ALSA: pcm: potential uninitialized return values
[pandora-kernel.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/export.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         if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
209                 return 0;
210
211         batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
212         if (!batch)
213                 return 0;
214
215         tlb->batch_count++;
216         batch->next = NULL;
217         batch->nr   = 0;
218         batch->max  = MAX_GATHER_BATCH;
219
220         tlb->active->next = batch;
221         tlb->active = batch;
222
223         return 1;
224 }
225
226 /* tlb_gather_mmu
227  *      Called to initialize an (on-stack) mmu_gather structure for page-table
228  *      tear-down from @mm. The @fullmm argument is used when @mm is without
229  *      users and we're going to destroy the full address space (exit/execve).
230  */
231 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm)
232 {
233         tlb->mm = mm;
234
235         tlb->fullmm     = fullmm;
236         tlb->need_flush = 0;
237         tlb->fast_mode  = (num_possible_cpus() == 1);
238         tlb->local.next = NULL;
239         tlb->local.nr   = 0;
240         tlb->local.max  = ARRAY_SIZE(tlb->__pages);
241         tlb->active     = &tlb->local;
242         tlb->batch_count = 0;
243
244 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
245         tlb->batch = NULL;
246 #endif
247 }
248
249 void tlb_flush_mmu(struct mmu_gather *tlb)
250 {
251         struct mmu_gather_batch *batch;
252
253         if (!tlb->need_flush)
254                 return;
255         tlb->need_flush = 0;
256         tlb_flush(tlb);
257 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
258         tlb_table_flush(tlb);
259 #endif
260
261         if (tlb_fast_mode(tlb))
262                 return;
263
264         for (batch = &tlb->local; batch; batch = batch->next) {
265                 free_pages_and_swap_cache(batch->pages, batch->nr);
266                 batch->nr = 0;
267         }
268         tlb->active = &tlb->local;
269 }
270
271 /* tlb_finish_mmu
272  *      Called at the end of the shootdown operation to free up any resources
273  *      that were required.
274  */
275 void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
276 {
277         struct mmu_gather_batch *batch, *next;
278
279         tlb_flush_mmu(tlb);
280
281         /* keep the page table cache within bounds */
282         check_pgt_cache();
283
284         for (batch = tlb->local.next; batch; batch = next) {
285                 next = batch->next;
286                 free_pages((unsigned long)batch, 0);
287         }
288         tlb->local.next = NULL;
289 }
290
291 /* __tlb_remove_page
292  *      Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
293  *      handling the additional races in SMP caused by other CPUs caching valid
294  *      mappings in their TLBs. Returns the number of free page slots left.
295  *      When out of page slots we must call tlb_flush_mmu().
296  */
297 int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
298 {
299         struct mmu_gather_batch *batch;
300
301         tlb->need_flush = 1;
302
303         if (tlb_fast_mode(tlb)) {
304                 free_page_and_swap_cache(page);
305                 return 1; /* avoid calling tlb_flush_mmu() */
306         }
307
308         batch = tlb->active;
309         batch->pages[batch->nr++] = page;
310         if (batch->nr == batch->max) {
311                 if (!tlb_next_batch(tlb))
312                         return 0;
313                 batch = tlb->active;
314         }
315         VM_BUG_ON(batch->nr > batch->max);
316
317         return batch->max - batch->nr;
318 }
319
320 #endif /* HAVE_GENERIC_MMU_GATHER */
321
322 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
323
324 /*
325  * See the comment near struct mmu_table_batch.
326  */
327
328 static void tlb_remove_table_smp_sync(void *arg)
329 {
330         /* Simply deliver the interrupt */
331 }
332
333 static void tlb_remove_table_one(void *table)
334 {
335         /*
336          * This isn't an RCU grace period and hence the page-tables cannot be
337          * assumed to be actually RCU-freed.
338          *
339          * It is however sufficient for software page-table walkers that rely on
340          * IRQ disabling. See the comment near struct mmu_table_batch.
341          */
342         smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
343         __tlb_remove_table(table);
344 }
345
346 static void tlb_remove_table_rcu(struct rcu_head *head)
347 {
348         struct mmu_table_batch *batch;
349         int i;
350
351         batch = container_of(head, struct mmu_table_batch, rcu);
352
353         for (i = 0; i < batch->nr; i++)
354                 __tlb_remove_table(batch->tables[i]);
355
356         free_page((unsigned long)batch);
357 }
358
359 void tlb_table_flush(struct mmu_gather *tlb)
360 {
361         struct mmu_table_batch **batch = &tlb->batch;
362
363         if (*batch) {
364                 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
365                 *batch = NULL;
366         }
367 }
368
369 void tlb_remove_table(struct mmu_gather *tlb, void *table)
370 {
371         struct mmu_table_batch **batch = &tlb->batch;
372
373         tlb->need_flush = 1;
374
375         /*
376          * When there's less then two users of this mm there cannot be a
377          * concurrent page-table walk.
378          */
379         if (atomic_read(&tlb->mm->mm_users) < 2) {
380                 __tlb_remove_table(table);
381                 return;
382         }
383
384         if (*batch == NULL) {
385                 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
386                 if (*batch == NULL) {
387                         tlb_remove_table_one(table);
388                         return;
389                 }
390                 (*batch)->nr = 0;
391         }
392         (*batch)->tables[(*batch)->nr++] = table;
393         if ((*batch)->nr == MAX_TABLE_BATCH)
394                 tlb_table_flush(tlb);
395 }
396
397 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */
398
399 /*
400  * If a p?d_bad entry is found while walking page tables, report
401  * the error, before resetting entry to p?d_none.  Usually (but
402  * very seldom) called out from the p?d_none_or_clear_bad macros.
403  */
404
405 void pgd_clear_bad(pgd_t *pgd)
406 {
407         pgd_ERROR(*pgd);
408         pgd_clear(pgd);
409 }
410
411 void pud_clear_bad(pud_t *pud)
412 {
413         pud_ERROR(*pud);
414         pud_clear(pud);
415 }
416
417 void pmd_clear_bad(pmd_t *pmd)
418 {
419         pmd_ERROR(*pmd);
420         pmd_clear(pmd);
421 }
422
423 /*
424  * Note: this doesn't free the actual pages themselves. That
425  * has been handled earlier when unmapping all the memory regions.
426  */
427 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
428                            unsigned long addr)
429 {
430         pgtable_t token = pmd_pgtable(*pmd);
431         pmd_clear(pmd);
432         pte_free_tlb(tlb, token, addr);
433         tlb->mm->nr_ptes--;
434 }
435
436 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
437                                 unsigned long addr, unsigned long end,
438                                 unsigned long floor, unsigned long ceiling)
439 {
440         pmd_t *pmd;
441         unsigned long next;
442         unsigned long start;
443
444         start = addr;
445         pmd = pmd_offset(pud, addr);
446         do {
447                 next = pmd_addr_end(addr, end);
448                 if (pmd_none_or_clear_bad(pmd))
449                         continue;
450                 free_pte_range(tlb, pmd, addr);
451         } while (pmd++, addr = next, addr != end);
452
453         start &= PUD_MASK;
454         if (start < floor)
455                 return;
456         if (ceiling) {
457                 ceiling &= PUD_MASK;
458                 if (!ceiling)
459                         return;
460         }
461         if (end - 1 > ceiling - 1)
462                 return;
463
464         pmd = pmd_offset(pud, start);
465         pud_clear(pud);
466         pmd_free_tlb(tlb, pmd, start);
467 }
468
469 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
470                                 unsigned long addr, unsigned long end,
471                                 unsigned long floor, unsigned long ceiling)
472 {
473         pud_t *pud;
474         unsigned long next;
475         unsigned long start;
476
477         start = addr;
478         pud = pud_offset(pgd, addr);
479         do {
480                 next = pud_addr_end(addr, end);
481                 if (pud_none_or_clear_bad(pud))
482                         continue;
483                 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
484         } while (pud++, addr = next, addr != end);
485
486         start &= PGDIR_MASK;
487         if (start < floor)
488                 return;
489         if (ceiling) {
490                 ceiling &= PGDIR_MASK;
491                 if (!ceiling)
492                         return;
493         }
494         if (end - 1 > ceiling - 1)
495                 return;
496
497         pud = pud_offset(pgd, start);
498         pgd_clear(pgd);
499         pud_free_tlb(tlb, pud, start);
500 }
501
502 /*
503  * This function frees user-level page tables of a process.
504  *
505  * Must be called with pagetable lock held.
506  */
507 void free_pgd_range(struct mmu_gather *tlb,
508                         unsigned long addr, unsigned long end,
509                         unsigned long floor, unsigned long ceiling)
510 {
511         pgd_t *pgd;
512         unsigned long next;
513
514         /*
515          * The next few lines have given us lots of grief...
516          *
517          * Why are we testing PMD* at this top level?  Because often
518          * there will be no work to do at all, and we'd prefer not to
519          * go all the way down to the bottom just to discover that.
520          *
521          * Why all these "- 1"s?  Because 0 represents both the bottom
522          * of the address space and the top of it (using -1 for the
523          * top wouldn't help much: the masks would do the wrong thing).
524          * The rule is that addr 0 and floor 0 refer to the bottom of
525          * the address space, but end 0 and ceiling 0 refer to the top
526          * Comparisons need to use "end - 1" and "ceiling - 1" (though
527          * that end 0 case should be mythical).
528          *
529          * Wherever addr is brought up or ceiling brought down, we must
530          * be careful to reject "the opposite 0" before it confuses the
531          * subsequent tests.  But what about where end is brought down
532          * by PMD_SIZE below? no, end can't go down to 0 there.
533          *
534          * Whereas we round start (addr) and ceiling down, by different
535          * masks at different levels, in order to test whether a table
536          * now has no other vmas using it, so can be freed, we don't
537          * bother to round floor or end up - the tests don't need that.
538          */
539
540         addr &= PMD_MASK;
541         if (addr < floor) {
542                 addr += PMD_SIZE;
543                 if (!addr)
544                         return;
545         }
546         if (ceiling) {
547                 ceiling &= PMD_MASK;
548                 if (!ceiling)
549                         return;
550         }
551         if (end - 1 > ceiling - 1)
552                 end -= PMD_SIZE;
553         if (addr > end - 1)
554                 return;
555
556         pgd = pgd_offset(tlb->mm, addr);
557         do {
558                 next = pgd_addr_end(addr, end);
559                 if (pgd_none_or_clear_bad(pgd))
560                         continue;
561                 free_pud_range(tlb, pgd, addr, next, floor, ceiling);
562         } while (pgd++, addr = next, addr != end);
563 }
564
565 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
566                 unsigned long floor, unsigned long ceiling)
567 {
568         while (vma) {
569                 struct vm_area_struct *next = vma->vm_next;
570                 unsigned long addr = vma->vm_start;
571
572                 /*
573                  * Hide vma from rmap and truncate_pagecache before freeing
574                  * pgtables
575                  */
576                 unlink_anon_vmas(vma);
577                 unlink_file_vma(vma);
578
579                 if (is_vm_hugetlb_page(vma)) {
580                         hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
581                                 floor, next? next->vm_start: ceiling);
582                 } else {
583                         /*
584                          * Optimization: gather nearby vmas into one call down
585                          */
586                         while (next && next->vm_start <= vma->vm_end + PMD_SIZE
587                                && !is_vm_hugetlb_page(next)) {
588                                 vma = next;
589                                 next = vma->vm_next;
590                                 unlink_anon_vmas(vma);
591                                 unlink_file_vma(vma);
592                         }
593                         free_pgd_range(tlb, addr, vma->vm_end,
594                                 floor, next? next->vm_start: ceiling);
595                 }
596                 vma = next;
597         }
598 }
599
600 int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
601                 pmd_t *pmd, unsigned long address)
602 {
603         pgtable_t new = pte_alloc_one(mm, address);
604         int wait_split_huge_page;
605         if (!new)
606                 return -ENOMEM;
607
608         /*
609          * Ensure all pte setup (eg. pte page lock and page clearing) are
610          * visible before the pte is made visible to other CPUs by being
611          * put into page tables.
612          *
613          * The other side of the story is the pointer chasing in the page
614          * table walking code (when walking the page table without locking;
615          * ie. most of the time). Fortunately, these data accesses consist
616          * of a chain of data-dependent loads, meaning most CPUs (alpha
617          * being the notable exception) will already guarantee loads are
618          * seen in-order. See the alpha page table accessors for the
619          * smp_read_barrier_depends() barriers in page table walking code.
