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[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / mm / memory.c
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1 /*
2 * linux/mm/memory.c
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 */
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
13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14 * pages started 02.12.91, seems to work. - Linus.
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.
20 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
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.
32 * 05.04.94 - Multi-page memory management added for v1.1.
33 * Idea by Alex Bligh (alex@cconcepts.co.uk)
35 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
36 * (Gerhard.Wichert@pdb.siemens.de)
38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
41 #include <linux/kernel_stat.h>
42 #include <linux/mm.h>
43 #include <linux/hugetlb.h>
44 #include <linux/mman.h>
45 #include <linux/swap.h>
46 #include <linux/highmem.h>
47 #include <linux/pagemap.h>
48 #include <linux/ksm.h>
49 #include <linux/rmap.h>
50 #include <linux/module.h>
51 #include <linux/delayacct.h>
52 #include <linux/init.h>
53 #include <linux/writeback.h>
54 #include <linux/memcontrol.h>
55 #include <linux/mmu_notifier.h>
56 #include <linux/kallsyms.h>
57 #include <linux/swapops.h>
58 #include <linux/elf.h>
59 #include <linux/gfp.h>
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>
68 #include "internal.h"
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;
75 EXPORT_SYMBOL(max_mapnr);
76 EXPORT_SYMBOL(mem_map);
77 #endif
79 unsigned long num_physpages;
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.
87 void * high_memory;
89 EXPORT_SYMBOL(num_physpages);
90 EXPORT_SYMBOL(high_memory);
93 * Randomize the address space (stacks, mmaps, brk, etc.).
95 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
96 * as ancient (libc5 based) binaries can segfault. )
98 int randomize_va_space __read_mostly =
99 #ifdef CONFIG_COMPAT_BRK
101 #else
103 #endif
105 static int __init disable_randmaps(char *s)
107 randomize_va_space = 0;
108 return 1;
110 __setup("norandmaps", disable_randmaps);
112 unsigned long zero_pfn __read_mostly;
113 unsigned long highest_memmap_pfn __read_mostly;
116 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
118 static int __init init_zero_pfn(void)
120 zero_pfn = page_to_pfn(ZERO_PAGE(0));
121 return 0;
123 core_initcall(init_zero_pfn);
126 #if defined(SPLIT_RSS_COUNTING)
128 static void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm)
130 int i;
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;
138 task->rss_stat.events = 0;
141 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
143 struct task_struct *task = current;
145 if (likely(task->mm == mm))
146 task->rss_stat.count[member] += val;
147 else
148 add_mm_counter(mm, member, val);
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)
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)
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);
163 unsigned long get_mm_counter(struct mm_struct *mm, int member)
165 long val = 0;
168 * Don't use task->mm here...for avoiding to use task_get_mm()..
169 * The caller must guarantee task->mm is not invalid.
171 val = atomic_long_read(&mm->rss_stat.count[member]);
173 * counter is updated in asynchronous manner and may go to minus.
174 * But it's never be expected number for users.
176 if (val < 0)
177 return 0;
178 return (unsigned long)val;
181 void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
183 __sync_task_rss_stat(task, mm);
185 #else /* SPLIT_RSS_COUNTING */
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)
190 static void check_sync_rss_stat(struct task_struct *task)
194 #endif /* SPLIT_RSS_COUNTING */
196 #ifdef HAVE_GENERIC_MMU_GATHER
198 static int tlb_next_batch(struct mmu_gather *tlb)
200 struct mmu_gather_batch *batch;
202 batch = tlb->active;
203 if (batch->next) {
204 tlb->active = batch->next;
205 return 1;
208 batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
209 if (!batch)
210 return 0;
212 batch->next = NULL;
213 batch->nr = 0;
214 batch->max = MAX_GATHER_BATCH;
216 tlb->active->next = batch;
217 tlb->active = batch;
219 return 1;
222 /* tlb_gather_mmu
223 * Called to initialize an (on-stack) mmu_gather structure for page-table
224 * tear-down from @mm. The @fullmm argument is used when @mm is without
225 * users and we're going to destroy the full address space (exit/execve).
227 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm)
229 tlb->mm = mm;
231 tlb->fullmm = fullmm;
232 tlb->need_flush = 0;
233 tlb->fast_mode = (num_possible_cpus() == 1);
234 tlb->local.next = NULL;
235 tlb->local.nr = 0;
236 tlb->local.max = ARRAY_SIZE(tlb->__pages);
237 tlb->active = &tlb->local;
239 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
240 tlb->batch = NULL;
241 #endif
244 void tlb_flush_mmu(struct mmu_gather *tlb)
246 struct mmu_gather_batch *batch;
248 if (!tlb->need_flush)
249 return;
250 tlb->need_flush = 0;
251 tlb_flush(tlb);
252 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
253 tlb_table_flush(tlb);
254 #endif
256 if (tlb_fast_mode(tlb))
257 return;
259 for (batch = &tlb->local; batch; batch = batch->next) {
260 free_pages_and_swap_cache(batch->pages, batch->nr);
261 batch->nr = 0;
263 tlb->active = &tlb->local;
266 /* tlb_finish_mmu
267 * Called at the end of the shootdown operation to free up any resources
268 * that were required.
270 void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
272 struct mmu_gather_batch *batch, *next;
274 tlb_flush_mmu(tlb);
276 /* keep the page table cache within bounds */
277 check_pgt_cache();
279 for (batch = tlb->local.next; batch; batch = next) {
280 next = batch->next;
281 free_pages((unsigned long)batch, 0);
283 tlb->local.next = NULL;
286 /* __tlb_remove_page
287 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
288 * handling the additional races in SMP caused by other CPUs caching valid
289 * mappings in their TLBs. Returns the number of free page slots left.
290 * When out of page slots we must call tlb_flush_mmu().
292 int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
294 struct mmu_gather_batch *batch;
296 tlb->need_flush = 1;
298 if (tlb_fast_mode(tlb)) {
299 free_page_and_swap_cache(page);
300 return 1; /* avoid calling tlb_flush_mmu() */
303 batch = tlb->active;
304 batch->pages[batch->nr++] = page;
305 if (batch->nr == batch->max) {
306 if (!tlb_next_batch(tlb))
307 return 0;
308 batch = tlb->active;
310 VM_BUG_ON(batch->nr > batch->max);
312 return batch->max - batch->nr;
315 #endif /* HAVE_GENERIC_MMU_GATHER */
317 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
320 * See the comment near struct mmu_table_batch.
323 static void tlb_remove_table_smp_sync(void *arg)
325 /* Simply deliver the interrupt */
328 static void tlb_remove_table_one(void *table)
331 * This isn't an RCU grace period and hence the page-tables cannot be
332 * assumed to be actually RCU-freed.
334 * It is however sufficient for software page-table walkers that rely on
335 * IRQ disabling. See the comment near struct mmu_table_batch.
337 smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
338 __tlb_remove_table(table);
341 static void tlb_remove_table_rcu(struct rcu_head *head)
343 struct mmu_table_batch *batch;
344 int i;
346 batch = container_of(head, struct mmu_table_batch, rcu);
348 for (i = 0; i < batch->nr; i++)
349 __tlb_remove_table(batch->tables[i]);
351 free_page((unsigned long)batch);
354 void tlb_table_flush(struct mmu_gather *tlb)
356 struct mmu_table_batch **batch = &tlb->batch;
358 if (*batch) {
359 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
360 *batch = NULL;
364 void tlb_remove_table(struct mmu_gather *tlb, void *table)
366 struct mmu_table_batch **batch = &tlb->batch;
368 tlb->need_flush = 1;
371 * When there's less then two users of this mm there cannot be a
372 * concurrent page-table walk.
374 if (atomic_read(&tlb->mm->mm_users) < 2) {
375 __tlb_remove_table(table);
376 return;
379 if (*batch == NULL) {
380 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
381 if (*batch == NULL) {
382 tlb_remove_table_one(table);
383 return;
385 (*batch)->nr = 0;
387 (*batch)->tables[(*batch)->nr++] = table;
388 if ((*batch)->nr == MAX_TABLE_BATCH)
389 tlb_table_flush(tlb);
392 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */
395 * If a p?d_bad entry is found while walking page tables, report
396 * the error, before resetting entry to p?d_none. Usually (but
397 * very seldom) called out from the p?d_none_or_clear_bad macros.
400 void pgd_clear_bad(pgd_t *pgd)
402 pgd_ERROR(*pgd);
403 pgd_clear(pgd);
406 void pud_clear_bad(pud_t *pud)
408 pud_ERROR(*pud);
409 pud_clear(pud);
412 void pmd_clear_bad(pmd_t *pmd)
414 pmd_ERROR(*pmd);
415 pmd_clear(pmd);
419 * Note: this doesn't free the actual pages themselves. That
420 * has been handled earlier when unmapping all the memory regions.
422 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
423 unsigned long addr)
425 pgtable_t token = pmd_pgtable(*pmd);
426 pmd_clear(pmd);
427 pte_free_tlb(tlb, token, addr);
428 tlb->mm->nr_ptes--;
431 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
432 unsigned long addr, unsigned long end,
433 unsigned long floor, unsigned long ceiling)
435 pmd_t *pmd;
436 unsigned long next;
437 unsigned long start;
439 start = addr;
440 pmd = pmd_offset(pud, addr);
441 do {
442 next = pmd_addr_end(addr, end);
443 if (pmd_none_or_clear_bad(pmd))
444 continue;
445 free_pte_range(tlb, pmd, addr);
446 } while (pmd++, addr = next, addr != end);
448 start &= PUD_MASK;
449 if (start < floor)
450 return;
451 if (ceiling) {
452 ceiling &= PUD_MASK;
453 if (!ceiling)
454 return;
456 if (end - 1 > ceiling - 1)
457 return;
459 pmd = pmd_offset(pud, start);
460 pud_clear(pud);
461 pmd_free_tlb(tlb, pmd, start);
464 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
465 unsigned long addr, unsigned long end,
466 unsigned long floor, unsigned long ceiling)
468 pud_t *pud;
469 unsigned long next;
470 unsigned long start;
472 start = addr;
473 pud = pud_offset(pgd, addr);
474 do {
475 next = pud_addr_end(addr, end);
476 if (pud_none_or_clear_bad(pud))
477 continue;
478 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
479 } while (pud++, addr = next, addr != end);
481 start &= PGDIR_MASK;
482 if (start < floor)
483 return;
484 if (ceiling) {
485 ceiling &= PGDIR_MASK;
486 if (!ceiling)
487 return;
489 if (end - 1 > ceiling - 1)
490 return;
492 pud = pud_offset(pgd, start);
493 pgd_clear(pgd);
494 pud_free_tlb(tlb, pud, start);
498 * This function frees user-level page tables of a process.
500 * Must be called with pagetable lock held.
502 void free_pgd_range(struct mmu_gather *tlb,
503 unsigned long addr, unsigned long end,
504 unsigned long floor, unsigned long ceiling)
506 pgd_t *pgd;
507 unsigned long next;
510 * The next few lines have given us lots of grief...
512 * Why are we testing PMD* at this top level? Because often
513 * there will be no work to do at all, and we'd prefer not to
514 * go all the way down to the bottom just to discover that.
516 * Why all these "- 1"s? Because 0 represents both the bottom
517 * of the address space and the top of it (using -1 for the
518 * top wouldn't help much: the masks would do the wrong thing).
519 * The rule is that addr 0 and floor 0 refer to the bottom of
520 * the address space, but end 0 and ceiling 0 refer to the top
521 * Comparisons need to use "end - 1" and "ceiling - 1" (though
522 * that end 0 case should be mythical).
524 * Wherever addr is brought up or ceiling brought down, we must
525 * be careful to reject "the opposite 0" before it confuses the
526 * subsequent tests. But what about where end is brought down
527 * by PMD_SIZE below? no, end can't go down to 0 there.
529 * Whereas we round start (addr) and ceiling down, by different
530 * masks at different levels, in order to test whether a table
531 * now has no other vmas using it, so can be freed, we don't
532 * bother to round floor or end up - the tests don't need that.
535 addr &= PMD_MASK;
536 if (addr < floor) {
537 addr += PMD_SIZE;
538 if (!addr)
539 return;
541 if (ceiling) {
542 ceiling &= PMD_MASK;
543 if (!ceiling)
544 return;
546 if (end - 1 > ceiling - 1)
547 end -= PMD_SIZE;
548 if (addr > end - 1)
549 return;
551 pgd = pgd_offset(tlb->mm, addr);
552 do {
553 next = pgd_addr_end(addr, end);
554 if (pgd_none_or_clear_bad(pgd))
555 continue;
556 free_pud_range(tlb, pgd, addr, next, floor, ceiling);
557 } while (pgd++, addr = next, addr != end);
560 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
561 unsigned long floor, unsigned long ceiling)
563 while (vma) {
564 struct vm_area_struct *next = vma->vm_next;
565 unsigned long addr = vma->vm_start;
568 * Hide vma from rmap and truncate_pagecache before freeing
569 * pgtables
571 unlink_anon_vmas(vma);
572 unlink_file_vma(vma);
574 if (is_vm_hugetlb_page(vma)) {
575 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
576 floor, next? next->vm_start: ceiling);
577 } else {
579 * Optimization: gather nearby vmas into one call down
581 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
582 && !is_vm_hugetlb_page(next)) {
583 vma = next;
584 next = vma->vm_next;
585 unlink_anon_vmas(vma);
586 unlink_file_vma(vma);
588 free_pgd_range(tlb, addr, vma->vm_end,
589 floor, next? next->vm_start: ceiling);
591 vma = next;
595 int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
596 pmd_t *pmd, unsigned long address)
598 pgtable_t new = pte_alloc_one(mm, address);
599 int wait_split_huge_page;
600 if (!new)
601 return -ENOMEM;
604 * Ensure all pte setup (eg. pte page lock and page clearing) are
605 * visible before the pte is made visible to other CPUs by being
606 * put into page tables.
608 * The other side of the story is the pointer chasing in the page
609 * table walking code (when walking the page table without locking;
610 * ie. most of the time). Fortunately, these data accesses consist
611 * of a chain of data-dependent loads, meaning most CPUs (alpha
612 * being the notable exception) will already guarantee loads are
613 * seen in-order. See the alpha page table accessors for the
614 * smp_read_barrier_depends() barriers in page table walking code.
