->vm_ops)
725                 print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
726                                 (unsigned long)vma->vm_ops->fault);
727         if (vma->vm_file && vma->vm_file->f_op)
728                 print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
729                                 (unsigned long)vma->vm_file->f_op->mmap);
730         dump_stack();
731         add_taint(TAINT_BAD_PAGE);
732 }
733
734 static inline int is_cow_mapping(vm_flags_t flags)
735 {
736         return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
737 }
738
739 #ifndef is_zero_pfn
740 static inline int is_zero_pfn(unsigned long pfn)
741 {
742         return pfn == zero_pfn;
743 }
744 #endif
745
746 #ifndef my_zero_pfn
747 static inline unsigned long my_zero_pfn(unsigned long addr)
748 {
749         return zero_pfn;
750 }
751 #endif
752
753 /*
754  * vm_normal_page -- This function gets the "struct page" associated with a pte.
755  *
756  * "Special" mappings do not wish to be associated with a "struct page" (either
757  * it doesn't exist, or it exists but they don't want to touch it). In this
758  * case, NULL is returned here. "Normal" mappings do have a struct page.
759  *
760  * There are 2 broad cases. Firstly, an architecture may define a pte_special()
761  * pte bit, in which case this function is trivial. Secondly, an architecture
762  * may not have a spare pte bit, which requires a more complicated scheme,
763  * described below.
764  *
765  * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
766  * special mapping (even if there are underlying and valid "struct pages").
767  * COWed pages of a VM_PFNMAP are always normal.
768  *
769  * The way we recognize COWed pages within VM_PFNMAP mappings is through the
770  * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
771  * set, and the vm_pgoff will point to the first PFN mapped: thus every special
772  * mapping will always honor the rule
773  *
774  *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
775  *
776  * And for normal mappings this is false.
777  *
778  * This restricts such mappings to be a linear translation from virtual address
779  * to pfn. To get around this restriction, we allow arbitrary mappings so long
780  * as the vma is not a COW mapping; in that case, we know that all ptes are
781  * special (because none can have been COWed).
782  *
783  *
784  * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
785  *
786  * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
787  * page" backing, however the difference is that _all_ pages with a struct
788  * page (that is, those where pfn_valid is true) are refcounted and considered
789  * normal pages by the VM. The disadvantage is that pages are refcounted
790  * (which can be slower and simply not an option for some PFNMAP users). The
791  * advantage is that we don't have to follow the strict linearity rule of
792  * PFNMAP mappings in order to support COWable mappings.
793  *
794  */
795 #ifdef __HAVE_ARCH_PTE_SPECIAL
796 # define HAVE_PTE_SPECIAL 1
797 #else
798 # define HAVE_PTE_SPECIAL 0
799 #endif
800 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
801                                 pte_t pte)
802 {
803         unsigned long pfn = pte_pfn(pte);
804
805         if (HAVE_PTE_SPECIAL) {
806                 if (likely(!pte_special(pte)))
807                         goto check_pfn;
808                 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
809                         return NULL;
810                 if (!is_zero_pfn(pfn))
811                         print_bad_pte(vma, addr, pte, NULL);
812                 return NULL;
813         }
814
815         /* !HAVE_PTE_SPECIAL case follows: */
816
817         if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
818                 if (vma->vm_flags & VM_MIXEDMAP) {
819                         if (!pfn_valid(pfn))
820                                 return NULL;
821                         goto out;
822                 } else {
823                         unsigned long off;
824                         off = (addr - vma->vm_start) >> PAGE_SHIFT;
825                         if (pfn == vma->vm_pgoff + off)
826                                 return NULL;
827                         if (!is_cow_mapping(vma->vm_flags))
828                                 return NULL;
829                 }
830         }
831
832         if (is_zero_pfn(pfn))
833                 return NULL;
834 check_pfn:
835         if (unlikely(pfn > highest_memmap_pfn)) {
836                 print_bad_pte(vma, addr, pte, NULL);
837                 return NULL;
838         }
839
840         /*
841          * NOTE! We still have PageReserved() pages in the page tables.
842          * eg. VDSO mappings can cause them to exist.
843          */
844 out:
845         return pfn_to_page(pfn);
846 }
847
848 /*
849  * copy one vm_area from one task to the other. Assumes the page tables
850  * already present in the new task to be cleared in the whole range
851  * covered by this vma.
852  */
853
854 static inline unsigned long
855 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
856                 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
857                 unsigned long addr, int *rss)
858 {
859         unsigned long vm_flags = vma->vm_flags;
860         pte_t pte = *src_pte;
861         struct page *page;
862
863         /* pte contains position in swap or file, so copy. */
864         if (unlikely(!pte_present(pte))) {
865                 if (!pte_file(pte)) {
866                         swp_entry_t entry = pte_to_swp_entry(pte);
867
868                         if (swap_duplicate(entry) < 0)
869                                 return entry.val;
870
871                         /* make sure dst_mm is on swapoff's mmlist. */
872                         if (unlikely(list_empty(&dst_mm->mmlist))) {
873                                 spin_lock(&mmlist_lock);
874                                 if (list_empty(&dst_mm->mmlist))
875                                         list_add(&dst_mm->mmlist,
876                                                  &src_mm->mmlist);
877                                 spin_unlock(&mmlist_lock);
878                         }
879                         if (likely(!non_swap_entry(entry)))
880                                 rss[MM_SWAPENTS]++;
881                         else if (is_write_migration_entry(entry) &&
882                                         is_cow_mapping(vm_flags)) {
883                                 /*
884                                  * COW mappings require pages in both parent
885                                  * and child to be set to read.
886                                  */
887                                 make_migration_entry_read(&entry);
888                                 pte = swp_entry_to_pte(entry);
889                                 set_pte_at(src_mm, addr, src_pte, pte);
890                         }
891                 }
892                 goto out_set_pte;
893         }
894
895         /*
896          * If it's a COW mapping, write protect it both
897          * in the parent and the child
898          */
899         if (is_cow_mapping(vm_flags)) {
900                 ptep_set_wrprotect(src_mm, addr, src_pte);
901                 pte = pte_wrprotect(pte);
902         }
903
904         /*
905          * If it's a shared mapping, mark it clean in
906          * the child
907          */
908         if (vm_flags & VM_SHARED)
909                 pte = pte_mkclean(pte);
910         pte = pte_mkold(pte);
911
912         page = vm_normal_page(vma, addr, pte);
913         if (page) {
914                 get_page(page);
915                 page_dup_rmap(page);
916                 if (PageAnon(page))
917                         rss[MM_ANONPAGES]++;
918                 else
919                         rss[MM_FILEPAGES]++;
920         }
921
922 out_set_pte:
923         set_pte_at(dst_mm, addr, dst_pte, pte);
924         return 0;
925 }
926
927 int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
928                    pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
929                    unsigned long addr, unsigned long end)
930 {
931         pte_t *orig_src_pte, *orig_dst_pte;
932         pte_t *src_pte, *dst_pte;
933         spinlock_t *src_ptl, *dst_ptl;
934         int progress = 0;
935         int rss[NR_MM_COUNTERS];
936         swp_entry_t entry = (swp_entry_t){0};
937
938 again:
939         init_rss_vec(rss);
940
941         dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
942         if (!dst_pte)
943                 return -ENOMEM;
944         src_pte = pte_offset_map(src_pmd, addr);
945         src_ptl = pte_lockptr(src_mm, src_pmd);
946         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
947         orig_src_pte = src_pte;
948         orig_dst_pte = dst_pte;
949         arch_enter_lazy_mmu_mode();
950
951         do {
952                 /*
953                  * We are holding two locks at this point - either of them
954                  * could generate latencies in another task on another CPU.
955                  */
956                 if (progress >= 32) {
957                         progress = 0;
958                         if (need_resched() ||
959                             spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
960                                 break;
961                 }
962                 if (pte_none(*src_pte)) {
963                         progress++;
964                         continue;
965                 }
966                 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
967                                                         vma, addr, rss);
968                 if (entry.val)
969                         break;
970                 progress += 8;
971         } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
972
973         arch_leave_lazy_mmu_mode();
974         spin_unlock(src_ptl);
975         pte_unmap(orig_src_pte);
976         add_mm_rss_vec(dst_mm, rss);
977         pte_unmap_unlock(orig_dst_pte, dst_ptl);
978         cond_resched();
979
980         if (entry.val) {
981                 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
982                         return -ENOMEM;
983                 progress = 0;
984         }
985         if (addr != end)
986                 goto again;
987         return 0;
988 }
989
990 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
991                 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
992                 unsigned long addr, unsigned long end)
993 {
994         pmd_t *src_pmd, *dst_pmd;
995         unsigned long next;
996
997         dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
998         if (!dst_pmd)
999                 return -ENOMEM;
1000         src_pmd = pmd_offset(src_pud, addr);
1001         do {
1002                 next = pmd_addr_end(addr, end);
1003                 if (pmd_trans_huge(*src_pmd)) {
1004                         int err;
1005                         VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
1006                         err = copy_huge_pmd(dst_mm, src_mm,
1007                                             dst_pmd, src_pmd, addr, vma);
1008                         if (err == -ENOMEM)
1009                                 return -ENOMEM;
1010                         if (!err)
1011                                 continue;
1012                         /* fall through */
1013                 }
1014                 if (pmd_none_or_clear_bad(src_pmd))
1015                         continue;
1016                 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1017                                                 vma, addr, next))
1018                         return -ENOMEM;
1019         } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1020         return 0;
1021 }
1022
1023 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1024                 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1025                 unsigned long addr, unsigned long end)
1026 {
1027         pud_t *src_pud, *dst_pud;
1028         unsigned long next;
1029
1030         dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
1031         if (!dst_pud)
1032                 return -ENOMEM;
1033         src_pud = pud_offset(src_pgd, addr);
1034         do {
1035                 next = pud_addr_end(addr, end);
1036                 if (pud_none_or_clear_bad(src_pud))
1037                         continue;
1038                 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1039                                                 vma, addr, next))
1040                         return -ENOMEM;
1041         } while (dst_pud++, src_pud++, addr = next, addr != end);
1042         return 0;
1043 }
1044
1045 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1046                 struct vm_area_struct *vma)
1047 {
1048         pgd_t *src_pgd, *dst_pgd;
1049         unsigned long next;
1050         unsigned long addr = vma->vm_start;
1051         unsigned long end = vma->vm_end;
1052         int ret;
1053
1054         /*
1055          * Don't copy ptes where a page fault will fill them correctly.
1056          * Fork becomes much lighter when there are big shared or private
1057          * readonly mappings. The tradeoff is that copy_page_range is more
1058          * efficient than faulting.
1059          */
1060         if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
1061                 if (!vma->anon_vma)
1062                         return 0;
1063         }
1064
1065         if (is_vm_hugetlb_page(vma))
1066                 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1067
1068         if (unlikely(is_pfn_mapping(vma))) {
1069                 /*
1070                  * We do not free on error cases below as remove_vma
1071                  * gets called on error from higher level routine
1072                  */
1073                 ret = track_pfn_vma_copy(vma);
1074                 if (ret)
1075                         return ret;
1076         }
1077
1078         /*
1079          * We need to invalidate the secondary MMU mappings only when
1080          * there could be a permission downgrade on the ptes of the
1081          * parent mm. And a permission downgrade will only happen if
1082          * is_cow_mapping() returns true.
1083          */
1084         if (is_cow_mapping(vma->vm_flags))
1085                 mmu_notifier_invalidate_range_start(src_mm, addr, end);
1086
1087         ret = 0;
1088         dst_pgd = pgd_offset(dst_mm, addr);
1089         src_pgd = pgd_offset(src_mm, addr);
1090         do {
1091                 next = pgd_addr_end(addr, end);
1092                 if (pgd_none_or_clear_bad(src_pgd))
1093                         continue;
1094                 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
1095                                             vma, addr, next))) {
1096                         ret = -ENOMEM;
1097                         break;
1098                 }
1099         } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1100
1101         if (is_cow_mapping(vma->vm_flags))
1102                 mmu_notifier_invalidate_range_end(src_mm,
1103                                                   vma->vm_start, end);
1104         return ret;
1105 }
1106
1107 static unsigned long zap_pte_range(struct mmu_gather *tlb,
1108                                 struct vm_area_struct *vma, pmd_t *pmd,
1109                                 unsigned long addr, unsigned long end,
1110                                 struct zap_details *details)
1111 {
1112         struct mm_struct *mm = tlb->mm;
1113         int force_flush = 0;
1114         int rss[NR_MM_COUNTERS];
1115         spinlock_t *ptl;
1116         pte_t *start_pte;
1117         pte_t *pte;
1118
1119 again:
1120         init_rss_vec(rss);
1121         start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1122         pte = start_pte;
1123         arch_enter_lazy_mmu_mode();
1124         do {
1125                 pte_t ptent = *pte;
1126                 if (pte_none(ptent)) {
1127                         continue;
1128                 }
1129
1130                 if (pte_present(ptent)) {
1131                         struct page *page;
1132
1133                         page = vm_normal_page(vma, addr, ptent);
1134                         if (unlikely(details) && page) {
1135                                 /*
1136                                  * unmap_shared_mapping_pages() wants to
1137                                  * invalidate cache without truncating:
1138                                  * unmap shared but keep private pages.
1139                                  */
1140                                 if (details->check_mapping &&
1141                                     details->check_mapping != page->mapping)
1142                                         continue;
1143                                 /*
1144                                  * Each page->index must be checked when
1145                                  * invalidating or truncating nonlinear.