620          */
621         smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
622
623         spin_lock(&mm->page_table_lock);
624         wait_split_huge_page = 0;
625         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
626                 mm->nr_ptes++;
627                 pmd_populate(mm, pmd, new);
628                 new = NULL;
629         } else if (unlikely(pmd_trans_splitting(*pmd)))
630                 wait_split_huge_page = 1;
631         spin_unlock(&mm->page_table_lock);
632         if (new)
633                 pte_free(mm, new);
634         if (wait_split_huge_page)
635                 wait_split_huge_page(vma->anon_vma, pmd);
636         return 0;
637 }
638
639 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
640 {
641         pte_t *new = pte_alloc_one_kernel(&init_mm, address);
642         if (!new)
643                 return -ENOMEM;
644
645         smp_wmb(); /* See comment in __pte_alloc */
646
647         spin_lock(&init_mm.page_table_lock);
648         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
649                 pmd_populate_kernel(&init_mm, pmd, new);
650                 new = NULL;
651         } else
652                 VM_BUG_ON(pmd_trans_splitting(*pmd));
653         spin_unlock(&init_mm.page_table_lock);
654         if (new)
655                 pte_free_kernel(&init_mm, new);
656         return 0;
657 }
658
659 static inline void init_rss_vec(int *rss)
660 {
661         memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
662 }
663
664 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
665 {
666         int i;
667
668         if (current->mm == mm)
669                 sync_mm_rss(current, mm);
670         for (i = 0; i < NR_MM_COUNTERS; i++)
671                 if (rss[i])
672                         add_mm_counter(mm, i, rss[i]);
673 }
674
675 /*
676  * This function is called to print an error when a bad pte
677  * is found. For example, we might have a PFN-mapped pte in
678  * a region that doesn't allow it.
679  *
680  * The calling function must still handle the error.
681  */
682 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
683                           pte_t pte, struct page *page)
684 {
685         pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
686         pud_t *pud = pud_offset(pgd, addr);
687         pmd_t *pmd = pmd_offset(pud, addr);
688         struct address_space *mapping;
689         pgoff_t index;
690         static unsigned long resume;
691         static unsigned long nr_shown;
692         static unsigned long nr_unshown;
693
694         /*
695          * Allow a burst of 60 reports, then keep quiet for that minute;
696          * or allow a steady drip of one report per second.
697          */
698         if (nr_shown == 60) {
699                 if (time_before(jiffies, resume)) {
700                         nr_unshown++;
701                         return;
702                 }
703                 if (nr_unshown) {
704                         printk(KERN_ALERT
705                                 "BUG: Bad page map: %lu messages suppressed\n",
706                                 nr_unshown);
707                         nr_unshown = 0;
708                 }
709                 nr_shown = 0;
710         }
711         if (nr_shown++ == 0)
712                 resume = jiffies + 60 * HZ;
713
714         mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
715         index = linear_page_index(vma, addr);
716
717         printk(KERN_ALERT
718                 "BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
719                 current->comm,
720                 (long long)pte_val(pte), (long long)pmd_val(*pmd));
721         if (page)
722                 dump_page(page);
723         printk(KERN_ALERT
724                 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
725                 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
726         /*
727          * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
728          */
729         if (vma->vm_ops)
730                 print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
731                                 (unsigned long)vma->vm_ops->fault);
732         if (vma->vm_file && vma->vm_file->f_op)
733                 print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
734                                 (unsigned long)vma->vm_file->f_op->mmap);
735         dump_stack();
736         add_taint(TAINT_BAD_PAGE);
737 }
738
739 static inline int is_cow_mapping(vm_flags_t flags)
740 {
741         return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
742 }
743
744 #ifndef is_zero_pfn
745 static inline int is_zero_pfn(unsigned long pfn)
746 {
747         return pfn == zero_pfn;
748 }
749 #endif
750
751 #ifndef my_zero_pfn
752 static inline unsigned long my_zero_pfn(unsigned long addr)
753 {
754         return zero_pfn;
755 }
756 #endif
757
758 /*
759  * vm_normal_page -- This function gets the "struct page" associated with a pte.
760  *
761  * "Special" mappings do not wish to be associated with a "struct page" (either
762  * it doesn't exist, or it exists but they don't want to touch it). In this
763  * case, NULL is returned here. "Normal" mappings do have a struct page.
764  *
765  * There are 2 broad cases. Firstly, an architecture may define a pte_special()
766  * pte bit, in which case this function is trivial. Secondly, an architecture
767  * may not have a spare pte bit, which requires a more complicated scheme,
768  * described below.
769  *
770  * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
771  * special mapping (even if there are underlying and valid "struct pages").
772  * COWed pages of a VM_PFNMAP are always normal.
773  *
774  * The way we recognize COWed pages within VM_PFNMAP mappings is through the
775  * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
776  * set, and the vm_pgoff will point to the first PFN mapped: thus every special
777  * mapping will always honor the rule
778  *
779  *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
780  *
781  * And for normal mappings this is false.
782  *
783  * This restricts such mappings to be a linear translation from virtual address
784  * to pfn. To get around this restriction, we allow arbitrary mappings so long
785  * as the vma is not a COW mapping; in that case, we know that all ptes are
786  * special (because none can have been COWed).
787  *
788  *
789  * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
790  *
791  * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
792  * page" backing, however the difference is that _all_ pages with a struct
793  * page (that is, those where pfn_valid is true) are refcounted and considered
794  * normal pages by the VM. The disadvantage is that pages are refcounted
795  * (which can be slower and simply not an option for some PFNMAP users). The
796  * advantage is that we don't have to follow the strict linearity rule of
797  * PFNMAP mappings in order to support COWable mappings.
798  *
799  */
800 #ifdef __HAVE_ARCH_PTE_SPECIAL
801 # define HAVE_PTE_SPECIAL 1
802 #else
803 # define HAVE_PTE_SPECIAL 0
804 #endif
805 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
806                                 pte_t pte)
807 {
808         unsigned long pfn = pte_pfn(pte);
809
810         if (HAVE_PTE_SPECIAL) {
811                 if (likely(!pte_special(pte)))
812                         goto check_pfn;
813                 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
814                         return NULL;
815                 if (!is_zero_pfn(pfn))
816                         print_bad_pte(vma, addr, pte, NULL);
817                 return NULL;
818         }
819
820         /* !HAVE_PTE_SPECIAL case follows: */
821
822         if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
823                 if (vma->vm_flags & VM_MIXEDMAP) {
824                         if (!pfn_valid(pfn))
825                                 return NULL;
826                         goto out;
827                 } else {
828                         unsigned long off;
829                         off = (addr - vma->vm_start) >> PAGE_SHIFT;
830                         if (pfn == vma->vm_pgoff + off)
831                                 return NULL;
832                         if (!is_cow_mapping(vma->vm_flags))
833                                 return NULL;
834                 }
835         }
836
837         if (is_zero_pfn(pfn))
838                 return NULL;
839 check_pfn:
840         if (unlikely(pfn > highest_memmap_pfn)) {
841                 print_bad_pte(vma, addr, pte, NULL);
842                 return NULL;
843         }
844
845         /*
846          * NOTE! We still have PageReserved() pages in the page tables.
847          * eg. VDSO mappings can cause them to exist.
848          */
849 out:
850         return pfn_to_page(pfn);
851 }
852
853 /*
854  * copy one vm_area from one task to the other. Assumes the page tables
855  * already present in the new task to be cleared in the whole range
856  * covered by this vma.
857  */
858
859 static inline unsigned long
860 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
861                 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
862                 unsigned long addr, int *rss)
863 {
864         unsigned long vm_flags = vma->vm_flags;
865         pte_t pte = *src_pte;
866         struct page *page;
867
868         /* pte contains position in swap or file, so copy. */
869         if (unlikely(!pte_present(pte))) {
870                 if (!pte_file(pte)) {
871                         swp_entry_t entry = pte_to_swp_entry(pte);
872
873                         if (likely(!non_swap_entry(entry))) {
874                                 if (swap_duplicate(entry) < 0)
875                                         return entry.val;
876
877                                 /* make sure dst_mm is on swapoff's mmlist. */
878                                 if (unlikely(list_empty(&dst_mm->mmlist))) {
879                                         spin_lock(&mmlist_lock);
880                                         if (list_empty(&dst_mm->mmlist))
881                                                 list_add(&dst_mm->mmlist,
882                                                          &src_mm->mmlist);
883                                         spin_unlock(&mmlist_lock);
884                                 }
885                                 rss[MM_SWAPENTS]++;
886                         } else if (is_write_migration_entry(entry) &&
887                                         is_cow_mapping(vm_flags)) {
888                                 /*
889                                  * COW mappings require pages in both parent
890                                  * and child to be set to read.
891                                  */
892                                 make_migration_entry_read(&entry);
893                                 pte = swp_entry_to_pte(entry);
894                                 set_pte_at(src_mm, addr, src_pte, pte);
895                         }
896                 }
897                 goto out_set_pte;
898         }
899
900         /*
901          * If it's a COW mapping, write protect it both
902          * in the parent and the child
903          */
904         if (is_cow_mapping(vm_flags)) {
905                 ptep_set_wrprotect(src_mm, addr, src_pte);
906                 pte = pte_wrprotect(pte);
907         }
908
909         /*
910          * If it's a shared mapping, mark it clean in
911          * the child
912          */
913         if (vm_flags & VM_SHARED)
914                 pte = pte_mkclean(pte);
915         pte = pte_mkold(pte);
916
917         page = vm_normal_page(vma, addr, pte);
918         if (page) {
919                 get_page(page);
920                 page_dup_rmap(page);
921                 if (PageAnon(page))
922                         rss[MM_ANONPAGES]++;
923                 else
924                         rss[MM_FILEPAGES]++;
925         }
926
927 out_set_pte:
928         set_pte_at(dst_mm, addr, dst_pte, pte);
929         return 0;
930 }
931
932 int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
933                    pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
934                    unsigned long addr, unsigned long end)
935 {
936         pte_t *orig_src_pte, *orig_dst_pte;
937         pte_t *src_pte, *dst_pte;
938         spinlock_t *src_ptl, *dst_ptl;
939         int progress = 0;
940         int rss[NR_MM_COUNTERS];
941         swp_entry_t entry = (swp_entry_t){0};
942
943 again:
944         init_rss_vec(rss);
945
946         dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
947         if (!dst_pte)
948                 return -ENOMEM;
949         src_pte = pte_offset_map(src_pmd, addr);
950         src_ptl = pte_lockptr(src_mm, src_pmd);
951         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
952         orig_src_pte = src_pte;
953         orig_dst_pte = dst_pte;
954         arch_enter_lazy_mmu_mode();
955
956         do {
957                 /*
958                  * We are holding two locks at this point - either of them
959                  * could generate latencies in another task on another CPU.
960                  */
961                 if (progress >= 32) {
962                         progress = 0;
963                         if (need_resched() ||
964                             spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
965                                 break;
966                 }
967                 if (pte_none(*src_pte)) {
968                         progress++;
969                         continue;
970                 }
971                 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
972                                                         vma, addr, rss);
973                 if (entry.val)
974                         break;
975                 progress += 8;
976         } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
977
978         arch_leave_lazy_mmu_mode();
979         spin_unlock(src_ptl);
980         pte_unmap(orig_src_pte);
981         add_mm_rss_vec(dst_mm, rss);
982         pte_unmap_unlock(orig_dst_pte, dst_ptl);
983         cond_resched();
984
985         if (entry.val) {
986                 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
987                         return -ENOMEM;
988                 progress = 0;
989         }
990         if (addr != end)
991                 goto again;
992         return 0;
993 }
994
995 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
996                 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
997                 unsigned long addr, unsigned long end)
998 {
999         pmd_t *src_pmd, *dst_pmd;
1000         unsigned long next;
1001
1002         dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
1003         if (!dst_pmd)
1004                 return -ENOMEM;
1005         src_pmd = pmd_offset(src_pud, addr);
1006         do {
1007                 next = pmd_addr_end(addr, end);
1008                 if (pmd_trans_huge(*src_pmd)) {
1009                         int err;
1010                         VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
1011                         err = copy_huge_pmd(dst_mm, src_mm,
1012                                             dst_pmd, src_pmd, addr, vma);
1013                         if (err == -ENOMEM)
1014                                 return -ENOMEM;
1015                         if (!err)
1016                                 continue;
1017                         /* fall through */
1018                 }
1019                 if (pmd_none_or_clear_bad(src_pmd))
1020                         continue;
1021                 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1022                                                 vma, addr, next))
1023                         return -ENOMEM;
1024         } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1025         return 0;
1026 }
1027
1028 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1029                 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1030                 unsigned long addr, unsigned long end)
1031 {
1032         pud_t *src_pud, *dst_pud;
1033         unsigned long next;
1034
1035         dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
1036         if (!dst_pud)
1037                 return -ENOMEM;
1038         src_pud = pud_offset(src_pgd, addr);
1039         do {
1040                 next = pud_addr_end(addr, end);
1041                 if (pud_none_or_clear_bad(src_pud))
1042                         continue;
1043                 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1044                                                 vma, addr, next))
1045                         return -ENOMEM;
1046         } while (dst_pud++, src_pud++, addr = next, addr != end);
1047         return 0;
1048 }
1049
1050 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1051                 struct vm_area_struct *vma)
1052 {
1053         pgd_t *src_pgd, *dst_pgd;
1054         unsigned long next;
1055         unsigned long addr = vma->vm_start;
1056         unsigned long end = vma->vm_end;
1057         int ret;
1058
1059         /*
1060          * Don't copy ptes where a page fault will fill them correctly.