616 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
618 spin_lock(&mm->page_table_lock);
619 wait_split_huge_page = 0;
620 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
621 mm->nr_ptes++;
622 pmd_populate(mm, pmd, new);
623 new = NULL;
624 } else if (unlikely(pmd_trans_splitting(*pmd)))
625 wait_split_huge_page = 1;
626 spin_unlock(&mm->page_table_lock);
627 if (new)
628 pte_free(mm, new);
629 if (wait_split_huge_page)
630 wait_split_huge_page(vma->anon_vma, pmd);
631 return 0;
634 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
636 pte_t *new = pte_alloc_one_kernel(&init_mm, address);
637 if (!new)
638 return -ENOMEM;
640 smp_wmb(); /* See comment in __pte_alloc */
642 spin_lock(&init_mm.page_table_lock);
643 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
644 pmd_populate_kernel(&init_mm, pmd, new);
645 new = NULL;
646 } else
647 VM_BUG_ON(pmd_trans_splitting(*pmd));
648 spin_unlock(&init_mm.page_table_lock);
649 if (new)
650 pte_free_kernel(&init_mm, new);
651 return 0;
654 static inline void init_rss_vec(int *rss)
656 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
659 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
661 int i;
663 if (current->mm == mm)
664 sync_mm_rss(current, mm);
665 for (i = 0; i < NR_MM_COUNTERS; i++)
666 if (rss[i])
667 add_mm_counter(mm, i, rss[i]);
671 * This function is called to print an error when a bad pte
672 * is found. For example, we might have a PFN-mapped pte in
673 * a region that doesn't allow it.
675 * The calling function must still handle the error.
677 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
678 pte_t pte, struct page *page)
680 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
681 pud_t *pud = pud_offset(pgd, addr);
682 pmd_t *pmd = pmd_offset(pud, addr);
683 struct address_space *mapping;
684 pgoff_t index;
685 static unsigned long resume;
686 static unsigned long nr_shown;
687 static unsigned long nr_unshown;
690 * Allow a burst of 60 reports, then keep quiet for that minute;
691 * or allow a steady drip of one report per second.
693 if (nr_shown == 60) {
694 if (time_before(jiffies, resume)) {
695 nr_unshown++;
696 return;
698 if (nr_unshown) {
699 printk(KERN_ALERT
700 "BUG: Bad page map: %lu messages suppressed\n",
701 nr_unshown);
702 nr_unshown = 0;
704 nr_shown = 0;
706 if (nr_shown++ == 0)
707 resume = jiffies + 60 * HZ;
709 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
710 index = linear_page_index(vma, addr);
712 printk(KERN_ALERT
713 "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
714 current->comm,
715 (long long)pte_val(pte), (long long)pmd_val(*pmd));
716 if (page)
717 dump_page(page);
718 printk(KERN_ALERT
719 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
720 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
722 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
724 if (vma->vm_ops)
725 print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
726 (unsigned long)vma->vm_ops->fault);
727 if (vma->vm_file && vma->vm_file->f_op)
728 print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
729 (unsigned long)vma->vm_file->f_op->mmap);
730 dump_stack();
731 add_taint(TAINT_BAD_PAGE);
734 static inline int is_cow_mapping(vm_flags_t flags)
736 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
739 #ifndef is_zero_pfn
740 static inline int is_zero_pfn(unsigned long pfn)
742 return pfn == zero_pfn;
744 #endif
746 #ifndef my_zero_pfn
747 static inline unsigned long my_zero_pfn(unsigned long addr)
749 return zero_pfn;
751 #endif
754 * vm_normal_page -- This function gets the "struct page" associated with a pte.
756 * "Special" mappings do not wish to be associated with a "struct page" (either
757 * it doesn't exist, or it exists but they don't want to touch it). In this
758 * case, NULL is returned here. "Normal" mappings do have a struct page.
760 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
761 * pte bit, in which case this function is trivial. Secondly, an architecture
762 * may not have a spare pte bit, which requires a more complicated scheme,
763 * described below.
765 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
766 * special mapping (even if there are underlying and valid "struct pages").
767 * COWed pages of a VM_PFNMAP are always normal.
769 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
770 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
771 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
772 * mapping will always honor the rule
774 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
776 * And for normal mappings this is false.
778 * This restricts such mappings to be a linear translation from virtual address
779 * to pfn. To get around this restriction, we allow arbitrary mappings so long
780 * as the vma is not a COW mapping; in that case, we know that all ptes are
781 * special (because none can have been COWed).
784 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
786 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
787 * page" backing, however the difference is that _all_ pages with a struct
788 * page (that is, those where pfn_valid is true) are refcounted and considered
789 * normal pages by the VM. The disadvantage is that pages are refcounted
790 * (which can be slower and simply not an option for some PFNMAP users). The
791 * advantage is that we don't have to follow the strict linearity rule of
792 * PFNMAP mappings in order to support COWable mappings.
795 #ifdef __HAVE_ARCH_PTE_SPECIAL
796 # define HAVE_PTE_SPECIAL 1
797 #else
798 # define HAVE_PTE_SPECIAL 0
799 #endif
800 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
801 pte_t pte)
803 unsigned long pfn = pte_pfn(pte);
805 if (HAVE_PTE_SPECIAL) {
806 if (likely(!pte_special(pte)))
807 goto check_pfn;
808 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
809 return NULL;
810 if (!is_zero_pfn(pfn))
811 print_bad_pte(vma, addr, pte, NULL);
812 return NULL;
815 /* !HAVE_PTE_SPECIAL case follows: */
817 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
818 if (vma->vm_flags & VM_MIXEDMAP) {
819 if (!pfn_valid(pfn))
820 return NULL;
821 goto out;
822 } else {
823 unsigned long off;
824 off = (addr - vma->vm_start) >> PAGE_SHIFT;
825 if (pfn == vma->vm_pgoff + off)
826 return NULL;
827 if (!is_cow_mapping(vma->vm_flags))
828 return NULL;
832 if (is_zero_pfn(pfn))
833 return NULL;
834 check_pfn:
835 if (unlikely(pfn > highest_memmap_pfn)) {
836 print_bad_pte(vma, addr, pte, NULL);
837 return NULL;
841 * NOTE! We still have PageReserved() pages in the page tables.
842 * eg. VDSO mappings can cause them to exist.
844 out:
845 return pfn_to_page(pfn);
849 * copy one vm_area from one task to the other. Assumes the page tables
850 * already present in the new task to be cleared in the whole range
851 * covered by this vma.
854 static inline unsigned long
855 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
856 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
857 unsigned long addr, int *rss)
859 unsigned long vm_flags = vma->vm_flags;
860 pte_t pte = *src_pte;
861 struct page *page;
863 /* pte contains position in swap or file, so copy. */
864 if (unlikely(!pte_present(pte))) {
865 if (!pte_file(pte)) {
866 swp_entry_t entry = pte_to_swp_entry(pte);
868 if (swap_duplicate(entry) < 0)
869 return entry.val;
871 /* make sure dst_mm is on swapoff's mmlist. */
872 if (unlikely(list_empty(&dst_mm->mmlist))) {
873 spin_lock(&mmlist_lock);
874 if (list_empty(&dst_mm->mmlist))
875 list_add(&dst_mm->mmlist,
876 &src_mm->mmlist);
877 spin_unlock(&mmlist_lock);
879 if (likely(!non_swap_entry(entry)))
880 rss[MM_SWAPENTS]++;
881 else if (is_write_migration_entry(entry) &&
882 is_cow_mapping(vm_flags)) {
884 * COW mappings require pages in both parent
885 * and child to be set to read.
887 make_migration_entry_read(&entry);
888 pte = swp_entry_to_pte(entry);
889 set_pte_at(src_mm, addr, src_pte, pte);
892 goto out_set_pte;
896 * If it's a COW mapping, write protect it both
897 * in the parent and the child
899 if (is_cow_mapping(vm_flags)) {
900 ptep_set_wrprotect(src_mm, addr, src_pte);
901 pte = pte_wrprotect(pte);
905 * If it's a shared mapping, mark it clean in
906 * the child
908 if (vm_flags & VM_SHARED)
909 pte = pte_mkclean(pte);
910 pte = pte_mkold(pte);
912 page = vm_normal_page(vma, addr, pte);
913 if (page) {
914 get_page(page);
915 page_dup_rmap(page);
916 if (PageAnon(page))
917 rss[MM_ANONPAGES]++;
918 else
919 rss[MM_FILEPAGES]++;
922 out_set_pte:
923 set_pte_at(dst_mm, addr, dst_pte, pte);
924 return 0;
927 int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
928 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
929 unsigned long addr, unsigned long end)
931 pte_t *orig_src_pte, *orig_dst_pte;
932 pte_t *src_pte, *dst_pte;
933 spinlock_t *src_ptl, *dst_ptl;
934 int progress = 0;
935 int rss[NR_MM_COUNTERS];
936 swp_entry_t entry = (swp_entry_t){0};
938 again:
939 init_rss_vec(rss);
941 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
942 if (!dst_pte)
943 return -ENOMEM;
944 src_pte = pte_offset_map(src_pmd, addr);
945 src_ptl = pte_lockptr(src_mm, src_pmd);
946 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
947 orig_src_pte = src_pte;
948 orig_dst_pte = dst_pte;
949 arch_enter_lazy_mmu_mode();
951 do {
953 * We are holding two locks at this point - either of them
954 * could generate latencies in another task on another CPU.
956 if (progress >= 32) {
957 progress = 0;
958 if (need_resched() ||
959 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
960 break;
962 if (pte_none(*src_pte)) {
963 progress++;
964 continue;
966 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
967 vma, addr, rss);
968 if (entry.val)
969 break;
970 progress += 8;
971 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
973 arch_leave_lazy_mmu_mode();
974 spin_unlock(src_ptl);
975 pte_unmap(orig_src_pte);
976 add_mm_rss_vec(dst_mm, rss);
977 pte_unmap_unlock(orig_dst_pte, dst_ptl);
978 cond_resched();
980 if (entry.val) {
981 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
982 return -ENOMEM;
983 progress = 0;
985 if (addr != end)
986 goto again;
987 return 0;
990 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
991 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
992 unsigned long addr, unsigned long end)
994 pmd_t *src_pmd, *dst_pmd;
995 unsigned long next;
997 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
998 if (!dst_pmd)
999 return -ENOMEM;
1000 src_pmd = pmd_offset(src_pud, addr);
1001 do {
1002 next = pmd_addr_end(addr, end);
1003 if (pmd_trans_huge(*src_pmd)) {
1004 int err;
1005 VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
1006 err = copy_huge_pmd(dst_mm, src_mm,
1007 dst_pmd, src_pmd, addr, vma);
1008 if (err == -ENOMEM)
1009 return -ENOMEM;
1010 if (!err)
1011 continue;
1012 /* fall through */
1014 if (pmd_none_or_clear_bad(src_pmd))
1015 continue;
1016 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1017 vma, addr, next))
1018 return -ENOMEM;
1019 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1020 return 0;
1023 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1024 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1025 unsigned long addr, unsigned long end)
1027 pud_t *src_pud, *dst_pud;
1028 unsigned long next;
1030 dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
1031 if (!dst_pud)
1032 return -ENOMEM;
1033 src_pud = pud_offset(src_pgd, addr);
1034 do {
1035 next = pud_addr_end(addr, end);
1036 if (pud_none_or_clear_bad(src_pud))
1037 continue;
1038 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1039 vma, addr, next))
1040 return -ENOMEM;
1041 } while (dst_pud++, src_pud++, addr = next, addr != end);
1042 return 0;
1045 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1046 struct vm_area_struct *vma)
1048 pgd_t *src_pgd, *dst_pgd;
1049 unsigned long next;
1050 unsigned long addr = vma->vm_start;
1051 unsigned long end = vma->vm_end;
1052 int ret;
1055 * Don't copy ptes where a page fault will fill them correctly.
1056 * Fork becomes much lighter when there are big shared or private
1057 * readonly mappings. The tradeoff is that copy_page_range is more
1058 * efficient than faulting.
1060 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
1061 if (!vma->anon_vma)
1062 return 0;
1065 if (is_vm_hugetlb_page(vma))
1066 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1068 if (unlikely(is_pfn_mapping(vma))) {
1070 * We do not free on error cases below as remove_vma
1071 * gets called on error from higher level routine
1073 ret = track_pfn_vma_copy(vma);
1074 if (ret)
1075 return ret;
1079 * We need to invalidate the secondary MMU mappings only when
1080 * there could be a permission downgrade on the ptes of the
1081 * parent mm. And a permission downgrade will only happen if
1082 * is_cow_mapping() returns true.
1084 if (is_cow_mapping(vma->vm_flags))
1085 mmu_notifier_invalidate_range_start(src_mm, addr, end);
1087 ret = 0;
1088 dst_pgd = pgd_offset(dst_mm, addr);
1089 src_pgd = pgd_offset(src_mm, addr);
1090 do {
1091 next = pgd_addr_end(addr, end);
1092 if (pgd_none_or_clear_bad(src_pgd))
1093 continue;
1094 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
1095 vma, addr, next))) {
1096 ret = -ENOMEM;
1097 break;
1099 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1101 if (is_cow_mapping(vma->vm_flags))
1102 mmu_notifier_invalidate_range_end(src_mm,
1103 vma->vm_start, end);
1104 return ret;
1107 static unsigned long zap_pte_range(struct mmu_gather *tlb,
1108 struct vm_area_struct *vma, pmd_t *pmd,
1109 unsigned long addr, unsigned long end,
1110 struct zap_details *details)
1112 struct mm_struct *mm = tlb->mm;
1113 int force_flush = 0;
1114 int rss[NR_MM_COUNTERS];
1115 spinlock_t *ptl;
1116 pte_t *start_pte;
1117 pte_t *pte;
1119 again:
1120 init_rss_vec(rss);
1121 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1122 pte = start_pte;
1123 arch_enter_lazy_mmu_mode();
1124 do {
1125 pte_t ptent = *pte;
1126 if (pte_none(ptent)) {
1127 continue;
1130 if (pte_present(ptent)) {
1131 struct page *page;
1133 page = vm_normal_page(vma, addr, ptent);
1134 if (unlikely(details) && page) {
1136 * unmap_shared_mapping_pages() wants to
1137 * invalidate cache without truncating:
1138 * unmap shared but keep private pages.
1140 if (details->check_mapping &&
1141 details->check_mapping != page->mapping)
1142 continue;
1144 * Each page->index must be checked when
1145 * invalidating or truncating nonlinear.