1146                                  */
1147                                 if (details->nonlinear_vma &&
1148                                     (page->index < details->first_index ||
1149                                      page->index > details->last_index))
1150                                         continue;
1151                         }
1152                         ptent = ptep_get_and_clear_full(mm, addr, pte,
1153                                                         tlb->fullmm);
1154                         tlb_remove_tlb_entry(tlb, pte, addr);
1155                         if (unlikely(!page))
1156                                 continue;
1157                         if (unlikely(details) && details->nonlinear_vma
1158                             && linear_page_index(details->nonlinear_vma,
1159                                                 addr) != page->index)
1160                                 set_pte_at(mm, addr, pte,
1161                                            pgoff_to_pte(page->index));
1162                         if (PageAnon(page))
1163                                 rss[MM_ANONPAGES]--;
1164                         else {
1165                                 if (pte_dirty(ptent))
1166                                         set_page_dirty(page);
1167                                 if (pte_young(ptent) &&
1168                                     likely(!VM_SequentialReadHint(vma)))
1169                                         mark_page_accessed(page);
1170                                 rss[MM_FILEPAGES]--;
1171                         }
1172                         page_remove_rmap(page);
1173                         if (unlikely(page_mapcount(page) < 0))
1174                                 print_bad_pte(vma, addr, ptent, page);
1175                         force_flush = !__tlb_remove_page(tlb, page);
1176                         if (force_flush)
1177                                 break;
1178                         continue;
1179                 }
1180                 /*
1181                  * If details->check_mapping, we leave swap entries;
1182                  * if details->nonlinear_vma, we leave file entries.
1183                  */
1184                 if (unlikely(details))
1185                         continue;
1186                 if (pte_file(ptent)) {
1187                         if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
1188                                 print_bad_pte(vma, addr, ptent, NULL);
1189                 } else {
1190                         swp_entry_t entry = pte_to_swp_entry(ptent);
1191
1192                         if (!non_swap_entry(entry))
1193                                 rss[MM_SWAPENTS]--;
1194                         if (unlikely(!free_swap_and_cache(entry)))
1195                                 print_bad_pte(vma, addr, ptent, NULL);
1196                 }
1197                 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1198         } while (pte++, addr += PAGE_SIZE, addr != end);
1199
1200         add_mm_rss_vec(mm, rss);
1201         arch_leave_lazy_mmu_mode();
1202         pte_unmap_unlock(start_pte, ptl);
1203
1204         /*
1205          * mmu_gather ran out of room to batch pages, we break out of
1206          * the PTE lock to avoid doing the potential expensive TLB invalidate
1207          * and page-free while holding it.
1208          */
1209         if (force_flush) {
1210                 force_flush = 0;
1211                 tlb_flush_mmu(tlb);
1212                 if (addr != end)
1213                         goto again;
1214         }
1215
1216         return addr;
1217 }
1218
1219 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1220                                 struct vm_area_struct *vma, pud_t *pud,
1221                                 unsigned long addr, unsigned long end,
1222                                 struct zap_details *details)
1223 {
1224         pmd_t *pmd;
1225         unsigned long next;
1226
1227         pmd = pmd_offset(pud, addr);
1228         do {
1229                 next = pmd_addr_end(addr, end);
1230                 if (pmd_trans_huge(*pmd)) {
1231                         if (next-addr != HPAGE_PMD_SIZE) {
1232                                 VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem));
1233                                 split_huge_page_pmd(vma->vm_mm, pmd);
1234                         } else if (zap_huge_pmd(tlb, vma, pmd))
1235                                 continue;
1236                         /* fall through */
1237                 }
1238                 if (pmd_none_or_clear_bad(pmd))
1239                         continue;
1240                 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1241                 cond_resched();
1242         } while (pmd++, addr = next, addr != end);
1243
1244         return addr;
1245 }
1246
1247 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1248                                 struct vm_area_struct *vma, pgd_t *pgd,
1249                                 unsigned long addr, unsigned long end,
1250                                 struct zap_details *details)
1251 {
1252         pud_t *pud;
1253         unsigned long next;
1254
1255         pud = pud_offset(pgd, addr);
1256         do {
1257                 next = pud_addr_end(addr, end);
1258                 if (pud_none_or_clear_bad(pud))
1259                         continue;
1260                 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1261         } while (pud++, addr = next, addr != end);
1262
1263         return addr;
1264 }
1265
1266 static unsigned long unmap_page_range(struct mmu_gather *tlb,
1267                                 struct vm_area_struct *vma,
1268                                 unsigned long addr, unsigned long end,
1269                                 struct zap_details *details)
1270 {
1271         pgd_t *pgd;
1272         unsigned long next;
1273
1274         if (details && !details->check_mapping && !details->nonlinear_vma)
1275                 details = NULL;
1276
1277         BUG_ON(addr >= end);
1278         mem_cgroup_uncharge_start();
1279         tlb_start_vma(tlb, vma);
1280         pgd = pgd_offset(vma->vm_mm, addr);
1281         do {
1282                 next = pgd_addr_end(addr, end);
1283                 if (pgd_none_or_clear_bad(pgd))
1284                         continue;
1285                 next = zap_pud_range(tlb, vma, pgd, addr, next, details);
1286         } while (pgd++, addr = next, addr != end);
1287         tlb_end_vma(tlb, vma);
1288         mem_cgroup_uncharge_end();
1289
1290         return addr;
1291 }
1292
1293 /**
1294  * unmap_vmas - unmap a range of memory covered by a list of vma's
1295  * @tlb: address of the caller's struct mmu_gather
1296  * @vma: the starting vma
1297  * @start_addr: virtual address at which to start unmapping
1298  * @end_addr: virtual address at which to end unmapping
1299  * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
1300  * @details: details of nonlinear truncation or shared cache invalidation
1301  *
1302  * Returns the end address of the unmapping (restart addr if interrupted).
1303  *
1304  * Unmap all pages in the vma list.
1305  *
1306  * Only addresses between `start' and `end' will be unmapped.
1307  *
1308  * The VMA list must be sorted in ascending virtual address order.
1309  *
1310  * unmap_vmas() assumes that the caller will flush the whole unmapped address
1311  * range after unmap_vmas() returns.  So the only responsibility here is to
1312  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1313  * drops the lock and schedules.
1314  */
1315 unsigned long unmap_vmas(struct mmu_gather *tlb,
1316                 struct vm_area_struct *vma, unsigned long start_addr,
1317                 unsigned long end_addr, unsigned long *nr_accounted,
1318                 struct zap_details *details)
1319 {
1320         unsigned long start = start_addr;
1321         struct mm_struct *mm = vma->vm_mm;
1322
1323         mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1324         for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
1325                 unsigned long end;
1326
1327                 start = max(vma->vm_start, start_addr);
1328                 if (start >= vma->vm_end)
1329                         continue;
1330                 end = min(vma->vm_end, end_addr);
1331                 if (end <= vma->vm_start)
1332                         continue;
1333
1334                 if (vma->vm_flags & VM_ACCOUNT)
1335                         *nr_accounted += (end - start) >> PAGE_SHIFT;
1336
1337                 if (unlikely(is_pfn_mapping(vma)))
1338                         untrack_pfn_vma(vma, 0, 0);
1339
1340                 while (start != end) {
1341                         if (unlikely(is_vm_hugetlb_page(vma))) {
1342                                 /*
1343                                  * It is undesirable to test vma->vm_file as it
1344                                  * should be non-null for valid hugetlb area.
1345                                  * However, vm_file will be NULL in the error
1346                                  * cleanup path of do_mmap_pgoff. When
1347                                  * hugetlbfs ->mmap method fails,
1348                                  * do_mmap_pgoff() nullifies vma->vm_file
1349                                  * before calling this function to clean up.
1350                                  * Since no pte has actually been setup, it is
1351                                  * safe to do nothing in this case.
1352                                  */
1353                                 if (vma->vm_file)
1354                                         unmap_hugepage_range(vma, start, end, NULL);
1355
1356                                 start = end;
1357                         } else
1358                                 start = unmap_page_range(tlb, vma, start, end, details);
1359                 }
1360         }
1361
1362         mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1363         return start;   /* which is now the end (or restart) address */
1364 }
1365
1366 /**
1367  * zap_page_range - remove user pages in a given range
1368  * @vma: vm_area_struct holding the applicable pages
1369  * @address: starting address of pages to zap
1370  * @size: number of bytes to zap
1371  * @details: details of nonlinear truncation or shared cache invalidation
1372  */
1373 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
1374                 unsigned long size, struct zap_details *details)
1375 {
1376         struct mm_struct *mm = vma->vm_mm;
1377         struct mmu_gather tlb;
1378         unsigned long end = address + size;
1379         unsigned long nr_accounted = 0;
1380
1381         lru_add_drain();
1382         tlb_gather_mmu(&tlb, mm, 0);
1383         update_hiwater_rss(mm);
1384         end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
1385         tlb_finish_mmu(&tlb, address, end);
1386         return end;
1387 }
1388
1389 /**
1390  * zap_vma_ptes - remove ptes mapping the vma
1391  * @vma: vm_area_struct holding ptes to be zapped
1392  * @address: starting address of pages to zap
1393  * @size: number of bytes to zap
1394  *
1395  * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1396  *
1397  * The entire address range must be fully contained within the vma.
1398  *
1399  * Returns 0 if successful.
1400  */
1401 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1402                 unsigned long size)
1403 {
1404         if (address < vma->vm_start || address + size > vma->vm_end ||
1405                         !(vma->vm_flags & VM_PFNMAP))
1406                 return -1;
1407         zap_page_range(vma, address, size, NULL);
1408         return 0;
1409 }
1410 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1411
1412 /**
1413  * follow_page - look up a page descriptor from a user-virtual address
1414  * @vma: vm_area_struct mapping @address
1415  * @address: virtual address to look up
1416  * @flags: flags modifying lookup behaviour
1417  *
1418  * @flags can have FOLL_ flags set, defined in <linux/mm.h>
1419  *
1420  * Returns the mapped (struct page *), %NULL if no mapping exists, or
1421  * an error pointer if there is a mapping to something not represented
1422  * by a page descriptor (see also vm_normal_page()).
1423  */
1424 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1425                         unsigned int flags)
1426 {
1427         pgd_t *pgd;
1428         pud_t *pud;
1429         pmd_t *pmd;
1430         pte_t *ptep, pte;
1431         spinlock_t *ptl;
1432         struct page *page;
1433         struct mm_struct *mm = vma->vm_mm;
1434
1435         page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1436         if (!IS_ERR(page)) {
1437                 BUG_ON(flags & FOLL_GET);
1438                 goto out;
1439         }
1440
1441         page = NULL;
1442         pgd = pgd_offset(mm, address);
1443         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1444                 goto no_page_table;
1445
1446         pud = pud_offset(pgd, address);
1447         if (pud_none(*pud))
1448                 goto no_page_table;
1449         if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
1450                 BUG_ON(flags & FOLL_GET);
1451                 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1452                 goto out;
1453         }
1454         if (unlikely(pud_bad(*pud)))
1455                 goto no_page_table;
1456
1457         pmd = pmd_offset(pud, address);
1458         if (pmd_none(*pmd))
1459                 goto no_page_table;
1460         if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
1461                 BUG_ON(flags & FOLL_GET);
1462                 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1463                 goto out;
1464         }
1465         if (pmd_trans_huge(*pmd)) {
1466                 if (flags & FOLL_SPLIT) {
1467                         split_huge_page_pmd(mm, pmd);
1468                         goto split_fallthrough;
1469                 }
1470                 spin_lock(&mm->page_table_lock);
1471                 if (likely(pmd_trans_huge(*pmd))) {
1472                         if (unlikely(pmd_trans_splitting(*pmd))) {
1473                                 spin_unlock(&mm->page_table_lock);
1474                                 wait_split_huge_page(vma->anon_vma, pmd);
1475                         } else {
1476                                 page = follow_trans_huge_pmd(mm, address,
1477                                                              pmd, flags);
1478                                 spin_unlock(&mm->page_table_lock);
1479                                 goto out;
1480                         }
1481                 } else
1482                         spin_unlock(&mm->page_table_lock);
1483                 /* fall through */
1484         }
1485 split_fallthrough:
1486         if (unlikely(pmd_bad(*pmd)))
1487                 goto no_page_table;
1488
1489         ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1490
1491         pte = *ptep;
1492         if (!pte_present(pte))
1493                 goto no_page;
1494         if ((flags & FOLL_WRITE) && !pte_write(pte))
1495                 goto unlock;
1496
1497         page = vm_normal_page(vma, address, pte);
1498         if (unlikely(!page)) {
1499                 if ((flags & FOLL_DUMP) ||
1500                     !is_zero_pfn(pte_pfn(pte)))
1501                         goto bad_page;
1502                 page = pte_page(pte);
1503         }
1504
1505         if (flags & FOLL_GET)
1506                 get_page(page);
1507         if (flags & FOLL_TOUCH) {
1508                 if ((flags & FOLL_WRITE) &&
1509                     !pte_dirty(pte) && !PageDirty(page))
1510                         set_page_dirty(page);
1511                 /*
1512                  * pte_mkyoung() would be more correct here, but atomic care
1513                  * is needed to avoid losing the dirty bit: it is easier to use
1514                  * mark_page_accessed().
1515                  */
1516                 mark_page_accessed(page);
1517         }
1518         if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1519                 /*
1520                  * The preliminary mapping check is mainly to avoid the
1521                  * pointless overhead of lock_page on the ZERO_PAGE
1522                  * which might bounce very badly if there is contention.
1523                  *
1524                  * If the page is already locked, we don't need to
1525                  * handle it now - vmscan will handle it later if and
1526                  * when it attempts to reclaim the page.
1527                  */
1528                 if (page->mapping && trylock_page(page)) {
1529                         lru_add_drain();  /* push cached pages to LRU */
1530                         /*
1531                          * Because we lock page here and migration is
1532                          * blocked by the pte's page reference, we need
1533                          * only check for file-cache page truncation.
1534                          */
1535                         if (page->mapping)
1536                                 mlock_vma_page(page);
1537                         unlock_page(page);
1538                 }
1539         }
1540 unlock:
1541         pte_unmap_unlock(ptep, ptl);
1542 out:
1543         return page;
1544
1545 bad_page:
1546         pte_unmap_unlock(ptep, ptl);
1547         return ERR_PTR(-EFAULT);
1548
1549 no_page:
1550         pte_unmap_unlock(ptep, ptl);
1551         if (!pte_none(pte))
1552                 return page;
1553
1554 no_page_table:
1555         /*
1556          * When core dumping an enormous anonymous area that nobody
1557          * has touched so far, we don't want to allocate unnecessary pages or
1558          * page tables.  Return error instead of NULL to skip handle_mm_fault,
1559          * then get_dump_page() will return NULL to leave a hole in the dump.