1061          * Fork becomes much lighter when there are big shared or private
1062          * readonly mappings. The tradeoff is that copy_page_range is more
1063          * efficient than faulting.
1064          */
1065         if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
1066                 if (!vma->anon_vma)
1067                         return 0;
1068         }
1069
1070         if (is_vm_hugetlb_page(vma))
1071                 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1072
1073         if (unlikely(is_pfn_mapping(vma))) {
1074                 /*
1075                  * We do not free on error cases below as remove_vma
1076                  * gets called on error from higher level routine
1077                  */
1078                 ret = track_pfn_vma_copy(vma);
1079                 if (ret)
1080                         return ret;
1081         }
1082
1083         /*
1084          * We need to invalidate the secondary MMU mappings only when
1085          * there could be a permission downgrade on the ptes of the
1086          * parent mm. And a permission downgrade will only happen if
1087          * is_cow_mapping() returns true.
1088          */
1089         if (is_cow_mapping(vma->vm_flags))
1090                 mmu_notifier_invalidate_range_start(src_mm, addr, end);
1091
1092         ret = 0;
1093         dst_pgd = pgd_offset(dst_mm, addr);
1094         src_pgd = pgd_offset(src_mm, addr);
1095         do {
1096                 next = pgd_addr_end(addr, end);
1097                 if (pgd_none_or_clear_bad(src_pgd))
1098                         continue;
1099                 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
1100                                             vma, addr, next))) {
1101                         ret = -ENOMEM;
1102                         break;
1103                 }
1104         } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1105
1106         if (is_cow_mapping(vma->vm_flags))
1107                 mmu_notifier_invalidate_range_end(src_mm,
1108                                                   vma->vm_start, end);
1109         return ret;
1110 }
1111
1112 static unsigned long zap_pte_range(struct mmu_gather *tlb,
1113                                 struct vm_area_struct *vma, pmd_t *pmd,
1114                                 unsigned long addr, unsigned long end,
1115                                 struct zap_details *details)
1116 {
1117         struct mm_struct *mm = tlb->mm;
1118         int force_flush = 0;
1119         int rss[NR_MM_COUNTERS];
1120         spinlock_t *ptl;
1121         pte_t *start_pte;
1122         pte_t *pte;
1123
1124 again:
1125         init_rss_vec(rss);
1126         start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1127         pte = start_pte;
1128         arch_enter_lazy_mmu_mode();
1129         do {
1130                 pte_t ptent = *pte;
1131                 if (pte_none(ptent)) {
1132                         continue;
1133                 }
1134
1135                 if (pte_present(ptent)) {
1136                         struct page *page;
1137
1138                         page = vm_normal_page(vma, addr, ptent);
1139                         if (unlikely(details) && page) {
1140                                 /*
1141                                  * unmap_shared_mapping_pages() wants to
1142                                  * invalidate cache without truncating:
1143                                  * unmap shared but keep private pages.
1144                                  */
1145                                 if (details->check_mapping &&
1146                                     details->check_mapping != page->mapping)
1147                                         continue;
1148                                 /*
1149                                  * Each page->index must be checked when
1150                                  * invalidating or truncating nonlinear.
1151                                  */
1152                                 if (details->nonlinear_vma &&
1153                                     (page->index < details->first_index ||
1154                                      page->index > details->last_index))
1155                                         continue;
1156                         }
1157                         ptent = ptep_get_and_clear_full(mm, addr, pte,
1158                                                         tlb->fullmm);
1159                         tlb_remove_tlb_entry(tlb, pte, addr);
1160                         if (unlikely(!page))
1161                                 continue;
1162                         if (unlikely(details) && details->nonlinear_vma
1163                             && linear_page_index(details->nonlinear_vma,
1164                                                 addr) != page->index)
1165                                 set_pte_at(mm, addr, pte,
1166                                            pgoff_to_pte(page->index));
1167                         if (PageAnon(page))
1168                                 rss[MM_ANONPAGES]--;
1169                         else {
1170                                 if (pte_dirty(ptent))
1171                                         set_page_dirty(page);
1172                                 if (pte_young(ptent) &&
1173                                     likely(!VM_SequentialReadHint(vma)))
1174                                         mark_page_accessed(page);
1175                                 rss[MM_FILEPAGES]--;
1176                         }
1177                         page_remove_rmap(page);
1178                         if (unlikely(page_mapcount(page) < 0))
1179                                 print_bad_pte(vma, addr, ptent, page);
1180                         force_flush = !__tlb_remove_page(tlb, page);
1181                         if (force_flush) {
1182                                 addr += PAGE_SIZE;
1183                                 break;
1184                         }
1185                         continue;
1186                 }
1187                 /*
1188                  * If details->check_mapping, we leave swap entries;
1189                  * if details->nonlinear_vma, we leave file entries.
1190                  */
1191                 if (unlikely(details))
1192                         continue;
1193                 if (pte_file(ptent)) {
1194                         if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
1195                                 print_bad_pte(vma, addr, ptent, NULL);
1196                 } else {
1197                         swp_entry_t entry = pte_to_swp_entry(ptent);
1198
1199                         if (!non_swap_entry(entry))
1200                                 rss[MM_SWAPENTS]--;
1201                         if (unlikely(!free_swap_and_cache(entry)))
1202                                 print_bad_pte(vma, addr, ptent, NULL);
1203                 }
1204                 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1205         } while (pte++, addr += PAGE_SIZE, addr != end);
1206
1207         add_mm_rss_vec(mm, rss);
1208         arch_leave_lazy_mmu_mode();
1209         pte_unmap_unlock(start_pte, ptl);
1210
1211         /*
1212          * mmu_gather ran out of room to batch pages, we break out of
1213          * the PTE lock to avoid doing the potential expensive TLB invalidate
1214          * and page-free while holding it.
1215          */
1216         if (force_flush) {
1217                 force_flush = 0;
1218                 tlb_flush_mmu(tlb);
1219                 if (addr != end)
1220                         goto again;
1221         }
1222
1223         return addr;
1224 }
1225
1226 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1227                                 struct vm_area_struct *vma, pud_t *pud,
1228                                 unsigned long addr, unsigned long end,
1229                                 struct zap_details *details)
1230 {
1231         pmd_t *pmd;
1232         unsigned long next;
1233
1234         pmd = pmd_offset(pud, addr);
1235         do {
1236                 next = pmd_addr_end(addr, end);
1237                 if (pmd_trans_huge(*pmd)) {
1238                         if (next - addr != HPAGE_PMD_SIZE) {
1239                                 VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem));
1240                                 split_huge_page_pmd(vma->vm_mm, pmd);
1241                         } else if (zap_huge_pmd(tlb, vma, pmd))
1242                                 goto next;
1243                         /* fall through */
1244                 }
1245                 /*
1246                  * Here there can be other concurrent MADV_DONTNEED or
1247                  * trans huge page faults running, and if the pmd is
1248                  * none or trans huge it can change under us. This is
1249                  * because MADV_DONTNEED holds the mmap_sem in read
1250                  * mode.
1251                  */
1252                 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1253                         goto next;
1254                 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1255 next:
1256                 cond_resched();
1257         } while (pmd++, addr = next, addr != end);
1258
1259         return addr;
1260 }
1261
1262 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1263                                 struct vm_area_struct *vma, pgd_t *pgd,
1264                                 unsigned long addr, unsigned long end,
1265                                 struct zap_details *details)
1266 {
1267         pud_t *pud;
1268         unsigned long next;
1269
1270         pud = pud_offset(pgd, addr);
1271         do {
1272                 next = pud_addr_end(addr, end);
1273                 if (pud_none_or_clear_bad(pud))
1274                         continue;
1275                 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1276         } while (pud++, addr = next, addr != end);
1277
1278         return addr;
1279 }
1280
1281 static unsigned long unmap_page_range(struct mmu_gather *tlb,
1282                                 struct vm_area_struct *vma,
1283                                 unsigned long addr, unsigned long end,
1284                                 struct zap_details *details)
1285 {
1286         pgd_t *pgd;
1287         unsigned long next;
1288
1289         if (details && !details->check_mapping && !details->nonlinear_vma)
1290                 details = NULL;
1291
1292         BUG_ON(addr >= end);
1293         mem_cgroup_uncharge_start();
1294         tlb_start_vma(tlb, vma);
1295         pgd = pgd_offset(vma->vm_mm, addr);
1296         do {
1297                 next = pgd_addr_end(addr, end);
1298                 if (pgd_none_or_clear_bad(pgd))
1299                         continue;
1300                 next = zap_pud_range(tlb, vma, pgd, addr, next, details);
1301         } while (pgd++, addr = next, addr != end);
1302         tlb_end_vma(tlb, vma);
1303         mem_cgroup_uncharge_end();
1304
1305         return addr;
1306 }
1307
1308 /**
1309  * unmap_vmas - unmap a range of memory covered by a list of vma's
1310  * @tlb: address of the caller's struct mmu_gather
1311  * @vma: the starting vma
1312  * @start_addr: virtual address at which to start unmapping
1313  * @end_addr: virtual address at which to end unmapping
1314  * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
1315  * @details: details of nonlinear truncation or shared cache invalidation
1316  *
1317  * Returns the end address of the unmapping (restart addr if interrupted).
1318  *
1319  * Unmap all pages in the vma list.
1320  *
1321  * Only addresses between `start' and `end' will be unmapped.
1322  *
1323  * The VMA list must be sorted in ascending virtual address order.
1324  *
1325  * unmap_vmas() assumes that the caller will flush the whole unmapped address
1326  * range after unmap_vmas() returns.  So the only responsibility here is to
1327  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1328  * drops the lock and schedules.
1329  */
1330 unsigned long unmap_vmas(struct mmu_gather *tlb,
1331                 struct vm_area_struct *vma, unsigned long start_addr,
1332                 unsigned long end_addr, unsigned long *nr_accounted,
1333                 struct zap_details *details)
1334 {
1335         unsigned long start = start_addr;
1336         struct mm_struct *mm = vma->vm_mm;
1337
1338         mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1339         for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
1340                 unsigned long end;
1341
1342                 start = max(vma->vm_start, start_addr);
1343                 if (start >= vma->vm_end)
1344                         continue;
1345                 end = min(vma->vm_end, end_addr);
1346                 if (end <= vma->vm_start)
1347                         continue;
1348
1349                 if (vma->vm_flags & VM_ACCOUNT)
1350                         *nr_accounted += (end - start) >> PAGE_SHIFT;
1351
1352                 if (unlikely(is_pfn_mapping(vma)))
1353                         untrack_pfn_vma(vma, 0, 0);
1354
1355                 while (start != end) {
1356                         if (unlikely(is_vm_hugetlb_page(vma))) {
1357                                 /*
1358                                  * It is undesirable to test vma->vm_file as it
1359                                  * should be non-null for valid hugetlb area.
1360                                  * However, vm_file will be NULL in the error
1361                                  * cleanup path of do_mmap_pgoff. When
1362                                  * hugetlbfs ->mmap method fails,
1363                                  * do_mmap_pgoff() nullifies vma->vm_file
1364                                  * before calling this function to clean up.
1365                                  * Since no pte has actually been setup, it is
1366                                  * safe to do nothing in this case.