1147 if (details->nonlinear_vma &&
1148 (page->index < details->first_index ||
1149 page->index > details->last_index))
1150 continue;
1152 ptent = ptep_get_and_clear_full(mm, addr, pte,
1153 tlb->fullmm);
1154 tlb_remove_tlb_entry(tlb, pte, addr);
1155 if (unlikely(!page))
1156 continue;
1157 if (unlikely(details) && details->nonlinear_vma
1158 && linear_page_index(details->nonlinear_vma,
1159 addr) != page->index)
1160 set_pte_at(mm, addr, pte,
1161 pgoff_to_pte(page->index));
1162 if (PageAnon(page))
1163 rss[MM_ANONPAGES]--;
1164 else {
1165 if (pte_dirty(ptent))
1166 set_page_dirty(page);
1167 if (pte_young(ptent) &&
1168 likely(!VM_SequentialReadHint(vma)))
1169 mark_page_accessed(page);
1170 rss[MM_FILEPAGES]--;
1172 page_remove_rmap(page);
1173 if (unlikely(page_mapcount(page) < 0))
1174 print_bad_pte(vma, addr, ptent, page);
1175 force_flush = !__tlb_remove_page(tlb, page);
1176 if (force_flush)
1177 break;
1178 continue;
1181 * If details->check_mapping, we leave swap entries;
1182 * if details->nonlinear_vma, we leave file entries.
1184 if (unlikely(details))
1185 continue;
1186 if (pte_file(ptent)) {
1187 if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
1188 print_bad_pte(vma, addr, ptent, NULL);
1189 } else {
1190 swp_entry_t entry = pte_to_swp_entry(ptent);
1192 if (!non_swap_entry(entry))
1193 rss[MM_SWAPENTS]--;
1194 if (unlikely(!free_swap_and_cache(entry)))
1195 print_bad_pte(vma, addr, ptent, NULL);
1197 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1198 } while (pte++, addr += PAGE_SIZE, addr != end);
1200 add_mm_rss_vec(mm, rss);
1201 arch_leave_lazy_mmu_mode();
1202 pte_unmap_unlock(start_pte, ptl);
1205 * mmu_gather ran out of room to batch pages, we break out of
1206 * the PTE lock to avoid doing the potential expensive TLB invalidate
1207 * and page-free while holding it.
1209 if (force_flush) {
1210 force_flush = 0;
1211 tlb_flush_mmu(tlb);
1212 if (addr != end)
1213 goto again;
1216 return addr;
1219 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1220 struct vm_area_struct *vma, pud_t *pud,
1221 unsigned long addr, unsigned long end,
1222 struct zap_details *details)
1224 pmd_t *pmd;
1225 unsigned long next;
1227 pmd = pmd_offset(pud, addr);
1228 do {
1229 next = pmd_addr_end(addr, end);
1230 if (pmd_trans_huge(*pmd)) {
1231 if (next-addr != HPAGE_PMD_SIZE) {
1232 VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem));
1233 split_huge_page_pmd(vma->vm_mm, pmd);
1234 } else if (zap_huge_pmd(tlb, vma, pmd))
1235 continue;
1236 /* fall through */
1238 if (pmd_none_or_clear_bad(pmd))
1239 continue;
1240 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1241 cond_resched();
1242 } while (pmd++, addr = next, addr != end);
1244 return addr;
1247 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1248 struct vm_area_struct *vma, pgd_t *pgd,
1249 unsigned long addr, unsigned long end,
1250 struct zap_details *details)
1252 pud_t *pud;
1253 unsigned long next;
1255 pud = pud_offset(pgd, addr);
1256 do {
1257 next = pud_addr_end(addr, end);
1258 if (pud_none_or_clear_bad(pud))
1259 continue;
1260 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1261 } while (pud++, addr = next, addr != end);
1263 return addr;
1266 static unsigned long unmap_page_range(struct mmu_gather *tlb,
1267 struct vm_area_struct *vma,
1268 unsigned long addr, unsigned long end,
1269 struct zap_details *details)
1271 pgd_t *pgd;
1272 unsigned long next;
1274 if (details && !details->check_mapping && !details->nonlinear_vma)
1275 details = NULL;
1277 BUG_ON(addr >= end);
1278 mem_cgroup_uncharge_start();
1279 tlb_start_vma(tlb, vma);
1280 pgd = pgd_offset(vma->vm_mm, addr);
1281 do {
1282 next = pgd_addr_end(addr, end);
1283 if (pgd_none_or_clear_bad(pgd))
1284 continue;
1285 next = zap_pud_range(tlb, vma, pgd, addr, next, details);
1286 } while (pgd++, addr = next, addr != end);
1287 tlb_end_vma(tlb, vma);
1288 mem_cgroup_uncharge_end();
1290 return addr;
1293 #ifdef CONFIG_PREEMPT
1294 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
1295 #else
1296 /* No preempt: go for improved straight-line efficiency */
1297 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
1298 #endif
1301 * unmap_vmas - unmap a range of memory covered by a list of vma's
1302 * @tlb: address of the caller's struct mmu_gather
1303 * @vma: the starting vma
1304 * @start_addr: virtual address at which to start unmapping
1305 * @end_addr: virtual address at which to end unmapping
1306 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
1307 * @details: details of nonlinear truncation or shared cache invalidation
1309 * Returns the end address of the unmapping (restart addr if interrupted).
1311 * Unmap all pages in the vma list.
1313 * We aim to not hold locks for too long (for scheduling latency reasons).
1314 * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to
1315 * return the ending mmu_gather to the caller.
1317 * Only addresses between `start' and `end' will be unmapped.
1319 * The VMA list must be sorted in ascending virtual address order.
1321 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1322 * range after unmap_vmas() returns. So the only responsibility here is to
1323 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1324 * drops the lock and schedules.
1326 unsigned long unmap_vmas(struct mmu_gather *tlb,
1327 struct vm_area_struct *vma, unsigned long start_addr,
1328 unsigned long end_addr, unsigned long *nr_accounted,
1329 struct zap_details *details)
1331 unsigned long start = start_addr;
1332 struct mm_struct *mm = vma->vm_mm;
1334 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1335 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
1336 unsigned long end;
1338 start = max(vma->vm_start, start_addr);
1339 if (start >= vma->vm_end)
1340 continue;
1341 end = min(vma->vm_end, end_addr);
1342 if (end <= vma->vm_start)
1343 continue;
1345 if (vma->vm_flags & VM_ACCOUNT)
1346 *nr_accounted += (end - start) >> PAGE_SHIFT;
1348 if (unlikely(is_pfn_mapping(vma)))
1349 untrack_pfn_vma(vma, 0, 0);
1351 while (start != end) {
1352 if (unlikely(is_vm_hugetlb_page(vma))) {
1354 * It is undesirable to test vma->vm_file as it
1355 * should be non-null for valid hugetlb area.
1356 * However, vm_file will be NULL in the error
1357 * cleanup path of do_mmap_pgoff. When
1358 * hugetlbfs ->mmap method fails,
1359 * do_mmap_pgoff() nullifies vma->vm_file
1360 * before calling this function to clean up.
1361 * Since no pte has actually been setup, it is
1362 * safe to do nothing in this case.
1364 if (vma->vm_file)
1365 unmap_hugepage_range(vma, start, end, NULL);
1367 start = end;
1368 } else
1369 start = unmap_page_range(tlb, vma, start, end, details);
1373 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1374 return start; /* which is now the end (or restart) address */
1378 * zap_page_range - remove user pages in a given range
1379 * @vma: vm_area_struct holding the applicable pages
1380 * @address: starting address of pages to zap
1381 * @size: number of bytes to zap
1382 * @details: details of nonlinear truncation or shared cache invalidation
1384 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
1385 unsigned long size, struct zap_details *details)
1387 struct mm_struct *mm = vma->vm_mm;
1388 struct mmu_gather tlb;
1389 unsigned long end = address + size;
1390 unsigned long nr_accounted = 0;
1392 lru_add_drain();
1393 tlb_gather_mmu(&tlb, mm, 0);
1394 update_hiwater_rss(mm);
1395 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
1396 tlb_finish_mmu(&tlb, address, end);
1397 return end;
1401 * zap_vma_ptes - remove ptes mapping the vma
1402 * @vma: vm_area_struct holding ptes to be zapped
1403 * @address: starting address of pages to zap
1404 * @size: number of bytes to zap
1406 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1408 * The entire address range must be fully contained within the vma.
1410 * Returns 0 if successful.
1412 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1413 unsigned long size)
1415 if (address < vma->vm_start || address + size > vma->vm_end ||
1416 !(vma->vm_flags & VM_PFNMAP))
1417 return -1;
1418 zap_page_range(vma, address, size, NULL);
1419 return 0;
1421 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1424 * follow_page - look up a page descriptor from a user-virtual address
1425 * @vma: vm_area_struct mapping @address
1426 * @address: virtual address to look up
1427 * @flags: flags modifying lookup behaviour
1429 * @flags can have FOLL_ flags set, defined in <linux/mm.h>
1431 * Returns the mapped (struct page *), %NULL if no mapping exists, or
1432 * an error pointer if there is a mapping to something not represented
1433 * by a page descriptor (see also vm_normal_page()).
1435 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1436 unsigned int flags)
1438 pgd_t *pgd;
1439 pud_t *pud;
1440 pmd_t *pmd;
1441 pte_t *ptep, pte;
1442 spinlock_t *ptl;
1443 struct page *page;
1444 struct mm_struct *mm = vma->vm_mm;
1446 page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1447 if (!IS_ERR(page)) {
1448 BUG_ON(flags & FOLL_GET);
1449 goto out;
1452 page = NULL;
1453 pgd = pgd_offset(mm, address);
1454 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1455 goto no_page_table;
1457 pud = pud_offset(pgd, address);
1458 if (pud_none(*pud))
1459 goto no_page_table;
1460 if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
1461 BUG_ON(flags & FOLL_GET);
1462 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1463 goto out;
1465 if (unlikely(pud_bad(*pud)))
1466 goto no_page_table;
1468 pmd = pmd_offset(pud, address);
1469 if (pmd_none(*pmd))
1470 goto no_page_table;
1471 if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
1472 BUG_ON(flags & FOLL_GET);
1473 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1474 goto out;
1476 if (pmd_trans_huge(*pmd)) {
1477 if (flags & FOLL_SPLIT) {
1478 split_huge_page_pmd(mm, pmd);
1479 goto split_fallthrough;
1481 spin_lock(&mm->page_table_lock);
1482 if (likely(pmd_trans_huge(*pmd))) {
1483 if (unlikely(pmd_trans_splitting(*pmd))) {
1484 spin_unlock(&mm->page_table_lock);
1485 wait_split_huge_page(vma->anon_vma, pmd);
1486 } else {
1487 page = follow_trans_huge_pmd(mm, address,
1488 pmd, flags);
1489 spin_unlock(&mm->page_table_lock);
1490 goto out;
1492 } else
1493 spin_unlock(&mm->page_table_lock);
1494 /* fall through */
1496 split_fallthrough:
1497 if (unlikely(pmd_bad(*pmd)))
1498 goto no_page_table;
1500 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1502 pte = *ptep;
1503 if (!pte_present(pte))
1504 goto no_page;
1505 if ((flags & FOLL_WRITE) && !pte_write(pte))
1506 goto unlock;
1508 page = vm_normal_page(vma, address, pte);
1509 if (unlikely(!page)) {
1510 if ((flags & FOLL_DUMP) ||
1511 !is_zero_pfn(pte_pfn(pte)))
1512 goto bad_page;
1513 page = pte_page(pte);
1516 if (flags & FOLL_GET)
1517 get_page_foll(page);
1518 if (flags & FOLL_TOUCH) {
1519 if ((flags & FOLL_WRITE) &&
1520 !pte_dirty(pte) && !PageDirty(page))
1521 set_page_dirty(page);
1523 * pte_mkyoung() would be more correct here, but atomic care
1524 * is needed to avoid losing the dirty bit: it is easier to use
1525 * mark_page_accessed().
1527 mark_page_accessed(page);
1529 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1531 * The preliminary mapping check is mainly to avoid the
1532 * pointless overhead of lock_page on the ZERO_PAGE
1533 * which might bounce very badly if there is contention.
1535 * If the page is already locked, we don't need to
1536 * handle it now - vmscan will handle it later if and
1537 * when it attempts to reclaim the page.
1539 if (page->mapping && trylock_page(page)) {
1540 lru_add_drain(); /* push cached pages to LRU */
1542 * Because we lock page here and migration is
1543 * blocked by the pte's page reference, we need
1544 * only check for file-cache page truncation.
1546 if (page->mapping)
1547 mlock_vma_page(page);
1548 unlock_page(page);
1551 unlock:
1552 pte_unmap_unlock(ptep, ptl);
1553 out:
1554 return page;
1556 bad_page:
1557 pte_unmap_unlock(ptep, ptl);
1558 return ERR_PTR(-EFAULT);
1560 no_page:
1561 pte_unmap_unlock(ptep, ptl);
1562 if (!pte_none(pte))
1563 return page;
1565 no_page_table:
1567 * When core dumping an enormous anonymous area that nobody
1568 * has touched so far, we don't want to allocate unnecessary pages or
1569 * page tables. Return error instead of NULL to skip handle_mm_fault,
1570 * then get_dump_page() will return NULL to leave a hole in the dump.
1571 * But we can only make this optimization where a hole would surely
1572 * be zero-filled if handle_mm_fault() actually did handle it.
1574 if ((flags & FOLL_DUMP) &&
1575 (!vma->vm_ops || !vma->vm_ops->fault))
1576 return ERR_PTR(-EFAULT);
1577 return page;
1580 static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
1582 return stack_guard_page_start(vma, addr) ||
1583 stack_guard_page_end(vma, addr+PAGE_SIZE);
1587 * __get_user_pages() - pin user pages in memory
1588 * @tsk: task_struct of target task
1589 * @mm: mm_struct of target mm
1590 * @start: starting user address
1591 * @nr_pages: number of pages from start to pin
1592 * @gup_flags: flags modifying pin behaviour
1593 * @pages: array that receives pointers to the pages pinned.
1594 * Should be at least nr_pages long. Or NULL, if caller
1595 * only intends to ensure the pages are faulted in.
1596 * @vmas: array of pointers to vmas corresponding to each page.
1597 * Or NULL if the caller does not require them.