1560          * But we can only make this optimization where a hole would surely
1561          * be zero-filled if handle_mm_fault() actually did handle it.
1562          */
1563         if ((flags & FOLL_DUMP) &&
1564             (!vma->vm_ops || !vma->vm_ops->fault))
1565                 return ERR_PTR(-EFAULT);
1566         return page;
1567 }
1568
1569 static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
1570 {
1571         return stack_guard_page_start(vma, addr) ||
1572                stack_guard_page_end(vma, addr+PAGE_SIZE);
1573 }
1574
1575 /**
1576  * __get_user_pages() - pin user pages in memory
1577  * @tsk:        task_struct of target task
1578  * @mm:         mm_struct of target mm
1579  * @start:      starting user address
1580  * @nr_pages:   number of pages from start to pin
1581  * @gup_flags:  flags modifying pin behaviour
1582  * @pages:      array that receives pointers to the pages pinned.
1583  *              Should be at least nr_pages long. Or NULL, if caller
1584  *              only intends to ensure the pages are faulted in.
1585  * @vmas:       array of pointers to vmas corresponding to each page.
1586  *              Or NULL if the caller does not require them.
1587  * @nonblocking: whether waiting for disk IO or mmap_sem contention
1588  *
1589  * Returns number of pages pinned. This may be fewer than the number
1590  * requested. If nr_pages is 0 or negative, returns 0. If no pages
1591  * were pinned, returns -errno. Each page returned must be released
1592  * with a put_page() call when it is finished with. vmas will only
1593  * remain valid while mmap_sem is held.
1594  *
1595  * Must be called with mmap_sem held for read or write.
1596  *
1597  * __get_user_pages walks a process's page tables and takes a reference to
1598  * each struct page that each user address corresponds to at a given
1599  * instant. That is, it takes the page that would be accessed if a user
1600  * thread accesses the given user virtual address at that instant.
1601  *
1602  * This does not guarantee that the page exists in the user mappings when
1603  * __get_user_pages returns, and there may even be a completely different
1604  * page there in some cases (eg. if mmapped pagecache has been invalidated
1605  * and subsequently re faulted). However it does guarantee that the page
1606  * won't be freed completely. And mostly callers simply care that the page
1607  * contains data that was valid *at some point in time*. Typically, an IO
1608  * or similar operation cannot guarantee anything stronger anyway because
1609  * locks can't be held over the syscall boundary.
1610  *
1611  * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
1612  * the page is written to, set_page_dirty (or set_page_dirty_lock, as
1613  * appropriate) must be called after the page is finished with, and
1614  * before put_page is called.
1615  *
1616  * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
1617  * or mmap_sem contention, and if waiting is needed to pin all pages,
1618  * *@nonblocking will be set to 0.
1619  *
1620  * In most cases, get_user_pages or get_user_pages_fast should be used
1621  * instead of __get_user_pages. __get_user_pages should be used only if
1622  * you need some special @gup_flags.
1623  */
1624 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1625                      unsigned long start, int nr_pages, unsigned int gup_flags,
1626                      struct page **pages, struct vm_area_struct **vmas,
1627                      int *nonblocking)
1628 {
1629         int i;
1630         unsigned long vm_flags;
1631
1632         if (nr_pages <= 0)
1633                 return 0;
1634
1635         VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
1636
1637         /* 
1638          * Require read or write permissions.
1639          * If FOLL_FORCE is set, we only require the "MAY" flags.
1640          */
1641         vm_flags  = (gup_flags & FOLL_WRITE) ?
1642                         (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1643         vm_flags &= (gup_flags & FOLL_FORCE) ?
1644                         (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1645         i = 0;
1646
1647         do {
1648                 struct vm_area_struct *vma;
1649
1650                 vma = find_extend_vma(mm, start);
1651                 if (!vma && in_gate_area(mm, start)) {
1652                         unsigned long pg = start & PAGE_MASK;
1653                         pgd_t *pgd;
1654                         pud_t *pud;
1655                         pmd_t *pmd;
1656                         pte_t *pte;
1657
1658                         /* user gate pages are read-only */
1659                         if (gup_flags & FOLL_WRITE)
1660                                 return i ? : -EFAULT;
1661                         if (pg > TASK_SIZE)
1662                                 pgd = pgd_offset_k(pg);
1663                         else
1664                                 pgd = pgd_offset_gate(mm, pg);
1665                         BUG_ON(pgd_none(*pgd));
1666                         pud = pud_offset(pgd, pg);
1667                         BUG_ON(pud_none(*pud));
1668                         pmd = pmd_offset(pud, pg);
1669                         if (pmd_none(*pmd))
1670                                 return i ? : -EFAULT;
1671                         VM_BUG_ON(pmd_trans_huge(*pmd));
1672                         pte = pte_offset_map(pmd, pg);
1673                         if (pte_none(*pte)) {
1674                                 pte_unmap(pte);
1675                                 return i ? : -EFAULT;
1676                         }
1677                         vma = get_gate_vma(mm);
1678                         if (pages) {
1679                                 struct page *page;
1680
1681                                 page = vm_normal_page(vma, start, *pte);
1682                                 if (!page) {
1683                                         if (!(gup_flags & FOLL_DUMP) &&
1684                                              is_zero_pfn(pte_pfn(*pte)))
1685                                                 page = pte_page(*pte);
1686                                         else {
1687                                                 pte_unmap(pte);
1688                                                 return i ? : -EFAULT;
1689                                         }
1690                                 }
1691                                 pages[i] = page;
1692                                 get_page(page);
1693                         }
1694                         pte_unmap(pte);
1695                         goto next_page;
1696                 }
1697
1698                 if (!vma ||
1699                     (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
1700                     !(vm_flags & vma->vm_flags))
1701                         return i ? : -EFAULT;
1702
1703                 if (is_vm_hugetlb_page(vma)) {
1704                         i = follow_hugetlb_page(mm, vma, pages, vmas,
1705                                         &start, &nr_pages, i, gup_flags);
1706                         continue;
1707                 }
1708
1709                 do {
1710                         struct page *page;
1711                         unsigned int foll_flags = gup_flags;
1712
1713                         /*
1714                          * If we have a pending SIGKILL, don't keep faulting
1715                          * pages and potentially allocating memory.
1716                          */
1717                         if (unlikely(fatal_signal_pending(current)))
1718                                 return i ? i : -ERESTARTSYS;
1719
1720                         cond_resched();
1721                         while (!(page = follow_page(vma, start, foll_flags))) {
1722                                 int ret;
1723                                 unsigned int fault_flags = 0;
1724
1725                                 /* For mlock, just skip the stack guard page. */
1726                                 if (foll_flags & FOLL_MLOCK) {
1727                                         if (stack_guard_page(vma, start))
1728                                                 goto next_page;
1729                                 }
1730                                 if (foll_flags & FOLL_WRITE)
1731                                         fault_flags |= FAULT_FLAG_WRITE;
1732                                 if (nonblocking)
1733                                         fault_flags |= FAULT_FLAG_ALLOW_RETRY;
1734                                 if (foll_flags & FOLL_NOWAIT)
1735                                         fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT);
1736
1737                                 ret = handle_mm_fault(mm, vma, start,
1738                                                         fault_flags);
1739
1740                                 if (ret & VM_FAULT_ERROR) {
1741                                         if (ret & VM_FAULT_OOM)
1742                                                 return i ? i : -ENOMEM;
1743                                         if (ret & (VM_FAULT_HWPOISON |
1744                                                    VM_FAULT_HWPOISON_LARGE)) {
1745                                                 if (i)
1746                                                         return i;
1747                                                 else if (gup_flags & FOLL_HWPOISON)
1748                                                         return -EHWPOISON;
1749                                                 else
1750                                                         return -EFAULT;
1751                                         }
1752                                         if (ret & VM_FAULT_SIGBUS)
1753                                                 return i ? i : -EFAULT;
1754                                         BUG();
1755                                 }
1756
1757                                 if (tsk) {
1758                                         if (ret & VM_FAULT_MAJOR)
1759                                                 tsk->maj_flt++;
1760                                         else
1761                                                 tsk->min_flt++;
1762                                 }
1763
1764                                 if (ret & VM_FAULT_RETRY) {
1765                                         if (nonblocking)
1766                                                 *nonblocking = 0;
1767                                         return i;
1768                                 }
1769
1770                                 /*
1771                                  * The VM_FAULT_WRITE bit tells us that
1772                                  * do_wp_page has broken COW when necessary,
1773                                  * even if maybe_mkwrite decided not to set
1774                                  * pte_write. We can thus safely do subsequent
1775                                  * page lookups as if they were reads. But only
1776                                  * do so when looping for pte_write is futile:
1777                                  * in some cases userspace may also be wanting
1778                                  * to write to the gotten user page, which a
1779                                  * read fault here might prevent (a readonly
1780                                  * page might get reCOWed by userspace write).
1781                                  */
1782                                 if ((ret & VM_FAULT_WRITE) &&
1783                                     !(vma->vm_flags & VM_WRITE))
1784                                         foll_flags &= ~FOLL_WRITE;
1785
1786                                 cond_resched();
1787                         }
1788                         if (IS_ERR(page))
1789                                 return i ? i : PTR_ERR(page);
1790                         if (pages) {
1791                                 pages[i] = page;
1792
1793                                 flush_anon_page(vma, page, start);
1794                                 flush_dcache_page(page);
1795                         }
1796 next_page:
1797                         if (vmas)
1798                                 vmas[i] = vma;
1799                         i++;
1800                         start += PAGE_SIZE;
1801                         nr_pages--;
1802                 } while (nr_pages && start < vma->vm_end);
1803         } while (nr_pages);
1804         return i;
1805 }
1806 EXPORT_SYMBOL(__get_user_pages);
1807
1808 /*
1809  * fixup_user_fault() - manually resolve a user page fault
1810  * @tsk:        the task_struct to use for page fault accounting, or
1811  *              NULL if faults are not to be recorded.
1812  * @mm:         mm_struct of target mm
1813  * @address:    user address
1814  * @fault_flags:flags to pass down to handle_mm_fault()
1815  *
1816  * This is meant to be called in the specific scenario where for locking reasons
1817  * we try to access user memory in atomic context (within a pagefault_disable()
1818  * section), this returns -EFAULT, and we want to resolve the user fault before
1819  * trying again.
1820  *
1821  * Typically this is meant to be used by the futex code.
1822  *
1823  * The main difference with get_user_pages() is that this function will
1824  * unconditionally call handle_mm_fault() which will in turn perform all the
1825  * necessary SW fixup of the dirty and young bits in the PTE, while
1826  * handle_mm_fault() only guarantees to update these in the struct page.
1827  *
1828  * This is important for some architectures where those bits also gate the
1829  * access permission to the page because they are maintained in software.  On
1830  * such architectures, gup() will not be enough to make a subsequent access
1831  * succeed.
1832  *
1833  * This should be called with the mm_sem held for read.
1834  */
1835 int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
1836                      unsigned long address, unsigned int fault_flags)
1837 {
1838         struct vm_area_struct *vma;
1839         int ret;
1840
1841         vma = find_extend_vma(mm, address);
1842         if (!vma || address < vma->vm_start)
1843                 return -EFAULT;
1844
1845         ret = handle_mm_fault(mm, vma, address, fault_flags);
1846         if (ret & VM_FAULT_ERROR) {
1847                 if (ret & VM_FAULT_OOM)
1848                         return -ENOMEM;
1849                 if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE))
1850                         return -EHWPOISON;
1851                 if (ret & VM_FAULT_SIGBUS)
1852                         return -EFAULT;
1853                 BUG();
1854         }
1855         if (tsk) {
1856                 if (ret & VM_FAULT_MAJOR)
1857                         tsk->maj_flt++;
1858                 else
1859                         tsk->min_flt++;
1860         }
1861         return 0;
1862 }
1863
1864 /*
1865  * get_user_pages() - pin user pages in memory
1866  * @tsk:        the task_struct to use for page fault accounting, or
1867  *              NULL if faults are not to be recorded.
1868  * @mm:         mm_struct of target mm
1869  * @start:      starting user address
1870  * @nr_pages:   number of pages from start to pin
1871  * @write:      whether pages will be written to by the caller
1872  * @force:      whether to force write access even if user mapping is
1873  *              readonly. This will result in the page being COWed even
1874  *              in MAP_SHARED mappings. You do not want this.
1875  * @pages:      array that receives pointers to the pages pinned.
1876  *              Should be at least nr_pages long. Or NULL, if caller
1877  *              only intends to ensure the pages are faulted in.
1878  * @vmas:       array of pointers to vmas corresponding to each page.
1879  *              Or NULL if the caller does not require them.
1880  *
1881  * Returns number of pages pinned. This may be fewer than the number
1882  * requested. If nr_pages is 0 or negative, returns 0. If no pages
1883  * were pinned, returns -errno. Each page returned must be released
1884  * with a put_page() call when it is finished with. vmas will only
1885  * remain valid while mmap_sem is held.
1886  *
1887  * Must be called with mmap_sem held for read or write.
1888  *
1889  * get_user_pages walks a process's page tables and takes a reference to
1890  * each struct page that each user address corresponds to at a given
1891  * instant. That is, it takes the page that would be accessed if a user
1892  * thread accesses the given user virtual address at that instant.
1893  *
1894  * This does not guarantee that the page exists in the user mappings when
1895  * get_user_pages returns, and there may even be a completely different
1896  * page there in some cases (eg. if mmapped pagecache has been invalidated
1897  * and subsequently re faulted). However it does guarantee that the page
1898  * won't be freed completely. And mostly callers simply care that the page
1899  * contains data that was valid *at some point in time*. Typically, an IO
1900  * or similar operation cannot guarantee anything stronger anyway because
1901  * locks can't be held over the syscall boundary.
