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