1367                                  */
1368                                 if (vma->vm_file) {
1369                                         mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
1370                                         __unmap_hugepage_range_final(vma, start, end, NULL);
1371                                         mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
1372                                 }
1373
1374                                 start = end;
1375                         } else
1376                                 start = unmap_page_range(tlb, vma, start, end, details);
1377                 }
1378         }
1379
1380         mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1381         return start;   /* which is now the end (or restart) address */
1382 }
1383
1384 /**
1385  * zap_page_range - remove user pages in a given range
1386  * @vma: vm_area_struct holding the applicable pages
1387  * @address: starting address of pages to zap
1388  * @size: number of bytes to zap
1389  * @details: details of nonlinear truncation or shared cache invalidation
1390  */
1391 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
1392                 unsigned long size, struct zap_details *details)
1393 {
1394         struct mm_struct *mm = vma->vm_mm;
1395         struct mmu_gather tlb;
1396         unsigned long end = address + size;
1397         unsigned long nr_accounted = 0;
1398
1399         lru_add_drain();
1400         tlb_gather_mmu(&tlb, mm, 0);
1401         update_hiwater_rss(mm);
1402         end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
1403         tlb_finish_mmu(&tlb, address, end);
1404         return end;
1405 }
1406
1407 /**
1408  * zap_vma_ptes - remove ptes mapping the vma
1409  * @vma: vm_area_struct holding ptes to be zapped
1410  * @address: starting address of pages to zap
1411  * @size: number of bytes to zap
1412  *
1413  * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1414  *
1415  * The entire address range must be fully contained within the vma.
1416  *
1417  * Returns 0 if successful.
1418  */
1419 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1420                 unsigned long size)
1421 {
1422         if (address < vma->vm_start || address + size > vma->vm_end ||
1423                         !(vma->vm_flags & VM_PFNMAP))
1424                 return -1;
1425         zap_page_range(vma, address, size, NULL);
1426         return 0;
1427 }
1428 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1429
1430 static inline bool can_follow_write_pte(pte_t pte, struct page *page,
1431                                         unsigned int flags)
1432 {
1433         if (pte_write(pte))
1434                 return true;
1435
1436         /*
1437          * Make sure that we are really following CoWed page. We do not really
1438          * have to care about exclusiveness of the page because we only want
1439          * to ensure that once COWed page hasn't disappeared in the meantime
1440          * or it hasn't been merged to a KSM page.
1441          */
1442         if ((flags & FOLL_FORCE) && (flags & FOLL_COW))
1443                 return page && PageAnon(page) && !PageKsm(page);
1444
1445         return false;
1446 }
1447
1448 /**
1449  * follow_page - look up a page descriptor from a user-virtual address
1450  * @vma: vm_area_struct mapping @address
1451  * @address: virtual address to look up
1452  * @flags: flags modifying lookup behaviour
1453  *
1454  * @flags can have FOLL_ flags set, defined in <linux/mm.h>
1455  *
1456  * Returns the mapped (struct page *), %NULL if no mapping exists, or
1457  * an error pointer if there is a mapping to something not represented
1458  * by a page descriptor (see also vm_normal_page()).
1459  */
1460 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1461                         unsigned int flags)
1462 {
1463         pgd_t *pgd;
1464         pud_t *pud;
1465         pmd_t *pmd;
1466         pte_t *ptep, pte;
1467         spinlock_t *ptl;
1468         struct page *page;
1469         struct mm_struct *mm = vma->vm_mm;
1470
1471         page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1472         if (!IS_ERR(page)) {
1473                 BUG_ON(flags & FOLL_GET);
1474                 goto out;
1475         }
1476
1477         page = NULL;
1478         pgd = pgd_offset(mm, address);
1479         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1480                 goto no_page_table;
1481
1482         pud = pud_offset(pgd, address);
1483         if (pud_none(*pud))
1484                 goto no_page_table;
1485         if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
1486                 BUG_ON(flags & FOLL_GET);
1487                 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1488                 goto out;
1489         }
1490         if (unlikely(pud_bad(*pud)))
1491                 goto no_page_table;
1492
1493         pmd = pmd_offset(pud, address);
1494         if (pmd_none(*pmd))
1495                 goto no_page_table;
1496         if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
1497                 BUG_ON(flags & FOLL_GET);
1498                 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1499                 goto out;
1500         }
1501         if (pmd_trans_huge(*pmd)) {
1502                 if (flags & FOLL_SPLIT) {
1503                         split_huge_page_pmd(mm, pmd);
1504                         goto split_fallthrough;
1505                 }
1506                 spin_lock(&mm->page_table_lock);
1507                 if (likely(pmd_trans_huge(*pmd))) {
1508                         if (unlikely(pmd_trans_splitting(*pmd))) {
1509                                 spin_unlock(&mm->page_table_lock);
1510                                 wait_split_huge_page(vma->anon_vma, pmd);
1511                         } else {
1512                                 page = follow_trans_huge_pmd(mm, address,
1513                                                              pmd, flags);
1514                                 spin_unlock(&mm->page_table_lock);
1515                                 goto out;
1516                         }
1517                 } else
1518                         spin_unlock(&mm->page_table_lock);
1519                 /* fall through */
1520         }
1521 split_fallthrough:
1522         if (unlikely(pmd_bad(*pmd)))
1523                 goto no_page_table;
1524
1525         ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1526
1527         pte = *ptep;
1528         if (!pte_present(pte))
1529                 goto no_page;
1530
1531         page = vm_normal_page(vma, address, pte);
1532         if ((flags & FOLL_WRITE) && !can_follow_write_pte(pte, page, flags)) {
1533                 pte_unmap_unlock(ptep, ptl);
1534                 return NULL;
1535         }
1536
1537         if (unlikely(!page)) {
1538                 if ((flags & FOLL_DUMP) ||
1539                     !is_zero_pfn(pte_pfn(pte)))
1540                         goto bad_page;
1541                 page = pte_page(pte);
1542         }
1543
1544         if (flags & FOLL_GET)
1545                 get_page_foll(page);
1546         if (flags & FOLL_TOUCH) {
1547                 if ((flags & FOLL_WRITE) &&
1548                     !pte_dirty(pte) && !PageDirty(page))
1549                         set_page_dirty(page);
1550                 /*
1551                  * pte_mkyoung() would be more correct here, but atomic care
1552                  * is needed to avoid losing the dirty bit: it is easier to use
1553                  * mark_page_accessed().
1554                  */
1555                 mark_page_accessed(page);
1556         }
1557         if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1558                 /*
1559                  * The preliminary mapping check is mainly to avoid the
1560                  * pointless overhead of lock_page on the ZERO_PAGE
1561                  * which might bounce very badly if there is contention.
1562                  *
1563                  * If the page is already locked, we don't need to
1564                  * handle it now - vmscan will handle it later if and
1565                  * when it attempts to reclaim the page.
1566                  */
1567                 if (page->mapping && trylock_page(page)) {
1568                         lru_add_drain();  /* push cached pages to LRU */
1569                         /*
1570                          * Because we lock page here and migration is
1571                          * blocked by the pte's page reference, we need
1572                          * only check for file-cache page truncation.
1573                          */
1574                         if (page->mapping)
1575                                 mlock_vma_page(page);
1576                         unlock_page(page);
1577                 }
1578         }
1579
1580         pte_unmap_unlock(ptep, ptl);
1581 out:
1582         return page;
1583
1584 bad_page:
1585         pte_unmap_unlock(ptep, ptl);
1586         return ERR_PTR(-EFAULT);
1587
1588 no_page:
1589         pte_unmap_unlock(ptep, ptl);
1590         if (!pte_none(pte))
1591                 return page;
1592
1593 no_page_table:
1594         /*
1595          * When core dumping an enormous anonymous area that nobody
1596          * has touched so far, we don't want to allocate unnecessary pages or
1597          * page tables.  Return error instead of NULL to skip handle_mm_fault,
1598          * then get_dump_page() will return NULL to leave a hole in the dump.
1599          * But we can only make this optimization where a hole would surely
1600          * be zero-filled if handle_mm_fault() actually did handle it.
1601          */
1602         if ((flags & FOLL_DUMP) &&
1603             (!vma->vm_ops || !vma->vm_ops->fault))
1604                 return ERR_PTR(-EFAULT);
1605         return page;
1606 }
1607
1608 /**
1609  * __get_user_pages() - pin user pages in memory
1610  * @tsk:        task_struct of target task
1611  * @mm:         mm_struct of target mm
1612  * @start:      starting user address
1613  * @nr_pages:   number of pages from start to pin
1614  * @gup_flags:  flags modifying pin behaviour
1615  * @pages:      array that receives pointers to the pages pinned.
1616  *              Should be at least nr_pages long. Or NULL, if caller
1617  *              only intends to ensure the pages are faulted in.
1618  * @vmas:       array of pointers to vmas corresponding to each page.
1619  *              Or NULL if the caller does not require them.
1620  * @nonblocking: whether waiting for disk IO or mmap_sem contention
1621  *
1622  * Returns number of pages pinned. This may be fewer than the number
1623  * requested. If nr_pages is 0 or negative, returns 0. If no pages
1624  * were pinned, returns -errno. Each page returned must be released
1625  * with a put_page() call when it is finished with. vmas will only
1626  * remain valid while mmap_sem is held.
1627  *
1628  * Must be called with mmap_sem held for read or write.
1629  *
1630  * __get_user_pages walks a process's page tables and takes a reference to
1631  * each struct page that each user address corresponds to at a given
1632  * instant. That is, it takes the page that would be accessed if a user
1633  * thread accesses the given user virtual address at that instant.
1634  *
1635  * This does not guarantee that the page exists in the user mappings when
1636  * __get_user_pages returns, and there may even be a completely different
1637  * page there in some cases (eg. if mmapped pagecache has been invalidated
1638  * and subsequently re faulted). However it does guarantee that the page
1639  * won't be freed completely. And mostly callers simply care that the page
1640  * contains data that was valid *at some point in time*. Typically, an IO
1641  * or similar operation cannot guarantee anything stronger anyway because
1642  * locks can't be held over the syscall boundary.
1643  *
1644  * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
1645  * the page is written to, set_page_dirty (or set_page_dirty_lock, as
1646  * appropriate) must be called after the page is finished with, and
1647  * before put_page is called.
1648  *
1649  * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
1650  * or mmap_sem contention, and if waiting is needed to pin all pages,
1651  * *@nonblocking will be set to 0.
1652  *
1653  * In most cases, get_user_pages or get_user_pages_fast should be used
1654  * instead of __get_user_pages. __get_user_pages should be used only if
1655  * you need some special @gup_flags.
1656  */
1657 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1658                      unsigned long start, int nr_pages, unsigned int gup_flags,
1659                      struct page **pages, struct vm_area_struct **vmas,
1660                      int *nonblocking)
1661 {
1662         int i;
1663         unsigned long vm_flags;
1664
1665         if (nr_pages <= 0)
1666                 return 0;
1667
1668         VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
1669
1670         /* 
1671          * Require read or write permissions.
1672          * If FOLL_FORCE is set, we only require the "MAY" flags.
1673          */
1674         vm_flags  = (gup_flags & FOLL_WRITE) ?
1675                         (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1676         vm_flags &= (gup_flags & FOLL_FORCE) ?
1677                         (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1678         i = 0;
1679
1680         do {
1681                 struct vm_area_struct *vma;
1682
1683                 vma = find_extend_vma(mm, start);
1684                 if (!vma && in_gate_area(mm, start)) {
1685                         unsigned long pg = start & PAGE_MASK;
1686                         pgd_t *pgd;
1687                         pud_t *pud;
1688                         pmd_t *pmd;
1689                         pte_t *pte;
1690
1691                         /* user gate pages are read-only */
1692                         if (gup_flags & FOLL_WRITE)
1693                                 return i ? : -EFAULT;
1694                         if (pg > TASK_SIZE)
1695                                 pgd = pgd_offset_k(pg);
1696                         else
1697                                 pgd = pgd_offset_gate(mm, pg);
1698                         BUG_ON(pgd_none(*pgd));
1699                         pud = pud_offset(pgd, pg);
1700                         BUG_ON(pud_none(*pud));
1701                         pmd = pmd_offset(pud, pg);
1702                         if (pmd_none(*pmd))
1703                                 return i ? : -EFAULT;
1704                         VM_BUG_ON(pmd_trans_huge(*pmd));
1705                         pte = pte_offset_map(pmd, pg);
1706                         if (pte_none(*pte)) {
1707                                 pte_unmap(pte);
1708                                 return i ? : -EFAULT;
1709                         }
1710                         vma = get_gate_vma(mm);
1711                         if (pages) {
1712                                 struct page *page;
1713
1714                                 page = vm_normal_page(vma, start, *pte);
1715                                 if (!page) {
1716                                         if (!(gup_flags & FOLL_DUMP) &&
1717                                              is_zero_pfn(pte_pfn(*pte)))
1718                                                 page = pte_page(*pte);
1719                                         else {
1720                                                 pte_unmap(pte);
1721                                                 return i ? : -EFAULT;
1722                                         }
1723                                 }
1724                                 pages[i] = page;
1725                                 get_page(page);
1726                         }
1727                         pte_unmap(pte);
1728                         goto next_page;
1729                 }
1730
1731                 if (!vma ||
1732                     (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
1733                     !(vm_flags & vma->vm_flags))
1734                         return i ? : -EFAULT;
1735
1736                 if (is_vm_hugetlb_page(vma)) {
1737                         i = follow_hugetlb_page(mm, vma, pages, vmas,
1738                                         &start, &nr_pages, i, gup_flags);
1739                         continue;
1740                 }
1741
1742                 do {
1743                         struct page *page;
1744                         unsigned int foll_flags = gup_flags;
1745
1746                         /*
1747                          * If we have a pending SIGKILL, don't keep faulting
1748                          * pages and potentially allocating memory.
1749                          */
1750                         if (unlikely(fatal_signal_pending(current)))
1751                                 return i ? i : -ERESTARTSYS;
1752
1753                         cond_resched();
1754                         while (!(page = follow_page(vma, start, foll_flags))) {
1755                                 int ret;
1756                                 unsigned int fault_flags = 0;
1757
1758                                 if (foll_flags & FOLL_WRITE)
1759                                         fault_flags |= FAULT_FLAG_WRITE;
1760                                 if (nonblocking)
1761                                         fault_flags |= FAULT_FLAG_ALLOW_RETRY;
1762                                 if (foll_flags & FOLL_NOWAIT)
1763                                         fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT);
1764
1765                                 ret = handle_mm_fault(mm, vma, start,
1766                                                         fault_flags);
1767
1768                                 if (ret & VM_FAULT_ERROR) {
1769                                         if (ret & VM_FAULT_OOM)
1770                                                 return i ? i : -ENOMEM;
1771                                         if (ret & (VM_FAULT_HWPOISON |
1772                                                    VM_FAULT_HWPOISON_LARGE)) {
1773                                                 if (i)
1774                                                         return i;
1775                                                 else if (gup_flags & FOLL_HWPOISON)
1776                                                         return -EHWPOISON;
1777                                                 else
1778                                                         return -EFAULT;
1779                                         }
1780                                         if (ret & (VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV))
1781                                                 return i ? i : -EFAULT;
1782                                         BUG();
1783                                 }
1784
1785                                 if (tsk) {
1786                                         if (ret & VM_FAULT_MAJOR)
1787                                                 tsk->maj_flt++;
1788                                         else
1789                                                 tsk->min_flt++;
1790                                 }
1791
1792                                 if (ret & VM_FAULT_RETRY) {
1793                                         if (nonblocking)
1794                                                 *nonblocking = 0;
1795                                         return i;
1796                                 }
1797
1798                                 /*
1799                                  * The VM_FAULT_WRITE bit tells us that
1800                                  * do_wp_page has broken COW when necessary,
1801                                  * even if maybe_mkwrite decided not to set
1802                                  * pte_write. We cannot simply drop FOLL_WRITE
1803                                  * here because the COWed page might be gone by
1804                                  * the time we do the subsequent page lookups.
1805                                  */
1806                                 if ((ret & VM_FAULT_WRITE) &&
1807                                     !(vma->vm_flags & VM_WRITE))
1808                                         foll_flags |= FOLL_COW;
1809
1810                                 cond_resched();
1811                         }
1812                         if (IS_ERR(page))
1813                                 return i ? i : PTR_ERR(page);
1814                         if (pages) {
1815                                 pages[i] = page;
1816
1817                                 flush_anon_page(vma, page, start);
1818                                 flush_dcache_page(page);
1819                         }
1820 next_page:
1821                         if (vmas)
1822                                 vmas[i] = vma;
1823                         i++;
1824                         start += PAGE_SIZE;
1825                         nr_pages--;
1826                 } while (nr_pages && start < vma->vm_end);
1827         } while (nr_pages);
1828         return i;
1829 }
1830 EXPORT_SYMBOL(__get_user_pages);
1831
1832 /*
1833  * fixup_user_fault() - manually resolve a user page fault
1834  * @tsk:        the task_struct to use for page fault accounting, or
1835  *              NULL if faults are not to be recorded.
1836  * @mm:         mm_struct of target mm
1837  * @address:    user address
1838  * @fault_flags:flags to pass down to handle_mm_fault()
1839  *
1840  * This is meant to be called in the specific scenario where for locking reasons
1841  * we try to access user memory in atomic context (within a pagefault_disable()
1842  * section), this returns -EFAULT, and we want to resolve the user fault before
1843  * trying again.
1844  *
1845  * Typically this is meant to be used by the futex code.
1846  *
1847  * The main difference with get_user_pages() is that this function will
1848  * unconditionally call handle_mm_fault() which will in turn perform all the
1849  * necessary SW fixup of the dirty and young bits in the PTE, while
1850  * handle_mm_fault() only guarantees to update these in the struct page.
1851  *
1852  * This is important for some architectures where those bits also gate the
1853  * access permission to the page because they are maintained in software.  On
1854  * such architectures, gup() will not be enough to make a subsequent access
1855  * succeed.
1856  *
1857  * This should be called with the mm_sem held for read.
1858  */
1859 int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
1860                      unsigned long address, unsigned int fault_flags)
1861 {
1862         struct vm_area_struct *vma;
1863         vm_flags_t vm_flags;
1864         int ret;
1865
1866         vma = find_extend_vma(mm, address);
1867         if (!vma || address < vma->vm_start)
1868                 return -EFAULT;
1869
1870         vm_flags = (fault_flags & FAULT_FLAG_WRITE) ? VM_WRITE : VM_READ;
1871         if (!(vm_flags & vma->vm_flags))
1872                 return -EFAULT;
1873
1874         ret = handle_mm_fault(mm, vma, address, fault_flags);
1875         if (ret & VM_FAULT_ERROR) {
1876                 if (ret & VM_FAULT_OOM)
1877                         return -ENOMEM;
1878                 if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE))
1879                         return -EHWPOISON;
1880                 if (ret & (VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV))
1881                         return -EFAULT;
1882                 BUG();
1883         }
1884         if (tsk) {
1885                 if (ret & VM_FAULT_MAJOR)
1886                         tsk->maj_flt++;
1887                 else
1888                         tsk->min_flt++;
1889         }
1890         return 0;
1891 }
1892
1893 /*
1894  * get_user_pages() - pin user pages in memory
1895  * @tsk:        the task_struct to use for page fault accounting, or
1896  *              NULL if faults are not to be recorded.
1897  * @mm:         mm_struct of target mm
1898  * @start:      starting user address
1899  * @nr_pages:   number of pages from start to pin
1900  * @write:      whether pages will be written to by the caller
1901  * @force:      whether to force write access even if user mapping is
1902  *              readonly. This will result in the page being COWed even
1903  *              in MAP_SHARED mappings. You do not want this.
1904  * @pages:      array that receives pointers to the pages pinned.
1905  *              Should be at least nr_pages long. Or NULL, if caller
1906  *              only intends to ensure the pages are faulted in.
1907  * @vmas:       array of pointers to vmas corresponding to each page.
1908  *              Or NULL if the caller does not require them.
1909  *
1910  * Returns number of pages pinned. This may be fewer than the number
1911  * requested. If nr_pages is 0 or negative, returns 0. If no pages
1912  * were pinned, returns -errno. Each page returned must be released
1913  * with a put_page() call when it is finished with. vmas will only
1914  * remain valid while mmap_sem is held.
1915  *
1916  * Must be called with mmap_sem held for read or write.
1917  *
1918  * get_user_pages walks a process's page tables and takes a reference to
1919  * each struct page that each user address corresponds to at a given
1920  * instant. That is, it takes the page that would be accessed if a user
1921  * thread accesses the given user virtual address at that instant.
1922  *
1923  * This does not guarantee that the page exists in the user mappings when
1924  * get_user_pages returns, and there may even be a completely different
1925  * page there in some cases (eg. if mmapped pagecache has been invalidated
1926  * and subsequently re faulted). However it does guarantee that the page
1927  * won't be freed completely. And mostly callers simply care that the page
1928  * contains data that was valid *at some point in time*. Typically, an IO
1929  * or similar operation cannot guarantee anything stronger anyway because
1930  * locks can't be held over the syscall boundary.
1931  *
1932  * If write=0, the page must not be written to. If the page is written to,
1933  * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1934  * after the page is finished with, and before put_page is called.
1935  *
1936  * get_user_pages is typically used for fewer-copy IO operations, to get a
1937  * handle on the memory by some means other than accesses via the user virtual
1938  * addresses. The pages may be submitted for DMA to devices or accessed via
1939  * their kernel linear mapping (via the kmap APIs). Care should be taken to
1940  * use the correct cache flushing APIs.
1941  *
1942  * See also get_user_pages_fast, for performance critical applications.
1943  */
1944 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1945                 unsigned long start, int nr_pages, int write, int force,
1946                 struct page **pages, struct vm_area_struct **vmas)
1947 {
1948         int flags = FOLL_TOUCH;
1949
1950         if (pages)
1951                 flags |= FOLL_GET;
1952         if (write)
1953                 flags |= FOLL_WRITE;
1954         if (force)
1955                 flags |= FOLL_FORCE;
1956
1957         return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
1958                                 NULL);
1959 }
1960 EXPORT_SYMBOL(get_user_pages);
1961
1962 /**
1963  * get_dump_page() - pin user page in memory while writing it to core dump
1964  * @addr: user address
1965  *
1966  * Returns struct page pointer of user page pinned for dump,
1967  * to be freed afterwards by page_cache_release() or put_page().
1968  *
1969  * Returns NULL on any kind of failure - a hole must then be inserted into
1970  * the corefile, to preserve alignment with its headers; and also returns
1971  * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
1972  * allowing a hole to be left in the corefile to save diskspace.
1973  *
1974  * Called without mmap_sem, but after all other threads have been killed.
1975  */
1976 #ifdef CONFIG_ELF_CORE
1977 struct page *get_dump_page(unsigned long addr)
1978 {
1979         struct vm_area_struct *vma;
1980         struct page *page;
1981
1982         if (__get_user_pages(current, current->mm, addr, 1,
1983                              FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
1984                              NULL) < 1)
1985                 return NULL;
1986         flush_cache_page(vma, addr, page_to_pfn(page));
1987         return page;
1988 }
1989 #endif /* CONFIG_ELF_CORE */
1990
1991 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1992                         spinlock_t **ptl)
1993 {
1994         pgd_t * pgd = pgd_offset(mm, addr);
1995         pud_t * pud = pud_alloc(mm, pgd, addr);
1996         if (pud) {
1997                 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1998                 if (pmd) {
1999                         VM_BUG_ON(pmd_trans_huge(*pmd));
2000                         return pte_alloc_map_lock(mm, pmd, addr, ptl);
2001                 }
2002         }
2003         return NULL;
2004 }
2005
2006 /*
2007  * This is the old fallback for page remapping.
2008  *
2009  * For historical reasons, it only allows reserved pages. Only
2010  * old drivers should use this, and they needed to mark their
2011  * pages reserved for the old functions anyway.
2012  */
2013 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
2014                         struct page *page, pgprot_t prot)
2015 {
2016         struct mm_struct *mm = vma->vm_mm;
2017         int retval;
2018         pte_t *pte;
2019         spinlock_t *ptl;
2020
2021         retval = -EINVAL;
2022         if (PageAnon(page))
2023                 goto out;
2024         retval = -ENOMEM;
2025         flush_dcache_page(page);
2026         pte = get_locked_pte(mm, addr, &ptl);
2027         if (!pte)
2028                 goto out;
2029         retval = -EBUSY;
2030         if (!pte_none(*pte))
2031                 goto out_unlock;
2032
2033         /* Ok, finally just insert the thing.. */
2034         get_page(page);
2035         inc_mm_counter_fast(mm, MM_FILEPAGES);
2036         page_add_file_rmap(page);
2037         set_pte_at(mm, addr, pte, mk_pte(page, prot));
2038
2039         retval = 0;
2040         pte_unmap_unlock(pte, ptl);
2041         return retval;
2042 out_unlock:
2043         pte_unmap_unlock(pte, ptl);
2044 out:
2045         return retval;
2046 }
2047
2048 /**
2049  * vm_insert_page - insert single page into user vma
2050  * @vma: user vma to map to
2051  * @addr: target user address of this page
2052  * @page: source kernel page
2053  *
2054  * This allows drivers to insert individual pages they've allocated
2055  * into a user vma.
2056  *
2057  * The page has to be a nice clean _individual_ kernel allocation.
2058  * If you allocate a compound page, you need to have marked it as
2059  * such (__GFP_COMP), or manually just split the page up yourself
2060  * (see split_page()).
2061  *
2062  * NOTE! Traditionally this was done with "remap_pfn_range()" which
2063  * took an arbitrary page protection parameter. This doesn't allow
2064  * that. Your vma protection will have to be set up correctly, which
2065  * means that if you want a shared writable mapping, you'd better
2066  * ask for a shared writable mapping!
2067  *
2068  * The page does not need to be reserved.
2069  */
2070 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
2071                         struct page *page)
2072 {
2073         if (addr < vma->vm_start || addr >= vma->vm_end)
2074                 return -EFAULT;
2075         if (!page_count(page))
2076                 return -EINVAL;
2077         vma->vm_flags |= VM_INSERTPAGE;
2078         return insert_page(vma, addr, page, vma->vm_page_prot);
2079 }
2080 EXPORT_SYMBOL(vm_insert_page);
2081
2082 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2083                         unsigned long pfn, pgprot_t prot)
2084 {
2085         struct mm_struct *mm = vma->vm_mm;
2086         int retval;
2087         pte_t *pte, entry;
2088         spinlock_t *ptl;
2089
2090         retval = -ENOMEM;
2091         pte = get_locked_pte(mm, addr, &ptl);
2092         if (!pte)
2093                 goto out;
2094         retval = -EBUSY;
2095         if (!pte_none(*pte))
2096                 goto out_unlock;
2097
2098         /* Ok, finally just insert the thing.. */
2099         entry = pte_mkspecial(pfn_pte(pfn, prot));
2100         set_pte_at(mm, addr, pte, entry);
2101         update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2102
2103         retval = 0;
2104 out_unlock:
2105         pte_unmap_unlock(pte, ptl);
2106 out:
2107         return retval;
2108 }
2109
2110 /**
2111  * vm_insert_pfn - insert single pfn into user vma
2112  * @vma: user vma to map to
2113  * @addr: target user address of this page
2114  * @pfn: source kernel pfn
2115  *
2116  * Similar to vm_inert_page, this allows drivers to insert individual pages
2117  * they've allocated into a user vma. Same comments apply.
2118  *
2119  * This function should only be called from a vm_ops->fault handler, and
2120  * in that case the handler should return NULL.
2121  *
2122  * vma cannot be a COW mapping.
2123  *
2124  * As this is called only for pages that do not currently exist, we
2125  * do not need to flush old virtual caches or the TLB.
2126  */
2127 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2128                         unsigned long pfn)
2129 {
2130         int ret;
2131         pgprot_t pgprot = vma->vm_page_prot;
2132         /*
2133          * Technically, architectures with pte_special can avoid all these
2134          * restrictions (same for remap_pfn_range).  However we would like
2135          * consistency in testing and feature parity among all, so we should
2136          * try to keep these invariants in place for everybody.
2137          */
2138         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
2139         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
2140                                                 (VM_PFNMAP|VM_MIXEDMAP));
2141         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2142         BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2143
2144         if (addr < vma->vm_start || addr >= vma->vm_end)
2145                 return -EFAULT;
2146         if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
2147                 return -EINVAL;
2148
2149         ret = insert_pfn(vma, addr, pfn, pgprot);
2150
2151         if (ret)
2152                 untrack_pfn_vma(vma, pfn, PAGE_SIZE);
2153
2154         return ret;
2155 }
2156 EXPORT_SYMBOL(vm_insert_pfn);
2157
2158 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2159                         unsigned long pfn)
2160 {
2161         BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
2162
2163         if (addr < vma->vm_start || addr >= vma->vm_end)
2164                 return -EFAULT;
2165
2166         /*
2167          * If we don't have pte special, then we have to use the pfn_valid()
2168          * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2169          * refcount the page if pfn_valid is true (hence insert_page rather
2170          * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
2171          * without pte special, it would there be refcounted as a normal page.
2172          */
2173         if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
2174                 struct page *page;
2175
2176                 page = pfn_to_page(pfn);
2177                 return insert_page(vma, addr, page, vma->vm_page_prot);
2178         }
2179         return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
2180 }
2181 EXPORT_SYMBOL(vm_insert_mixed);
2182
2183 /*
2184  * maps a range of physical memory into the requested pages. the old
2185  * mappings are removed. any references to nonexistent pages results
2186  * in null mappings (currently treated as "copy-on-access")
2187  */
2188 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2189                         unsigned long addr, unsigned long end,
2190                         unsigned long pfn, pgprot_t prot)
2191 {
2192         pte_t *pte;
2193         spinlock_t *ptl;
2194
2195         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2196         if (!pte)
2197                 return -ENOMEM;
2198         arch_enter_lazy_mmu_mode();
2199         do {
2200                 BUG_ON(!pte_none(*pte));
2201                 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2202                 pfn++;
2203         } while (pte++, addr += PAGE_SIZE, addr != end);
2204         arch_leave_lazy_mmu_mode();
2205         pte_unmap_unlock(pte - 1, ptl);
2206         return 0;
2207 }
2208
2209 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2210                         unsigned long addr, unsigned long end,
2211                         unsigned long pfn, pgprot_t prot)
2212 {
2213         pmd_t *pmd;
2214         unsigned long next;
2215
2216         pfn -= addr >> PAGE_SHIFT;
2217         pmd = pmd_alloc(mm, pud, addr);
2218         if (!pmd)
2219                 return -ENOMEM;
2220         VM_BUG_ON(pmd_trans_huge(*pmd));
2221         do {
2222                 next = pmd_addr_end(addr, end);
2223                 if (remap_pte_range(mm, pmd, addr, next,
2224                                 pfn + (addr >> PAGE_SHIFT), prot))
2225                         return -ENOMEM;
2226         } while (pmd++, addr = next, addr != end);
2227         return 0;
2228 }
2229
2230 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
2231                         unsigned long addr, unsigned long end,
2232                         unsigned long pfn, pgprot_t prot)
2233 {
2234         pud_t *pud;
2235         unsigned long next;
2236
2237         pfn -= addr >> PAGE_SHIFT;
2238         pud = pud_alloc(mm, pgd, addr);
2239         if (!pud)
2240                 return -ENOMEM;
2241         do {
2242                 next = pud_addr_end(addr, end);
2243                 if (remap_pmd_range(mm, pud, addr, next,
2244                                 pfn + (addr >> PAGE_SHIFT), prot))
2245                         return -ENOMEM;
2246         } while (pud++, addr = next, addr != end);
2247         return 0;
2248 }
2249
2250 /**
2251  * remap_pfn_range - remap kernel memory to userspace
2252  * @vma: user vma to map to
2253  * @addr: target user address to start at
2254  * @pfn: physical address of kernel memory
2255  * @size: size of map area
2256  * @prot: page protection flags for this mapping
2257  *
2258  *  Note: this is only safe if the mm semaphore is held when called.
2259  */
2260 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2261                     unsigned long pfn, unsigned long size, pgprot_t prot)
2262 {
2263         pgd_t *pgd;
2264         unsigned long next;
2265         unsigned long end = addr + PAGE_ALIGN(size);
2266         struct mm_struct *mm = vma->vm_mm;
2267         int err;
2268
2269         /*
2270          * Physically remapped pages are special. Tell the
2271          * rest of the world about it:
2272          *   VM_IO tells people not to look at these pages
2273          *      (accesses can have side effects).
2274          *   VM_RESERVED is specified all over the place, because
2275          *      in 2.4 it kept swapout's vma scan off this vma; but
2276          *      in 2.6 the LRU scan won't even find its pages, so this
2277          *      flag means no more than count its pages in reserved_vm,
2278          *      and omit it from core dump, even when VM_IO turned off.
2279          *   VM_PFNMAP tells the core MM that the base pages are just
2280          *      raw PFN mappings, and do not have a "struct page" associated
2281          *      with them.
2282          *
2283          * There's a horrible special case to handle copy-on-write
2284          * behaviour that some programs depend on. We mark the "original"
2285          * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2286          */
2287         if (addr == vma->vm_start && end == vma->vm_end) {
2288                 vma->vm_pgoff = pfn;
2289                 vma->vm_flags |= VM_PFN_AT_MMAP;
2290         } else if (is_cow_mapping(vma->vm_flags))
2291                 return -EINVAL;
2292
2293         vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
2294
2295         err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
2296         if (err) {
2297                 /*
2298                  * To indicate that track_pfn related cleanup is not
2299                  * needed from higher level routine calling unmap_vmas
2300                  */
2301                 vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
2302                 vma->vm_flags &= ~VM_PFN_AT_MMAP;
2303                 return -EINVAL;
2304         }
2305
2306         BUG_ON(addr >= end);
2307         pfn -= addr >> PAGE_SHIFT;
2308         pgd = pgd_offset(mm, addr);
2309         flush_cache_range(vma, addr, end);
2310         do {
2311                 next = pgd_addr_end(addr, end);
2312                 err = remap_pud_range(mm, pgd, addr, next,
2313                                 pfn + (addr >> PAGE_SHIFT), prot);
2314                 if (err)
2315                         break;
2316         } while (pgd++, addr = next, addr != end);
2317
2318         if (err)
2319                 untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
2320
2321         return err;
2322 }
2323 EXPORT_SYMBOL(remap_pfn_range);
2324
2325 /**
2326  * vm_iomap_memory - remap memory to userspace
2327  * @vma: user vma to map to
2328  * @start: start of area
2329  * @len: size of area
2330  *
2331  * This is a simplified io_remap_pfn_range() for common driver use. The
2332  * driver just needs to give us the physical memory range to be mapped,
2333  * we'll figure out the rest from the vma information.
2334  *
2335  * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2336  * whatever write-combining details or similar.
2337  */
2338 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2339 {
2340         unsigned long vm_len, pfn, pages;
2341
2342         /* Check that the physical memory area passed in looks valid */
2343         if (start + len < start)
2344                 return -EINVAL;
2345         /*
2346          * You *really* shouldn't map things that aren't page-aligned,
2347          * but we've historically allowed it because IO memory might
2348          * just have smaller alignment.
2349          */
2350         len += start & ~PAGE_MASK;
2351         pfn = start >> PAGE_SHIFT;
2352         pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2353         if (pfn + pages < pfn)
2354                 return -EINVAL;
2355
2356         /* We start the mapping 'vm_pgoff' pages into the area */
2357         if (vma->vm_pgoff > pages)
2358                 return -EINVAL;
2359         pfn += vma->vm_pgoff;
2360         pages -= vma->vm_pgoff;
2361
2362         /* Can we fit all of the mapping? */
2363         vm_len = vma->vm_end - vma->vm_start;
2364         if (vm_len >> PAGE_SHIFT > pages)
2365                 return -EINVAL;
2366
2367         /* Ok, let it rip */
2368         return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2369 }
2370 EXPORT_SYMBOL(vm_iomap_memory);
2371
2372 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2373                                      unsigned long addr, unsigned long end,
2374                                      pte_fn_t fn, void *data)
2375 {
2376         pte_t *pte;
2377         int err;
2378         pgtable_t token;
2379         spinlock_t *uninitialized_var(ptl);
2380
2381         pte = (mm == &init_mm) ?
2382                 pte_alloc_kernel(pmd, addr) :
2383                 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2384         if (!pte)
2385                 return -ENOMEM;
2386
2387         BUG_ON(pmd_huge(*pmd));
2388
2389         arch_enter_lazy_mmu_mode();
2390
2391         token = pmd_pgtable(*pmd);
2392
2393         do {
2394                 err = fn(pte++, token, addr, data);
2395                 if (err)
2396                         break;
2397         } while (addr += PAGE_SIZE, addr != end);
2398
2399         arch_leave_lazy_mmu_mode();
2400
2401         if (mm != &init_mm)
2402                 pte_unmap_unlock(pte-1, ptl);
2403         return err;
2404 }
2405
2406 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2407                                      unsigned long addr, unsigned long end,
2408                                      pte_fn_t fn, void *data)
2409 {
2410         pmd_t *pmd;
2411         unsigned long next;
2412         int err;
2413
2414         BUG_ON(pud_huge(*pud));
2415
2416         pmd = pmd_alloc(mm, pud, addr);
2417         if (!pmd)
2418                 return -ENOMEM;
2419         do {
2420                 next = pmd_addr_end(addr, end);
2421                 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2422                 if (err)
2423                         break;
2424         } while (pmd++, addr = next, addr != end);
2425         return err;
2426 }
2427
2428 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
2429                                      unsigned long addr, unsigned long end,
2430                                      pte_fn_t fn, void *data)
2431 {
2432         pud_t *pud;
2433         unsigned long next;
2434         int err;
2435
2436         pud = pud_alloc(mm, pgd, addr);
2437         if (!pud)
2438                 return -ENOMEM;
2439         do {
2440                 next = pud_addr_end(addr, end);
2441                 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2442                 if (err)
2443                         break;
2444         } while (pud++, addr = next, addr != end);
2445         return err;
2446 }
2447
2448 /*
2449  * Scan a region of virtual memory, filling in page tables as necessary
2450  * and calling a provided function on each leaf page table.
2451  */
2452 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2453                         unsigned long size, pte_fn_t fn, void *data)
2454 {
2455         pgd_t *pgd;
2456         unsigned long next;
2457         unsigned long end = addr + size;
2458         int err;
2459
2460         BUG_ON(addr >= end);
2461         pgd = pgd_offset(mm, addr);
2462         do {
2463                 next = pgd_addr_end(addr, end);
2464                 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
2465                 if (err)
2466                         break;
2467         } while (pgd++, addr = next, addr != end);
2468
2469         return err;
2470 }
2471 EXPORT_SYMBOL_GPL(apply_to_page_range);
2472
2473 /*
2474  * handle_pte_fault chooses page fault handler according to an entry
2475  * which was read non-atomically.  Before making any commitment, on
2476  * those architectures or configurations (e.g. i386 with PAE) which
2477  * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
2478  * must check under lock before unmapping the pte and proceeding
2479  * (but do_wp_page is only called after already making such a check;
2480  * and do_anonymous_page can safely check later on).
2481  */
2482 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2483                                 pte_t *page_table, pte_t orig_pte)
2484 {
2485         int same = 1;
2486 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2487         if (sizeof(pte_t) > sizeof(unsigned long)) {
2488                 spinlock_t *ptl = pte_lockptr(mm, pmd);
2489                 spin_lock(ptl);
2490                 same = pte_same(*page_table, orig_pte);
2491                 spin_unlock(ptl);
2492         }
2493 #endif
2494         pte_unmap(page_table);
2495         return same;
2496 }
2497
2498 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2499 {
2500         /*
2501          * If the source page was a PFN mapping, we don't have
2502          * a "struct page" for it. We do a best-effort copy by
2503          * just copying from the original user address. If that
2504          * fails, we just zero-fill it. Live with it.
2505          */
2506         if (unlikely(!src)) {
2507                 void *kaddr = kmap_atomic(dst, KM_USER0);
2508                 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2509
2510                 /*
2511                  * This really shouldn't fail, because the page is there
2512                  * in the page tables. But it might just be unreadable,
2513                  * in which case we just give up and fill the result with
2514                  * zeroes.
2515                  */
2516                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2517                         clear_page(kaddr);
2518                 kunmap_atomic(kaddr, KM_USER0);
2519                 flush_dcache_page(dst);
2520         } else
2521                 copy_user_highpage(dst, src, va, vma);
2522 }
2523
2524 /*
2525  * This routine handles present pages, when users try to write
2526  * to a shared page. It is done by copying the page to a new address
2527  * and decrementing the shared-page counter for the old page.
2528  *
2529  * Note that this routine assumes that the protection checks have been
2530  * done by the caller (the low-level page fault routine in most cases).
2531  * Thus we can safely just mark it writable once we've done any necessary
2532  * COW.
2533  *
2534  * We also mark the page dirty at this point even though the page will
2535  * change only once the write actually happens. This avoids a few races,
2536  * and potentially makes it more efficient.
2537  *
2538  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2539  * but allow concurrent faults), with pte both mapped and locked.
2540  * We return with mmap_sem still held, but pte unmapped and unlocked.
2541  */
2542 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
2543                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2544                 spinlock_t *ptl, pte_t orig_pte)
2545         __releases(ptl)
2546 {
2547         struct page *old_page, *new_page;
2548         pte_t entry;
2549         int ret = 0;
2550         int page_mkwrite = 0;
2551         struct page *dirty_page = NULL;
2552
2553         old_page = vm_normal_page(vma, address, orig_pte);
2554         if (!old_page) {
2555                 /*
2556                  * VM_MIXEDMAP !pfn_valid() case
2557                  *
2558                  * We should not cow pages in a shared writeable mapping.
2559                  * Just mark the pages writable as we can't do any dirty
2560                  * accounting on raw pfn maps.
2561                  */
2562                 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2563                                      (VM_WRITE|VM_SHARED))
2564                         goto reuse;
2565                 goto gotten;
2566         }
2567
2568         /*
2569          * Take out anonymous pages first, anonymous shared vmas are
2570          * not dirty accountable.
2571          */
2572         if (PageAnon(old_page) && !PageKsm(old_page)) {
2573                 if (!trylock_page(old_page)) {
2574                         page_cache_get(old_page);
2575                         pte_unmap_unlock(page_table, ptl);
2576                         lock_page(old_page);
2577                         page_table = pte_offset_map_lock(mm, pmd, address,
2578                                                          &ptl);
2579                         if (!pte_same(*page_table, orig_pte)) {
2580                                 unlock_page(old_page);
2581                                 goto unlock;
2582                         }
2583                         page_cache_release(old_page);
2584                 }
2585                 if (reuse_swap_page(old_page)) {
2586                         /*
2587                          * The page is all ours.  Move it to our anon_vma so
2588                          * the rmap code will not search our parent or siblings.
2589                          * Protected against the rmap code by the page lock.
2590                          */
2591                         page_move_anon_rmap(old_page, vma, address);
2592                         unlock_page(old_page);
2593                         goto reuse;
2594                 }
2595                 unlock_page(old_page);
2596         } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2597                                         (VM_WRITE|VM_SHARED))) {
2598                 /*
2599                  * Only catch write-faults on shared writable pages,
2600                  * read-only shared pages can get COWed by
2601                  * get_user_pages(.write=1, .force=1).
2602                  */
2603                 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2604                         struct vm_fault vmf;
2605                         int tmp;
2606
2607                         vmf.virtual_address = (void __user *)(address &
2608                                                                 PAGE_MASK);
2609                         vmf.pgoff = old_page->index;
2610                         vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2611                         vmf.page = old_page;
2612
2613                         /*
2614                          * Notify the address space that the page is about to
2615                          * become writable so that it can prohibit this or wait
2616                          * for the page to get into an appropriate state.
2617                          *
2618                          * We do this without the lock held, so that it can
2619                          * sleep if it needs to.
2620                          */
2621                         page_cache_get(old_page);
2622                         pte_unmap_unlock(page_table, ptl);
2623
2624                         tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2625                         if (unlikely(tmp &
2626                                         (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2627                                 ret = tmp;
2628                                 goto unwritable_page;
2629                         }
2630                         if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2631                                 lock_page(old_page);
2632                                 if (!old_page->mapping) {
2633                                         ret = 0; /* retry the fault */
2634                                         unlock_page(old_page);
2635                                         goto unwritable_page;
2636                                 }
2637                         } else
2638                                 VM_BUG_ON(!PageLocked(old_page));
2639
2640                         /*
2641                          * Since we dropped the lock we need to revalidate
2642                          * the PTE as someone else may have changed it.  If
2643                          * they did, we just return, as we can count on the
2644                          * MMU to tell us if they didn't also make it writable.
2645                          */
2646                         page_table = pte_offset_map_lock(mm, pmd, address,
2647                                                          &ptl);
2648                         if (!pte_same(*page_table, orig_pte)) {
2649                                 unlock_page(old_page);
2650                                 goto unlock;
2651                         }
2652
2653                         page_mkwrite = 1;
2654                 }
2655                 dirty_page = old_page;
2656                 get_page(dirty_page);
2657
2658 reuse:
2659                 flush_cache_page(vma, address, pte_pfn(orig_pte));
2660                 entry = pte_mkyoung(orig_pte);
2661                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2662                 if (ptep_set_access_flags(vma, address, page_table, entry,1))
2663                         update_mmu_cache(vma, address, page_table);
2664                 pte_unmap_unlock(page_table, ptl);
2665                 ret |= VM_FAULT_WRITE;
2666
2667                 if (!dirty_page)
2668                         return ret;
2669
2670                 if (!page_mkwrite) {
2671                         struct address_space *mapping;
2672                         int dirtied;
2673
2674                         lock_page(dirty_page);
2675                         dirtied = set_page_dirty(dirty_page);
2676                         VM_BUG_ON(PageAnon(dirty_page));
2677                         mapping = dirty_page->mapping;
2678                         unlock_page(dirty_page);
2679
2680                         if (dirtied && mapping) {
2681                                 /*
2682                                  * Some device drivers do not set page.mapping
2683                                  * but still dirty their pages
2684                                  */
2685                                 balance_dirty_pages_ratelimited(mapping);
2686                         }
2687
2688                 }
2689                 put_page(dirty_page);
2690                 if (page_mkwrite) {
2691                         struct address_space *mapping = dirty_page->mapping;
2692
2693                         set_page_dirty(dirty_page);
2694                         unlock_page(dirty_page);
2695                         page_cache_release(dirty_page);
2696                         if (mapping)    {
2697                                 /*
2698                                  * Some device drivers do not set page.mapping
2699                                  * but still dirty their pages
2700                                  */
2701                                 balance_dirty_pages_ratelimited(mapping);
2702                         }
2703                 }
2704
2705                 /* file_update_time outside page_lock */
2706                 if (vma->vm_file)
2707                         file_update_time(vma->vm_file);
2708
2709                 return ret;
2710         }
2711
2712         /*
2713          * Ok, we need to copy. Oh, well..
2714          */
2715         page_cache_get(old_page);
2716 gotten:
2717         pte_unmap_unlock(page_table, ptl);
2718
2719         if (unlikely(anon_vma_prepare(vma)))
2720                 goto oom;
2721
2722         if (is_zero_pfn(pte_pfn(orig_pte))) {
2723                 new_page = alloc_zeroed_user_highpage_movable(vma, address);
2724                 if (!new_page)
2725                         goto oom;
2726         } else {
2727                 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2728                 if (!new_page)
2729                         goto oom;
2730                 cow_user_page(new_page, old_page, address, vma);
2731         }
2732         __SetPageUptodate(new_page);
2733
2734         if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2735                 goto oom_free_new;
2736
2737         /*
2738          * Re-check the pte - we dropped the lock
2739          */
2740         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2741         if (likely(pte_same(*page_table, orig_pte))) {
2742                 if (old_page) {
2743                         if (!PageAnon(old_page)) {
2744                                 dec_mm_counter_fast(mm, MM_FILEPAGES);
2745                                 inc_mm_counter_fast(mm, MM_ANONPAGES);
2746                         }
2747                 } else
2748                         inc_mm_counter_fast(mm, MM_ANONPAGES);
2749                 flush_cache_page(vma, address, pte_pfn(orig_pte));
2750                 entry = mk_pte(new_page, vma->vm_page_prot);
2751                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2752                 /*
2753                  * Clear the pte entry and flush it first, before updating the
2754                  * pte with the new entry. This will avoid a race condition
2755                  * seen in the presence of one thread doing SMC and another
2756                  * thread doing COW.
2757                  */
2758                 ptep_clear_flush(vma, address, page_table);
2759                 page_add_new_anon_rmap(new_page, vma, address);
2760                 /*
2761                  * We call the notify macro here because, when using secondary
2762                  * mmu page tables (such as kvm shadow page tables), we want the
2763                  * new page to be mapped directly into the secondary page table.
2764                  */
2765                 set_pte_at_notify(mm, address, page_table, entry);
2766                 update_mmu_cache(vma, address, page_table);
2767                 if (old_page) {
2768                         /*
2769                          * Only after switching the pte to the new page may
2770                          * we remove the mapcount here. Otherwise another
2771                          * process may come and find the rmap count decremented
2772                          * before the pte is switched to the new page, and
2773                          * "reuse" the old page writing into it while our pte
2774                          * here still points into it and can be read by other
2775                          * threads.
2776                          *
2777                          * The critical issue is to order this
2778                          * page_remove_rmap with the ptp_clear_flush above.
2779                          * Those stores are ordered by (if nothing else,)
2780                          * the barrier present in the atomic_add_negative
2781                          * in page_remove_rmap.
2782                          *
2783                          * Then the TLB flush in ptep_clear_flush ensures that
2784                          * no process can access the old page before the
2785                          * decremented mapcount is visible. And the old page
2786                          * cannot be reused until after the decremented
2787                          * mapcount is visible. So transitively, TLBs to
2788                          * old page will be flushed before it can be reused.
2789                          */
2790                         page_remove_rmap(old_page);
2791                 }
2792
2793                 /* Free the old page.. */
2794                 new_page = old_page;
2795                 ret |= VM_FAULT_WRITE;
2796         } else
2797                 mem_cgroup_uncharge_page(new_page);
2798
2799         if (new_page)
2800                 page_cache_release(new_page);
2801 unlock:
2802         pte_unmap_unlock(page_table, ptl);
2803         if (old_page) {
2804                 /*
2805                  * Don't let another task, with possibly unlocked vma,
2806                  * keep the mlocked page.
2807                  */
2808                 if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
2809                         lock_page(old_page);    /* LRU manipulation */
2810                         munlock_vma_page(old_page);
2811                         unlock_page(old_page);
2812                 }
2813                 page_cache_release(old_page);
2814         }
2815         return ret;
2816 oom_free_new:
2817         page_cache_release(new_page);
2818 oom:
2819         if (old_page) {
2820                 if (page_mkwrite) {
2821                         unlock_page(old_page);
2822                         page_cache_release(old_page);
2823                 }
2824                 page_cache_release(old_page);
2825         }
2826         return VM_FAULT_OOM;
2827
2828 unwritable_page:
2829         page_cache_release(old_page);
2830         return ret;
2831 }
2832
2833 static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2834                 unsigned long start_addr, unsigned long end_addr,
2835                 struct zap_details *details)
2836 {
2837         zap_page_range(vma, start_addr, end_addr - start_addr, details);
2838 }
2839
2840 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
2841                                             struct zap_details *details)
2842 {
2843         struct vm_area_struct *vma;
2844         struct prio_tree_iter iter;
2845         pgoff_t vba, vea, zba, zea;
2846
2847         vma_prio_tree_foreach(vma, &iter, root,
2848                         details->first_index, details->last_index) {
2849
2850                 vba = vma->vm_pgoff;
2851                 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
2852                 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2853                 zba = details->first_index;
2854                 if (zba < vba)
2855                         zba = vba;
2856                 zea = details->last_index;
2857                 if (zea > vea)
2858                         zea = vea;
2859
2860                 unmap_mapping_range_vma(vma,
2861                         ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2862                         ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2863                                 details);
2864         }
2865 }
2866
2867 static inline void unmap_mapping_range_list(struct list_head *head,
2868                                             struct zap_details *details)
2869 {
2870         struct vm_area_struct *vma;
2871
2872         /*
2873          * In nonlinear VMAs there is no correspondence between virtual address
2874          * offset and file offset.  So we must perform an exhaustive search
2875          * across *all* the pages in each nonlinear VMA, not just the pages
2876          * whose virtual address lies outside the file truncation point.
2877          */
2878         list_for_each_entry(vma, head, shared.vm_set.list) {
2879                 details->nonlinear_vma = vma;
2880                 unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
2881         }
2882 }
2883
2884 /**
2885  * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2886  * @mapping: the address space containing mmaps to be unmapped.
2887  * @holebegin: byte in first page to unmap, relative to the start of
2888  * the underlying file.  This will be rounded down to a PAGE_SIZE
2889  * boundary.  Note that this is different from truncate_pagecache(), which
2890  * must keep the partial page.  In contrast, we must get rid of
2891  * partial pages.
2892  * @holelen: size of prospective hole in bytes.  This will be rounded
2893  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
2894  * end of the file.
2895  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2896  * but 0 when invalidating pagecache, don't throw away private data.
2897  */
2898 void unmap_mapping_range(struct address_space *mapping,
2899                 loff_t const holebegin, loff_t const holelen, int even_cows)
2900 {
2901         struct zap_details details;
2902         pgoff_t hba = holebegin >> PAGE_SHIFT;
2903         pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2904
2905         /* Check for overflow. */
2906         if (sizeof(holelen) > sizeof(hlen)) {
2907                 long long holeend =
2908                         (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2909                 if (holeend & ~(long long)ULONG_MAX)
2910                         hlen = ULONG_MAX - hba + 1;
2911         }
2912
2913         details.check_mapping = even_cows? NULL: mapping;
2914         details.nonlinear_vma = NULL;
2915         details.first_index = hba;
2916         details.last_index = hba + hlen - 1;
2917         if (details.last_index < details.first_index)
2918                 details.last_index = ULONG_MAX;
2919
2920
2921         mutex_lock(&mapping->i_mmap_mutex);
2922         if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
2923                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2924         if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2925                 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2926         mutex_unlock(&mapping->i_mmap_mutex);
2927 }
2928 EXPORT_SYMBOL(unmap_mapping_range);
2929
2930 /*
2931  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2932  * but allow concurrent faults), and pte mapped but not yet locked.
2933  * We return with mmap_sem still held, but pte unmapped and unlocked.
2934  */
2935 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2936                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2937                 unsigned int flags, pte_t orig_pte)
2938 {
2939         spinlock_t *ptl;
2940         struct page *page, *swapcache = NULL;
2941         swp_entry_t entry;
2942         pte_t pte;
2943         int locked;
2944         struct mem_cgroup *ptr;
2945         int exclusive = 0;
2946         int ret = 0;
2947
2948         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2949                 goto out;
2950
2951         entry = pte_to_swp_entry(orig_pte);
2952         if (unlikely(non_swap_entry(entry))) {
2953                 if (is_migration_entry(entry)) {
2954                         migration_entry_wait(mm, pmd, address);
2955                 } else if (is_hwpoison_entry(entry)) {
2956                         ret = VM_FAULT_HWPOISON;
2957                 } else {
2958                         print_bad_pte(vma, address, orig_pte, NULL);
2959                         ret = VM_FAULT_SIGBUS;
2960                 }
2961                 goto out;
2962         }
2963         delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2964         page = lookup_swap_cache(entry);
2965         if (!page) {
2966                 grab_swap_token(mm); /* Contend for token _before_ read-in */
2967                 page = swapin_readahead(entry,
2968                                         GFP_HIGHUSER_MOVABLE, vma, address);
2969                 if (!page) {
2970                         /*
2971                          * Back out if somebody else faulted in this pte
2972                          * while we released the pte lock.
2973                          */
2974                         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2975                         if (likely(pte_same(*page_table, orig_pte)))
2976                                 ret = VM_FAULT_OOM;
2977                         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2978                         goto unlock;
2979                 }
2980
2981                 /* Had to read the page from swap area: Major fault */
2982                 ret = VM_FAULT_MAJOR;
2983                 count_vm_event(PGMAJFAULT);
2984                 mem_cgroup_count_vm_event(mm, PGMAJFAULT);
2985         } else if (PageHWPoison(page)) {
2986                 /*
2987                  * hwpoisoned dirty swapcache pages are kept for killing
2988                  * owner processes (which may be unknown at hwpoison time)
2989                  */
2990                 ret = VM_FAULT_HWPOISON;
2991                 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2992                 goto out_release;
2993         }
2994
2995         locked = lock_page_or_retry(page, mm, flags);
2996         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2997         if (!locked) {
2998                 ret |= VM_FAULT_RETRY;
2999                 goto out_release;
3000         }
3001
3002         /*
3003          * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
3004          * release the swapcache from under us.  The page pin, and pte_same
3005          * test below, are not enough to exclude that.  Even if it is still
3006          * swapcache, we need to check that the page's swap has not changed.
3007          */
3008         if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
3009                 goto out_page;
3010
3011         if (ksm_might_need_to_copy(page, vma, address)) {
3012                 swapcache = page;
3013                 page = ksm_does_need_to_copy(page, vma, address);
3014
3015                 if (unlikely(!page)) {
3016                         ret = VM_FAULT_OOM;
3017                         page = swapcache;
3018                         swapcache = NULL;
3019                         goto out_page;
3020                 }
3021         }
3022
3023         if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
3024                 ret = VM_FAULT_OOM;
3025                 goto out_page;
3026         }
3027
3028         /*
3029          * Back out if somebody else already faulted in this pte.
3030          */
3031         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3032         if (unlikely(!pte_same(*page_table, orig_pte)))
3033                 goto out_nomap;
3034
3035         if (unlikely(!PageUptodate(page))) {
3036                 ret = VM_FAULT_SIGBUS;
3037                 goto out_nomap;
3038         }
3039
3040         /*
3041          * The page isn't present yet, go ahead with the fault.
3042          *
3043          * Be careful about the sequence of operations here.
3044          * To get its accounting right, reuse_swap_page() must be called
3045          * while the page is counted on swap but not yet in mapcount i.e.
3046          * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
3047          * must be called after the swap_free(), or it will never succeed.
3048          * Because delete_from_swap_page() may be called by reuse_swap_page(),
3049          * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
3050          * in page->private. In this case, a record in swap_cgroup  is silently
3051          * discarded at swap_free().
3052          */
3053
3054         inc_mm_counter_fast(mm, MM_ANONPAGES);
3055         dec_mm_counter_fast(mm, MM_SWAPENTS);
3056         pte = mk_pte(page, vma->vm_page_prot);
3057         if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
3058                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
3059                 flags &= ~FAULT_FLAG_WRITE;
3060                 ret |= VM_FAULT_WRITE;
3061                 exclusive = 1;
3062         }
3063         flush_icache_page(vma, page);
3064         set_pte_at(mm, address, page_table, pte);
3065         do_page_add_anon_rmap(page, vma, address, exclusive);
3066         /* It's better to call commit-charge after rmap is established */
3067         mem_cgroup_commit_charge_swapin(page, ptr);
3068
3069         swap_free(entry);
3070         if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
3071                 try_to_free_swap(page);
3072         unlock_page(page);
3073         if (swapcache) {
3074                 /*
3075                  * Hold the lock to avoid the swap entry to be reused
3076                  * until we take the PT lock for the pte_same() check
3077                  * (to avoid false positives from pte_same). For
3078                  * further safety release the lock after the swap_free
3079                  * so that the swap count won't change under a
3080                  * parallel locked swapcache.
3081                  */
3082                 unlock_page(swapcache);
3083                 page_cache_release(swapcache);
3084         }
3085
3086         if (flags & FAULT_FLAG_WRITE) {
3087                 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
3088                 if (ret & VM_FAULT_ERROR)
3089                         ret &= VM_FAULT_ERROR;
3090                 goto out;
3091         }
3092
3093         /* No need to invalidate - it was non-present before */
3094         update_mmu_cache(vma, address, page_table);
3095 unlock:
3096         pte_unmap_unlock(page_table, ptl);
3097 out:
3098         return ret;
3099 out_nomap:
3100         mem_cgroup_cancel_charge_swapin(ptr);
3101         pte_unmap_unlock(page_table, ptl);
3102 out_page:
3103         unlock_page(page);
3104 out_release:
3105         page_cache_release(page);
3106         if (swapcache) {
3107                 unlock_page(swapcache);
3108                 page_cache_release(swapcache);
3109         }
3110         return ret;
3111 }
3112
3113 /*
3114  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3115  * but allow concurrent faults), and pte mapped but not yet locked.
3116  * We return with mmap_sem still held, but pte unmapped and unlocked.
3117  */
3118 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
3119                 unsigned long address, pte_t *page_table, pmd_t *pmd,
3120                 unsigned int flags)
3121 {
3122         struct page *page;
3123         spinlock_t *ptl;
3124         pte_t entry;
3125
3126         pte_unmap(page_table);
3127
3128         /* File mapping without ->vm_ops ? */
3129         if (vma->vm_flags & VM_SHARED)
3130                 return VM_FAULT_SIGBUS;
3131
3132         /* Use the zero-page for reads */
3133         if (!(flags & FAULT_FLAG_WRITE)) {
3134                 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
3135                                                 vma->vm_page_prot));
3136                 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3137                 if (!pte_none(*page_table))
3138                         goto unlock;
3139                 goto setpte;
3140         }
3141
3142         /* Allocate our own private page. */
3143         if (unlikely(anon_vma_prepare(vma)))
3144                 goto oom;
3145         page = alloc_zeroed_user_highpage_movable(vma, address);
3146         if (!page)
3147                 goto oom;
3148         __SetPageUptodate(page);
3149
3150         if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
3151                 goto oom_free_page;
3152
3153         entry = mk_pte(page, vma->vm_page_prot);
3154         if (vma->vm_flags & VM_WRITE)
3155                 entry = pte_mkwrite(pte_mkdirty(entry));
3156
3157         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3158         if (!pte_none(*page_table))
3159                 goto release;
3160
3161         inc_mm_counter_fast(mm, MM_ANONPAGES);
3162         page_add_new_anon_rmap(page, vma, address);
3163 setpte:
3164         set_pte_at(mm, address, page_table, entry);
3165
3166         /* No need to invalidate - it was non-present before */
3167         update_mmu_cache(vma, address, page_table);
3168 unlock:
3169         pte_unmap_unlock(page_table, ptl);
3170         return 0;
3171 release:
3172         mem_cgroup_uncharge_page(page);
3173         page_cache_release(page);
3174         goto unlock;
3175 oom_free_page:
3176         page_cache_release(page);
3177 oom:
3178         return VM_FAULT_OOM;
3179 }
3180
3181 /*
3182  * __do_fault() tries to create a new page mapping. It aggressively