1598 * @nonblocking: whether waiting for disk IO or mmap_sem contention
1600 * Returns number of pages pinned. This may be fewer than the number
1601 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1602 * were pinned, returns -errno. Each page returned must be released
1603 * with a put_page() call when it is finished with. vmas will only
1604 * remain valid while mmap_sem is held.
1606 * Must be called with mmap_sem held for read or write.
1608 * __get_user_pages walks a process's page tables and takes a reference to
1609 * each struct page that each user address corresponds to at a given
1610 * instant. That is, it takes the page that would be accessed if a user
1611 * thread accesses the given user virtual address at that instant.
1613 * This does not guarantee that the page exists in the user mappings when
1614 * __get_user_pages returns, and there may even be a completely different
1615 * page there in some cases (eg. if mmapped pagecache has been invalidated
1616 * and subsequently re faulted). However it does guarantee that the page
1617 * won't be freed completely. And mostly callers simply care that the page
1618 * contains data that was valid *at some point in time*. Typically, an IO
1619 * or similar operation cannot guarantee anything stronger anyway because
1620 * locks can't be held over the syscall boundary.
1622 * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
1623 * the page is written to, set_page_dirty (or set_page_dirty_lock, as
1624 * appropriate) must be called after the page is finished with, and
1625 * before put_page is called.
1627 * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
1628 * or mmap_sem contention, and if waiting is needed to pin all pages,
1629 * *@nonblocking will be set to 0.
1631 * In most cases, get_user_pages or get_user_pages_fast should be used
1632 * instead of __get_user_pages. __get_user_pages should be used only if
1633 * you need some special @gup_flags.
1635 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1636 unsigned long start, int nr_pages, unsigned int gup_flags,
1637 struct page **pages, struct vm_area_struct **vmas,
1638 int *nonblocking)
1640 int i;
1641 unsigned long vm_flags;
1643 if (nr_pages <= 0)
1644 return 0;
1646 VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
1649 * Require read or write permissions.
1650 * If FOLL_FORCE is set, we only require the "MAY" flags.
1652 vm_flags = (gup_flags & FOLL_WRITE) ?
1653 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1654 vm_flags &= (gup_flags & FOLL_FORCE) ?
1655 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1656 i = 0;
1658 do {
1659 struct vm_area_struct *vma;
1661 vma = find_extend_vma(mm, start);
1662 if (!vma && in_gate_area(mm, start)) {
1663 unsigned long pg = start & PAGE_MASK;
1664 pgd_t *pgd;
1665 pud_t *pud;
1666 pmd_t *pmd;
1667 pte_t *pte;
1669 /* user gate pages are read-only */
1670 if (gup_flags & FOLL_WRITE)
1671 return i ? : -EFAULT;
1672 if (pg > TASK_SIZE)
1673 pgd = pgd_offset_k(pg);
1674 else
1675 pgd = pgd_offset_gate(mm, pg);
1676 BUG_ON(pgd_none(*pgd));
1677 pud = pud_offset(pgd, pg);
1678 BUG_ON(pud_none(*pud));
1679 pmd = pmd_offset(pud, pg);
1680 if (pmd_none(*pmd))
1681 return i ? : -EFAULT;
1682 VM_BUG_ON(pmd_trans_huge(*pmd));
1683 pte = pte_offset_map(pmd, pg);
1684 if (pte_none(*pte)) {
1685 pte_unmap(pte);
1686 return i ? : -EFAULT;
1688 vma = get_gate_vma(mm);
1689 if (pages) {
1690 struct page *page;
1692 page = vm_normal_page(vma, start, *pte);
1693 if (!page) {
1694 if (!(gup_flags & FOLL_DUMP) &&
1695 is_zero_pfn(pte_pfn(*pte)))
1696 page = pte_page(*pte);
1697 else {
1698 pte_unmap(pte);
1699 return i ? : -EFAULT;
1702 pages[i] = page;
1703 get_page(page);
1705 pte_unmap(pte);
1706 goto next_page;
1709 if (!vma ||
1710 (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
1711 !(vm_flags & vma->vm_flags))
1712 return i ? : -EFAULT;
1714 if (is_vm_hugetlb_page(vma)) {
1715 i = follow_hugetlb_page(mm, vma, pages, vmas,
1716 &start, &nr_pages, i, gup_flags);
1717 continue;
1720 do {
1721 struct page *page;
1722 unsigned int foll_flags = gup_flags;
1725 * If we have a pending SIGKILL, don't keep faulting
1726 * pages and potentially allocating memory.
1728 if (unlikely(fatal_signal_pending(current)))
1729 return i ? i : -ERESTARTSYS;
1731 cond_resched();
1732 while (!(page = follow_page(vma, start, foll_flags))) {
1733 int ret;
1734 unsigned int fault_flags = 0;
1736 /* For mlock, just skip the stack guard page. */
1737 if (foll_flags & FOLL_MLOCK) {
1738 if (stack_guard_page(vma, start))
1739 goto next_page;
1741 if (foll_flags & FOLL_WRITE)
1742 fault_flags |= FAULT_FLAG_WRITE;
1743 if (nonblocking)
1744 fault_flags |= FAULT_FLAG_ALLOW_RETRY;
1745 if (foll_flags & FOLL_NOWAIT)
1746 fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT);
1748 ret = handle_mm_fault(mm, vma, start,
1749 fault_flags);
1751 if (ret & VM_FAULT_ERROR) {
1752 if (ret & VM_FAULT_OOM)
1753 return i ? i : -ENOMEM;
1754 if (ret & (VM_FAULT_HWPOISON |
1755 VM_FAULT_HWPOISON_LARGE)) {
1756 if (i)
1757 return i;
1758 else if (gup_flags & FOLL_HWPOISON)
1759 return -EHWPOISON;
1760 else
1761 return -EFAULT;
1763 if (ret & VM_FAULT_SIGBUS)
1764 return i ? i : -EFAULT;
1765 BUG();
1768 if (tsk) {
1769 if (ret & VM_FAULT_MAJOR)
1770 tsk->maj_flt++;
1771 else
1772 tsk->min_flt++;
1775 if (ret & VM_FAULT_RETRY) {
1776 if (nonblocking)
1777 *nonblocking = 0;
1778 return i;
1782 * The VM_FAULT_WRITE bit tells us that
1783 * do_wp_page has broken COW when necessary,
1784 * even if maybe_mkwrite decided not to set
1785 * pte_write. We can thus safely do subsequent
1786 * page lookups as if they were reads. But only
1787 * do so when looping for pte_write is futile:
1788 * in some cases userspace may also be wanting
1789 * to write to the gotten user page, which a
1790 * read fault here might prevent (a readonly
1791 * page might get reCOWed by userspace write).
1793 if ((ret & VM_FAULT_WRITE) &&
1794 !(vma->vm_flags & VM_WRITE))
1795 foll_flags &= ~FOLL_WRITE;
1797 cond_resched();
1799 if (IS_ERR(page))
1800 return i ? i : PTR_ERR(page);
1801 if (pages) {
1802 pages[i] = page;
1804 flush_anon_page(vma, page, start);
1805 flush_dcache_page(page);
1807 next_page:
1808 if (vmas)
1809 vmas[i] = vma;
1810 i++;
1811 start += PAGE_SIZE;
1812 nr_pages--;
1813 } while (nr_pages && start < vma->vm_end);
1814 } while (nr_pages);
1815 return i;
1817 EXPORT_SYMBOL(__get_user_pages);
1820 * fixup_user_fault() - manually resolve a user page fault
1821 * @tsk: the task_struct to use for page fault accounting, or
1822 * NULL if faults are not to be recorded.
1823 * @mm: mm_struct of target mm
1824 * @address: user address
1825 * @fault_flags:flags to pass down to handle_mm_fault()
1827 * This is meant to be called in the specific scenario where for locking reasons
1828 * we try to access user memory in atomic context (within a pagefault_disable()
1829 * section), this returns -EFAULT, and we want to resolve the user fault before
1830 * trying again.
1832 * Typically this is meant to be used by the futex code.
1834 * The main difference with get_user_pages() is that this function will
1835 * unconditionally call handle_mm_fault() which will in turn perform all the
1836 * necessary SW fixup of the dirty and young bits in the PTE, while
1837 * handle_mm_fault() only guarantees to update these in the struct page.
1839 * This is important for some architectures where those bits also gate the
1840 * access permission to the page because they are maintained in software. On
1841 * such architectures, gup() will not be enough to make a subsequent access
1842 * succeed.
1844 * This should be called with the mm_sem held for read.
1846 int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
1847 unsigned long address, unsigned int fault_flags)
1849 struct vm_area_struct *vma;
1850 int ret;
1852 vma = find_extend_vma(mm, address);
1853 if (!vma || address < vma->vm_start)
1854 return -EFAULT;
1856 ret = handle_mm_fault(mm, vma, address, fault_flags);
1857 if (ret & VM_FAULT_ERROR) {
1858 if (ret & VM_FAULT_OOM)
1859 return -ENOMEM;
1860 if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE))
1861 return -EHWPOISON;
1862 if (ret & VM_FAULT_SIGBUS)
1863 return -EFAULT;
1864 BUG();
1866 if (tsk) {
1867 if (ret & VM_FAULT_MAJOR)
1868 tsk->maj_flt++;
1869 else
1870 tsk->min_flt++;
1872 return 0;
1876 * get_user_pages() - pin user pages in memory
1877 * @tsk: the task_struct to use for page fault accounting, or
1878 * NULL if faults are not to be recorded.
1879 * @mm: mm_struct of target mm
1880 * @start: starting user address
1881 * @nr_pages: number of pages from start to pin
1882 * @write: whether pages will be written to by the caller
1883 * @force: whether to force write access even if user mapping is
1884 * readonly. This will result in the page being COWed even
1885 * in MAP_SHARED mappings. You do not want this.
1886 * @pages: array that receives pointers to the pages pinned.
1887 * Should be at least nr_pages long. Or NULL, if caller
1888 * only intends to ensure the pages are faulted in.
1889 * @vmas: array of pointers to vmas corresponding to each page.
1890 * Or NULL if the caller does not require them.
1892 * Returns number of pages pinned. This may be fewer than the number
1893 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1894 * were pinned, returns -errno. Each page returned must be released
1895 * with a put_page() call when it is finished with. vmas will only
1896 * remain valid while mmap_sem is held.
1898 * Must be called with mmap_sem held for read or write.
1900 * get_user_pages walks a process's page tables and takes a reference to
1901 * each struct page that each user address corresponds to at a given
1902 * instant. That is, it takes the page that would be accessed if a user
1903 * thread accesses the given user virtual address at that instant.
1905 * This does not guarantee that the page exists in the user mappings when
1906 * get_user_pages returns, and there may even be a completely different
1907 * page there in some cases (eg. if mmapped pagecache has been invalidated
1908 * and subsequently re faulted). However it does guarantee that the page
1909 * won't be freed completely. And mostly callers simply care that the page
1910 * contains data that was valid *at some point in time*. Typically, an IO
1911 * or similar operation cannot guarantee anything stronger anyway because
1912 * locks can't be held over the syscall boundary.
1914 * If write=0, the page must not be written to. If the page is written to,
1915 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1916 * after the page is finished with, and before put_page is called.
1918 * get_user_pages is typically used for fewer-copy IO operations, to get a
1919 * handle on the memory by some means other than accesses via the user virtual
1920 * addresses. The pages may be submitted for DMA to devices or accessed via
1921 * their kernel linear mapping (via the kmap APIs). Care should be taken to
1922 * use the correct cache flushing APIs.
1924 * See also get_user_pages_fast, for performance critical applications.
1926 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1927 unsigned long start, int nr_pages, int write, int force,
1928 struct page **pages, struct vm_area_struct **vmas)
1930 int flags = FOLL_TOUCH;
1932 if (pages)
1933 flags |= FOLL_GET;
1934 if (write)
1935 flags |= FOLL_WRITE;
1936 if (force)
1937 flags |= FOLL_FORCE;
1939 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
1940 NULL);
1942 EXPORT_SYMBOL(get_user_pages);
1945 * get_dump_page() - pin user page in memory while writing it to core dump
1946 * @addr: user address
1948 * Returns struct page pointer of user page pinned for dump,
1949 * to be freed afterwards by page_cache_release() or put_page().
1951 * Returns NULL on any kind of failure - a hole must then be inserted into
1952 * the corefile, to preserve alignment with its headers; and also returns
1953 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
1954 * allowing a hole to be left in the corefile to save diskspace.
1956 * Called without mmap_sem, but after all other threads have been killed.
1958 #ifdef CONFIG_ELF_CORE
1959 struct page *get_dump_page(unsigned long addr)
1961 struct vm_area_struct *vma;
1962 struct page *page;
1964 if (__get_user_pages(current, current->mm, addr, 1,
1965 FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
1966 NULL) < 1)
1967 return NULL;
1968 flush_cache_page(vma, addr, page_to_pfn(page));
1969 return page;
1971 #endif /* CONFIG_ELF_CORE */
1973 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1974 spinlock_t **ptl)
1976 pgd_t * pgd = pgd_offset(mm, addr);
1977 pud_t * pud = pud_alloc(mm, pgd, addr);
1978 if (pud) {
1979 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1980 if (pmd) {
1981 VM_BUG_ON(pmd_trans_huge(*pmd));
1982 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1985 return NULL;
1989 * This is the old fallback for page remapping.
1991 * For historical reasons, it only allows reserved pages. Only
1992 * old drivers should use this, and they needed to mark their
1993 * pages reserved for the old functions anyway.
1995 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1996 struct page *page, pgprot_t prot)
1998 struct mm_struct *mm = vma->vm_mm;
1999 int retval;
2000 pte_t *pte;
2001 spinlock_t *ptl;
2003 retval = -EINVAL;
2004 if (PageAnon(page))
2005 goto out;
2006 retval = -ENOMEM;
2007 flush_dcache_page(page);
2008 pte = get_locked_pte(mm, addr, &ptl);
2009 if (!pte)
2010 goto out;
2011 retval = -EBUSY;
2012 if (!pte_none(*pte))
2013 goto out_unlock;
2015 /* Ok, finally just insert the thing.. */
2016 get_page(page);
2017 inc_mm_counter_fast(mm, MM_FILEPAGES);
2018 page_add_file_rmap(page);
2019 set_pte_at(mm, addr, pte, mk_pte(page, prot));
2021 retval = 0;
2022 pte_unmap_unlock(pte, ptl);
2023 return retval;
2024 out_unlock:
2025 pte_unmap_unlock(pte, ptl);
2026 out:
2027 return retval;
2031 * vm_insert_page - insert single page into user vma
2032 * @vma: user vma to map to
2033 * @addr: target user address of this page
2034 * @page: source kernel page
2036 * This allows drivers to insert individual pages they've allocated
2037 * into a user vma.
2039 * The page has to be a nice clean _individual_ kernel allocation.
2040 * If you allocate a compound page, you need to have marked it as
2041 * such (__GFP_COMP), or manually just split the page up yourself
2042 * (see split_page()).
2044 * NOTE! Traditionally this was done with "remap_pfn_range()" which
2045 * took an arbitrary page protection parameter. This doesn't allow
2046 * that. Your vma protection will have to be set up correctly, which
2047 * means that if you want a shared writable mapping, you'd better
2048 * ask for a shared writable mapping!
2050 * The page does not need to be reserved.
2052 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
2053 struct page *page)
2055 if (addr < vma->vm_start || addr >= vma->vm_end)
2056 return -EFAULT;
2057 if (!page_count(page))
2058 return -EINVAL;
2059 vma->vm_flags |= VM_INSERTPAGE;
2060 return insert_page(vma, addr, page, vma->vm_page_prot);
2062 EXPORT_SYMBOL(vm_insert_page);
2064 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2065 unsigned long pfn, pgprot_t prot)
2067 struct mm_struct *mm = vma->vm_mm;
2068 int retval;
2069 pte_t *pte, entry;
2070 spinlock_t *ptl;
2072 retval = -ENOMEM;
2073 pte = get_locked_pte(mm, addr, &ptl);
2074 if (!pte)
2075 goto out;
2076 retval = -EBUSY;
2077 if (!pte_none(*pte))
2078 goto out_unlock;
2080 /* Ok, finally just insert the thing.. */
2081 entry = pte_mkspecial(pfn_pte(pfn, prot));
2082 set_pte_at(mm, addr, pte, entry);
2083 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2085 retval = 0;
2086 out_unlock:
2087 pte_unmap_unlock(pte, ptl);
2088 out:
2089 return retval;
2093 * vm_insert_pfn - insert single pfn into user vma
2094 * @vma: user vma to map to
2095 * @addr: target user address of this page
2096 * @pfn: source kernel pfn
2098 * Similar to vm_inert_page, this allows drivers to insert individual pages
2099 * they've allocated into a user vma. Same comments apply.
2101 * This function should only be called from a vm_ops->fault handler, and
2102 * in that case the handler should return NULL.
2104 * vma cannot be a COW mapping.
2106 * As this is called only for pages that do not currently exist, we
2107 * do not need to flush old virtual caches or the TLB.
2109 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2110 unsigned long pfn)
2112 int ret;
2113 pgprot_t pgprot = vma->vm_page_prot;
2115 * Technically, architectures with pte_special can avoid all these
2116 * restrictions (same for remap_pfn_range). However we would like
2117 * consistency in testing and feature parity among all, so we should
2118 * try to keep these invariants in place for everybody.
2120 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
2121 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
2122 (VM_PFNMAP|VM_MIXEDMAP));
2123 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2124 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2126 if (addr < vma->vm_start || addr >= vma->vm_end)
2127 return -EFAULT;
2128 if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
2129 return -EINVAL;
2131 ret = insert_pfn(vma, addr, pfn, pgprot);
2133 if (ret)
2134 untrack_pfn_vma(vma, pfn, PAGE_SIZE);
2136 return ret;
2138 EXPORT_SYMBOL(vm_insert_pfn);
2140 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2141 unsigned long pfn)
2143 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
2145 if (addr < vma->vm_start || addr >= vma->vm_end)
2146 return -EFAULT;
2149 * If we don't have pte special, then we have to use the pfn_valid()
2150 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2151 * refcount the page if pfn_valid is true (hence insert_page rather
2152 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
2153 * without pte special, it would there be refcounted as a normal page.
2155 if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
2156 struct page *page;
2158 page = pfn_to_page(pfn);
2159 return insert_page(vma, addr, page, vma->vm_page_prot);
2161 return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
2163 EXPORT_SYMBOL(vm_insert_mixed);
2166 * maps a range of physical memory into the requested pages. the old
2167 * mappings are removed. any references to nonexistent pages results
2168 * in null mappings (currently treated as "copy-on-access")
2170 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2171 unsigned long addr, unsigned long end,
2172 unsigned long pfn, pgprot_t prot)
2174 pte_t *pte;
2175 spinlock_t *ptl;
2177 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2178 if (!pte)
2179 return -ENOMEM;
2180 arch_enter_lazy_mmu_mode();
2181 do {
2182 BUG_ON(!pte_none(*pte));
2183 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2184 pfn++;
2185 } while (pte++, addr += PAGE_SIZE, addr != end);
2186 arch_leave_lazy_mmu_mode();
2187 pte_unmap_unlock(pte - 1, ptl);
2188 return 0;
2191 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2192 unsigned long addr, unsigned long end,
2193 unsigned long pfn, pgprot_t prot)
2195 pmd_t *pmd;
2196 unsigned long next;
2198 pfn -= addr >> PAGE_SHIFT;
2199 pmd = pmd_alloc(mm, pud, addr);
2200 if (!pmd)
2201 return -ENOMEM;
2202 VM_BUG_ON(pmd_trans_huge(*pmd));
2203 do {
2204 next = pmd_addr_end(addr, end);
2205 if (remap_pte_range(mm, pmd, addr, next,
2206 pfn + (addr >> PAGE_SHIFT), prot))
2207 return -ENOMEM;
2208 } while (pmd++, addr = next, addr != end);
2209 return 0;
2212 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
2213 unsigned long addr, unsigned long end,
2214 unsigned long pfn, pgprot_t prot)
2216 pud_t *pud;
2217 unsigned long next;
2219 pfn -= addr >> PAGE_SHIFT;
2220 pud = pud_alloc(mm, pgd, addr);
2221 if (!pud)
2222 return -ENOMEM;
2223 do {
2224 next = pud_addr_end(addr, end);
2225 if (remap_pmd_range(mm, pud, addr, next,
2226 pfn + (addr >> PAGE_SHIFT), prot))
2227 return -ENOMEM;
2228 } while (pud++, addr = next, addr != end);
2229 return 0;
2233 * remap_pfn_range - remap kernel memory to userspace
2234 * @vma: user vma to map to
2235 * @addr: target user address to start at
2236 * @pfn: physical address of kernel memory
2237 * @size: size of map area
2238 * @prot: page protection flags for this mapping
2240 * Note: this is only safe if the mm semaphore is held when called.
2242 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2243 unsigned long pfn, unsigned long size, pgprot_t prot)
2245 pgd_t *pgd;
2246 unsigned long next;
2247 unsigned long end = addr + PAGE_ALIGN(size);
2248 struct mm_struct *mm = vma->vm_mm;
2249 int err;
2252 * Physically remapped pages are special. Tell the
2253 * rest of the world about it:
2254 * VM_IO tells people not to look at these pages
2255 * (accesses can have side effects).
2256 * VM_RESERVED is specified all over the place, because
2257 * in 2.4 it kept swapout's vma scan off this vma; but
2258 * in 2.6 the LRU scan won't even find its pages, so this
2259 * flag means no more than count its pages in reserved_vm,
2260 * and omit it from core dump, even when VM_IO turned off.
2261 * VM_PFNMAP tells the core MM that the base pages are just
2262 * raw PFN mappings, and do not have a "struct page" associated
2263 * with them.
2265 * There's a horrible special case to handle copy-on-write
2266 * behaviour that some programs depend on. We mark the "original"
2267 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2269 if (addr == vma->vm_start && end == vma->vm_end) {
2270 vma->vm_pgoff = pfn;
2271 vma->vm_flags |= VM_PFN_AT_MMAP;
2272 } else if (is_cow_mapping(vma->vm_flags))
2273 return -EINVAL;
2275 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
2277 err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
2278 if (err) {
2280 * To indicate that track_pfn related cleanup is not
2281 * needed from higher level routine calling unmap_vmas
2283 vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
2284 vma->vm_flags &= ~VM_PFN_AT_MMAP;
2285 return -EINVAL;
2288 BUG_ON(addr >= end);
2289 pfn -= addr >> PAGE_SHIFT;
2290 pgd = pgd_offset(mm, addr);
2291 flush_cache_range(vma, addr, end);
2292 do {
2293 next = pgd_addr_end(addr, end);
2294 err = remap_pud_range(mm, pgd, addr, next,
2295 pfn + (addr >> PAGE_SHIFT), prot);
2296 if (err)
2297 break;
2298 } while (pgd++, addr = next, addr != end);
2300 if (err)
2301 untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
2303 return err;
2305 EXPORT_SYMBOL(remap_pfn_range);
2307 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2308 unsigned long addr, unsigned long end,
2309 pte_fn_t fn, void *data)
2311 pte_t *pte;
2312 int err;
2313 pgtable_t token;
2314 spinlock_t *uninitialized_var(ptl);
2316 pte = (mm == &init_mm) ?
2317 pte_alloc_kernel(pmd, addr) :
2318 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2319 if (!pte)
2320 return -ENOMEM;
2322 BUG_ON(pmd_huge(*pmd));
2324 arch_enter_lazy_mmu_mode();
2326 token = pmd_pgtable(*pmd);
2328 do {
2329 err = fn(pte++, token, addr, data);
2330 if (err)
2331 break;
2332 } while (addr += PAGE_SIZE, addr != end);
2334 arch_leave_lazy_mmu_mode();
2336 if (mm != &init_mm)
2337 pte_unmap_unlock(pte-1, ptl);
2338 return err;
2341 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2342 unsigned long addr, unsigned long end,
2343 pte_fn_t fn, void *data)
2345 pmd_t *pmd;
2346 unsigned long next;
2347 int err;
2349 BUG_ON(pud_huge(*pud));
2351 pmd = pmd_alloc(mm, pud, addr);
2352 if (!pmd)
2353 return -ENOMEM;
2354 do {
2355 next = pmd_addr_end(addr, end);
2356 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2357 if (err)
2358 break;
2359 } while (pmd++, addr = next, addr != end);
2360 return err;
2363 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
2364 unsigned long addr, unsigned long end,
2365 pte_fn_t fn, void *data)
2367 pud_t *pud;
2368 unsigned long next;
2369 int err;
2371 pud = pud_alloc(mm, pgd, addr);
2372 if (!pud)
2373 return -ENOMEM;
2374 do {
2375 next = pud_addr_end(addr, end);
2376 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2377 if (err)
2378 break;
2379 } while (pud++, addr = next, addr != end);
2380 return err;
2384 * Scan a region of virtual memory, filling in page tables as necessary
2385 * and calling a provided function on each leaf page table.
2387 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2388 unsigned long size, pte_fn_t fn, void *data)
2390 pgd_t *pgd;
2391 unsigned long next;
2392 unsigned long end = addr + size;
2393 int err;
2395 BUG_ON(addr >= end);
2396 pgd = pgd_offset(mm, addr);
2397 do {
2398 next = pgd_addr_end(addr, end);
2399 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
2400 if (err)
2401 break;
2402 } while (pgd++, addr = next, addr != end);
2404 return err;
2406 EXPORT_SYMBOL_GPL(apply_to_page_range);
2409 * handle_pte_fault chooses page fault handler according to an entry
2410 * which was read non-atomically. Before making any commitment, on
2411 * those architectures or configurations (e.g. i386 with PAE) which
2412 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
2413 * must check under lock before unmapping the pte and proceeding
2414 * (but do_wp_page is only called after already making such a check;
2415 * and do_anonymous_page can safely check later on).
2417 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2418 pte_t *page_table, pte_t orig_pte)
2420 int same = 1;
2421 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2422 if (sizeof(pte_t) > sizeof(unsigned long)) {
2423 spinlock_t *ptl = pte_lockptr(mm, pmd);
2424 spin_lock(ptl);
2425 same = pte_same(*page_table, orig_pte);
2426 spin_unlock(ptl);
2428 #endif
2429 pte_unmap(page_table);
2430 return same;
2433 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2436 * If the source page was a PFN mapping, we don't have
2437 * a "struct page" for it. We do a best-effort copy by
2438 * just copying from the original user address. If that
2439 * fails, we just zero-fill it. Live with it.
2441 if (unlikely(!src)) {
2442 void *kaddr = kmap_atomic(dst, KM_USER0);
2443 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2446 * This really shouldn't fail, because the page is there
2447 * in the page tables. But it might just be unreadable,
2448 * in which case we just give up and fill the result with
2449 * zeroes.
2451 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2452 clear_page(kaddr);
2453 kunmap_atomic(kaddr, KM_USER0);
2454 flush_dcache_page(dst);
2455 } else
2456 copy_user_highpage(dst, src, va, vma);
2460 * This routine handles present pages, when users try to write
2461 * to a shared page. It is done by copying the page to a new address
2462 * and decrementing the shared-page counter for the old page.
2464 * Note that this routine assumes that the protection checks have been
2465 * done by the caller (the low-level page fault routine in most cases).
2466 * Thus we can safely just mark it writable once we've done any necessary
2467 * COW.
2469 * We also mark the page dirty at this point even though the page will
2470 * change only once the write actually happens. This avoids a few races,
2471 * and potentially makes it more efficient.
2473 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2474 * but allow concurrent faults), with pte both mapped and locked.
2475 * We return with mmap_sem still held, but pte unmapped and unlocked.
2477 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
2478 unsigned long address, pte_t *page_table, pmd_t *pmd,
2479 spinlock_t *ptl, pte_t orig_pte)
2480 __releases(ptl)
2482 struct page *old_page, *new_page;
2483 pte_t entry;
2484 int ret = 0;
2485 int page_mkwrite = 0;
2486 struct page *dirty_page = NULL;
2488 old_page = vm_normal_page(vma, address, orig_pte);
2489 if (!old_page) {
2491 * VM_MIXEDMAP !pfn_valid() case
2493 * We should not cow pages in a shared writeable mapping.
2494 * Just mark the pages writable as we can't do any dirty
2495 * accounting on raw pfn maps.
2497 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2498 (VM_WRITE|VM_SHARED))
2499 goto reuse;
2500 goto gotten;
2504 * Take out anonymous pages first, anonymous shared vmas are
2505 * not dirty accountable.
2507 if (PageAnon(old_page) && !PageKsm(old_page)) {
2508 if (!trylock_page(old_page)) {
2509 page_cache_get(old_page);
2510 pte_unmap_unlock(page_table, ptl);
2511 lock_page(old_page);
2512 page_table = pte_offset_map_lock(mm, pmd, address,
2513 &ptl);
2514 if (!pte_same(*page_table, orig_pte)) {
2515 unlock_page(old_page);
2516 goto unlock;
2518 page_cache_release(old_page);
2520 if (reuse_swap_page(old_page)) {
2522 * The page is all ours. Move it to our anon_vma so
2523 * the rmap code will not search our parent or siblings.
2524 * Protected against the rmap code by the page lock.
2526 page_move_anon_rmap(old_page, vma, address);
2527 unlock_page(old_page);
2528 goto reuse;
2530 unlock_page(old_page);
2531 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2532 (VM_WRITE|VM_SHARED))) {
2534 * Only catch write-faults on shared writable pages,
2535 * read-only shared pages can get COWed by
2536 * get_user_pages(.write=1, .force=1).
2538 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2539 struct vm_fault vmf;
2540 int tmp;
2542 vmf.virtual_address = (void __user *)(address &
2543 PAGE_MASK);
2544 vmf.pgoff = old_page->index;
2545 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2546 vmf.page = old_page;
2549 * Notify the address space that the page is about to
2550 * become writable so that it can prohibit this or wait
2551 * for the page to get into an appropriate state.
2553 * We do this without the lock held, so that it can
2554 * sleep if it needs to.
2556 page_cache_get(old_page);
2557 pte_unmap_unlock(page_table, ptl);
2559 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2560 if (unlikely(tmp &
2561 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2562 ret = tmp;
2563 goto unwritable_page;
2565 if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2566 lock_page(old_page);
2567 if (!old_page->mapping) {
2568 ret = 0; /* retry the fault */
2569 unlock_page(old_page);
2570 goto unwritable_page;
2572 } else
2573 VM_BUG_ON(!PageLocked(old_page));
2576 * Since we dropped the lock we need to revalidate
2577 * the PTE as someone else may have changed it. If
2578 * they did, we just return, as we can count on the
2579 * MMU to tell us if they didn't also make it writable.
2581 page_table = pte_offset_map_lock(mm, pmd, address,
2582 &ptl);
2583 if (!pte_same(*page_table, orig_pte)) {
2584 unlock_page(old_page);
2585 goto unlock;
2588 page_mkwrite = 1;
2590 dirty_page = old_page;
2591 get_page(dirty_page);
2593 reuse:
2594 flush_cache_page(vma, address, pte_pfn(orig_pte));
2595 entry = pte_mkyoung(orig_pte);
2596 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2597 if (ptep_set_access_flags(vma, address, page_table, entry,1))
2598 update_mmu_cache(vma, address, page_table);
2599 pte_unmap_unlock(page_table, ptl);
2600 ret |= VM_FAULT_WRITE;
2602 if (!dirty_page)
2603 return ret;
2606 * Yes, Virginia, this is actually required to prevent a race
2607 * with clear_page_dirty_for_io() from clearing the page dirty
2608 * bit after it clear all dirty ptes, but before a racing
2609 * do_wp_page installs a dirty pte.
2611 * __do_fault is protected similarly.
2613 if (!page_mkwrite) {
2614 wait_on_page_locked(dirty_page);
2615 set_page_dirty_balance(dirty_page, page_mkwrite);
2617 put_page(dirty_page);
2618 if (page_mkwrite) {
2619 struct address_space *mapping = dirty_page->mapping;
2621 set_page_dirty(dirty_page);
2622 unlock_page(dirty_page);
2623 page_cache_release(dirty_page);
2624 if (mapping) {
2626 * Some device drivers do not set page.mapping
2627 * but still dirty their pages
2629 balance_dirty_pages_ratelimited(mapping);
2633 /* file_update_time outside page_lock */
2634 if (vma->vm_file)
2635 file_update_time(vma->vm_file);
2637 return ret;
2641 * Ok, we need to copy. Oh, well..
2643 page_cache_get(old_page);
2644 gotten:
2645 pte_unmap_unlock(page_table, ptl);
2647 if (unlikely(anon_vma_prepare(vma)))
2648 goto oom;
2650 if (is_zero_pfn(pte_pfn(orig_pte))) {
2651 new_page = alloc_zeroed_user_highpage_movable(vma, address);
2652 if (!new_page)
2653 goto oom;
2654 } else {
2655 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2656 if (!new_page)
2657 goto oom;
2658 cow_user_page(new_page, old_page, address, vma);
2660 __SetPageUptodate(new_page);
2662 if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2663 goto oom_free_new;
2666 * Re-check the pte - we dropped the lock
2668 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2669 if (likely(pte_same(*page_table, orig_pte))) {
2670 if (old_page) {
2671 if (!PageAnon(old_page)) {
2672 dec_mm_counter_fast(mm, MM_FILEPAGES);
2673 inc_mm_counter_fast(mm, MM_ANONPAGES);
2675 } else
2676 inc_mm_counter_fast(mm, MM_ANONPAGES);
2677 flush_cache_page(vma, address, pte_pfn(orig_pte));
2678 entry = mk_pte(new_page, vma->vm_page_prot);
2679 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2681 * Clear the pte entry and flush it first, before updating the
2682 * pte with the new entry. This will avoid a race condition
2683 * seen in the presence of one thread doing SMC and another
2684 * thread doing COW.
2686 ptep_clear_flush(vma, address, page_table);
2687 page_add_new_anon_rmap(new_page, vma, address);
2689 * We call the notify macro here because, when using secondary
2690 * mmu page tables (such as kvm shadow page tables), we want the
2691 * new page to be mapped directly into the secondary page table.
2693 set_pte_at_notify(mm, address, page_table, entry);
2694 update_mmu_cache(vma, address, page_table);
2695 if (old_page) {
2697 * Only after switching the pte to the new page may
2698 * we remove the mapcount here. Otherwise another
2699 * process may come and find the rmap count decremented
2700 * before the pte is switched to the new page, and
2701 * "reuse" the old page writing into it while our pte
2702 * here still points into it and can be read by other
2703 * threads.
2705 * The critical issue is to order this
2706 * page_remove_rmap with the ptp_clear_flush above.
2707 * Those stores are ordered by (if nothing else,)
2708 * the barrier present in the atomic_add_negative
2709 * in page_remove_rmap.
2711 * Then the TLB flush in ptep_clear_flush ensures that
2712 * no process can access the old page before the
2713 * decremented mapcount is visible. And the old page
2714 * cannot be reused until after the decremented
2715 * mapcount is visible. So transitively, TLBs to
2716 * old page will be flushed before it can be reused.
2718 page_remove_rmap(old_page);
2721 /* Free the old page.. */
2722 new_page = old_page;
2723 ret |= VM_FAULT_WRITE;
2724 } else
2725 mem_cgroup_uncharge_page(new_page);
2727 if (new_page)
2728 page_cache_release(new_page);
2729 unlock:
2730 pte_unmap_unlock(page_table, ptl);
2731 if (old_page) {
2733 * Don't let another task, with possibly unlocked vma,
2734 * keep the mlocked page.
2736 if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
2737 lock_page(old_page); /* LRU manipulation */
2738 munlock_vma_page(old_page);
2739 unlock_page(old_page);
2741 page_cache_release(old_page);
2743 return ret;
2744 oom_free_new:
2745 page_cache_release(new_page);
2746 oom:
2747 if (old_page) {
2748 if (page_mkwrite) {
2749 unlock_page(old_page);
2750 page_cache_release(old_page);
2752 page_cache_release(old_page);
2754 return VM_FAULT_OOM;
2756 unwritable_page:
2757 page_cache_release(old_page);
2758 return ret;
2761 static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2762 unsigned long start_addr, unsigned long end_addr,
2763 struct zap_details *details)
2765 zap_page_range(vma, start_addr, end_addr - start_addr, details);
2768 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
2769 struct zap_details *details)
2771 struct vm_area_struct *vma;
2772 struct prio_tree_iter iter;
2773 pgoff_t vba, vea, zba, zea;
2775 vma_prio_tree_foreach(vma, &iter, root,
2776 details->first_index, details->last_index) {
2778 vba = vma->vm_pgoff;
2779 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
2780 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2781 zba = details->first_index;
2782 if (zba < vba)
2783 zba = vba;
2784 zea = details->last_index;
2785 if (zea > vea)
2786 zea = vea;
2788 unmap_mapping_range_vma(vma,
2789 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2790 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2791 details);
2795 static inline void unmap_mapping_range_list(struct list_head *head,
2796 struct zap_details *details)
2798 struct vm_area_struct *vma;
2801 * In nonlinear VMAs there is no correspondence between virtual address
2802 * offset and file offset. So we must perform an exhaustive search
2803 * across *all* the pages in each nonlinear VMA, not just the pages
2804 * whose virtual address lies outside the file truncation point.
2806 list_for_each_entry(vma, head, shared.vm_set.list) {
2807 details->nonlinear_vma = vma;
2808 unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
2813 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2814 * @mapping: the address space containing mmaps to be unmapped.
2815 * @holebegin: byte in first page to unmap, relative to the start of
2816 * the underlying file. This will be rounded down to a PAGE_SIZE
2817 * boundary. Note that this is different from truncate_pagecache(), which
2818 * must keep the partial page. In contrast, we must get rid of
2819 * partial pages.
2820 * @holelen: size of prospective hole in bytes. This will be rounded
2821 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2822 * end of the file.
2823 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2824 * but 0 when invalidating pagecache, don't throw away private data.
2826 void unmap_mapping_range(struct address_space *mapping,
2827 loff_t const holebegin, loff_t const holelen, int even_cows)
2829 struct zap_details details;
2830 pgoff_t hba = holebegin >> PAGE_SHIFT;
2831 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2833 /* Check for overflow. */
2834 if (sizeof(holelen) > sizeof(hlen)) {
2835 long long holeend =
2836 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2837 if (holeend & ~(long long)ULONG_MAX)
2838 hlen = ULONG_MAX - hba + 1;
2841 details.check_mapping = even_cows? NULL: mapping;
2842 details.nonlinear_vma = NULL;
2843 details.first_index = hba;
2844 details.last_index = hba + hlen - 1;
2845 if (details.last_index < details.first_index)
2846 details.last_index = ULONG_MAX;
2849 mutex_lock(&mapping->i_mmap_mutex);
2850 if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
2851 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2852 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2853 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2854 mutex_unlock(&mapping->i_mmap_mutex);
2856 EXPORT_SYMBOL(unmap_mapping_range);
2859 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2860 * but allow concurrent faults), and pte mapped but not yet locked.
2861 * We return with mmap_sem still held, but pte unmapped and unlocked.
2863 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2864 unsigned long address, pte_t *page_table, pmd_t *pmd,
2865 unsigned int flags, pte_t orig_pte)
2867 spinlock_t *ptl;
2868 struct page *page, *swapcache = NULL;
2869 swp_entry_t entry;
2870 pte_t pte;
2871 int locked;
2872 struct mem_cgroup *ptr;
2873 int exclusive = 0;
2874 int ret = 0;
2876 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2877 goto out;
2879 entry = pte_to_swp_entry(orig_pte);
2880 if (unlikely(non_swap_entry(entry))) {
2881 if (is_migration_entry(entry)) {
2882 migration_entry_wait(mm, pmd, address);
2883 } else if (is_hwpoison_entry(entry)) {
2884 ret = VM_FAULT_HWPOISON;
2885 } else {
2886 print_bad_pte(vma, address, orig_pte, NULL);
2887 ret = VM_FAULT_SIGBUS;
2889 goto out;
2891 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2892 page = lookup_swap_cache(entry);
2893 if (!page) {
2894 grab_swap_token(mm); /* Contend for token _before_ read-in */
2895 page = swapin_readahead(entry,
2896 GFP_HIGHUSER_MOVABLE, vma, address);
2897 if (!page) {
2899 * Back out if somebody else faulted in this pte
2900 * while we released the pte lock.
2902 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2903 if (likely(pte_same(*page_table, orig_pte)))
2904 ret = VM_FAULT_OOM;
2905 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2906 goto unlock;
2909 /* Had to read the page from swap area: Major fault */
2910 ret = VM_FAULT_MAJOR;
2911 count_vm_event(PGMAJFAULT);
2912 mem_cgroup_count_vm_event(mm, PGMAJFAULT);
2913 } else if (PageHWPoison(page)) {
2915 * hwpoisoned dirty swapcache pages are kept for killing
2916 * owner processes (which may be unknown at hwpoison time)
2918 ret = VM_FAULT_HWPOISON;
2919 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2920 goto out_release;
2923 locked = lock_page_or_retry(page, mm, flags);
2924 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2925 if (!locked) {
2926 ret |= VM_FAULT_RETRY;
2927 goto out_release;
2931 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2932 * release the swapcache from under us. The page pin, and pte_same
2933 * test below, are not enough to exclude that. Even if it is still
2934 * swapcache, we need to check that the page's swap has not changed.
2936 if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
2937 goto out_page;
2939 if (ksm_might_need_to_copy(page, vma, address)) {
2940 swapcache = page;
2941 page = ksm_does_need_to_copy(page, vma, address);
2943 if (unlikely(!page)) {
2944 ret = VM_FAULT_OOM;
2945 page = swapcache;
2946 swapcache = NULL;
2947 goto out_page;
2951 if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2952 ret = VM_FAULT_OOM;
2953 goto out_page;
2957 * Back out if somebody else already faulted in this pte.
2959 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2960 if (unlikely(!pte_same(*page_table, orig_pte)))
2961 goto out_nomap;
2963 if (unlikely(!PageUptodate(page))) {
2964 ret = VM_FAULT_SIGBUS;
2965 goto out_nomap;
2969 * The page isn't present yet, go ahead with the fault.
2971 * Be careful about the sequence of operations here.
2972 * To get its accounting right, reuse_swap_page() must be called
2973 * while the page is counted on swap but not yet in mapcount i.e.
2974 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2975 * must be called after the swap_free(), or it will never succeed.
2976 * Because delete_from_swap_page() may be called by reuse_swap_page(),
2977 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
2978 * in page->private. In this case, a record in swap_cgroup is silently
2979 * discarded at swap_free().
2982 inc_mm_counter_fast(mm, MM_ANONPAGES);
2983 dec_mm_counter_fast(mm, MM_SWAPENTS);
2984 pte = mk_pte(page, vma->vm_page_prot);
2985 if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
2986 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2987 flags &= ~FAULT_FLAG_WRITE;
2988 ret |= VM_FAULT_WRITE;
2989 exclusive = 1;
2991 flush_icache_page(vma, page);
2992 set_pte_at(mm, address, page_table, pte);
2993 do_page_add_anon_rmap(page, vma, address, exclusive);
2994 /* It's better to call commit-charge after rmap is established */
2995 mem_cgroup_commit_charge_swapin(page, ptr);
2997 swap_free(entry);
2998 if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2999 try_to_free_swap(page);
3000 unlock_page(page);
3001 if (swapcache) {
3003 * Hold the lock to avoid the swap entry to be reused
3004 * until we take the PT lock for the pte_same() check
3005 * (to avoid false positives from pte_same). For
3006 * further safety release the lock after the swap_free
3007 * so that the swap count won't change under a
3008 * parallel locked swapcache.
3010 unlock_page(swapcache);
3011 page_cache_release(swapcache);
3014 if (flags & FAULT_FLAG_WRITE) {
3015 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
3016 if (ret & VM_FAULT_ERROR)
3017 ret &= VM_FAULT_ERROR;
3018 goto out;
3021 /* No need to invalidate - it was non-present before */
3022 update_mmu_cache(vma, address, page_table);
3023 unlock:
3024 pte_unmap_unlock(page_table, ptl);
3025 out:
3026 return ret;
3027 out_nomap:
3028 mem_cgroup_cancel_charge_swapin(ptr);
3029 pte_unmap_unlock(page_table, ptl);
3030 out_page:
3031 unlock_page(page);
3032 out_release:
3033 page_cache_release(page);
3034 if (swapcache) {
3035 unlock_page(swapcache);
3036 page_cache_release(swapcache);
3038 return ret;
3042 * This is like a special single-page "expand_{down|up}wards()",
3043 * except we must first make sure that 'address{-|+}PAGE_SIZE'
3044 * doesn't hit another vma.
3046 static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
3048 address &= PAGE_MASK;
3049 if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
3050 struct vm_area_struct *prev = vma->vm_prev;
3053 * Is there a mapping abutting this one below?
3055 * That's only ok if it's the same stack mapping
3056 * that has gotten split..
3058 if (prev && prev->vm_end == address)
3059 return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
3061 expand_downwards(vma, address - PAGE_SIZE);
3063 if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
3064 struct vm_area_struct *next = vma->vm_next;
3066 /* As VM_GROWSDOWN but s/below/above/ */
3067 if (next && next->vm_start == address + PAGE_SIZE)
3068 return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
3070 expand_upwards(vma, address + PAGE_SIZE);
3072 return 0;
3076 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3077 * but allow concurrent faults), and pte mapped but not yet locked.
3078 * We return with mmap_sem still held, but pte unmapped and unlocked.
3080 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
3081 unsigned long address, pte_t *page_table, pmd_t *pmd,
3082 unsigned int flags)
3084 struct page *page;
3085 spinlock_t *ptl;
3086 pte_t entry;
3088 pte_unmap(page_table);
3090 /* Check if we need to add a guard page to the stack */
3091 if (check_stack_guard_page(vma, address) < 0)
3092 return VM_FAULT_SIGBUS;
3094 /* Use the zero-page for reads */
3095 if (!(flags & FAULT_FLAG_WRITE)) {
3096 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
3097 vma->vm_page_prot));
3098 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3099 if (!pte_none(*page_table))
3100 goto unlock;
3101 goto setpte;
3104 /* Allocate our own private page. */
3105 if (unlikely(anon_vma_prepare(vma)))
3106 goto oom;
3107 page = alloc_zeroed_user_highpage_movable(vma, address);
3108 if (!page)
3109 goto oom;
3110 __SetPageUptodate(page);
3112 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
3113 goto oom_free_page;
3115 entry = mk_pte(page, vma->vm_page_prot);
3116 if (vma->vm_flags & VM_WRITE)
3117 entry = pte_mkwrite(pte_mkdirty(entry));
3119 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3120 if (!pte_none(*page_table))
3121 goto release;
3123 inc_mm_counter_fast(mm, MM_ANONPAGES);
3124 page_add_new_anon_rmap(page, vma, address);
3125 setpte:
3126 set_pte_at(mm, address, page_table, entry);
3128 /* No need to invalidate - it was non-present before */
3129 update_mmu_cache(vma, address, page_table);
3130 unlock:
3131 pte_unmap_unlock(page_table, ptl);
3132 return 0;
3133 release:
3134 mem_cgroup_uncharge_page(page);
3135 page_cache_release(page);
3136 goto unlock;
3137 oom_free_page:
3138 page_cache_release(page);
3139 oom:
3140 return VM_FAULT_OOM;
3144 * __do_fault() tries to create a new page mapping. It aggressively
3145 * tries to share with existing pages, but makes a separate copy if
3146 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
3147 * the next page fault.
3149 * As this is called only for pages that do not currently exist, we
3150 * do not need to flush old virtual caches or the TLB.
3152 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3153 * but allow concurrent faults), and pte neither mapped nor locked.
3154 * We return with mmap_sem still held, but pte unmapped and unlocked.
3156 static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3157 unsigned long address, pmd_t *pmd,
3158 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3160 pte_t *page_table;
3161 spinlock_t *ptl;
3162 struct page *page;
3163 pte_t entry;
3164 int anon = 0;
3165 int charged = 0;
3166 struct page *dirty_page = NULL;
3167 struct vm_fault vmf;
3168 int ret;
3169 int page_mkwrite = 0;
3171 vmf.virtual_address = (void __user *)(address & PAGE_MASK);
3172 vmf.pgoff = pgoff;
3173 vmf.flags = flags;
3174 vmf.page = NULL;
3176 ret = vma->vm_ops->fault(vma, &vmf);
3177 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3178 VM_FAULT_RETRY)))
3179 return ret;
3181 if (unlikely(PageHWPoison(vmf.page))) {
3182 if (ret & VM_FAULT_LOCKED)
3183 unlock_page(vmf.page);
3184 return VM_FAULT_HWPOISON;
3188 * For consistency in subsequent calls, make the faulted page always
3189 * locked.
3191 if (unlikely(!(ret & VM_FAULT_LOCKED)))
3192 lock_page(vmf.page);
3193 else
3194 VM_BUG_ON(!PageLocked(vmf.page));
3197 * Should we do an early C-O-W break?
3199 page = vmf.page;
3200 if (flags & FAULT_FLAG_WRITE) {
3201 if (!(vma->vm_flags & VM_SHARED)) {
3202 anon = 1;
3203 if (unlikely(anon_vma_prepare(vma))) {
3204 ret = VM_FAULT_OOM;
3205 goto out;
3207 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
3208 vma, address);
3209 if (!page) {
3210 ret = VM_FAULT_OOM;
3211 goto out;
3213 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
3214 ret = VM_FAULT_OOM;
3215 page_cache_release(page);
3216 goto out;
3218 charged = 1;
3219 copy_user_highpage(page, vmf.page, address, vma);
3220 __SetPageUptodate(page);
3221 } else {
3223 * If the page will be shareable, see if the backing
3224 * address space wants to know that the page is about
3225 * to become writable
3227 if (vma->vm_ops->page_mkwrite) {
3228 int tmp;
3230 unlock_page(page);
3231 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
3232 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
3233 if (unlikely(tmp &
3234 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3235 ret = tmp;
3236 goto unwritable_page;
3238 if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
3239 lock_page(page);
3240 if (!page->mapping) {
3241 ret = 0; /* retry the fault */
3242 unlock_page(page);
3243 goto unwritable_page;
3245 } else
3246 VM_BUG_ON(!PageLocked(page));
3247 page_mkwrite = 1;
3253 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3256 * This silly early PAGE_DIRTY setting removes a race
3257 * due to the bad i386 page protection. But it's valid
3258 * for other architectures too.
3260 * Note that if FAULT_FLAG_WRITE is set, we either now have
3261 * an exclusive copy of the page, or this is a shared mapping,
3262 * so we can make it writable and dirty to avoid having to
3263 * handle that later.
3265 /* Only go through if we didn't race with anybody else... */
3266 if (likely(pte_same(*page_table, orig_pte))) {
3267 flush_icache_page(vma, page);
3268 entry = mk_pte(page, vma->vm_page_prot);
3269 if (flags & FAULT_FLAG_WRITE)
3270 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3271 if (anon) {
3272 inc_mm_counter_fast(mm, MM_ANONPAGES);
3273 page_add_new_anon_rmap(page, vma, address);
3274 } else {
3275 inc_mm_counter_fast(mm, MM_FILEPAGES);
3276 page_add_file_rmap(page);
3277 if (flags & FAULT_FLAG_WRITE) {
3278 dirty_page = page;
3279 get_page(dirty_page);
3282 set_pte_at(mm, address, page_table, entry);
3284 /* no need to invalidate: a not-present page won't be cached */
3285 update_mmu_cache(vma, address, page_table);
3286 } else {
3287 if (charged)
3288 mem_cgroup_uncharge_page(page);
3289 if (anon)
3290 page_cache_release(page);
3291 else
3292 anon = 1; /* no anon but release faulted_page */
3295 pte_unmap_unlock(page_table, ptl);
3297 out:
3298 if (dirty_page) {
3299 struct address_space *mapping = page->mapping;
3301 if (set_page_dirty(dirty_page))
3302 page_mkwrite = 1;
3303 unlock_page(dirty_page);
3304 put_page(dirty_page);
3305 if (page_mkwrite && mapping) {
3307 * Some device drivers do not set page.mapping but still
3308 * dirty their pages
3310 balance_dirty_pages_ratelimited(mapping);
3313 /* file_update_time outside page_lock */
3314 if (vma->vm_file)
3315 file_update_time(vma->vm_file);
3316 } else {
3317 unlock_page(vmf.page);
3318 if (anon)
3319 page_cache_release(vmf.page);
3322 return ret;
3324 unwritable_page:
3325 page_cache_release(page);
3326 return ret;
3329 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3330 unsigned long address, pte_t *page_table, pmd_t *pmd,
3331 unsigned int flags, pte_t orig_pte)
3333 pgoff_t pgoff = (((address & PAGE_MASK)
3334 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3336 pte_unmap(page_table);
3337 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3341 * Fault of a previously existing named mapping. Repopulate the pte
3342 * from the encoded file_pte if possible. This enables swappable
3343 * nonlinear vmas.
3345 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3346 * but allow concurrent faults), and pte mapped but not yet locked.
3347 * We return with mmap_sem still held, but pte unmapped and unlocked.
3349 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3350 unsigned long address, pte_t *page_table, pmd_t *pmd,
3351 unsigned int flags, pte_t orig_pte)
3353 pgoff_t pgoff;
3355 flags |= FAULT_FLAG_NONLINEAR;
3357 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3358 return 0;
3360 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3362 * Page table corrupted: show pte and kill process.
3364 print_bad_pte(vma, address, orig_pte, NULL);
3365 return VM_FAULT_SIGBUS;
3368 pgoff = pte_to_pgoff(orig_pte);
3369 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3373 * These routines also need to handle stuff like marking pages dirty
3374 * and/or accessed for architectures that don't do it in hardware (most
3375 * RISC architectures). The early dirtying is also good on the i386.
3377 * There is also a hook called "update_mmu_cache()" that architectures
3378 * with external mmu caches can use to update those (ie the Sparc or
3379 * PowerPC hashed page tables that act as extended TLBs).
3381 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3382 * but allow concurrent faults), and pte mapped but not yet locked.
3383 * We return with mmap_sem still held, but pte unmapped and unlocked.
3385 int handle_pte_fault(struct mm_struct *mm,
3386 struct vm_area_struct *vma, unsigned long address,
3387 pte_t *pte, pmd_t *pmd, unsigned int flags)
3389 pte_t entry;
3390 spinlock_t *ptl;
3392 entry = *pte;
3393 if (!pte_present(entry)) {
3394 if (pte_none(entry)) {
3395 if (vma->vm_ops) {
3396 if (likely(vma->vm_ops->fault))
3397 return do_linear_fault(mm, vma, address,
3398 pte, pmd, flags, entry);
3400 return do_anonymous_page(mm, vma, address,
3401 pte, pmd, flags);
3403 if (pte_file(entry))
3404 return do_nonlinear_fault(mm, vma, address,
3405 pte, pmd, flags, entry);
3406 return do_swap_page(mm, vma, address,
3407 pte, pmd, flags, entry);
3410 ptl = pte_lockptr(mm, pmd);
3411 spin_lock(ptl);
3412 if (unlikely(!pte_same(*pte, entry)))
3413 goto unlock;
3414 if (flags & FAULT_FLAG_WRITE) {
3415 if (!pte_write(entry))
3416 return do_wp_page(mm, vma, address,
3417 pte, pmd, ptl, entry);
3418 entry = pte_mkdirty(entry);
3420 entry = pte_mkyoung(entry);
3421 if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3422 update_mmu_cache(vma, address, pte);
3423 } else {
3425 * This is needed only for protection faults but the arch code
3426 * is not yet telling us if this is a protection fault or not.
3427 * This still avoids useless tlb flushes for .text page faults
3428 * with threads.
3430 if (flags & FAULT_FLAG_WRITE)
3431 flush_tlb_fix_spurious_fault(vma, address);
3433 unlock:
3434 pte_unmap_unlock(pte, ptl);
3435 return 0;
3439 * By the time we get here, we already hold the mm semaphore
3441 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3442 unsigned long address, unsigned int flags)
3444 pgd_t *pgd;
3445 pud_t *pud;
3446 pmd_t *pmd;
3447 pte_t *pte;
3449 __set_current_state(TASK_RUNNING);
3451 count_vm_event(PGFAULT);
3452 mem_cgroup_count_vm_event(mm, PGFAULT);
3454 /* do counter updates before entering really critical section. */
3455 check_sync_rss_stat(current);
3457 if (unlikely(is_vm_hugetlb_page(vma)))
3458 return hugetlb_fault(mm, vma, address, flags);
3460 pgd = pgd_offset(mm, address);
3461 pud = pud_alloc(mm, pgd, address);
3462 if (!pud)
3463 return VM_FAULT_OOM;
3464 pmd = pmd_alloc(mm, pud, address);
3465 if (!pmd)
3466 return VM_FAULT_OOM;
3467 if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3468 if (!vma->vm_ops)
3469 return do_huge_pmd_anonymous_page(mm, vma, address,
3470 pmd, flags);
3471 } else {
3472 pmd_t orig_pmd = *pmd;
3473 barrier();
3474 if (pmd_trans_huge(orig_pmd)) {
3475 if (flags & FAULT_FLAG_WRITE &&
3476 !pmd_write(orig_pmd) &&
3477 !pmd_trans_splitting(orig_pmd))
3478 return do_huge_pmd_wp_page(mm, vma, address,
3479 pmd, orig_pmd);
3480 return 0;
3485 * Use __pte_alloc instead of pte_alloc_map, because we can't
3486 * run pte_offset_map on the pmd, if an huge pmd could
3487 * materialize from under us from a different thread.
3489 if (unlikely(pmd_none(*pmd)) && __pte_alloc(mm, vma, pmd, address))
3490 return VM_FAULT_OOM;
3491 /* if an huge pmd materialized from under us just retry later */
3492 if (unlikely(pmd_trans_huge(*pmd)))
3493 return 0;
3495 * A regular pmd is established and it can't morph into a huge pmd
3496 * from under us anymore at this point because we hold the mmap_sem
3497 * read mode and khugepaged takes it in write mode. So now it's
3498 * safe to run pte_offset_map().
3500 pte = pte_offset_map(pmd, address);
3502 return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3505 #ifndef __PAGETABLE_PUD_FOLDED
3507 * Allocate page upper directory.
3508 * We've already handled the fast-path in-line.
3510 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3512 pud_t *new = pud_alloc_one(mm, address);
3513 if (!new)
3514 return -ENOMEM;
3516 smp_wmb(); /* See comment in __pte_alloc */
3518 spin_lock(&mm->page_table_lock);
3519 if (pgd_present(*pgd)) /* Another has populated it */
3520 pud_free(mm, new);
3521 else
3522 pgd_populate(mm, pgd, new);
3523 spin_unlock(&mm->page_table_lock);
3524 return 0;
3526 #endif /* __PAGETABLE_PUD_FOLDED */
3528 #ifndef __PAGETABLE_PMD_FOLDED
3530 * Allocate page middle directory.
3531 * We've already handled the fast-path in-line.
3533 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3535 pmd_t *new = pmd_alloc_one(mm, address);
3536 if (!new)
3537 return -ENOMEM;
3539 smp_wmb(); /* See comment in __pte_alloc */
3541 spin_lock(&mm->page_table_lock);
3542 #ifndef __ARCH_HAS_4LEVEL_HACK
3543 if (pud_present(*pud)) /* Another has populated it */
3544 pmd_free(mm, new);
3545 else
3546 pud_populate(mm, pud, new);
3547 #else
3548 if (pgd_present(*pud)) /* Another has populated it */
3549 pmd_free(mm, new);
3550 else
3551 pgd_populate(mm, pud, new);
3552 #endif /* __ARCH_HAS_4LEVEL_HACK */
3553 spin_unlock(&mm->page_table_lock);
3554 return 0;
3556 #endif /* __PAGETABLE_PMD_FOLDED */
3558 int make_pages_present(unsigned long addr, unsigned long end)
3560 int ret, len, write;
3561 struct vm_area_struct * vma;
3563 vma = find_vma(current->mm, addr);
3564 if (!vma)
3565 return -ENOMEM;
3567 * We want to touch writable mappings with a write fault in order
3568 * to break COW, except for shared mappings because these don't COW
3569 * and we would not want to dirty them for nothing.
3571 write = (vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE;
3572 BUG_ON(addr >= end);
3573 BUG_ON(end > vma->vm_end);
3574 len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
3575 ret = get_user_pages(current, current->mm, addr,
3576 len, write, 0, NULL, NULL);
3577 if (ret < 0)
3578 return ret;
3579 return ret == len ? 0 : -EFAULT;
3582 #if !defined(__HAVE_ARCH_GATE_AREA)
3584 #if defined(AT_SYSINFO_EHDR)
3585 static struct vm_area_struct gate_vma;
3587 static int __init gate_vma_init(void)
3589 gate_vma.vm_mm = NULL;
3590 gate_vma.vm_start = FIXADDR_USER_START;
3591 gate_vma.vm_end = FIXADDR_USER_END;
3592 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
3593 gate_vma.vm_page_prot = __P101;
3595 * Make sure the vDSO gets into every core dump.
3596 * Dumping its contents makes post-mortem fully interpretable later
3597 * without matching up the same kernel and hardware config to see
3598 * what PC values meant.
3600 gate_vma.vm_flags |= VM_ALWAYSDUMP;
3601 return 0;
3603 __initcall(gate_vma_init);
3604 #endif
3606 struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
3608 #ifdef AT_SYSINFO_EHDR
3609 return &gate_vma;
3610 #else
3611 return NULL;
3612 #endif
3615 int in_gate_area_no_mm(unsigned long addr)
3617 #ifdef AT_SYSINFO_EHDR
3618 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3619 return 1;
3620 #endif
3621 return 0;
3624 #endif /* __HAVE_ARCH_GATE_AREA */
3626 static int __follow_pte(struct mm_struct *mm, unsigned long address,
3627 pte_t **ptepp, spinlock_t **ptlp)
3629 pgd_t *pgd;
3630 pud_t *pud;
3631 pmd_t *pmd;
3632 pte_t *ptep;
3634 pgd = pgd_offset(mm, address);
3635 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3636 goto out;
3638 pud = pud_offset(pgd, address);
3639 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3640 goto out;
3642 pmd = pmd_offset(pud, address);
3643 VM_BUG_ON(pmd_trans_huge(*pmd));
3644 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3645 goto out;
3647 /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3648 if (pmd_huge(*pmd))
3649 goto out;
3651 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3652 if (!ptep)
3653 goto out;
3654 if (!pte_present(*ptep))
3655 goto unlock;
3656 *ptepp = ptep;
3657 return 0;
3658 unlock:
3659 pte_unmap_unlock(ptep, *ptlp);
3660 out:
3661 return -EINVAL;
3664 static inline int follow_pte(struct mm_struct *mm, unsigned long address,
3665 pte_t **ptepp, spinlock_t **ptlp)
3667 int res;
3669 /* (void) is needed to make gcc happy */
3670 (void) __cond_lock(*ptlp,
3671 !(res = __follow_pte(mm, address, ptepp, ptlp)));
3672 return res;
3676 * follow_pfn - look up PFN at a user virtual address
3677 * @vma: memory mapping
3678 * @address: user virtual address
3679 * @pfn: location to store found PFN
3681 * Only IO mappings and raw PFN mappings are allowed.
3683 * Returns zero and the pfn at @pfn on success, -ve otherwise.
3685 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3686 unsigned long *pfn)
3688 int ret = -EINVAL;
3689 spinlock_t *ptl;
3690 pte_t *ptep;
3692 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3693 return ret;
3695 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3696 if (ret)
3697 return ret;
3698 *pfn = pte_pfn(*ptep);
3699 pte_unmap_unlock(ptep, ptl);
3700 return 0;
3702 EXPORT_SYMBOL(follow_pfn);
3704 #ifdef CONFIG_HAVE_IOREMAP_PROT
3705 int follow_phys(struct vm_area_struct *vma,
3706 unsigned long address, unsigned int flags,
3707 unsigned long *prot, resource_size_t *phys)
3709 int ret = -EINVAL;
3710 pte_t *ptep, pte;
3711 spinlock_t *ptl;
3713 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3714 goto out;
3716 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3717 goto out;
3718 pte = *ptep;
3720 if ((flags & FOLL_WRITE) && !pte_write(pte))
3721 goto unlock;
3723 *prot = pgprot_val(pte_pgprot(pte));
3724 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3726 ret = 0;
3727 unlock:
3728 pte_unmap_unlock(ptep, ptl);
3729 out:
3730 return ret;
3733 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3734 void *buf, int len, int write)
3736 resource_size_t phys_addr;
3737 unsigned long prot = 0;
3738 void __iomem *maddr;
3739 int offset = addr & (PAGE_SIZE-1);
3741 if (follow_phys(vma, addr, write, &prot, &phys_addr))
3742 return -EINVAL;
3744 maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
3745 if (write)
3746 memcpy_toio(maddr + offset, buf, len);
3747 else
3748 memcpy_fromio(buf, maddr + offset, len);
3749 iounmap(maddr);
3751 return len;
3753 #endif
3756 * Access another process' address space as given in mm. If non-NULL, use the
3757 * given task for page fault accounting.
3759 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
3760 unsigned long addr, void *buf, int len, int write)
3762 struct vm_area_struct *vma;
3763 void *old_buf = buf;
3765 down_read(&mm->mmap_sem);
3766 /* ignore errors, just check how much was successfully transferred */
3767 while (len) {
3768 int bytes, ret, offset;
3769 void *maddr;
3770 struct page *page = NULL;
3772 ret = get_user_pages(tsk, mm, addr, 1,
3773 write, 1, &page, &vma);
3774 if (ret <= 0) {
3776 * Check if this is a VM_IO | VM_PFNMAP VMA, which
3777 * we can access using slightly different code.
3779 #ifdef CONFIG_HAVE_IOREMAP_PROT
3780 vma = find_vma(mm, addr);
3781 if (!vma || vma->vm_start > addr)
3782 break;
3783 if (vma->vm_ops && vma->vm_ops->access)
3784 ret = vma->vm_ops->access(vma, addr, buf,
3785 len, write);
3786 if (ret <= 0)
3787 #endif
3788 break;
3789 bytes = ret;
3790 } else {
3791 bytes = len;
3792 offset = addr & (PAGE_SIZE-1);
3793 if (bytes > PAGE_SIZE-offset)
3794 bytes = PAGE_SIZE-offset;
3796 maddr = kmap(page);
3797 if (write) {
3798 copy_to_user_page(vma, page, addr,
3799 maddr + offset, buf, bytes);
3800 set_page_dirty_lock(page);
3801 } else {
3802 copy_from_user_page(vma, page, addr,
3803 buf, maddr + offset, bytes);
3805 kunmap(page);
3806 page_cache_release(page);
3808 len -= bytes;
3809 buf += bytes;
3810 addr += bytes;
3812 up_read(&mm->mmap_sem);
3814 return buf - old_buf;
3818 * access_remote_vm - access another process' address space
3819 * @mm: the mm_struct of the target address space
3820 * @addr: start address to access
3821 * @buf: source or destination buffer
3822 * @len: number of bytes to transfer
3823 * @write: whether the access is a write
3825 * The caller must hold a reference on @mm.
3827 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
3828 void *buf, int len, int write)
3830 return __access_remote_vm(NULL, mm, addr, buf, len, write);
3834 * Access another process' address space.
3835 * Source/target buffer must be kernel space,
3836 * Do not walk the page table directly, use get_user_pages
3838 int access_process_vm(struct task_struct *tsk, unsigned long addr,
3839 void *buf, int len, int write)
3841 struct mm_struct *mm;
3842 int ret;
3844 mm = get_task_mm(tsk);
3845 if (!mm)
3846 return 0;
3848 ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
3849 mmput(mm);
3851 return ret;
3855 * Print the name of a VMA.
3857 void print_vma_addr(char *prefix, unsigned long ip)
3859 struct mm_struct *mm = current->mm;
3860 struct vm_area_struct *vma;
3863 * Do not print if we are in atomic
3864 * contexts (in exception stacks, etc.):
3866 if (preempt_count())
3867 return;
3869 down_read(&mm->mmap_sem);
3870 vma = find_vma(mm, ip);
3871 if (vma && vma->vm_file) {
3872 struct file *f = vma->vm_file;
3873 char *buf = (char *)__get_free_page(GFP_KERNEL);
3874 if (buf) {
3875 char *p, *s;
3877 p = d_path(&f->f_path, buf, PAGE_SIZE);
3878 if (IS_ERR(p))
3879 p = "?";
3880 s = strrchr(p, '/');
3881 if (s)
3882 p = s+1;
3883 printk("%s%s[%lx+%lx]", prefix, p,
3884 vma->vm_start,
3885 vma->vm_end - vma->vm_start);
3886 free_page((unsigned long)buf);
3889 up_read(&current->mm->mmap_sem);
3892 #ifdef CONFIG_PROVE_LOCKING
3893 void might_fault(void)
3896 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
3897 * holding the mmap_sem, this is safe because kernel memory doesn't
3898 * get paged out, therefore we'll never actually fault, and the
3899 * below annotations will generate false positives.
3901 if (segment_eq(get_fs(), KERNEL_DS))
3902 return;
3904 might_sleep();
3906 * it would be nicer only to annotate paths which are not under
3907 * pagefault_disable, however that requires a larger audit and
3908 * providing helpers like get_user_atomic.
3910 if (!in_atomic() && current->mm)
3911 might_lock_read(&current->mm->mmap_sem);
3913 EXPORT_SYMBOL(might_fault);
3914 #endif
3916 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
3917 static void clear_gigantic_page(struct page *page,
3918 unsigned long addr,
3919 unsigned int pages_per_huge_page)
3921 int i;
3922 struct page *p = page;
3924 might_sleep();
3925 for (i = 0; i < pages_per_huge_page;
3926 i++, p = mem_map_next(p, page, i)) {
3927 cond_resched();
3928 clear_user_highpage(p, addr + i * PAGE_SIZE);
3931 void clear_huge_page(struct page *page,
3932 unsigned long addr, unsigned int pages_per_huge_page)
3934 int i;
3936 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3937 clear_gigantic_page(page, addr, pages_per_huge_page);
3938 return;
3941 might_sleep();
3942 for (i = 0; i < pages_per_huge_page; i++) {
3943 cond_resched();
3944 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
3948 static void copy_user_gigantic_page(struct page *dst, struct page *src,
3949 unsigned long addr,
3950 struct vm_area_struct *vma,
3951 unsigned int pages_per_huge_page)
3953 int i;
3954 struct page *dst_base = dst;
3955 struct page *src_base = src;
3957 for (i = 0; i < pages_per_huge_page; ) {
3958 cond_resched();
3959 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
3961 i++;
3962 dst = mem_map_next(dst, dst_base, i);
3963 src = mem_map_next(src, src_base, i);
3967 void copy_user_huge_page(struct page *dst, struct page *src,
3968 unsigned long addr, struct vm_area_struct *vma,
3969 unsigned int pages_per_huge_page)
3971 int i;
3973 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3974 copy_user_gigantic_page(dst, src, addr, vma,
3975 pages_per_huge_page);
3976 return;
3979 might_sleep();
3980 for (i = 0; i < pages_per_huge_page; i++) {
3981 cond_resched();
3982 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
3985 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */