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