1902  *
1903  * If write=0, the page must not be written to. If the page is written to,
1904  * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1905  * after the page is finished with, and before put_page is called.
1906  *
1907  * get_user_pages is typically used for fewer-copy IO operations, to get a
1908  * handle on the memory by some means other than accesses via the user virtual
1909  * addresses. The pages may be submitted for DMA to devices or accessed via
1910  * their kernel linear mapping (via the kmap APIs). Care should be taken to
1911  * use the correct cache flushing APIs.
1912  *
1913  * See also get_user_pages_fast, for performance critical applications.
1914  */
1915 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1916                 unsigned long start, int nr_pages, int write, int force,
1917                 struct page **pages, struct vm_area_struct **vmas)
1918 {
1919         int flags = FOLL_TOUCH;
1920
1921         if (pages)
1922                 flags |= FOLL_GET;
1923         if (write)
1924                 flags |= FOLL_WRITE;
1925         if (force)
1926                 flags |= FOLL_FORCE;
1927
1928         return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
1929                                 NULL);
1930 }
1931 EXPORT_SYMBOL(get_user_pages);
1932
1933 /**
1934  * get_dump_page() - pin user page in memory while writing it to core dump
1935  * @addr: user address
1936  *
1937  * Returns struct page pointer of user page pinned for dump,
1938  * to be freed afterwards by page_cache_release() or put_page().
1939  *
1940  * Returns NULL on any kind of failure - a hole must then be inserted into
1941  * the corefile, to preserve alignment with its headers; and also returns
1942  * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
1943  * allowing a hole to be left in the corefile to save diskspace.
1944  *
1945  * Called without mmap_sem, but after all other threads have been killed.
1946  */
1947 #ifdef CONFIG_ELF_CORE
1948 struct page *get_dump_page(unsigned long addr)
1949 {
1950         struct vm_area_struct *vma;
1951         struct page *page;
1952
1953         if (__get_user_pages(current, current->mm, addr, 1,
1954                              FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
1955                              NULL) < 1)
1956                 return NULL;
1957         flush_cache_page(vma, addr, page_to_pfn(page));
1958         return page;
1959 }
1960 #endif /* CONFIG_ELF_CORE */
1961
1962 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1963                         spinlock_t **ptl)
1964 {
1965         pgd_t * pgd = pgd_offset(mm, addr);
1966         pud_t * pud = pud_alloc(mm, pgd, addr);
1967         if (pud) {
1968                 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1969                 if (pmd) {
1970                         VM_BUG_ON(pmd_trans_huge(*pmd));
1971                         return pte_alloc_map_lock(mm, pmd, addr, ptl);
1972                 }
1973         }
1974         return NULL;
1975 }
1976
1977 /*
1978  * This is the old fallback for page remapping.
1979  *
1980  * For historical reasons, it only allows reserved pages. Only
1981  * old drivers should use this, and they needed to mark their
1982  * pages reserved for the old functions anyway.
1983  */
1984 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1985                         struct page *page, pgprot_t prot)
1986 {
1987         struct mm_struct *mm = vma->vm_mm;
1988         int retval;
1989         pte_t *pte;
1990         spinlock_t *ptl;
1991
1992         retval = -EINVAL;
1993         if (PageAnon(page))
1994                 goto out;
1995         retval = -ENOMEM;
1996         flush_dcache_page(page);
1997         pte = get_locked_pte(mm, addr, &ptl);
1998         if (!pte)
1999                 goto out;
2000         retval = -EBUSY;
2001         if (!pte_none(*pte))
2002                 goto out_unlock;
2003
2004         /* Ok, finally just insert the thing.. */
2005         get_page(page);
2006         inc_mm_counter_fast(mm, MM_FILEPAGES);
2007         page_add_file_rmap(page);
2008         set_pte_at(mm, addr, pte, mk_pte(page, prot));
2009
2010         retval = 0;
2011         pte_unmap_unlock(pte, ptl);
2012         return retval;
2013 out_unlock:
2014         pte_unmap_unlock(pte, ptl);
2015 out:
2016         return retval;
2017 }
2018
2019 /**
2020  * vm_insert_page - insert single page into user vma
2021  * @vma: user vma to map to
2022  * @addr: target user address of this page
2023  * @page: source kernel page
2024  *
2025  * This allows drivers to insert individual pages they've allocated
2026  * into a user vma.
2027  *
2028  * The page has to be a nice clean _individual_ kernel allocation.
2029  * If you allocate a compound page, you need to have marked it as
2030  * such (__GFP_COMP), or manually just split the page up yourself
2031  * (see split_page()).
2032  *
2033  * NOTE! Traditionally this was done with "remap_pfn_range()" which
2034  * took an arbitrary page protection parameter. This doesn't allow
2035  * that. Your vma protection will have to be set up correctly, which
2036  * means that if you want a shared writable mapping, you'd better
2037  * ask for a shared writable mapping!
2038  *
2039  * The page does not need to be reserved.
2040  */
2041 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
2042                         struct page *page)
2043 {
2044         if (addr < vma->vm_start || addr >= vma->vm_end)
2045                 return -EFAULT;
2046         if (!page_count(page))
2047                 return -EINVAL;
2048         vma->vm_flags |= VM_INSERTPAGE;
2049         return insert_page(vma, addr, page, vma->vm_page_prot);
2050 }
2051 EXPORT_SYMBOL(vm_insert_page);
2052
2053 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2054                         unsigned long pfn, pgprot_t prot)
2055 {
2056         struct mm_struct *mm = vma->vm_mm;
2057         int retval;
2058         pte_t *pte, entry;
2059         spinlock_t *ptl;
2060
2061         retval = -ENOMEM;
2062         pte = get_locked_pte(mm, addr, &ptl);
2063         if (!pte)
2064                 goto out;
2065         retval = -EBUSY;
2066         if (!pte_none(*pte))
2067                 goto out_unlock;
2068
2069         /* Ok, finally just insert the thing.. */
2070         entry = pte_mkspecial(pfn_pte(pfn, prot));
2071         set_pte_at(mm, addr, pte, entry);
2072         update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2073
2074         retval = 0;
2075 out_unlock:
2076         pte_unmap_unlock(pte, ptl);
2077 out:
2078         return retval;
2079 }
2080
2081 /**
2082  * vm_insert_pfn - insert single pfn into user vma
2083  * @vma: user vma to map to
2084  * @addr: target user address of this page
2085  * @pfn: source kernel pfn
2086  *
2087  * Similar to vm_inert_page, this allows drivers to insert individual pages
2088  * they've allocated into a user vma. Same comments apply.
2089  *
2090  * This function should only be called from a vm_ops->fault handler, and
2091  * in that case the handler should return NULL.
2092  *
2093  * vma cannot be a COW mapping.
2094  *
2095  * As this is called only for pages that do not currently exist, we
2096  * do not need to flush old virtual caches or the TLB.
2097  */
2098 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2099                         unsigned long pfn)
2100 {
2101         int ret;
2102         pgprot_t pgprot = vma->vm_page_prot;
2103         /*
2104          * Technically, architectures with pte_special can avoid all these
2105          * restrictions (same for remap_pfn_range).  However we would like
2106          * consistency in testing and feature parity among all, so we should
2107          * try to keep these invariants in place for everybody.
2108          */
2109         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
2110         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
2111                                                 (VM_PFNMAP|VM_MIXEDMAP));
2112         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2113         BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2114
2115         if (addr < vma->vm_start || addr >= vma->vm_end)
2116                 return -EFAULT;
2117         if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
2118                 return -EINVAL;
2119
2120         ret = insert_pfn(vma, addr, pfn, pgprot);
2121
2122         if (ret)
2123                 untrack_pfn_vma(vma, pfn, PAGE_SIZE);
2124
2125         return ret;
2126 }
2127 EXPORT_SYMBOL(vm_insert_pfn);
2128
2129 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2130                         unsigned long pfn)
2131 {
2132         BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
2133
2134         if (addr < vma->vm_start || addr >= vma->vm_end)
2135                 return -EFAULT;
2136
2137         /*
2138          * If we don't have pte special, then we have to use the pfn_valid()
2139          * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2140          * refcount the page if pfn_valid is true (hence insert_page rather
2141          * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
2142          * without pte special, it would there be refcounted as a normal page.
2143          */
2144         if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
2145                 struct page *page;
2146
2147                 page = pfn_to_page(pfn);
2148                 return insert_page(vma, addr, page, vma->vm_page_prot);
2149         }
2150         return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
2151 }
2152 EXPORT_SYMBOL(vm_insert_mixed);
2153
2154 /*
2155  * maps a range of physical memory into the requested pages. the old
2156  * mappings are removed. any references to nonexistent pages results
2157  * in null mappings (currently treated as "copy-on-access")
2158  */
2159 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2160                         unsigned long addr, unsigned long end,
2161                         unsigned long pfn, pgprot_t prot)
2162 {
2163         pte_t *pte;
2164         spinlock_t *ptl;
2165
2166         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2167         if (!pte)
2168                 return -ENOMEM;
2169         arch_enter_lazy_mmu_mode();
2170         do {
2171                 BUG_ON(!pte_none(*pte));
2172                 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2173                 pfn++;
2174         } while (pte++, addr += PAGE_SIZE, addr != end);
2175         arch_leave_lazy_mmu_mode();
2176         pte_unmap_unlock(pte - 1, ptl);
2177         return 0;
2178 }
2179
2180 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2181                         unsigned long addr, unsigned long end,
2182                         unsigned long pfn, pgprot_t prot)
2183 {
2184         pmd_t *pmd;
2185         unsigned long next;
2186
2187         pfn -= addr >> PAGE_SHIFT;
2188         pmd = pmd_alloc(mm, pud, addr);
2189         if (!pmd)
2190                 return -ENOMEM;
2191         VM_BUG_ON(pmd_trans_huge(*pmd));
2192         do {
2193                 next = pmd_addr_end(addr, end);
2194                 if (remap_pte_range(mm, pmd, addr, next,
2195                                 pfn + (addr >> PAGE_SHIFT), prot))
2196                         return -ENOMEM;
2197         } while (pmd++, addr = next, addr != end);
2198         return 0;
2199 }
2200
2201 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
2202                         unsigned long addr, unsigned long end,
2203                         unsigned long pfn, pgprot_t prot)
2204 {
2205         pud_t *pud;
2206         unsigned long next;
2207
2208         pfn -= addr >> PAGE_SHIFT;
2209         pud = pud_alloc(mm, pgd, addr);
2210         if (!pud)
2211                 return -ENOMEM;
2212         do {
2213                 next = pud_addr_end(addr, end);
2214                 if (remap_pmd_range(mm, pud, addr, next,
2215                                 pfn + (addr >> PAGE_SHIFT), prot))
2216                         return -ENOMEM;
2217         } while (pud++, addr = next, addr != end);
2218         return 0;
2219 }
2220
2221 /**
2222  * remap_pfn_range - remap kernel memory to userspace
2223  * @vma: user vma to map to
2224  * @addr: target user address to start at
2225  * @pfn: physical address of kernel memory
2226  * @size: size of map area
2227  * @prot: page protection flags for this mapping
2228  *
2229  *  Note: this is only safe if the mm semaphore is held when called.
2230  */
2231 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2232                     unsigned long pfn, unsigned long size, pgprot_t prot)
2233 {
2234         pgd_t *pgd;
2235         unsigned long next;
2236         unsigned long end = addr + PAGE_ALIGN(size);
2237         struct mm_struct *mm = vma->vm_mm;
2238         int err;
2239
2240         /*
2241          * Physically remapped pages are special. Tell the
2242          * rest of the world about it:
2243          *   VM_IO tells people not to look at these pages
2244          *      (accesses can have side effects).
2245          *   VM_RESERVED is specified all over the place, because
2246          *      in 2.4 it kept swapout's vma scan off this vma; but
2247          *      in 2.6 the LRU scan won't even find its pages, so this
2248          *      flag means no more than count its pages in reserved_vm,
2249          *      and omit it from core dump, even when VM_IO turned off.
2250          *   VM_PFNMAP tells the core MM that the base pages are just
2251          *      raw PFN mappings, and do not have a "struct page" associated
2252          *      with them.
2253          *
2254          * There's a horrible special case to handle copy-on-write
2255          * behaviour that some programs depend on. We mark the "original"
2256          * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2257          */
2258         if (addr == vma->vm_start && end == vma->vm_end) {
2259                 vma->vm_pgoff = pfn;
2260                 vma->vm_flags |= VM_PFN_AT_MMAP;
2261         } else if (is_cow_mapping(vma->vm_flags))
2262                 return -EINVAL;
2263
2264         vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
2265
2266         err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
2267         if (err) {
2268                 /*
2269                  * To indicate that track_pfn related cleanup is not
2270                  * needed from higher level routine calling unmap_vmas
2271                  */
2272                 vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
2273                 vma->vm_flags &= ~VM_PFN_AT_MMAP;
2274                 return -EINVAL;
2275         }
2276
2277         BUG_ON(addr >= end);
2278         pfn -= addr >> PAGE_SHIFT;
2279         pgd = pgd_offset(mm, addr);
2280         flush_cache_range(vma, addr, end);
2281         do {
2282                 next = pgd_addr_end(addr, end);
2283                 err = remap_pud_range(mm, pgd, addr, next,
2284                                 pfn + (addr >> PAGE_SHIFT), prot);
2285                 if (err)
2286                         break;
2287         } while (pgd++, addr = next, addr != end);
2288
2289         if (err)
2290                 untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
2291
2292         return err;
2293 }
2294 EXPORT_SYMBOL(remap_pfn_range);
2295
2296 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2297                                      unsigned long addr, unsigned long end,
2298                                      pte_fn_t fn, void *data)
2299 {
2300         pte_t *pte;
2301         int err;
2302         pgtable_t token;
2303         spinlock_t *uninitialized_var(ptl);
2304
2305         pte = (mm == &init_mm) ?
2306                 pte_alloc_kernel(pmd, addr) :
2307                 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2308         if (!pte)
2309                 return -ENOMEM;
2310
2311         BUG_ON(pmd_huge(*pmd));
2312
2313         arch_enter_lazy_mmu_mode();
2314
2315         token = pmd_pgtable(*pmd);
2316
2317         do {
2318                 err = fn(pte++, token, addr, data);
2319                 if (err)
2320                         break;
2321         } while (addr += PAGE_SIZE, addr != end);
2322
2323         arch_leave_lazy_mmu_mode();
2324
2325         if (mm != &init_mm)
2326                 pte_unmap_unlock(pte-1, ptl);
2327         return err;
2328 }
2329
2330 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2331                                      unsigned long addr, unsigned long end,
2332                                      pte_fn_t fn, void *data)
2333 {
2334         pmd_t *pmd;
2335         unsigned long next;
2336         int err;
2337
2338         BUG_ON(pud_huge(*pud));
2339
2340         pmd = pmd_alloc(mm, pud, addr);
2341         if (!pmd)
2342                 return -ENOMEM;
2343         do {
2344                 next = pmd_addr_end(addr, end);
2345                 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2346                 if (err)
2347                         break;
2348         } while (pmd++, addr = next, addr != end);
2349         return err;
2350 }
2351
2352 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
2353                                      unsigned long addr, unsigned long end,
2354                                      pte_fn_t fn, void *data)
2355 {
2356         pud_t *pud;
2357         unsigned long next;
2358         int err;
2359
2360         pud = pud_alloc(mm, pgd, addr);
2361         if (!pud)
2362                 return -ENOMEM;
2363         do {
2364                 next = pud_addr_end(addr, end);
2365                 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2366                 if (err)
2367                         break;
2368         } while (pud++, addr = next, addr != end);
2369         return err;
2370 }
2371
2372 /*
2373  * Scan a region of virtual memory, filling in page tables as necessary
2374  * and calling a provided function on each leaf page table.
2375  */
2376 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2377                         unsigned long size, pte_fn_t fn, void *data)
2378 {
2379         pgd_t *pgd;
2380         unsigned long next;
2381         unsigned long end = addr + size;
2382         int err;
2383
2384         BUG_ON(addr >= end);
2385         pgd = pgd_offset(mm, addr);
2386         do {
2387                 next = pgd_addr_end(addr, end);
2388                 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
2389                 if (err)
2390                         break;
2391         } while (pgd++, addr = next, addr != end);
2392
2393         return err;
2394 }
2395 EXPORT_SYMBOL_GPL(apply_to_page_range);
2396
2397 /*
2398  * handle_pte_fault chooses page fault handler according to an entry
2399  * which was read non-atomically.  Before making any commitment, on
2400  * those architectures or configurations (e.g. i386 with PAE) which
2401  * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
2402  * must check under lock before unmapping the pte and proceeding
2403  * (but do_wp_page is only called after already making such a check;
2404  * and do_anonymous_page can safely check later on).
2405  */
2406 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2407                                 pte_t *page_table, pte_t orig_pte)
2408 {
2409         int same = 1;
2410 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2411         if (sizeof(pte_t) > sizeof(unsigned long)) {
2412                 spinlock_t *ptl = pte_lockptr(mm, pmd);
2413                 spin_lock(ptl);
2414                 same = pte_same(*page_table, orig_pte);
2415                 spin_unlock(ptl);
2416         }
2417 #endif
2418         pte_unmap(page_table);
2419         return same;
2420 }
2421
2422 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2423 {
2424         /*
2425          * If the source page was a PFN mapping, we don't have
2426          * a "struct page" for it. We do a best-effort copy by
2427          * just copying from the original user address. If that
2428          * fails, we just zero-fill it. Live with it.
2429          */
2430         if (unlikely(!src)) {
2431                 void *kaddr = kmap_atomic(dst, KM_USER0);
2432                 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2433
2434                 /*
2435                  * This really shouldn't fail, because the page is there
2436                  * in the page tables. But it might just be unreadable,
2437                  * in which case we just give up and fill the result with
2438                  * zeroes.
2439                  */
2440                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2441                         clear_page(kaddr);
2442                 kunmap_atomic(kaddr, KM_USER0);
2443                 flush_dcache_page(dst);
2444         } else
2445                 copy_user_highpage(dst, src, va, vma);
2446 }
2447
2448 /*
2449  * This routine handles present pages, when users try to write
2450  * to a shared page. It is done by copying the page to a new address
2451  * and decrementing the shared-page counter for the old page.
2452  *
2453  * Note that this routine assumes that the protection checks have been
2454  * done by the caller (the low-level page fault routine in most cases).
2455  * Thus we can safely just mark it writable once we've done any necessary
2456  * COW.
2457  *
2458  * We also mark the page dirty at this point even though the page will
2459  * change only once the write actually happens. This avoids a few races,
2460  * and potentially makes it more efficient.
2461  *
2462  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2463  * but allow concurrent faults), with pte both mapped and locked.
2464  * We return with mmap_sem still held, but pte unmapped and unlocked.
2465  */
2466 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
2467                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2468                 spinlock_t *ptl, pte_t orig_pte)
2469         __releases(ptl)
2470 {
2471         struct page *old_page, *new_page;
2472         pte_t entry;
2473         int ret = 0;
2474         int page_mkwrite = 0;
2475         struct page *dirty_page = NULL;
2476
2477         old_page = vm_normal_page(vma, address, orig_pte);
2478         if (!old_page) {
2479                 /*
2480                  * VM_MIXEDMAP !pfn_valid() case
2481                  *
2482                  * We should not cow pages in a shared writeable mapping.
2483                  * Just mark the pages writable as we can't do any dirty
2484                  * accounting on raw pfn maps.
2485                  */
2486                 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2487                                      (VM_WRITE|VM_SHARED))
2488                         goto reuse;
2489                 goto gotten;
2490         }
2491
2492         /*
2493          * Take out anonymous pages first, anonymous shared vmas are
2494          * not dirty accountable.
2495          */
2496         if (PageAnon(old_page) && !PageKsm(old_page)) {
2497                 if (!trylock_page(old_page)) {
2498                         page_cache_get(old_page);
2499                         pte_unmap_unlock(page_table, ptl);
2500                         lock_page(old_page);
2501                         page_table = pte_offset_map_lock(mm, pmd, address,
2502                                                          &ptl);
2503                         if (!pte_same(*page_table, orig_pte)) {
2504                                 unlock_page(old_page);
2505                                 goto unlock;
2506                         }
2507                         page_cache_release(old_page);
2508                 }
2509                 if (reuse_swap_page(old_page)) {
2510                         /*
2511                          * The page is all ours.  Move it to our anon_vma so
2512                          * the rmap code will not search our parent or siblings.
2513                          * Protected against the rmap code by the page lock.
2514                          */
2515                         page_move_anon_rmap(old_page, vma, address);
2516                         unlock_page(old_page);
2517                         goto reuse;
2518                 }
2519                 unlock_page(old_page);
2520         } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2521                                         (VM_WRITE|VM_SHARED))) {
2522                 /*
2523                  * Only catch write-faults on shared writable pages,
2524                  * read-only shared pages can get COWed by
2525                  * get_user_pages(.write=1, .force=1).
2526                  */
2527                 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2528                         struct vm_fault vmf;
2529                         int tmp;
2530
2531                         vmf.virtual_address = (void __user *)(address &
2532                                                                 PAGE_MASK);
2533                         vmf.pgoff = old_page->index;
2534                         vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2535                         vmf.page = old_page;
2536
2537                         /*
2538                          * Notify the address space that the page is about to
2539                          * become writable so that it can prohibit this or wait
2540                          * for the page to get into an appropriate state.
2541                          *
2542                          * We do this without the lock held, so that it can
2543                          * sleep if it needs to.
2544                          */
2545                         page_cache_get(old_page);
2546                         pte_unmap_unlock(page_table, ptl);
2547
2548                         tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2549                         if (unlikely(tmp &
2550                                         (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2551                                 ret = tmp;
2552                                 goto unwritable_page;
2553                         }
2554                         if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2555                                 lock_page(old_page);
2556                                 if (!old_page->mapping) {
2557                                         ret = 0; /* retry the fault */
2558                                         unlock_page(old_page);
2559                                         goto unwritable_page;
2560                                 }
2561                         } else
2562                                 VM_BUG_ON(!PageLocked(old_page));
2563
2564                         /*
2565                          * Since we dropped the lock we need to revalidate
2566                          * the PTE as someone else may have changed it.  If
2567                          * they did, we just return, as we can count on the
2568                          * MMU to tell us if they didn't also make it writable.
2569                          */
2570                         page_table = pte_offset_map_lock(mm, pmd, address,
2571                                                          &ptl);
2572                         if (!pte_same(*page_table, orig_pte)) {
2573                                 unlock_page(old_page);
2574                                 goto unlock;
2575                         }
2576
2577                         page_mkwrite = 1;
2578                 }
2579                 dirty_page = old_page;
2580                 get_page(dirty_page);
2581
2582 reuse:
2583                 flush_cache_page(vma, address, pte_pfn(orig_pte));
2584                 entry = pte_mkyoung(orig_pte);
2585                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2586                 if (ptep_set_access_flags(vma, address, page_table, entry,1))
2587                         update_mmu_cache(vma, address, page_table);
2588                 pte_unmap_unlock(page_table, ptl);
2589                 ret |= VM_FAULT_WRITE;
2590
2591                 if (!dirty_page)
2592                         return ret;
2593
2594                 /*
2595                  * Yes, Virginia, this is actually required to prevent a race
2596                  * with clear_page_dirty_for_io() from clearing the page dirty
2597                  * bit after it clear all dirty ptes, but before a racing
2598                  * do_wp_page installs a dirty pte.
2599                  *
2600                  * __do_fault is protected similarly.
2601                  */
2602                 if (!page_mkwrite) {
2603                         wait_on_page_locked(dirty_page);
2604                         set_page_dirty_balance(dirty_page, page_mkwrite);
2605                 }
2606                 put_page(dirty_page);
2607                 if (page_mkwrite) {
2608                         struct address_space *mapping = dirty_page->mapping;
2609
2610                         set_page_dirty(dirty_page);
2611                         unlock_page(dirty_page);
2612                         page_cache_release(dirty_page);
2613                         if (mapping)    {
2614                                 /*
2615                                  * Some device drivers do not set page.mapping
2616                                  * but still dirty their pages
2617                                  */
2618                                 balance_dirty_pages_ratelimited(mapping);
2619                         }
2620                 }
2621
2622                 /* file_update_time outside page_lock */
2623                 if (vma->vm_file)
2624                         file_update_time(vma->vm_file);
2625
2626                 return ret;
2627         }
2628
2629         /*
2630          * Ok, we need to copy. Oh, well..
2631          */
2632         page_cache_get(old_page);
2633 gotten:
2634         pte_unmap_unlock(page_table, ptl);
2635
2636         if (unlikely(anon_vma_prepare(vma)))
2637                 goto oom;
2638
2639         if (is_zero_pfn(pte_pfn(orig_pte))) {
2640                 new_page = alloc_zeroed_user_highpage_movable(vma, address);
2641                 if (!new_page)
2642                         goto oom;
2643         } else {
2644                 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2645                 if (!new_page)
2646                         goto oom;
2647                 cow_user_page(new_page, old_page, address, vma);
2648         }
2649         __SetPageUptodate(new_page);
2650
2651         if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2652                 goto oom_free_new;
2653
2654         /*
2655          * Re-check the pte - we dropped the lock
2656          */
2657         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2658         if (likely(pte_same(*page_table, orig_pte))) {
2659                 if (old_page) {
2660                         if (!PageAnon(old_page)) {
2661                                 dec_mm_counter_fast(mm, MM_FILEPAGES);
2662                                 inc_mm_counter_fast(mm, MM_ANONPAGES);
2663                         }
2664                 } else
2665                         inc_mm_counter_fast(mm, MM_ANONPAGES);
2666                 flush_cache_page(vma, address, pte_pfn(orig_pte));
2667                 entry = mk_pte(new_page, vma->vm_page_prot);
2668                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2669                 /*
2670                  * Clear the pte entry and flush it first, before updating the
2671                  * pte with the new entry. This will avoid a race condition
2672                  * seen in the presence of one thread doing SMC and another
2673                  * thread doing COW.
2674                  */
2675                 ptep_clear_flush(vma, address, page_table);
2676                 page_add_new_anon_rmap(new_page, vma, address);
2677                 /*
2678                  * We call the notify macro here because, when using secondary
2679                  * mmu page tables (such as kvm shadow page tables), we want the
2680                  * new page to be mapped directly into the secondary page table.
2681                  */
2682                 set_pte_at_notify(mm, address, page_table, entry);
2683                 update_mmu_cache(vma, address, page_table);
2684                 if (old_page) {
2685                         /*
2686                          * Only after switching the pte to the new page may
2687                          * we remove the mapcount here. Otherwise another
2688                          * process may come and find the rmap count decremented
2689                          * before the pte is switched to the new page, and
2690                          * "reuse" the old page writing into it while our pte
2691                          * here still points into it and can be read by other
2692                          * threads.
2693                          *
2694                          * The critical issue is to order this
2695                          * page_remove_rmap with the ptp_clear_flush above.
2696                          * Those stores are ordered by (if nothing else,)
2697                          * the barrier present in the atomic_add_negative
2698                          * in page_remove_rmap.
2699                          *
2700                          * Then the TLB flush in ptep_clear_flush ensures that
2701                          * no process can access the old page before the
2702                          * decremented mapcount is visible. And the old page
2703                          * cannot be reused until after the decremented
2704                          * mapcount is visible. So transitively, TLBs to
2705                          * old page will be flushed before it can be reused.
2706                          */
2707                         page_remove_rmap(old_page);
2708                 }
2709
2710                 /* Free the old page.. */
2711                 new_page = old_page;
2712                 ret |= VM_FAULT_WRITE;
2713         } else
2714                 mem_cgroup_uncharge_page(new_page);
2715
2716         if (new_page)
2717                 page_cache_release(new_page);
2718 unlock:
2719         pte_unmap_unlock(page_table, ptl);
2720         if (old_page) {
2721                 /*
2722                  * Don't let another task, with possibly unlocked vma,
2723                  * keep the mlocked page.
2724                  */
2725                 if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
2726                         lock_page(old_page);    /* LRU manipulation */
2727                         munlock_vma_page(old_page);
2728                         unlock_page(old_page);
2729                 }
2730                 page_cache_release(old_page);
2731         }
2732         return ret;
2733 oom_free_new:
2734         page_cache_release(new_page);
2735 oom:
2736         if (old_page) {
2737                 if (page_mkwrite) {
2738                         unlock_page(old_page);
2739                         page_cache_release(old_page);
2740                 }
2741                 page_cache_release(old_page);
2742         }
2743         return VM_FAULT_OOM;
2744
2745 unwritable_page:
2746         page_cache_release(old_page);
2747         return ret;
2748 }
2749
2750 static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2751                 unsigned long start_addr, unsigned long end_addr,
2752                 struct zap_details *details)
2753 {
2754         zap_page_range(vma, start_addr, end_addr - start_addr, details);
2755 }
2756
2757 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
2758                                             struct zap_details *details)
2759 {
2760         struct vm_area_struct *vma;
2761         struct prio_tree_iter iter;
2762         pgoff_t vba, vea, zba, zea;
2763
2764         vma_prio_tree_foreach(vma, &iter, root,
2765                         details->first_index, details->last_index) {
2766
2767                 vba = vma->vm_pgoff;
2768                 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
2769                 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2770                 zba = details->first_index;
2771                 if (zba < vba)
2772                         zba = vba;
2773                 zea = details->last_index;
2774                 if (zea > vea)
2775                         zea = vea;
2776
2777                 unmap_mapping_range_vma(vma,
2778                         ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2779                         ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2780                                 details);
2781         }
2782 }
2783
2784 static inline void unmap_mapping_range_list(struct list_head *head,
2785                                             struct zap_details *details)
2786 {
2787         struct vm_area_struct *vma;
2788
2789         /*
2790          * In nonlinear VMAs there is no correspondence between virtual address
2791          * offset and file offset.  So we must perform an exhaustive search
2792          * across *all* the pages in each nonlinear VMA, not just the pages
2793          * whose virtual address lies outside the file truncation point.
2794          */
2795         list_for_each_entry(vma, head, shared.vm_set.list) {
2796                 details->nonlinear_vma = vma;
2797                 unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
2798         }
2799 }
2800
2801 /**
2802  * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2803  * @mapping: the address space containing mmaps to be unmapped.
2804  * @holebegin: byte in first page to unmap, relative to the start of
2805  * the underlying file.  This will be rounded down to a PAGE_SIZE
2806  * boundary.  Note that this is different from truncate_pagecache(), which
2807  * must keep the partial page.  In contrast, we must get rid of
2808  * partial pages.
2809  * @holelen: size of prospective hole in bytes.  This will be rounded
2810  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
2811  * end of the file.
2812  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2813  * but 0 when invalidating pagecache, don't throw away private data.
2814  */
2815 void unmap_mapping_range(struct address_space *mapping,
2816                 loff_t const holebegin, loff_t const holelen, int even_cows)
2817 {
2818         struct zap_details details;
2819         pgoff_t hba = holebegin >> PAGE_SHIFT;
2820         pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2821
2822         /* Check for overflow. */
2823         if (sizeof(holelen) > sizeof(hlen)) {
2824                 long long holeend =
2825                         (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2826                 if (holeend & ~(long long)ULONG_MAX)
2827                         hlen = ULONG_MAX - hba + 1;
2828         }
2829
2830         details.check_mapping = even_cows? NULL: mapping;
2831         details.nonlinear_vma = NULL;
2832         details.first_index = hba;
2833         details.last_index = hba + hlen - 1;
2834         if (details.last_index < details.first_index)
2835                 details.last_index = ULONG_MAX;
2836
2837
2838         mutex_lock(&mapping->i_mmap_mutex);
2839         if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
2840                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2841         if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2842                 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2843         mutex_unlock(&mapping->i_mmap_mutex);
2844 }
2845 EXPORT_SYMBOL(unmap_mapping_range);
2846
2847 /*
2848  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2849  * but allow concurrent faults), and pte mapped but not yet locked.
2850  * We return with mmap_sem still held, but pte unmapped and unlocked.
2851  */
2852 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2853                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2854                 unsigned int flags, pte_t orig_pte)
2855 {
2856         spinlock_t *ptl;
2857         struct page *page, *swapcache = NULL;
2858         swp_entry_t entry;
2859         pte_t pte;
2860         int locked;
2861         struct mem_cgroup *ptr;
2862         int exclusive = 0;
2863         int ret = 0;
2864
2865         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2866                 goto out;
2867
2868         entry = pte_to_swp_entry(orig_pte);
2869         if (unlikely(non_swap_entry(entry))) {
2870                 if (is_migration_entry(entry)) {
2871                         migration_entry_wait(mm, pmd, address);
2872                 } else if (is_hwpoison_entry(entry)) {
2873                         ret = VM_FAULT_HWPOISON;
2874                 } else {
2875                         print_bad_pte(vma, address, orig_pte, NULL);
2876                         ret = VM_FAULT_SIGBUS;
2877                 }
2878                 goto out;
2879         }
2880         delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2881         page = lookup_swap_cache(entry);
2882         if (!page) {
2883                 grab_swap_token(mm); /* Contend for token _before_ read-in */
2884                 page = swapin_readahead(entry,
2885                                         GFP_HIGHUSER_MOVABLE, vma, address);
2886                 if (!page) {
2887                         /*
2888                          * Back out if somebody else faulted in this pte
2889                          * while we released the pte lock.
2890                          */
2891                         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2892                         if (likely(pte_same(*page_table, orig_pte)))
2893                                 ret = VM_FAULT_OOM;
2894                         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2895                         goto unlock;
2896                 }
2897
2898                 /* Had to read the page from swap area: Major fault */
2899                 ret = VM_FAULT_MAJOR;
2900                 count_vm_event(PGMAJFAULT);
2901                 mem_cgroup_count_vm_event(mm, PGMAJFAULT);
2902         } else if (PageHWPoison(page)) {
2903                 /*
2904                  * hwpoisoned dirty swapcache pages are kept for killing
2905                  * owner processes (which may be unknown at hwpoison time)
2906                  */
2907                 ret = VM_FAULT_HWPOISON;
2908                 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2909                 goto out_release;
2910         }
2911
2912         locked = lock_page_or_retry(page, mm, flags);
2913         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2914         if (!locked) {
2915                 ret |= VM_FAULT_RETRY;
2916                 goto out_release;
2917         }
2918
2919         /*
2920          * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2921          * release the swapcache from under us.  The page pin, and pte_same
2922          * test below, are not enough to exclude that.  Even if it is still
2923          * swapcache, we need to check that the page's swap has not changed.
2924          */
2925         if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
2926                 goto out_page;
2927
2928         if (ksm_might_need_to_copy(page, vma, address)) {
2929                 swapcache = page;
2930                 page = ksm_does_need_to_copy(page, vma, address);
2931
2932                 if (unlikely(!page)) {
2933                         ret = VM_FAULT_OOM;
2934                         page = swapcache;
2935                         swapcache = NULL;
2936                         goto out_page;
2937                 }
2938         }
2939
2940         if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2941                 ret = VM_FAULT_OOM;
2942                 goto out_page;
2943         }
2944
2945         /*
2946          * Back out if somebody else already faulted in this pte.
2947          */
2948         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2949         if (unlikely(!pte_same(*page_table, orig_pte)))
2950                 goto out_nomap;
2951
2952         if (unlikely(!PageUptodate(page))) {
2953                 ret = VM_FAULT_SIGBUS;
2954                 goto out_nomap;
2955         }
2956
2957         /*
2958          * The page isn't present yet, go ahead with the fault.
2959          *
2960          * Be careful about the sequence of operations here.
2961          * To get its accounting right, reuse_swap_page() must be called
2962          * while the page is counted on swap but not yet in mapcount i.e.
2963          * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2964          * must be called after the swap_free(), or it will never succeed.
2965          * Because delete_from_swap_page() may be called by reuse_swap_page(),
2966          * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
2967          * in page->private. In this case, a record in swap_cgroup  is silently
2968          * discarded at swap_free().
2969          */
2970
2971         inc_mm_counter_fast(mm, MM_ANONPAGES);
2972         dec_mm_counter_fast(mm, MM_SWAPENTS);
2973         pte = mk_pte(page, vma->vm_page_prot);
2974         if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
2975                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2976                 flags &= ~FAULT_FLAG_WRITE;
2977                 ret |= VM_FAULT_WRITE;
2978                 exclusive = 1;
2979         }
2980         flush_icache_page(vma, page);
2981         set_pte_at(mm, address, page_table, pte);
2982         do_page_add_anon_rmap(page, vma, address, exclusive);
2983         /* It's better to call commit-charge after rmap is established */
2984         mem_cgroup_commit_charge_swapin(page, ptr);
2985
2986         swap_free(entry);
2987         if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2988                 try_to_free_swap(page);
2989         unlock_page(page);
2990         if (swapcache) {
2991                 /*
2992                  * Hold the lock to avoid the swap entry to be reused
2993                  * until we take the PT lock for the pte_same() check
2994                  * (to avoid false positives from pte_same). For
2995                  * further safety release the lock after the swap_free
2996                  * so that the swap count won't change under a
2997                  * parallel locked swapcache.
2998                  */
2999                 unlock_page(swapcache);
3000                 page_cache_release(swapcache);
3001         }
3002
3003         if (flags & FAULT_FLAG_WRITE) {
3004                 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
3005                 if (ret & VM_FAULT_ERROR)
3006                         ret &= VM_FAULT_ERROR;
3007                 goto out;
3008         }
3009
3010         /* No need to invalidate - it was non-present before */
3011         update_mmu_cache(vma, address, page_table);
3012 unlock:
3013         pte_unmap_unlock(page_table, ptl);
3014 out:
3015         return ret;
3016 out_nomap:
3017         mem_cgroup_cancel_charge_swapin(ptr);
3018         pte_unmap_unlock(page_table, ptl);
3019 out_page:
3020         unlock_page(page);
3021 out_release:
3022         page_cache_release(page);
3023         if (swapcache) {
3024                 unlock_page(swapcache);
3025                 page_cache_release(swapcache);
3026         }
3027         return ret;
3028 }
3029
3030 /*
3031  * This is like a special single-page "expand_{down|up}wards()",
3032  * except we must first make sure that 'address{-|+}PAGE_SIZE'
3033  * doesn't hit another vma.
3034  */
3035 static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
3036 {
3037         address &= PAGE_MASK;
3038         if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
3039                 struct vm_area_struct *prev = vma->vm_prev;
3040
3041                 /*
3042                  * Is there a mapping abutting this one below?
3043                  *
3044                  * That's only ok if it's the same stack mapping
3045                  * that has gotten split..
3046                  */
3047                 if (prev && prev->vm_end == address)
3048                         return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
3049
3050                 expand_downwards(vma, address - PAGE_SIZE);
3051         }
3052         if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
3053                 struct vm_area_struct *next = vma->vm_next;
3054
3055                 /* As VM_GROWSDOWN but s/below/above/ */
3056                 if (next && next->vm_start == address + PAGE_SIZE)
3057                         return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
3058
3059                 expand_upwards(vma, address + PAGE_SIZE);
3060         }
3061         return 0;
3062 }
3063
3064 /*
3065  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3066  * but allow concurrent faults), and pte mapped but not yet locked.
3067  * We return with mmap_sem still held, but pte unmapped and unlocked.
3068  */
3069 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
3070                 unsigned long address, pte_t *page_table, pmd_t *pmd,
3071                 unsigned int flags)
3072 {
3073         struct page *page;
3074         spinlock_t *ptl;
3075         pte_t entry;
3076
3077         pte_unmap(page_table);
3078
3079         /* Check if we need to add a guard page to the stack */
3080         if (check_stack_guard_page(vma, address) < 0)
3081                 return VM_FAULT_SIGBUS;
3082
3083         /* Use the zero-page for reads */
3084         if (!(flags & FAULT_FLAG_WRITE)) {
3085                 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
3086                                                 vma->vm_page_prot));
3087                 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3088                 if (!pte_none(*page_table))
3089                         goto unlock;
3090                 goto setpte;
3091         }
3092
3093         /* Allocate our own private page. */
3094         if (unlikely(anon_vma_prepare(vma)))
3095                 goto oom;
3096         page = alloc_zeroed_user_highpage_movable(vma, address);
3097         if (!page)
3098                 goto oom;
3099         __SetPageUptodate(page);
3100
3101         if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
3102                 goto oom_free_page;
3103
3104         entry = mk_pte(page, vma->vm_page_prot);
3105         if (vma->vm_flags & VM_WRITE)
3106                 entry = pte_mkwrite(pte_mkdirty(entry));
3107
3108         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3109         if (!pte_none(*page_table))
3110                 goto release;
3111
3112         inc_mm_counter_fast(mm, MM_ANONPAGES);
3113         page_add_new_anon_rmap(page, vma, address);
3114 setpte:
3115         set_pte_at(mm, address, page_table, entry);
3116
3117         /* No need to invalidate - it was non-present before */
3118         update_mmu_cache(vma, address, page_table);
3119 unlock:
3120         pte_unmap_unlock(page_table, ptl);
3121         return 0;
3122 release:
3123         mem_cgroup_uncharge_page(page);
3124         page_cache_release(page);
3125         goto unlock;
3126 oom_free_page:
3127         page_cache_release(page);
3128 oom:
3129         return VM_FAULT_OOM;
3130 }
3131
3132 /*
3133  * __do_fault() tries to create a new page mapping. It aggressively
3134  * tries to share with existing pages, but makes a separate copy if
3135  * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
3136  * the next page fault.
3137  *
3138  * As this is called only for pages that do not currently exist, we
3139  * do not need to flush old virtual caches or the TLB.
3140  *
3141  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3142  * but allow concurrent faults), and pte neither mapped nor locked.
3143  * We return with mmap_sem still held, but pte unmapped and unlocked.
3144  */
3145 static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3146                 unsigned long address, pmd_t *pmd,
3147                 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3148 {
3149         pte_t *page_table;
3150         spinlock_t *ptl;
3151         struct page *page;
3152         struct page *cow_page;
3153         pte_t entry;
3154         int anon = 0;
3155         struct page *dirty_page = NULL;
3156         struct vm_fault vmf;
3157         int ret;
3158         int page_mkwrite = 0;
3159
3160         /*
3161          * If we do COW later, allocate page befor taking lock_page()
3162          * on the file cache page. This will reduce lock holding time.
3163          */
3164         if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3165
3166                 if (unlikely(anon_vma_prepare(vma)))
3167                         return VM_FAULT_OOM;
3168
3169                 cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
3170                 if (!cow_page)
3171                         return VM_FAULT_OOM;
3172
3173                 if (mem_cgroup_newpage_charge(cow_page, mm, GFP_KERNEL)) {
3174                         page_cache_release(cow_page);
3175                         return VM_FAULT_OOM;
3176                 }
3177         } else
3178                 cow_page = NULL;
3179
3180         vmf.virtual_address = (void __user *)(address & PAGE_MASK);
3181         vmf.pgoff = pgoff;
3182         vmf.flags = flags;
3183         vmf.page = NULL;
3184
3185         ret = vma->vm_ops->fault(vma, &vmf);
3186         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3187                             VM_FAULT_RETRY)))
3188                 goto uncharge_out;
3189
3190         if (unlikely(PageHWPoison(vmf.page))) {
3191                 if (ret & VM_FAULT_LOCKED)
3192                         unlock_page(vmf.page);
3193                 ret = VM_FAULT_HWPOISON;
3194                 goto uncharge_out;
3195         }
3196
3197         /*
3198          * For consistency in subsequent calls, make the faulted page always
3199          * locked.
3200          */
3201         if (unlikely(!(ret & VM_FAULT_LOCKED)))
3202                 lock_page(vmf.page);
3203         else
3204                 VM_BUG_ON(!PageLocked(vmf.page));
3205
3206         /*
3207          * Should we do an early C-O-W break?
3208          */
3209         page = vmf.page;
3210         if (flags & FAULT_FLAG_WRITE) {
3211                 if (!(vma->vm_flags & VM_SHARED)) {
3212                         page = cow_page;
3213                         anon = 1;
3214                         copy_user_highpage(page, vmf.page, address, vma);
3215                         __SetPageUptodate(page);
3216                 } else {
3217                         /*
3218                          * If the page will be shareable, see if the backing
3219                          * address space wants to know that the page is about
3220                          * to become writable
3221                          */
3222                         if (vma->vm_ops->page_mkwrite) {
3223                                 int tmp;
3224
3225                                 unlock_page(page);
3226                                 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
3227                                 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
3228                                 if (unlikely(tmp &
3229                                           (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3230                                         ret = tmp;
3231                                         goto unwritable_page;
3232                                 }
3233                                 if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
3234                                         lock_page(page);
3235                                         if (!page->mapping) {
3236                                                 ret = 0; /* retry the fault */
3237                                                 unlock_page(page);
3238                                                 goto unwritable_page;
3239                                         }
3240                                 } else
3241                                         VM_BUG_ON(!PageLocked(page));
3242                                 page_mkwrite = 1;
3243                         }
3244                 }
3245
3246         }
3247
3248         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3249
3250         /*
3251          * This silly early PAGE_DIRTY setting removes a race
3252          * due to the bad i386 page protection. But it's valid
3253          * for other architectures too.
3254          *
3255          * Note that if FAULT_FLAG_WRITE is set, we either now have
3256          * an exclusive copy of the page, or this is a shared mapping,
3257          * so we can make it writable and dirty to avoid having to
3258          * handle that later.
3259          */
3260         /* Only go through if we didn't race with anybody else... */
3261         if (likely(pte_same(*page_table, orig_pte))) {
3262                 flush_icache_page(vma, page);
3263                 entry = mk_pte(page, vma->vm_page_prot);
3264                 if (flags & FAULT_FLAG_WRITE)
3265                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3266                 if (anon) {
3267                         inc_mm_counter_fast(mm, MM_ANONPAGES);
3268                         page_add_new_anon_rmap(page, vma, address);
3269                 } else {
3270                         inc_mm_counter_fast(mm, MM_FILEPAGES);
3271                         page_add_file_rmap(page);
3272                         if (flags & FAULT_FLAG_WRITE) {
3273                                 dirty_page = page;
3274                                 get_page(dirty_page);
3275                         }
3276                 }
3277                 set_pte_at(mm, address, page_table, entry);
3278
3279                 /* no need to invalidate: a not-present page won't be cached */
3280                 update_mmu_cache(vma, address, page_table);
3281         } else {
3282                 if (cow_page)
3283                         mem_cgroup_uncharge_page(cow_page);
3284                 if (anon)
3285                         page_cache_release(page);
3286                 else
3287                         anon = 1; /* no anon but release faulted_page */
3288         }
3289
3290         pte_unmap_unlock(page_table, ptl);
3291
3292         if (dirty_page) {
3293                 struct address_space *mapping = page->mapping;
3294
3295                 if (set_page_dirty(dirty_page))
3296                         page_mkwrite = 1;
3297                 unlock_page(dirty_page);
3298                 put_page(dirty_page);
3299                 if (page_mkwrite && mapping) {
3300                         /*
3301                          * Some device drivers do not set page.mapping but still
3302                          * dirty their pages
3303                          */
3304                         balance_dirty_pages_ratelimited(mapping);
3305                 }
3306
3307                 /* file_update_time outside page_lock */
3308                 if (vma->vm_file)
3309                         file_update_time(vma->vm_file);
3310         } else {
3311                 unlock_page(vmf.page);
3312                 if (anon)
3313                         page_cache_release(vmf.page);
3314         }
3315
3316         return ret;
3317
3318 unwritable_page:
3319         page_cache_release(page);
3320         return ret;
3321 uncharge_out:
3322         /* fs's fault handler get error */
3323         if (cow_page) {
3324                 mem_cgroup_uncharge_page(cow_page);
3325                 page_cache_release(cow_page);
3326         }
3327         return ret;
3328 }
3329
3330 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3331                 unsigned long address, pte_t *page_table, pmd_t *pmd,
3332                 unsigned int flags, pte_t orig_pte)
3333 {
3334         pgoff_t pgoff = (((address & PAGE_MASK)
3335                         - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3336
3337         pte_unmap(page_table);
3338         return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3339 }
3340
3341 /*
3342  * Fault of a previously existing named mapping. Repopulate the pte
3343  * from the encoded file_pte if possible. This enables swappable
3344  * nonlinear vmas.
3345  *
3346  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3347  * but allow concurrent faults), and pte mapped but not yet locked.
3348  * We return with mmap_sem still held, but pte unmapped and unlocked.
3349  */
3350 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3351                 unsigned long address, pte_t *page_table, pmd_t *pmd,
3352                 unsigned int flags, pte_t orig_pte)
3353 {
3354         pgoff_t pgoff;
3355
3356         flags |= FAULT_FLAG_NONLINEAR;
3357
3358         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3359                 return 0;
3360
3361         if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3362                 /*
3363                  * Page table corrupted: show pte and kill process.
3364                  */
3365                 print_bad_pte(vma, address, orig_pte, NULL);
3366                 return VM_FAULT_SIGBUS;
3367         }
3368
3369         pgoff = pte_to_pgoff(orig_pte);
3370         return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3371 }
3372
3373 /*
3374  * These routines also need to handle stuff like marking pages dirty
3375  * and/or accessed for architectures that don't do it in hardware (most
3376  * RISC architectures).  The early dirtying is also good on the i386.
3377  *
3378  * There is also a hook called "update_mmu_cache()" that architectures
3379  * with external mmu caches can use to update those (ie the Sparc or
3380  * PowerPC hashed page tables that act as extended TLBs).
3381  *
3382  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3383  * but allow concurrent faults), and pte mapped but not yet locked.
3384  * We return with mmap_sem still held, but pte unmapped and unlocked.
3385  */
3386 int handle_pte_fault(struct mm_struct *mm,
3387                      struct vm_area_struct *vma, unsigned long address,
3388                      pte_t *pte, pmd_t *pmd, unsigned int flags)
3389 {
3390         pte_t entry;
3391         spinlock_t *ptl;
3392
3393         entry = *pte;
3394         if (!pte_present(entry)) {
3395                 if (pte_none(entry)) {
3396                         if (vma->vm_ops) {
3397                                 if (likely(vma->vm_ops->fault))
3398                                         return do_linear_fault(mm, vma, address,
3399                                                 pte, pmd, flags, entry);
3400                         }
3401                         return do_anonymous_page(mm, vma, address,
3402                                                  pte, pmd, flags);
3403                 }
3404                 if (pte_file(entry))
3405                         return do_nonlinear_fault(mm, vma, address,
3406                                         pte, pmd, flags, entry);
3407                 return do_swap_page(mm, vma, address,
3408                                         pte, pmd, flags, entry);
3409         }
3410
3411         ptl = pte_lockptr(mm, pmd);
3412         spin_lock(ptl);
3413         if (unlikely(!pte_same(*pte, entry)))
3414                 goto unlock;
3415         if (flags & FAULT_FLAG_WRITE) {
3416                 if (!pte_write(entry))
3417                         return do_wp_page(mm, vma, address,
3418                                         pte, pmd, ptl, entry);
3419                 entry = pte_mkdirty(entry);
3420         }
3421         entry = pte_mkyoung(entry);
3422         if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3423                 update_mmu_cache(vma, address, pte);
3424         } else {
3425                 /*
3426                  * This is needed only for protection faults but the arch code
3427                  * is not yet telling us if this is a protection fault or not.
3428                  * This still avoids useless tlb flushes for .text page faults
3429                  * with threads.
3430                  */
3431                 if (flags & FAULT_FLAG_WRITE)
3432                         flush_tlb_fix_spurious_fault(vma, address);
3433         }
3434 unlock:
3435         pte_unmap_unlock(pte, ptl);
3436         return 0;
3437 }
3438
3439 /*
3440  * By the time we get here, we already hold the mm semaphore
3441  */
3442 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3443                 unsigned long address, unsigned int flags)
3444 {
3445         pgd_t *pgd;
3446         pud_t *pud;
3447         pmd_t *pmd;
3448         pte_t *pte;
3449
3450         __set_current_state(TASK_RUNNING);
3451
3452         count_vm_event(PGFAULT);
3453         mem_cgroup_count_vm_event(mm, PGFAULT);
3454
3455         /* do counter updates before entering really critical section. */
3456         check_sync_rss_stat(current);
3457
3458         if (unlikely(is_vm_hugetlb_page(vma)))
3459                 return hugetlb_fault(mm, vma, address, flags);
3460
3461         pgd = pgd_offset(mm, address);
3462         pud = pud_alloc(mm, pgd, address);
3463         if (!pud)
3464                 return VM_FAULT_OOM;
3465         pmd = pmd_alloc(mm, pud, address);
3466         if (!pmd)
3467                 return VM_FAULT_OOM;
3468         if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3469                 if (!vma->vm_ops)
3470                         return do_huge_pmd_anonymous_page(mm, vma, address,
3471                                                           pmd, flags);
3472         } else {
3473                 pmd_t orig_pmd = *pmd;
3474                 barrier();
3475                 if (pmd_trans_huge(orig_pmd)) {
3476                         if (flags & FAULT_FLAG_WRITE &&
3477                             !pmd_write(orig_pmd) &&
3478                             !pmd_trans_splitting(orig_pmd))
3479                                 return do_huge_pmd_wp_page(mm, vma, address,
3480                                                            pmd, orig_pmd);
3481                         return 0;
3482                 }
3483         }
3484
3485         /*
3486          * Use __pte_alloc instead of pte_alloc_map, because we can't
3487          * run pte_offset_map on the pmd, if an huge pmd could
3488          * materialize from under us from a different thread.
3489          */
3490         if (unlikely(pmd_none(*pmd)) && __pte_alloc(mm, vma, pmd, address))
3491                 return VM_FAULT_OOM;
3492         /* if an huge pmd materialized from under us just retry later */
3493         if (unlikely(pmd_trans_huge(*pmd)))
3494                 return 0;
3495         /*
3496          * A regular pmd is established and it can't morph into a huge pmd
3497          * from under us anymore at this point because we hold the mmap_sem
3498          * read mode and khugepaged takes it in write mode. So now it's
3499          * safe to run pte_offset_map().
3500          */
3501         pte = pte_offset_map(pmd, address);
3502
3503         return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3504 }
3505
3506 #ifndef __PAGETABLE_PUD_FOLDED
3507 /*
3508  * Allocate page upper directory.
3509  * We've already handled the fast-path in-line.
3510  */
3511 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3512 {
3513         pud_t *new = pud_alloc_one(mm, address);
3514         if (!new)
3515                 return -ENOMEM;
3516
3517         smp_wmb(); /* See comment in __pte_alloc */
3518
3519         spin_lock(&mm->page_table_lock);
3520         if (pgd_present(*pgd))          /* Another has populated it */
3521                 pud_free(mm, new);
3522         else
3523                 pgd_populate(mm, pgd, new);
3524         spin_unlock(&mm->page_table_lock);
3525         return 0;
3526 }
3527 #endif /* __PAGETABLE_PUD_FOLDED */
3528
3529 #ifndef __PAGETABLE_PMD_FOLDED
3530 /*
3531  * Allocate page middle directory.
3532  * We've already handled the fast-path in-line.
3533  */
3534 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3535 {
3536         pmd_t *new = pmd_alloc_one(mm, address);
3537         if (!new)
3538                 return -ENOMEM;
3539
3540         smp_wmb(); /* See comment in __pte_alloc */
3541
3542         spin_lock(&mm->page_table_lock);
3543 #ifndef __ARCH_HAS_4LEVEL_HACK
3544         if (pud_present(*pud))          /* Another has populated it */
3545                 pmd_free(mm, new);
3546         else
3547                 pud_populate(mm, pud, new);
3548 #else
3549         if (pgd_present(*pud))          /* Another has populated it */
3550                 pmd_free(mm, new);
3551         else
3552                 pgd_populate(mm, pud, new);
3553 #endif /* __ARCH_HAS_4LEVEL_HACK */
3554         spin_unlock(&mm->page_table_lock);
3555         return 0;
3556 }
3557 #endif /* __PAGETABLE_PMD_FOLDED */
3558
3559 int make_pages_present(unsigned long addr, unsigned long end)
3560 {
3561         int ret, len, write;
3562         struct vm_area_struct * vma;
3563
3564         vma = find_vma(current->mm, addr);
3565         if (!vma)
3566                 return -ENOMEM;
3567         /*
3568          * We want to touch writable mappings with a write fault in order
3569          * to break COW, except for shared mappings because these don't COW
3570          * and we would not want to dirty them for nothing.
3571          */
3572         write = (vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE;
3573         BUG_ON(addr >= end);
3574         BUG_ON(end > vma->vm_end);
3575         len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
3576         ret = get_user_pages(current, current->mm, addr,
3577                         len, write, 0, NULL, NULL);
3578         if (ret < 0)
3579                 return ret;
3580         return ret == len ? 0 : -EFAULT;
3581 }
3582
3583 #if !defined(__HAVE_ARCH_GATE_AREA)
3584
3585 #if defined(AT_SYSINFO_EHDR)
3586 static struct vm_area_struct gate_vma;
3587
3588 static int __init gate_vma_init(void)
3589 {
3590         gate_vma.vm_mm = NULL;
3591         gate_vma.vm_start = FIXADDR_USER_START;
3592         gate_vma.vm_end = FIXADDR_USER_END;
3593         gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
3594         gate_vma.vm_page_prot = __P101;
3595         /*
3596          * Make sure the vDSO gets into every core dump.
3597          * Dumping its contents makes post-mortem fully interpretable later
3598          * without matching up the same kernel and hardware config to see
3599          * what PC values meant.
3600          */
3601         gate_vma.vm_flags |= VM_ALWAYSDUMP;
3602         return 0;
3603 }
3604 __initcall(gate_vma_init);
3605 #endif
3606
3607 struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
3608 {
3609 #ifdef AT_SYSINFO_EHDR
3610         return &gate_vma;
3611 #else
3612         return NULL;
3613 #endif
3614 }
3615
3616 int in_gate_area_no_mm(unsigned long addr)
3617 {
3618 #ifdef AT_SYSINFO_EHDR
3619         if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3620                 return 1;
3621 #endif
3622         return 0;
3623 }
3624
3625 #endif  /* __HAVE_ARCH_GATE_AREA */
3626
3627 static int __follow_pte(struct mm_struct *mm, unsigned long address,
3628                 pte_t **ptepp, spinlock_t **ptlp)
3629 {
3630         pgd_t *pgd;
3631         pud_t *pud;
3632         pmd_t *pmd;
3633         pte_t *ptep;
3634
3635         pgd = pgd_offset(mm, address);
3636         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3637                 goto out;
3638
3639         pud = pud_offset(pgd, address);
3640         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3641                 goto out;
3642
3643         pmd = pmd_offset(pud, address);
3644         VM_BUG_ON(pmd_trans_huge(*pmd));
3645         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3646                 goto out;
3647
3648         /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3649         if (pmd_huge(*pmd))
3650                 goto out;
3651
3652         ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3653         if (!ptep)
3654                 goto out;
3655         if (!pte_present(*ptep))
3656                 goto unlock;
3657         *ptepp = ptep;
3658         return 0;
3659 unlock:
3660         pte_unmap_unlock(ptep, *ptlp);
3661 out:
3662         return -EINVAL;
3663 }
3664
3665 static inline int follow_pte(struct mm_struct *mm, unsigned long address,
3666                              pte_t **ptepp, spinlock_t **ptlp)
3667 {
3668         int res;
3669
3670         /* (void) is needed to make gcc happy */
3671         (void) __cond_lock(*ptlp,
3672                            !(res = __follow_pte(mm, address, ptepp, ptlp)));
3673         return res;
3674 }
3675
3676 /**
3677  * follow_pfn - look up PFN at a user virtual address
3678  * @vma: memory mapping
3679  * @address: user virtual address
3680  * @pfn: location to store found PFN
3681  *
3682  * Only IO mappings and raw PFN mappings are allowed.
3683  *
3684  * Returns zero and the pfn at @pfn on success, -ve otherwise.
3685  */
3686 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3687         unsigned long *pfn)
3688 {
3689         int ret = -EINVAL;
3690         spinlock_t *ptl;
3691         pte_t *ptep;
3692
3693         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3694                 return ret;
3695
3696         ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3697         if (ret)
3698                 return ret;
3699         *pfn = pte_pfn(*ptep);
3700         pte_unmap_unlock(ptep, ptl);
3701         return 0;
3702 }
3703 EXPORT_SYMBOL(follow_pfn);
3704
3705 #ifdef CONFIG_HAVE_IOREMAP_PROT
3706 int follow_phys(struct vm_area_struct *vma,
3707                 unsigned long address, unsigned int flags,
3708                 unsigned long *prot, resource_size_t *phys)
3709 {
3710         int ret = -EINVAL;
3711         pte_t *ptep, pte;
3712         spinlock_t *ptl;
3713
3714         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3715                 goto out;
3716
3717         if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3718                 goto out;
3719         pte = *ptep;
3720
3721         if ((flags & FOLL_WRITE) && !pte_write(pte))
3722                 goto unlock;
3723
3724         *prot = pgprot_val(pte_pgprot(pte));
3725         *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3726
3727         ret = 0;
3728 unlock:
3729         pte_unmap_unlock(ptep, ptl);
3730 out:
3731         return ret;
3732 }
3733
3734 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3735                         void *buf, int len, int write)
3736 {
3737         resource_size_t phys_addr;
3738         unsigned long prot = 0;
3739         void __iomem *maddr;
3740         int offset = addr & (PAGE_SIZE-1);
3741
3742         if (follow_phys(vma, addr, write, &prot, &phys_addr))
3743                 return -EINVAL;
3744
3745         maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
3746         if (write)
3747                 memcpy_toio(maddr + offset, buf, len);
3748         else
3749                 memcpy_fromio(buf, maddr + offset, len);
3750         iounmap(maddr);
3751
3752         return len;
3753 }
3754 #endif
3755
3756 /*
3757  * Access another process' address space as given in mm.  If non-NULL, use the
3758  * given task for page fault accounting.
3759  */
3760 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
3761                 unsigned long addr, void *buf, int len, int write)
3762 {
3763         struct vm_area_struct *vma;
3764         void *old_buf = buf;
3765
3766         down_read(&mm->mmap_sem);
3767         /* ignore errors, just check how much was successfully transferred */
3768         while (len) {
3769                 int bytes, ret, offset;
3770                 void *maddr;
3771                 struct page *page = NULL;
3772
3773                 ret = get_user_pages(tsk, mm, addr, 1,
3774                                 write, 1, &page, &vma);
3775                 if (ret <= 0) {
3776                         /*
3777                          * Check if this is a VM_IO | VM_PFNMAP VMA, which
3778                          * we can access using slightly different code.
3779                          */
3780 #ifdef CONFIG_HAVE_IOREMAP_PROT
3781                         vma = find_vma(mm, addr);
3782                         if (!vma || vma->vm_start > addr)
3783                                 break;
3784                         if (vma->vm_ops && vma->vm_ops->access)
3785                                 ret = vma->vm_ops->access(vma, addr, buf,
3786                                                           len, write);
3787                         if (ret <= 0)
3788 #endif
3789                                 break;
3790                         bytes = ret;
3791                 } else {
3792                         bytes = len;
3793                         offset = addr & (PAGE_SIZE-1);
3794                         if (bytes > PAGE_SIZE-offset)
3795                                 bytes = PAGE_SIZE-offset;
3796
3797                         maddr = kmap(page);
3798                         if (write) {
3799                                 copy_to_user_page(vma, page, addr,
3800                                                   maddr + offset, buf, bytes);
3801                                 set_page_dirty_lock(page);
3802                         } else {
3803                                 copy_from_user_page(vma, page, addr,
3804                                                     buf, maddr + offset, bytes);
3805                         }
3806                         kunmap(page);
3807                         page_cache_release(page);
3808                 }
3809                 len -= bytes;
3810                 buf += bytes;
3811                 addr += bytes;
3812         }
3813         up_read(&mm->mmap_sem);
3814
3815         return buf - old_buf;
3816 }
3817
3818 /**
3819  * access_remote_vm - access another process' address space
3820  * @mm:         the mm_struct of the target address space
3821  * @addr:       start address to access
3822  * @buf:        source or destination buffer
3823  * @len:        number of bytes to transfer
3824  * @write:      whether the access is a write
3825  *
3826  * The caller must hold a reference on @mm.
3827  */
3828 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
3829                 void *buf, int len, int write)
3830 {
3831         return __access_remote_vm(NULL, mm, addr, buf, len, write);
3832 }
3833
3834 /*
3835  * Access another process' address space.
3836  * Source/target buffer must be kernel space,
3837  * Do not walk the page table directly, use get_user_pages
3838  */
3839 int access_process_vm(struct task_struct *tsk, unsigned long addr,
3840                 void *buf, int len, int write)
3841 {
3842         struct mm_struct *mm;
3843         int ret;
3844
3845         mm = get_task_mm(tsk);
3846         if (!mm)
3847                 return 0;
3848
3849         ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
3850         mmput(mm);
3851
3852         return ret;
3853 }
3854
3855 /*
3856  * Print the name of a VMA.
3857  */
3858 void print_vma_addr(char *prefix, unsigned long ip)
3859 {
3860         struct mm_struct *mm = current->mm;
3861         struct vm_area_struct *vma;
3862
3863         /*
3864          * Do not print if we are in atomic
3865          * contexts (in exception stacks, etc.):
3866          */
3867         if (preempt_count())
3868                 return;
3869
3870         down_read(&mm->mmap_sem);
3871         vma = find_vma(mm, ip);
3872         if (vma && vma->vm_file) {
3873                 struct file *f = vma->vm_file;
3874                 char *buf = (char *)__get_free_page(GFP_KERNEL);
3875                 if (buf) {
3876                         char *p, *s;
3877
3878                         p = d_path(&f->f_path, buf, PAGE_SIZE);
3879                         if (IS_ERR(p))
3880                                 p = "?";
3881                         s = strrchr(p, '/');
3882                         if (s)
3883                                 p = s+1;
3884                         printk("%s%s[%lx+%lx]", prefix, p,
3885                                         vma->vm_start,
3886                                         vma->vm_end - vma->vm_start);
3887                         free_page((unsigned long)buf);
3888                 }
3889         }
3890         up_read(&current->mm->mmap_sem);
3891 }
3892
3893 #ifdef CONFIG_PROVE_LOCKING
3894 void might_fault(void)
3895 {
3896         /*
3897          * Some code (nfs/sunrpc) uses socket ops on kernel memory while
3898          * holding the mmap_sem, this is safe because kernel memory doesn't
3899          * get paged out, therefore we'll never actually fault, and the
3900          * below annotations will generate false positives.
3901          */
3902         if (segment_eq(get_fs(), KERNEL_DS))
3903                 return;
3904
3905         might_sleep();
3906         /*
3907          * it would be nicer only to annotate paths which are not under
3908          * pagefault_disable, however that requires a larger audit and
3909          * providing helpers like get_user_atomic.
3910          */
3911         if (!in_atomic() && current->mm)
3912                 might_lock_read(&current->mm->mmap_sem);
3913 }
3914 EXPORT_SYMBOL(might_fault);
3915 #endif
3916
3917 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
3918 static void clear_gigantic_page(struct page *page,
3919                                 unsigned long addr,
3920                                 unsigned int pages_per_huge_page)
3921 {
3922         int i;
3923         struct page *p = page;
3924
3925         might_sleep();
3926         for (i = 0; i < pages_per_huge_page;
3927              i++, p = mem_map_next(p, page, i)) {
3928                 cond_resched();
3929                 clear_user_highpage(p, addr + i * PAGE_SIZE);
3930         }
3931 }
3932 void clear_huge_page(struct page *page,
3933                      unsigned long addr, unsigned int pages_per_huge_page)
3934 {
3935         int i;
3936
3937         if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3938                 clear_gigantic_page(page, addr, pages_per_huge_page);
3939                 return;
3940         }
3941
3942         might_sleep();
3943         for (i = 0; i < pages_per_huge_page; i++) {
3944                 cond_resched();
3945                 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
3946         }
3947 }
3948
3949 static void copy_user_gigantic_page(struct page *dst, struct page *src,
3950                                     unsigned long addr,
3951                                     struct vm_area_struct *vma,
3952                                     unsigned int pages_per_huge_page)
3953 {
3954         int i;
3955         struct page *dst_base = dst;
3956         struct page *src_base = src;
3957
3958         for (i = 0; i < pages_per_huge_page; ) {
3959                 cond_resched();
3960                 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
3961
3962                 i++;
3963                 dst = mem_map_next(dst, dst_base, i);
3964                 src = mem_map_next(src, src_base, i);
3965         }
3966 }
3967
3968 void copy_user_huge_page(struct page *dst, struct page *src,
3969                          unsigned long addr, struct vm_area_struct *vma,
3970                          unsigned int pages_per_huge_page)
3971 {
3972         int i;
3973
3974         if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3975                 copy_user_gigantic_page(dst, src, addr, vma,
3976                                         pages_per_huge_page);
3977                 return;
3978         }
3979
3980         might_sleep();
3981         for (i = 0; i < pages_per_huge_page; i++) {
3982                 cond_resched();
3983                 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
3984         }
3985 }
3986 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */