4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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
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>
43 #include <linux/hugetlb.h>
44 #include <linux/mman.h>
45 #include <linux/swap.h>
46 #include <linux/highmem.h>
47 #include <linux/pagemap.h>
48 #include <linux/ksm.h>
49 #include <linux/rmap.h>
50 #include <linux/export.h>
51 #include <linux/delayacct.h>
52 #include <linux/init.h>
53 #include <linux/writeback.h>
54 #include <linux/memcontrol.h>
55 #include <linux/mmu_notifier.h>
56 #include <linux/kallsyms.h>
57 #include <linux/swapops.h>
58 #include <linux/elf.h>
59 #include <linux/gfp.h>
60 #include <linux/migrate.h>
61 #include <linux/string.h>
64 #include <asm/pgalloc.h>
65 #include <asm/uaccess.h>
67 #include <asm/tlbflush.h>
68 #include <asm/pgtable.h>
72 #ifndef CONFIG_NEED_MULTIPLE_NODES
73 /* use the per-pgdat data instead for discontigmem - mbligh */
74 unsigned long max_mapnr
;
77 EXPORT_SYMBOL(max_mapnr
);
78 EXPORT_SYMBOL(mem_map
);
81 unsigned long num_physpages
;
83 * A number of key systems in x86 including ioremap() rely on the assumption
84 * that high_memory defines the upper bound on direct map memory, then end
85 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
86 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
91 EXPORT_SYMBOL(num_physpages
);
92 EXPORT_SYMBOL(high_memory
);
95 * Randomize the address space (stacks, mmaps, brk, etc.).
97 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
98 * as ancient (libc5 based) binaries can segfault. )
100 int randomize_va_space __read_mostly
=
101 #ifdef CONFIG_COMPAT_BRK
107 static int __init
disable_randmaps(char *s
)
109 randomize_va_space
= 0;
112 __setup("norandmaps", disable_randmaps
);
114 unsigned long zero_pfn __read_mostly
;
115 unsigned long highest_memmap_pfn __read_mostly
;
118 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
120 static int __init
init_zero_pfn(void)
122 zero_pfn
= page_to_pfn(ZERO_PAGE(0));
125 core_initcall(init_zero_pfn
);
128 #if defined(SPLIT_RSS_COUNTING)
130 void sync_mm_rss(struct mm_struct
*mm
)
134 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
135 if (current
->rss_stat
.count
[i
]) {
136 add_mm_counter(mm
, i
, current
->rss_stat
.count
[i
]);
137 current
->rss_stat
.count
[i
] = 0;
140 current
->rss_stat
.events
= 0;
143 static void add_mm_counter_fast(struct mm_struct
*mm
, int member
, int val
)
145 struct task_struct
*task
= current
;
147 if (likely(task
->mm
== mm
))
148 task
->rss_stat
.count
[member
] += val
;
150 add_mm_counter(mm
, member
, val
);
152 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
153 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
155 /* sync counter once per 64 page faults */
156 #define TASK_RSS_EVENTS_THRESH (64)
157 static void check_sync_rss_stat(struct task_struct
*task
)
159 if (unlikely(task
!= current
))
161 if (unlikely(task
->rss_stat
.events
++ > TASK_RSS_EVENTS_THRESH
))
162 sync_mm_rss(task
->mm
);
164 #else /* SPLIT_RSS_COUNTING */
166 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
167 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
169 static void check_sync_rss_stat(struct task_struct
*task
)
173 #endif /* SPLIT_RSS_COUNTING */
175 #ifdef HAVE_GENERIC_MMU_GATHER
177 static int tlb_next_batch(struct mmu_gather
*tlb
)
179 struct mmu_gather_batch
*batch
;
183 tlb
->active
= batch
->next
;
187 batch
= (void *)__get_free_pages(GFP_NOWAIT
| __GFP_NOWARN
, 0);
193 batch
->max
= MAX_GATHER_BATCH
;
195 tlb
->active
->next
= batch
;
202 * Called to initialize an (on-stack) mmu_gather structure for page-table
203 * tear-down from @mm. The @fullmm argument is used when @mm is without
204 * users and we're going to destroy the full address space (exit/execve).
206 void tlb_gather_mmu(struct mmu_gather
*tlb
, struct mm_struct
*mm
, bool fullmm
)
210 tlb
->fullmm
= fullmm
;
214 tlb
->fast_mode
= (num_possible_cpus() == 1);
215 tlb
->local
.next
= NULL
;
217 tlb
->local
.max
= ARRAY_SIZE(tlb
->__pages
);
218 tlb
->active
= &tlb
->local
;
220 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
225 void tlb_flush_mmu(struct mmu_gather
*tlb
)
227 struct mmu_gather_batch
*batch
;
229 if (!tlb
->need_flush
)
233 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
234 tlb_table_flush(tlb
);
237 if (tlb_fast_mode(tlb
))
240 for (batch
= &tlb
->local
; batch
; batch
= batch
->next
) {
241 free_pages_and_swap_cache(batch
->pages
, batch
->nr
);
244 tlb
->active
= &tlb
->local
;
248 * Called at the end of the shootdown operation to free up any resources
249 * that were required.
251 void tlb_finish_mmu(struct mmu_gather
*tlb
, unsigned long start
, unsigned long end
)
253 struct mmu_gather_batch
*batch
, *next
;
259 /* keep the page table cache within bounds */
262 for (batch
= tlb
->local
.next
; batch
; batch
= next
) {
264 free_pages((unsigned long)batch
, 0);
266 tlb
->local
.next
= NULL
;
270 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
271 * handling the additional races in SMP caused by other CPUs caching valid
272 * mappings in their TLBs. Returns the number of free page slots left.
273 * When out of page slots we must call tlb_flush_mmu().
275 int __tlb_remove_page(struct mmu_gather
*tlb
, struct page
*page
)
277 struct mmu_gather_batch
*batch
;
279 VM_BUG_ON(!tlb
->need_flush
);
281 if (tlb_fast_mode(tlb
)) {
282 free_page_and_swap_cache(page
);
283 return 1; /* avoid calling tlb_flush_mmu() */
287 batch
->pages
[batch
->nr
++] = page
;
288 if (batch
->nr
== batch
->max
) {
289 if (!tlb_next_batch(tlb
))
293 VM_BUG_ON(batch
->nr
> batch
->max
);
295 return batch
->max
- batch
->nr
;
298 #endif /* HAVE_GENERIC_MMU_GATHER */
300 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
303 * See the comment near struct mmu_table_batch.
306 static void tlb_remove_table_smp_sync(void *arg
)
308 /* Simply deliver the interrupt */
311 static void tlb_remove_table_one(void *table
)
314 * This isn't an RCU grace period and hence the page-tables cannot be
315 * assumed to be actually RCU-freed.
317 * It is however sufficient for software page-table walkers that rely on
318 * IRQ disabling. See the comment near struct mmu_table_batch.
320 smp_call_function(tlb_remove_table_smp_sync
, NULL
, 1);
321 __tlb_remove_table(table
);
324 static void tlb_remove_table_rcu(struct rcu_head
*head
)
326 struct mmu_table_batch
*batch
;
329 batch
= container_of(head
, struct mmu_table_batch
, rcu
);
331 for (i
= 0; i
< batch
->nr
; i
++)
332 __tlb_remove_table(batch
->tables
[i
]);
334 free_page((unsigned long)batch
);
337 void tlb_table_flush(struct mmu_gather
*tlb
)
339 struct mmu_table_batch
**batch
= &tlb
->batch
;
342 call_rcu_sched(&(*batch
)->rcu
, tlb_remove_table_rcu
);
347 void tlb_remove_table(struct mmu_gather
*tlb
, void *table
)
349 struct mmu_table_batch
**batch
= &tlb
->batch
;
354 * When there's less then two users of this mm there cannot be a
355 * concurrent page-table walk.
357 if (atomic_read(&tlb
->mm
->mm_users
) < 2) {
358 __tlb_remove_table(table
);
362 if (*batch
== NULL
) {
363 *batch
= (struct mmu_table_batch
*)__get_free_page(GFP_NOWAIT
| __GFP_NOWARN
);
364 if (*batch
== NULL
) {
365 tlb_remove_table_one(table
);
370 (*batch
)->tables
[(*batch
)->nr
++] = table
;
371 if ((*batch
)->nr
== MAX_TABLE_BATCH
)
372 tlb_table_flush(tlb
);
375 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */
378 * If a p?d_bad entry is found while walking page tables, report
379 * the error, before resetting entry to p?d_none. Usually (but
380 * very seldom) called out from the p?d_none_or_clear_bad macros.
383 void pgd_clear_bad(pgd_t
*pgd
)
389 void pud_clear_bad(pud_t
*pud
)
395 void pmd_clear_bad(pmd_t
*pmd
)
402 * Note: this doesn't free the actual pages themselves. That
403 * has been handled earlier when unmapping all the memory regions.
405 static void free_pte_range(struct mmu_gather
*tlb
, pmd_t
*pmd
,
408 pgtable_t token
= pmd_pgtable(*pmd
);
410 pte_free_tlb(tlb
, token
, addr
);
414 static inline void free_pmd_range(struct mmu_gather
*tlb
, pud_t
*pud
,
415 unsigned long addr
, unsigned long end
,
416 unsigned long floor
, unsigned long ceiling
)
423 pmd
= pmd_offset(pud
, addr
);
425 next
= pmd_addr_end(addr
, end
);
426 if (pmd_none_or_clear_bad(pmd
))
428 free_pte_range(tlb
, pmd
, addr
);
429 } while (pmd
++, addr
= next
, addr
!= end
);
439 if (end
- 1 > ceiling
- 1)
442 pmd
= pmd_offset(pud
, start
);
444 pmd_free_tlb(tlb
, pmd
, start
);
447 static inline void free_pud_range(struct mmu_gather
*tlb
, pgd_t
*pgd
,
448 unsigned long addr
, unsigned long end
,
449 unsigned long floor
, unsigned long ceiling
)
456 pud
= pud_offset(pgd
, addr
);
458 next
= pud_addr_end(addr
, end
);
459 if (pud_none_or_clear_bad(pud
))
461 free_pmd_range(tlb
, pud
, addr
, next
, floor
, ceiling
);
462 } while (pud
++, addr
= next
, addr
!= end
);
468 ceiling
&= PGDIR_MASK
;
472 if (end
- 1 > ceiling
- 1)
475 pud
= pud_offset(pgd
, start
);
477 pud_free_tlb(tlb
, pud
, start
);
481 * This function frees user-level page tables of a process.
483 * Must be called with pagetable lock held.
485 void free_pgd_range(struct mmu_gather
*tlb
,
486 unsigned long addr
, unsigned long end
,
487 unsigned long floor
, unsigned long ceiling
)
493 * The next few lines have given us lots of grief...
495 * Why are we testing PMD* at this top level? Because often
496 * there will be no work to do at all, and we'd prefer not to
497 * go all the way down to the bottom just to discover that.
499 * Why all these "- 1"s? Because 0 represents both the bottom
500 * of the address space and the top of it (using -1 for the
501 * top wouldn't help much: the masks would do the wrong thing).
502 * The rule is that addr 0 and floor 0 refer to the bottom of
503 * the address space, but end 0 and ceiling 0 refer to the top
504 * Comparisons need to use "end - 1" and "ceiling - 1" (though
505 * that end 0 case should be mythical).
507 * Wherever addr is brought up or ceiling brought down, we must
508 * be careful to reject "the opposite 0" before it confuses the
509 * subsequent tests. But what about where end is brought down
510 * by PMD_SIZE below? no, end can't go down to 0 there.
512 * Whereas we round start (addr) and ceiling down, by different
513 * masks at different levels, in order to test whether a table
514 * now has no other vmas using it, so can be freed, we don't
515 * bother to round floor or end up - the tests don't need that.
529 if (end
- 1 > ceiling
- 1)
534 pgd
= pgd_offset(tlb
->mm
, addr
);
536 next
= pgd_addr_end(addr
, end
);
537 if (pgd_none_or_clear_bad(pgd
))
539 free_pud_range(tlb
, pgd
, addr
, next
, floor
, ceiling
);
540 } while (pgd
++, addr
= next
, addr
!= end
);
543 void free_pgtables(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
544 unsigned long floor
, unsigned long ceiling
)
547 struct vm_area_struct
*next
= vma
->vm_next
;
548 unsigned long addr
= vma
->vm_start
;
551 * Hide vma from rmap and truncate_pagecache before freeing
554 unlink_anon_vmas(vma
);
555 unlink_file_vma(vma
);
557 if (is_vm_hugetlb_page(vma
)) {
558 hugetlb_free_pgd_range(tlb
, addr
, vma
->vm_end
,
559 floor
, next
? next
->vm_start
: ceiling
);
562 * Optimization: gather nearby vmas into one call down
564 while (next
&& next
->vm_start
<= vma
->vm_end
+ PMD_SIZE
565 && !is_vm_hugetlb_page(next
)) {
568 unlink_anon_vmas(vma
);
569 unlink_file_vma(vma
);
571 free_pgd_range(tlb
, addr
, vma
->vm_end
,
572 floor
, next
? next
->vm_start
: ceiling
);
578 int __pte_alloc(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
579 pmd_t
*pmd
, unsigned long address
)
581 pgtable_t
new = pte_alloc_one(mm
, address
);
582 int wait_split_huge_page
;
587 * Ensure all pte setup (eg. pte page lock and page clearing) are
588 * visible before the pte is made visible to other CPUs by being
589 * put into page tables.
591 * The other side of the story is the pointer chasing in the page
592 * table walking code (when walking the page table without locking;
593 * ie. most of the time). Fortunately, these data accesses consist
594 * of a chain of data-dependent loads, meaning most CPUs (alpha
595 * being the notable exception) will already guarantee loads are
596 * seen in-order. See the alpha page table accessors for the
597 * smp_read_barrier_depends() barriers in page table walking code.
599 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
601 spin_lock(&mm
->page_table_lock
);
602 wait_split_huge_page
= 0;
603 if (likely(pmd_none(*pmd
))) { /* Has another populated it ? */
605 pmd_populate(mm
, pmd
, new);
607 } else if (unlikely(pmd_trans_splitting(*pmd
)))
608 wait_split_huge_page
= 1;
609 spin_unlock(&mm
->page_table_lock
);
612 if (wait_split_huge_page
)
613 wait_split_huge_page(vma
->anon_vma
, pmd
);
617 int __pte_alloc_kernel(pmd_t
*pmd
, unsigned long address
)
619 pte_t
*new = pte_alloc_one_kernel(&init_mm
, address
);
623 smp_wmb(); /* See comment in __pte_alloc */
625 spin_lock(&init_mm
.page_table_lock
);
626 if (likely(pmd_none(*pmd
))) { /* Has another populated it ? */
627 pmd_populate_kernel(&init_mm
, pmd
, new);
630 VM_BUG_ON(pmd_trans_splitting(*pmd
));
631 spin_unlock(&init_mm
.page_table_lock
);
633 pte_free_kernel(&init_mm
, new);
637 static inline void init_rss_vec(int *rss
)
639 memset(rss
, 0, sizeof(int) * NR_MM_COUNTERS
);
642 static inline void add_mm_rss_vec(struct mm_struct
*mm
, int *rss
)
646 if (current
->mm
== mm
)
648 for (i
= 0; i
< NR_MM_COUNTERS
; i
++)
650 add_mm_counter(mm
, i
, rss
[i
]);
654 * This function is called to print an error when a bad pte
655 * is found. For example, we might have a PFN-mapped pte in
656 * a region that doesn't allow it.
658 * The calling function must still handle the error.
660 static void print_bad_pte(struct vm_area_struct
*vma
, unsigned long addr
,
661 pte_t pte
, struct page
*page
)
663 pgd_t
*pgd
= pgd_offset(vma
->vm_mm
, addr
);
664 pud_t
*pud
= pud_offset(pgd
, addr
);
665 pmd_t
*pmd
= pmd_offset(pud
, addr
);
666 struct address_space
*mapping
;
668 static unsigned long resume
;
669 static unsigned long nr_shown
;
670 static unsigned long nr_unshown
;
673 * Allow a burst of 60 reports, then keep quiet for that minute;
674 * or allow a steady drip of one report per second.
676 if (nr_shown
== 60) {
677 if (time_before(jiffies
, resume
)) {
683 "BUG: Bad page map: %lu messages suppressed\n",
690 resume
= jiffies
+ 60 * HZ
;
692 mapping
= vma
->vm_file
? vma
->vm_file
->f_mapping
: NULL
;
693 index
= linear_page_index(vma
, addr
);
696 "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
698 (long long)pte_val(pte
), (long long)pmd_val(*pmd
));
702 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
703 (void *)addr
, vma
->vm_flags
, vma
->anon_vma
, mapping
, index
);
705 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
708 print_symbol(KERN_ALERT
"vma->vm_ops->fault: %s\n",
709 (unsigned long)vma
->vm_ops
->fault
);
710 if (vma
->vm_file
&& vma
->vm_file
->f_op
)
711 print_symbol(KERN_ALERT
"vma->vm_file->f_op->mmap: %s\n",
712 (unsigned long)vma
->vm_file
->f_op
->mmap
);
714 add_taint(TAINT_BAD_PAGE
);
717 static inline bool is_cow_mapping(vm_flags_t flags
)
719 return (flags
& (VM_SHARED
| VM_MAYWRITE
)) == VM_MAYWRITE
;
723 * vm_normal_page -- This function gets the "struct page" associated with a pte.
725 * "Special" mappings do not wish to be associated with a "struct page" (either
726 * it doesn't exist, or it exists but they don't want to touch it). In this
727 * case, NULL is returned here. "Normal" mappings do have a struct page.
729 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
730 * pte bit, in which case this function is trivial. Secondly, an architecture
731 * may not have a spare pte bit, which requires a more complicated scheme,
734 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
735 * special mapping (even if there are underlying and valid "struct pages").
736 * COWed pages of a VM_PFNMAP are always normal.
738 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
739 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
740 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
741 * mapping will always honor the rule
743 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
745 * And for normal mappings this is false.
747 * This restricts such mappings to be a linear translation from virtual address
748 * to pfn. To get around this restriction, we allow arbitrary mappings so long
749 * as the vma is not a COW mapping; in that case, we know that all ptes are
750 * special (because none can have been COWed).
753 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
755 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
756 * page" backing, however the difference is that _all_ pages with a struct
757 * page (that is, those where pfn_valid is true) are refcounted and considered
758 * normal pages by the VM. The disadvantage is that pages are refcounted
759 * (which can be slower and simply not an option for some PFNMAP users). The
760 * advantage is that we don't have to follow the strict linearity rule of
761 * PFNMAP mappings in order to support COWable mappings.
764 #ifdef __HAVE_ARCH_PTE_SPECIAL
765 # define HAVE_PTE_SPECIAL 1
767 # define HAVE_PTE_SPECIAL 0
769 struct page
*vm_normal_page(struct vm_area_struct
*vma
, unsigned long addr
,
772 unsigned long pfn
= pte_pfn(pte
);
774 if (HAVE_PTE_SPECIAL
) {
775 if (likely(!pte_special(pte
)))
777 if (vma
->vm_flags
& (VM_PFNMAP
| VM_MIXEDMAP
))
779 if (!is_zero_pfn(pfn
))
780 print_bad_pte(vma
, addr
, pte
, NULL
);
784 /* !HAVE_PTE_SPECIAL case follows: */
786 if (unlikely(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
))) {
787 if (vma
->vm_flags
& VM_MIXEDMAP
) {
793 off
= (addr
- vma
->vm_start
) >> PAGE_SHIFT
;
794 if (pfn
== vma
->vm_pgoff
+ off
)
796 if (!is_cow_mapping(vma
->vm_flags
))
801 if (is_zero_pfn(pfn
))
804 if (unlikely(pfn
> highest_memmap_pfn
)) {
805 print_bad_pte(vma
, addr
, pte
, NULL
);
810 * NOTE! We still have PageReserved() pages in the page tables.
811 * eg. VDSO mappings can cause them to exist.
814 return pfn_to_page(pfn
);
818 * copy one vm_area from one task to the other. Assumes the page tables
819 * already present in the new task to be cleared in the whole range
820 * covered by this vma.
823 static inline unsigned long
824 copy_one_pte(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
825 pte_t
*dst_pte
, pte_t
*src_pte
, struct vm_area_struct
*vma
,
826 unsigned long addr
, int *rss
)
828 unsigned long vm_flags
= vma
->vm_flags
;
829 pte_t pte
= *src_pte
;
832 /* pte contains position in swap or file, so copy. */
833 if (unlikely(!pte_present(pte
))) {
834 if (!pte_file(pte
)) {
835 swp_entry_t entry
= pte_to_swp_entry(pte
);
837 if (swap_duplicate(entry
) < 0)
840 /* make sure dst_mm is on swapoff's mmlist. */
841 if (unlikely(list_empty(&dst_mm
->mmlist
))) {
842 spin_lock(&mmlist_lock
);
843 if (list_empty(&dst_mm
->mmlist
))
844 list_add(&dst_mm
->mmlist
,
846 spin_unlock(&mmlist_lock
);
848 if (likely(!non_swap_entry(entry
)))
850 else if (is_migration_entry(entry
)) {
851 page
= migration_entry_to_page(entry
);
858 if (is_write_migration_entry(entry
) &&
859 is_cow_mapping(vm_flags
)) {
861 * COW mappings require pages in both
862 * parent and child to be set to read.
864 make_migration_entry_read(&entry
);
865 pte
= swp_entry_to_pte(entry
);
866 set_pte_at(src_mm
, addr
, src_pte
, pte
);
874 * If it's a COW mapping, write protect it both
875 * in the parent and the child
877 if (is_cow_mapping(vm_flags
)) {
878 ptep_set_wrprotect(src_mm
, addr
, src_pte
);
879 pte
= pte_wrprotect(pte
);
883 * If it's a shared mapping, mark it clean in
886 if (vm_flags
& VM_SHARED
)
887 pte
= pte_mkclean(pte
);
888 pte
= pte_mkold(pte
);
890 page
= vm_normal_page(vma
, addr
, pte
);
901 set_pte_at(dst_mm
, addr
, dst_pte
, pte
);
905 int copy_pte_range(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
906 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, struct vm_area_struct
*vma
,
907 unsigned long addr
, unsigned long end
)
909 pte_t
*orig_src_pte
, *orig_dst_pte
;
910 pte_t
*src_pte
, *dst_pte
;
911 spinlock_t
*src_ptl
, *dst_ptl
;
913 int rss
[NR_MM_COUNTERS
];
914 swp_entry_t entry
= (swp_entry_t
){0};
919 dst_pte
= pte_alloc_map_lock(dst_mm
, dst_pmd
, addr
, &dst_ptl
);
922 src_pte
= pte_offset_map(src_pmd
, addr
);
923 src_ptl
= pte_lockptr(src_mm
, src_pmd
);
924 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
925 orig_src_pte
= src_pte
;
926 orig_dst_pte
= dst_pte
;
927 arch_enter_lazy_mmu_mode();
931 * We are holding two locks at this point - either of them
932 * could generate latencies in another task on another CPU.
934 if (progress
>= 32) {
936 if (need_resched() ||
937 spin_needbreak(src_ptl
) || spin_needbreak(dst_ptl
))
940 if (pte_none(*src_pte
)) {
944 entry
.val
= copy_one_pte(dst_mm
, src_mm
, dst_pte
, src_pte
,
949 } while (dst_pte
++, src_pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
951 arch_leave_lazy_mmu_mode();
952 spin_unlock(src_ptl
);
953 pte_unmap(orig_src_pte
);
954 add_mm_rss_vec(dst_mm
, rss
);
955 pte_unmap_unlock(orig_dst_pte
, dst_ptl
);
959 if (add_swap_count_continuation(entry
, GFP_KERNEL
) < 0)
968 static inline int copy_pmd_range(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
969 pud_t
*dst_pud
, pud_t
*src_pud
, struct vm_area_struct
*vma
,
970 unsigned long addr
, unsigned long end
)
972 pmd_t
*src_pmd
, *dst_pmd
;
975 dst_pmd
= pmd_alloc(dst_mm
, dst_pud
, addr
);
978 src_pmd
= pmd_offset(src_pud
, addr
);
980 next
= pmd_addr_end(addr
, end
);
981 if (pmd_trans_huge(*src_pmd
)) {
983 VM_BUG_ON(next
-addr
!= HPAGE_PMD_SIZE
);
984 err
= copy_huge_pmd(dst_mm
, src_mm
,
985 dst_pmd
, src_pmd
, addr
, vma
);
992 if (pmd_none_or_clear_bad(src_pmd
))
994 if (copy_pte_range(dst_mm
, src_mm
, dst_pmd
, src_pmd
,
997 } while (dst_pmd
++, src_pmd
++, addr
= next
, addr
!= end
);
1001 static inline int copy_pud_range(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
1002 pgd_t
*dst_pgd
, pgd_t
*src_pgd
, struct vm_area_struct
*vma
,
1003 unsigned long addr
, unsigned long end
)
1005 pud_t
*src_pud
, *dst_pud
;
1008 dst_pud
= pud_alloc(dst_mm
, dst_pgd
, addr
);
1011 src_pud
= pud_offset(src_pgd
, addr
);
1013 next
= pud_addr_end(addr
, end
);
1014 if (pud_none_or_clear_bad(src_pud
))
1016 if (copy_pmd_range(dst_mm
, src_mm
, dst_pud
, src_pud
,
1019 } while (dst_pud
++, src_pud
++, addr
= next
, addr
!= end
);
1023 int copy_page_range(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
1024 struct vm_area_struct
*vma
)
1026 pgd_t
*src_pgd
, *dst_pgd
;
1028 unsigned long addr
= vma
->vm_start
;
1029 unsigned long end
= vma
->vm_end
;
1030 unsigned long mmun_start
; /* For mmu_notifiers */
1031 unsigned long mmun_end
; /* For mmu_notifiers */
1036 * Don't copy ptes where a page fault will fill them correctly.
1037 * Fork becomes much lighter when there are big shared or private
1038 * readonly mappings. The tradeoff is that copy_page_range is more
1039 * efficient than faulting.
1041 if (!(vma
->vm_flags
& (VM_HUGETLB
| VM_NONLINEAR
|
1042 VM_PFNMAP
| VM_MIXEDMAP
))) {
1047 if (is_vm_hugetlb_page(vma
))
1048 return copy_hugetlb_page_range(dst_mm
, src_mm
, vma
);
1050 if (unlikely(vma
->vm_flags
& VM_PFNMAP
)) {
1052 * We do not free on error cases below as remove_vma
1053 * gets called on error from higher level routine
1055 ret
= track_pfn_copy(vma
);
1061 * We need to invalidate the secondary MMU mappings only when
1062 * there could be a permission downgrade on the ptes of the
1063 * parent mm. And a permission downgrade will only happen if
1064 * is_cow_mapping() returns true.
1066 is_cow
= is_cow_mapping(vma
->vm_flags
);
1070 mmu_notifier_invalidate_range_start(src_mm
, mmun_start
,
1074 dst_pgd
= pgd_offset(dst_mm
, addr
);
1075 src_pgd
= pgd_offset(src_mm
, addr
);
1077 next
= pgd_addr_end(addr
, end
);
1078 if (pgd_none_or_clear_bad(src_pgd
))
1080 if (unlikely(copy_pud_range(dst_mm
, src_mm
, dst_pgd
, src_pgd
,
1081 vma
, addr
, next
))) {
1085 } while (dst_pgd
++, src_pgd
++, addr
= next
, addr
!= end
);
1088 mmu_notifier_invalidate_range_end(src_mm
, mmun_start
, mmun_end
);
1092 static unsigned long zap_pte_range(struct mmu_gather
*tlb
,
1093 struct vm_area_struct
*vma
, pmd_t
*pmd
,
1094 unsigned long addr
, unsigned long end
,
1095 struct zap_details
*details
)
1097 struct mm_struct
*mm
= tlb
->mm
;
1098 int force_flush
= 0;
1099 int rss
[NR_MM_COUNTERS
];
1106 start_pte
= pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
1108 arch_enter_lazy_mmu_mode();
1111 if (pte_none(ptent
)) {
1115 if (pte_present(ptent
)) {
1118 page
= vm_normal_page(vma
, addr
, ptent
);
1119 if (unlikely(details
) && page
) {
1121 * unmap_shared_mapping_pages() wants to
1122 * invalidate cache without truncating:
1123 * unmap shared but keep private pages.
1125 if (details
->check_mapping
&&
1126 details
->check_mapping
!= page
->mapping
)
1129 * Each page->index must be checked when
1130 * invalidating or truncating nonlinear.
1132 if (details
->nonlinear_vma
&&
1133 (page
->index
< details
->first_index
||
1134 page
->index
> details
->last_index
))
1137 ptent
= ptep_get_and_clear_full(mm
, addr
, pte
,
1139 tlb_remove_tlb_entry(tlb
, pte
, addr
);
1140 if (unlikely(!page
))
1142 if (unlikely(details
) && details
->nonlinear_vma
1143 && linear_page_index(details
->nonlinear_vma
,
1144 addr
) != page
->index
)
1145 set_pte_at(mm
, addr
, pte
,
1146 pgoff_to_pte(page
->index
));
1148 rss
[MM_ANONPAGES
]--;
1150 if (pte_dirty(ptent
))
1151 set_page_dirty(page
);
1152 if (pte_young(ptent
) &&
1153 likely(!VM_SequentialReadHint(vma
)))
1154 mark_page_accessed(page
);
1155 rss
[MM_FILEPAGES
]--;
1157 page_remove_rmap(page
);
1158 if (unlikely(page_mapcount(page
) < 0))
1159 print_bad_pte(vma
, addr
, ptent
, page
);
1160 force_flush
= !__tlb_remove_page(tlb
, page
);
1166 * If details->check_mapping, we leave swap entries;
1167 * if details->nonlinear_vma, we leave file entries.
1169 if (unlikely(details
))
1171 if (pte_file(ptent
)) {
1172 if (unlikely(!(vma
->vm_flags
& VM_NONLINEAR
)))
1173 print_bad_pte(vma
, addr
, ptent
, NULL
);
1175 swp_entry_t entry
= pte_to_swp_entry(ptent
);
1177 if (!non_swap_entry(entry
))
1179 else if (is_migration_entry(entry
)) {
1182 page
= migration_entry_to_page(entry
);
1185 rss
[MM_ANONPAGES
]--;
1187 rss
[MM_FILEPAGES
]--;
1189 if (unlikely(!free_swap_and_cache(entry
)))
1190 print_bad_pte(vma
, addr
, ptent
, NULL
);
1192 pte_clear_not_present_full(mm
, addr
, pte
, tlb
->fullmm
);
1193 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
1195 add_mm_rss_vec(mm
, rss
);
1196 arch_leave_lazy_mmu_mode();
1197 pte_unmap_unlock(start_pte
, ptl
);
1200 * mmu_gather ran out of room to batch pages, we break out of
1201 * the PTE lock to avoid doing the potential expensive TLB invalidate
1202 * and page-free while holding it.
1207 #ifdef HAVE_GENERIC_MMU_GATHER
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
)
1227 pmd
= pmd_offset(pud
, addr
);
1229 next
= pmd_addr_end(addr
, end
);
1230 if (pmd_trans_huge(*pmd
)) {
1231 if (next
- addr
!= HPAGE_PMD_SIZE
) {
1232 #ifdef CONFIG_DEBUG_VM
1233 if (!rwsem_is_locked(&tlb
->mm
->mmap_sem
)) {
1234 pr_err("%s: mmap_sem is unlocked! addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n",
1235 __func__
, addr
, end
,
1241 split_huge_page_pmd(vma
, addr
, pmd
);
1242 } else if (zap_huge_pmd(tlb
, vma
, pmd
, addr
))
1247 * Here there can be other concurrent MADV_DONTNEED or
1248 * trans huge page faults running, and if the pmd is
1249 * none or trans huge it can change under us. This is
1250 * because MADV_DONTNEED holds the mmap_sem in read
1253 if (pmd_none_or_trans_huge_or_clear_bad(pmd
))
1255 next
= zap_pte_range(tlb
, vma
, pmd
, addr
, next
, details
);
1258 } while (pmd
++, addr
= next
, addr
!= end
);
1263 static inline unsigned long zap_pud_range(struct mmu_gather
*tlb
,
1264 struct vm_area_struct
*vma
, pgd_t
*pgd
,
1265 unsigned long addr
, unsigned long end
,
1266 struct zap_details
*details
)
1271 pud
= pud_offset(pgd
, addr
);
1273 next
= pud_addr_end(addr
, end
);
1274 if (pud_none_or_clear_bad(pud
))
1276 next
= zap_pmd_range(tlb
, vma
, pud
, addr
, next
, details
);
1277 } while (pud
++, addr
= next
, addr
!= end
);
1282 static void unmap_page_range(struct mmu_gather
*tlb
,
1283 struct vm_area_struct
*vma
,
1284 unsigned long addr
, unsigned long end
,
1285 struct zap_details
*details
)
1290 if (details
&& !details
->check_mapping
&& !details
->nonlinear_vma
)
1293 BUG_ON(addr
>= end
);
1294 mem_cgroup_uncharge_start();
1295 tlb_start_vma(tlb
, vma
);
1296 pgd
= pgd_offset(vma
->vm_mm
, addr
);
1298 next
= pgd_addr_end(addr
, end
);
1299 if (pgd_none_or_clear_bad(pgd
))
1301 next
= zap_pud_range(tlb
, vma
, pgd
, addr
, next
, details
);
1302 } while (pgd
++, addr
= next
, addr
!= end
);
1303 tlb_end_vma(tlb
, vma
);
1304 mem_cgroup_uncharge_end();
1308 static void unmap_single_vma(struct mmu_gather
*tlb
,
1309 struct vm_area_struct
*vma
, unsigned long start_addr
,
1310 unsigned long end_addr
,
1311 struct zap_details
*details
)
1313 unsigned long start
= max(vma
->vm_start
, start_addr
);
1316 if (start
>= vma
->vm_end
)
1318 end
= min(vma
->vm_end
, end_addr
);
1319 if (end
<= vma
->vm_start
)
1323 uprobe_munmap(vma
, start
, end
);
1325 if (unlikely(vma
->vm_flags
& VM_PFNMAP
))
1326 untrack_pfn(vma
, 0, 0);
1329 if (unlikely(is_vm_hugetlb_page(vma
))) {
1331 * It is undesirable to test vma->vm_file as it
1332 * should be non-null for valid hugetlb area.
1333 * However, vm_file will be NULL in the error
1334 * cleanup path of do_mmap_pgoff. When
1335 * hugetlbfs ->mmap method fails,
1336 * do_mmap_pgoff() nullifies vma->vm_file
1337 * before calling this function to clean up.
1338 * Since no pte has actually been setup, it is
1339 * safe to do nothing in this case.
1342 mutex_lock(&vma
->vm_file
->f_mapping
->i_mmap_mutex
);
1343 __unmap_hugepage_range_final(tlb
, vma
, start
, end
, NULL
);
1344 mutex_unlock(&vma
->vm_file
->f_mapping
->i_mmap_mutex
);
1347 unmap_page_range(tlb
, vma
, start
, end
, details
);
1352 * unmap_vmas - unmap a range of memory covered by a list of vma's
1353 * @tlb: address of the caller's struct mmu_gather
1354 * @vma: the starting vma
1355 * @start_addr: virtual address at which to start unmapping
1356 * @end_addr: virtual address at which to end unmapping
1358 * Unmap all pages in the vma list.
1360 * Only addresses between `start' and `end' will be unmapped.
1362 * The VMA list must be sorted in ascending virtual address order.
1364 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1365 * range after unmap_vmas() returns. So the only responsibility here is to
1366 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1367 * drops the lock and schedules.
1369 void unmap_vmas(struct mmu_gather
*tlb
,
1370 struct vm_area_struct
*vma
, unsigned long start_addr
,
1371 unsigned long end_addr
)
1373 struct mm_struct
*mm
= vma
->vm_mm
;
1375 mmu_notifier_invalidate_range_start(mm
, start_addr
, end_addr
);
1376 for ( ; vma
&& vma
->vm_start
< end_addr
; vma
= vma
->vm_next
)
1377 unmap_single_vma(tlb
, vma
, start_addr
, end_addr
, NULL
);
1378 mmu_notifier_invalidate_range_end(mm
, start_addr
, end_addr
);
1382 * zap_page_range - remove user pages in a given range
1383 * @vma: vm_area_struct holding the applicable pages
1384 * @start: starting address of pages to zap
1385 * @size: number of bytes to zap
1386 * @details: details of nonlinear truncation or shared cache invalidation
1388 * Caller must protect the VMA list
1390 void zap_page_range(struct vm_area_struct
*vma
, unsigned long start
,
1391 unsigned long size
, struct zap_details
*details
)
1393 struct mm_struct
*mm
= vma
->vm_mm
;
1394 struct mmu_gather tlb
;
1395 unsigned long end
= start
+ size
;
1398 tlb_gather_mmu(&tlb
, mm
, 0);
1399 update_hiwater_rss(mm
);
1400 mmu_notifier_invalidate_range_start(mm
, start
, end
);
1401 for ( ; vma
&& vma
->vm_start
< end
; vma
= vma
->vm_next
)
1402 unmap_single_vma(&tlb
, vma
, start
, end
, details
);
1403 mmu_notifier_invalidate_range_end(mm
, start
, end
);
1404 tlb_finish_mmu(&tlb
, start
, end
);
1408 * zap_page_range_single - remove user pages in a given range
1409 * @vma: vm_area_struct holding the applicable pages
1410 * @address: starting address of pages to zap
1411 * @size: number of bytes to zap
1412 * @details: details of nonlinear truncation or shared cache invalidation
1414 * The range must fit into one VMA.
1416 static void zap_page_range_single(struct vm_area_struct
*vma
, unsigned long address
,
1417 unsigned long size
, struct zap_details
*details
)
1419 struct mm_struct
*mm
= vma
->vm_mm
;
1420 struct mmu_gather tlb
;
1421 unsigned long end
= address
+ size
;
1424 tlb_gather_mmu(&tlb
, mm
, 0);
1425 update_hiwater_rss(mm
);
1426 mmu_notifier_invalidate_range_start(mm
, address
, end
);
1427 unmap_single_vma(&tlb
, vma
, address
, end
, details
);
1428 mmu_notifier_invalidate_range_end(mm
, address
, end
);
1429 tlb_finish_mmu(&tlb
, address
, end
);
1433 * zap_vma_ptes - remove ptes mapping the vma
1434 * @vma: vm_area_struct holding ptes to be zapped
1435 * @address: starting address of pages to zap
1436 * @size: number of bytes to zap
1438 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1440 * The entire address range must be fully contained within the vma.
1442 * Returns 0 if successful.
1444 int zap_vma_ptes(struct vm_area_struct
*vma
, unsigned long address
,
1447 if (address
< vma
->vm_start
|| address
+ size
> vma
->vm_end
||
1448 !(vma
->vm_flags
& VM_PFNMAP
))
1450 zap_page_range_single(vma
, address
, size
, NULL
);
1453 EXPORT_SYMBOL_GPL(zap_vma_ptes
);
1456 * follow_page - look up a page descriptor from a user-virtual address
1457 * @vma: vm_area_struct mapping @address
1458 * @address: virtual address to look up
1459 * @flags: flags modifying lookup behaviour
1461 * @flags can have FOLL_ flags set, defined in <linux/mm.h>
1463 * Returns the mapped (struct page *), %NULL if no mapping exists, or
1464 * an error pointer if there is a mapping to something not represented
1465 * by a page descriptor (see also vm_normal_page()).
1467 struct page
*follow_page(struct vm_area_struct
*vma
, unsigned long address
,
1476 struct mm_struct
*mm
= vma
->vm_mm
;
1478 page
= follow_huge_addr(mm
, address
, flags
& FOLL_WRITE
);
1479 if (!IS_ERR(page
)) {
1480 BUG_ON(flags
& FOLL_GET
);
1485 pgd
= pgd_offset(mm
, address
);
1486 if (pgd_none(*pgd
) || unlikely(pgd_bad(*pgd
)))
1489 pud
= pud_offset(pgd
, address
);
1492 if (pud_huge(*pud
) && vma
->vm_flags
& VM_HUGETLB
) {
1493 BUG_ON(flags
& FOLL_GET
);
1494 page
= follow_huge_pud(mm
, address
, pud
, flags
& FOLL_WRITE
);
1497 if (unlikely(pud_bad(*pud
)))
1500 pmd
= pmd_offset(pud
, address
);
1503 if (pmd_huge(*pmd
) && vma
->vm_flags
& VM_HUGETLB
) {
1504 BUG_ON(flags
& FOLL_GET
);
1505 page
= follow_huge_pmd(mm
, address
, pmd
, flags
& FOLL_WRITE
);
1508 if ((flags
& FOLL_NUMA
) && pmd_numa(*pmd
))
1510 if (pmd_trans_huge(*pmd
)) {
1511 if (flags
& FOLL_SPLIT
) {
1512 split_huge_page_pmd(vma
, address
, pmd
);
1513 goto split_fallthrough
;
1515 spin_lock(&mm
->page_table_lock
);
1516 if (likely(pmd_trans_huge(*pmd
))) {
1517 if (unlikely(pmd_trans_splitting(*pmd
))) {
1518 spin_unlock(&mm
->page_table_lock
);
1519 wait_split_huge_page(vma
->anon_vma
, pmd
);
1521 page
= follow_trans_huge_pmd(vma
, address
,
1523 spin_unlock(&mm
->page_table_lock
);
1527 spin_unlock(&mm
->page_table_lock
);
1531 if (unlikely(pmd_bad(*pmd
)))
1534 ptep
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
1537 if (!pte_present(pte
))
1539 if ((flags
& FOLL_NUMA
) && pte_numa(pte
))
1541 if ((flags
& FOLL_WRITE
) && !pte_write(pte
))
1544 page
= vm_normal_page(vma
, address
, pte
);
1545 if (unlikely(!page
)) {
1546 if ((flags
& FOLL_DUMP
) ||
1547 !is_zero_pfn(pte_pfn(pte
)))
1549 page
= pte_page(pte
);
1552 if (flags
& FOLL_GET
)
1553 get_page_foll(page
);
1554 if (flags
& FOLL_TOUCH
) {
1555 if ((flags
& FOLL_WRITE
) &&
1556 !pte_dirty(pte
) && !PageDirty(page
))
1557 set_page_dirty(page
);
1559 * pte_mkyoung() would be more correct here, but atomic care
1560 * is needed to avoid losing the dirty bit: it is easier to use
1561 * mark_page_accessed().
1563 mark_page_accessed(page
);
1565 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1567 * The preliminary mapping check is mainly to avoid the
1568 * pointless overhead of lock_page on the ZERO_PAGE
1569 * which might bounce very badly if there is contention.
1571 * If the page is already locked, we don't need to
1572 * handle it now - vmscan will handle it later if and
1573 * when it attempts to reclaim the page.
1575 if (page
->mapping
&& trylock_page(page
)) {
1576 lru_add_drain(); /* push cached pages to LRU */
1578 * Because we lock page here, and migration is
1579 * blocked by the pte's page reference, and we
1580 * know the page is still mapped, we don't even
1581 * need to check for file-cache page truncation.
1583 mlock_vma_page(page
);
1588 pte_unmap_unlock(ptep
, ptl
);
1593 pte_unmap_unlock(ptep
, ptl
);
1594 return ERR_PTR(-EFAULT
);
1597 pte_unmap_unlock(ptep
, ptl
);
1603 * When core dumping an enormous anonymous area that nobody
1604 * has touched so far, we don't want to allocate unnecessary pages or
1605 * page tables. Return error instead of NULL to skip handle_mm_fault,
1606 * then get_dump_page() will return NULL to leave a hole in the dump.
1607 * But we can only make this optimization where a hole would surely
1608 * be zero-filled if handle_mm_fault() actually did handle it.
1610 if ((flags
& FOLL_DUMP
) &&
1611 (!vma
->vm_ops
|| !vma
->vm_ops
->fault
))
1612 return ERR_PTR(-EFAULT
);
1616 static inline int stack_guard_page(struct vm_area_struct
*vma
, unsigned long addr
)
1618 return stack_guard_page_start(vma
, addr
) ||
1619 stack_guard_page_end(vma
, addr
+PAGE_SIZE
);
1623 * __get_user_pages() - pin user pages in memory
1624 * @tsk: task_struct of target task
1625 * @mm: mm_struct of target mm
1626 * @start: starting user address
1627 * @nr_pages: number of pages from start to pin
1628 * @gup_flags: flags modifying pin behaviour
1629 * @pages: array that receives pointers to the pages pinned.
1630 * Should be at least nr_pages long. Or NULL, if caller
1631 * only intends to ensure the pages are faulted in.
1632 * @vmas: array of pointers to vmas corresponding to each page.
1633 * Or NULL if the caller does not require them.
1634 * @nonblocking: whether waiting for disk IO or mmap_sem contention
1636 * Returns number of pages pinned. This may be fewer than the number
1637 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1638 * were pinned, returns -errno. Each page returned must be released
1639 * with a put_page() call when it is finished with. vmas will only
1640 * remain valid while mmap_sem is held.
1642 * Must be called with mmap_sem held for read or write.
1644 * __get_user_pages walks a process's page tables and takes a reference to
1645 * each struct page that each user address corresponds to at a given
1646 * instant. That is, it takes the page that would be accessed if a user
1647 * thread accesses the given user virtual address at that instant.
1649 * This does not guarantee that the page exists in the user mappings when
1650 * __get_user_pages returns, and there may even be a completely different
1651 * page there in some cases (eg. if mmapped pagecache has been invalidated
1652 * and subsequently re faulted). However it does guarantee that the page
1653 * won't be freed completely. And mostly callers simply care that the page
1654 * contains data that was valid *at some point in time*. Typically, an IO
1655 * or similar operation cannot guarantee anything stronger anyway because
1656 * locks can't be held over the syscall boundary.
1658 * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
1659 * the page is written to, set_page_dirty (or set_page_dirty_lock, as
1660 * appropriate) must be called after the page is finished with, and
1661 * before put_page is called.
1663 * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
1664 * or mmap_sem contention, and if waiting is needed to pin all pages,
1665 * *@nonblocking will be set to 0.
1667 * In most cases, get_user_pages or get_user_pages_fast should be used
1668 * instead of __get_user_pages. __get_user_pages should be used only if
1669 * you need some special @gup_flags.
1671 int __get_user_pages(struct task_struct
*tsk
, struct mm_struct
*mm
,
1672 unsigned long start
, int nr_pages
, unsigned int gup_flags
,
1673 struct page
**pages
, struct vm_area_struct
**vmas
,
1677 unsigned long vm_flags
;
1682 VM_BUG_ON(!!pages
!= !!(gup_flags
& FOLL_GET
));
1685 * Require read or write permissions.
1686 * If FOLL_FORCE is set, we only require the "MAY" flags.
1688 vm_flags
= (gup_flags
& FOLL_WRITE
) ?
1689 (VM_WRITE
| VM_MAYWRITE
) : (VM_READ
| VM_MAYREAD
);
1690 vm_flags
&= (gup_flags
& FOLL_FORCE
) ?
1691 (VM_MAYREAD
| VM_MAYWRITE
) : (VM_READ
| VM_WRITE
);
1694 * If FOLL_FORCE and FOLL_NUMA are both set, handle_mm_fault
1695 * would be called on PROT_NONE ranges. We must never invoke
1696 * handle_mm_fault on PROT_NONE ranges or the NUMA hinting
1697 * page faults would unprotect the PROT_NONE ranges if
1698 * _PAGE_NUMA and _PAGE_PROTNONE are sharing the same pte/pmd
1699 * bitflag. So to avoid that, don't set FOLL_NUMA if
1700 * FOLL_FORCE is set.
1702 if (!(gup_flags
& FOLL_FORCE
))
1703 gup_flags
|= FOLL_NUMA
;
1708 struct vm_area_struct
*vma
;
1710 vma
= find_extend_vma(mm
, start
);
1711 if (!vma
&& in_gate_area(mm
, start
)) {
1712 unsigned long pg
= start
& PAGE_MASK
;
1718 /* user gate pages are read-only */
1719 if (gup_flags
& FOLL_WRITE
)
1720 return i
? : -EFAULT
;
1722 pgd
= pgd_offset_k(pg
);
1724 pgd
= pgd_offset_gate(mm
, pg
);
1725 BUG_ON(pgd_none(*pgd
));
1726 pud
= pud_offset(pgd
, pg
);
1727 BUG_ON(pud_none(*pud
));
1728 pmd
= pmd_offset(pud
, pg
);
1730 return i
? : -EFAULT
;
1731 VM_BUG_ON(pmd_trans_huge(*pmd
));
1732 pte
= pte_offset_map(pmd
, pg
);
1733 if (pte_none(*pte
)) {
1735 return i
? : -EFAULT
;
1737 vma
= get_gate_vma(mm
);
1741 page
= vm_normal_page(vma
, start
, *pte
);
1743 if (!(gup_flags
& FOLL_DUMP
) &&
1744 is_zero_pfn(pte_pfn(*pte
)))
1745 page
= pte_page(*pte
);
1748 return i
? : -EFAULT
;
1759 (vma
->vm_flags
& (VM_IO
| VM_PFNMAP
)) ||
1760 !(vm_flags
& vma
->vm_flags
))
1761 return i
? : -EFAULT
;
1763 if (is_vm_hugetlb_page(vma
)) {
1764 i
= follow_hugetlb_page(mm
, vma
, pages
, vmas
,
1765 &start
, &nr_pages
, i
, gup_flags
);
1771 unsigned int foll_flags
= gup_flags
;
1774 * If we have a pending SIGKILL, don't keep faulting
1775 * pages and potentially allocating memory.
1777 if (unlikely(fatal_signal_pending(current
)))
1778 return i
? i
: -ERESTARTSYS
;
1781 while (!(page
= follow_page(vma
, start
, foll_flags
))) {
1783 unsigned int fault_flags
= 0;
1785 /* For mlock, just skip the stack guard page. */
1786 if (foll_flags
& FOLL_MLOCK
) {
1787 if (stack_guard_page(vma
, start
))
1790 if (foll_flags
& FOLL_WRITE
)
1791 fault_flags
|= FAULT_FLAG_WRITE
;
1793 fault_flags
|= FAULT_FLAG_ALLOW_RETRY
;
1794 if (foll_flags
& FOLL_NOWAIT
)
1795 fault_flags
|= (FAULT_FLAG_ALLOW_RETRY
| FAULT_FLAG_RETRY_NOWAIT
);
1797 ret
= handle_mm_fault(mm
, vma
, start
,
1800 if (ret
& VM_FAULT_ERROR
) {
1801 if (ret
& VM_FAULT_OOM
)
1802 return i
? i
: -ENOMEM
;
1803 if (ret
& (VM_FAULT_HWPOISON
|
1804 VM_FAULT_HWPOISON_LARGE
)) {
1807 else if (gup_flags
& FOLL_HWPOISON
)
1812 if (ret
& VM_FAULT_SIGBUS
)
1813 return i
? i
: -EFAULT
;
1818 if (ret
& VM_FAULT_MAJOR
)
1824 if (ret
& VM_FAULT_RETRY
) {
1831 * The VM_FAULT_WRITE bit tells us that
1832 * do_wp_page has broken COW when necessary,
1833 * even if maybe_mkwrite decided not to set
1834 * pte_write. We can thus safely do subsequent
1835 * page lookups as if they were reads. But only
1836 * do so when looping for pte_write is futile:
1837 * in some cases userspace may also be wanting
1838 * to write to the gotten user page, which a
1839 * read fault here might prevent (a readonly
1840 * page might get reCOWed by userspace write).
1842 if ((ret
& VM_FAULT_WRITE
) &&
1843 !(vma
->vm_flags
& VM_WRITE
))
1844 foll_flags
&= ~FOLL_WRITE
;
1849 return i
? i
: PTR_ERR(page
);
1853 flush_anon_page(vma
, page
, start
);
1854 flush_dcache_page(page
);
1862 } while (nr_pages
&& start
< vma
->vm_end
);
1866 EXPORT_SYMBOL(__get_user_pages
);
1869 * fixup_user_fault() - manually resolve a user page fault
1870 * @tsk: the task_struct to use for page fault accounting, or
1871 * NULL if faults are not to be recorded.
1872 * @mm: mm_struct of target mm
1873 * @address: user address
1874 * @fault_flags:flags to pass down to handle_mm_fault()
1876 * This is meant to be called in the specific scenario where for locking reasons
1877 * we try to access user memory in atomic context (within a pagefault_disable()
1878 * section), this returns -EFAULT, and we want to resolve the user fault before
1881 * Typically this is meant to be used by the futex code.
1883 * The main difference with get_user_pages() is that this function will
1884 * unconditionally call handle_mm_fault() which will in turn perform all the
1885 * necessary SW fixup of the dirty and young bits in the PTE, while
1886 * handle_mm_fault() only guarantees to update these in the struct page.
1888 * This is important for some architectures where those bits also gate the
1889 * access permission to the page because they are maintained in software. On
1890 * such architectures, gup() will not be enough to make a subsequent access
1893 * This should be called with the mm_sem held for read.
1895 int fixup_user_fault(struct task_struct
*tsk
, struct mm_struct
*mm
,
1896 unsigned long address
, unsigned int fault_flags
)
1898 struct vm_area_struct
*vma
;
1901 vma
= find_extend_vma(mm
, address
);
1902 if (!vma
|| address
< vma
->vm_start
)
1905 ret
= handle_mm_fault(mm
, vma
, address
, fault_flags
);
1906 if (ret
& VM_FAULT_ERROR
) {
1907 if (ret
& VM_FAULT_OOM
)
1909 if (ret
& (VM_FAULT_HWPOISON
| VM_FAULT_HWPOISON_LARGE
))
1911 if (ret
& VM_FAULT_SIGBUS
)
1916 if (ret
& VM_FAULT_MAJOR
)
1925 * get_user_pages() - pin user pages in memory
1926 * @tsk: the task_struct to use for page fault accounting, or
1927 * NULL if faults are not to be recorded.
1928 * @mm: mm_struct of target mm
1929 * @start: starting user address
1930 * @nr_pages: number of pages from start to pin
1931 * @write: whether pages will be written to by the caller
1932 * @force: whether to force write access even if user mapping is
1933 * readonly. This will result in the page being COWed even
1934 * in MAP_SHARED mappings. You do not want this.
1935 * @pages: array that receives pointers to the pages pinned.
1936 * Should be at least nr_pages long. Or NULL, if caller
1937 * only intends to ensure the pages are faulted in.
1938 * @vmas: array of pointers to vmas corresponding to each page.
1939 * Or NULL if the caller does not require them.
1941 * Returns number of pages pinned. This may be fewer than the number
1942 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1943 * were pinned, returns -errno. Each page returned must be released
1944 * with a put_page() call when it is finished with. vmas will only
1945 * remain valid while mmap_sem is held.
1947 * Must be called with mmap_sem held for read or write.
1949 * get_user_pages walks a process's page tables and takes a reference to
1950 * each struct page that each user address corresponds to at a given
1951 * instant. That is, it takes the page that would be accessed if a user
1952 * thread accesses the given user virtual address at that instant.
1954 * This does not guarantee that the page exists in the user mappings when
1955 * get_user_pages returns, and there may even be a completely different
1956 * page there in some cases (eg. if mmapped pagecache has been invalidated
1957 * and subsequently re faulted). However it does guarantee that the page
1958 * won't be freed completely. And mostly callers simply care that the page
1959 * contains data that was valid *at some point in time*. Typically, an IO
1960 * or similar operation cannot guarantee anything stronger anyway because
1961 * locks can't be held over the syscall boundary.
1963 * If write=0, the page must not be written to. If the page is written to,
1964 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1965 * after the page is finished with, and before put_page is called.
1967 * get_user_pages is typically used for fewer-copy IO operations, to get a
1968 * handle on the memory by some means other than accesses via the user virtual
1969 * addresses. The pages may be submitted for DMA to devices or accessed via
1970 * their kernel linear mapping (via the kmap APIs). Care should be taken to
1971 * use the correct cache flushing APIs.
1973 * See also get_user_pages_fast, for performance critical applications.
1975 int get_user_pages(struct task_struct
*tsk
, struct mm_struct
*mm
,
1976 unsigned long start
, int nr_pages
, int write
, int force
,
1977 struct page
**pages
, struct vm_area_struct
**vmas
)
1979 int flags
= FOLL_TOUCH
;
1984 flags
|= FOLL_WRITE
;
1986 flags
|= FOLL_FORCE
;
1988 return __get_user_pages(tsk
, mm
, start
, nr_pages
, flags
, pages
, vmas
,
1991 EXPORT_SYMBOL(get_user_pages
);
1994 * get_dump_page() - pin user page in memory while writing it to core dump
1995 * @addr: user address
1997 * Returns struct page pointer of user page pinned for dump,
1998 * to be freed afterwards by page_cache_release() or put_page().
2000 * Returns NULL on any kind of failure - a hole must then be inserted into
2001 * the corefile, to preserve alignment with its headers; and also returns
2002 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
2003 * allowing a hole to be left in the corefile to save diskspace.
2005 * Called without mmap_sem, but after all other threads have been killed.
2007 #ifdef CONFIG_ELF_CORE
2008 struct page
*get_dump_page(unsigned long addr
)
2010 struct vm_area_struct
*vma
;
2013 if (__get_user_pages(current
, current
->mm
, addr
, 1,
2014 FOLL_FORCE
| FOLL_DUMP
| FOLL_GET
, &page
, &vma
,
2017 flush_cache_page(vma
, addr
, page_to_pfn(page
));
2020 #endif /* CONFIG_ELF_CORE */
2022 pte_t
*__get_locked_pte(struct mm_struct
*mm
, unsigned long addr
,
2025 pgd_t
* pgd
= pgd_offset(mm
, addr
);
2026 pud_t
* pud
= pud_alloc(mm
, pgd
, addr
);
2028 pmd_t
* pmd
= pmd_alloc(mm
, pud
, addr
);
2030 VM_BUG_ON(pmd_trans_huge(*pmd
));
2031 return pte_alloc_map_lock(mm
, pmd
, addr
, ptl
);
2038 * This is the old fallback for page remapping.
2040 * For historical reasons, it only allows reserved pages. Only
2041 * old drivers should use this, and they needed to mark their
2042 * pages reserved for the old functions anyway.
2044 static int insert_page(struct vm_area_struct
*vma
, unsigned long addr
,
2045 struct page
*page
, pgprot_t prot
)
2047 struct mm_struct
*mm
= vma
->vm_mm
;
2056 flush_dcache_page(page
);
2057 pte
= get_locked_pte(mm
, addr
, &ptl
);
2061 if (!pte_none(*pte
))
2064 /* Ok, finally just insert the thing.. */
2066 inc_mm_counter_fast(mm
, MM_FILEPAGES
);
2067 page_add_file_rmap(page
);
2068 set_pte_at(mm
, addr
, pte
, mk_pte(page
, prot
));
2071 pte_unmap_unlock(pte
, ptl
);
2074 pte_unmap_unlock(pte
, ptl
);
2080 * vm_insert_page - insert single page into user vma
2081 * @vma: user vma to map to
2082 * @addr: target user address of this page
2083 * @page: source kernel page
2085 * This allows drivers to insert individual pages they've allocated
2088 * The page has to be a nice clean _individual_ kernel allocation.
2089 * If you allocate a compound page, you need to have marked it as
2090 * such (__GFP_COMP), or manually just split the page up yourself
2091 * (see split_page()).
2093 * NOTE! Traditionally this was done with "remap_pfn_range()" which
2094 * took an arbitrary page protection parameter. This doesn't allow
2095 * that. Your vma protection will have to be set up correctly, which
2096 * means that if you want a shared writable mapping, you'd better
2097 * ask for a shared writable mapping!
2099 * The page does not need to be reserved.
2101 * Usually this function is called from f_op->mmap() handler
2102 * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
2103 * Caller must set VM_MIXEDMAP on vma if it wants to call this
2104 * function from other places, for example from page-fault handler.
2106 int vm_insert_page(struct vm_area_struct
*vma
, unsigned long addr
,
2109 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
2111 if (!page_count(page
))
2113 if (!(vma
->vm_flags
& VM_MIXEDMAP
)) {
2114 BUG_ON(down_read_trylock(&vma
->vm_mm
->mmap_sem
));
2115 BUG_ON(vma
->vm_flags
& VM_PFNMAP
);
2116 vma
->vm_flags
|= VM_MIXEDMAP
;
2118 return insert_page(vma
, addr
, page
, vma
->vm_page_prot
);
2120 EXPORT_SYMBOL(vm_insert_page
);
2122 static int insert_pfn(struct vm_area_struct
*vma
, unsigned long addr
,
2123 unsigned long pfn
, pgprot_t prot
)
2125 struct mm_struct
*mm
= vma
->vm_mm
;
2131 pte
= get_locked_pte(mm
, addr
, &ptl
);
2135 if (!pte_none(*pte
))
2138 /* Ok, finally just insert the thing.. */
2139 entry
= pte_mkspecial(pfn_pte(pfn
, prot
));
2140 set_pte_at(mm
, addr
, pte
, entry
);
2141 update_mmu_cache(vma
, addr
, pte
); /* XXX: why not for insert_page? */
2145 pte_unmap_unlock(pte
, ptl
);
2151 * vm_insert_pfn - insert single pfn into user vma
2152 * @vma: user vma to map to
2153 * @addr: target user address of this page
2154 * @pfn: source kernel pfn
2156 * Similar to vm_insert_page, this allows drivers to insert individual pages
2157 * they've allocated into a user vma. Same comments apply.
2159 * This function should only be called from a vm_ops->fault handler, and
2160 * in that case the handler should return NULL.
2162 * vma cannot be a COW mapping.
2164 * As this is called only for pages that do not currently exist, we
2165 * do not need to flush old virtual caches or the TLB.
2167 int vm_insert_pfn(struct vm_area_struct
*vma
, unsigned long addr
,
2171 pgprot_t pgprot
= vma
->vm_page_prot
;
2173 * Technically, architectures with pte_special can avoid all these
2174 * restrictions (same for remap_pfn_range). However we would like
2175 * consistency in testing and feature parity among all, so we should
2176 * try to keep these invariants in place for everybody.
2178 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)));
2179 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
2180 (VM_PFNMAP
|VM_MIXEDMAP
));
2181 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
2182 BUG_ON((vma
->vm_flags
& VM_MIXEDMAP
) && pfn_valid(pfn
));
2184 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
2186 if (track_pfn_insert(vma
, &pgprot
, pfn
))
2189 ret
= insert_pfn(vma
, addr
, pfn
, pgprot
);
2193 EXPORT_SYMBOL(vm_insert_pfn
);
2195 int vm_insert_mixed(struct vm_area_struct
*vma
, unsigned long addr
,
2198 BUG_ON(!(vma
->vm_flags
& VM_MIXEDMAP
));
2200 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
2204 * If we don't have pte special, then we have to use the pfn_valid()
2205 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2206 * refcount the page if pfn_valid is true (hence insert_page rather
2207 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
2208 * without pte special, it would there be refcounted as a normal page.
2210 if (!HAVE_PTE_SPECIAL
&& pfn_valid(pfn
)) {
2213 page
= pfn_to_page(pfn
);
2214 return insert_page(vma
, addr
, page
, vma
->vm_page_prot
);
2216 return insert_pfn(vma
, addr
, pfn
, vma
->vm_page_prot
);
2218 EXPORT_SYMBOL(vm_insert_mixed
);
2221 * maps a range of physical memory into the requested pages. the old
2222 * mappings are removed. any references to nonexistent pages results
2223 * in null mappings (currently treated as "copy-on-access")
2225 static int remap_pte_range(struct mm_struct
*mm
, pmd_t
*pmd
,
2226 unsigned long addr
, unsigned long end
,
2227 unsigned long pfn
, pgprot_t prot
)
2232 pte
= pte_alloc_map_lock(mm
, pmd
, addr
, &ptl
);
2235 arch_enter_lazy_mmu_mode();
2237 BUG_ON(!pte_none(*pte
));
2238 set_pte_at(mm
, addr
, pte
, pte_mkspecial(pfn_pte(pfn
, prot
)));
2240 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
2241 arch_leave_lazy_mmu_mode();
2242 pte_unmap_unlock(pte
- 1, ptl
);
2246 static inline int remap_pmd_range(struct mm_struct
*mm
, pud_t
*pud
,
2247 unsigned long addr
, unsigned long end
,
2248 unsigned long pfn
, pgprot_t prot
)
2253 pfn
-= addr
>> PAGE_SHIFT
;
2254 pmd
= pmd_alloc(mm
, pud
, addr
);
2257 VM_BUG_ON(pmd_trans_huge(*pmd
));
2259 next
= pmd_addr_end(addr
, end
);
2260 if (remap_pte_range(mm
, pmd
, addr
, next
,
2261 pfn
+ (addr
>> PAGE_SHIFT
), prot
))
2263 } while (pmd
++, addr
= next
, addr
!= end
);
2267 static inline int remap_pud_range(struct mm_struct
*mm
, pgd_t
*pgd
,
2268 unsigned long addr
, unsigned long end
,
2269 unsigned long pfn
, pgprot_t prot
)
2274 pfn
-= addr
>> PAGE_SHIFT
;
2275 pud
= pud_alloc(mm
, pgd
, addr
);
2279 next
= pud_addr_end(addr
, end
);
2280 if (remap_pmd_range(mm
, pud
, addr
, next
,
2281 pfn
+ (addr
>> PAGE_SHIFT
), prot
))
2283 } while (pud
++, addr
= next
, addr
!= end
);
2288 * remap_pfn_range - remap kernel memory to userspace
2289 * @vma: user vma to map to
2290 * @addr: target user address to start at
2291 * @pfn: physical address of kernel memory
2292 * @size: size of map area
2293 * @prot: page protection flags for this mapping
2295 * Note: this is only safe if the mm semaphore is held when called.
2297 int remap_pfn_range(struct vm_area_struct
*vma
, unsigned long addr
,
2298 unsigned long pfn
, unsigned long size
, pgprot_t prot
)
2302 unsigned long end
= addr
+ PAGE_ALIGN(size
);
2303 struct mm_struct
*mm
= vma
->vm_mm
;
2307 * Physically remapped pages are special. Tell the
2308 * rest of the world about it:
2309 * VM_IO tells people not to look at these pages
2310 * (accesses can have side effects).
2311 * VM_PFNMAP tells the core MM that the base pages are just
2312 * raw PFN mappings, and do not have a "struct page" associated
2315 * Disable vma merging and expanding with mremap().
2317 * Omit vma from core dump, even when VM_IO turned off.
2319 * There's a horrible special case to handle copy-on-write
2320 * behaviour that some programs depend on. We mark the "original"
2321 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2322 * See vm_normal_page() for details.
2324 if (is_cow_mapping(vma
->vm_flags
)) {
2325 if (addr
!= vma
->vm_start
|| end
!= vma
->vm_end
)
2327 vma
->vm_pgoff
= pfn
;
2330 err
= track_pfn_remap(vma
, &prot
, pfn
, addr
, PAGE_ALIGN(size
));
2334 vma
->vm_flags
|= VM_IO
| VM_PFNMAP
| VM_DONTEXPAND
| VM_DONTDUMP
;
2336 BUG_ON(addr
>= end
);
2337 pfn
-= addr
>> PAGE_SHIFT
;
2338 pgd
= pgd_offset(mm
, addr
);
2339 flush_cache_range(vma
, addr
, end
);
2341 next
= pgd_addr_end(addr
, end
);
2342 err
= remap_pud_range(mm
, pgd
, addr
, next
,
2343 pfn
+ (addr
>> PAGE_SHIFT
), prot
);
2346 } while (pgd
++, addr
= next
, addr
!= end
);
2349 untrack_pfn(vma
, pfn
, PAGE_ALIGN(size
));
2353 EXPORT_SYMBOL(remap_pfn_range
);
2355 static int apply_to_pte_range(struct mm_struct
*mm
, pmd_t
*pmd
,
2356 unsigned long addr
, unsigned long end
,
2357 pte_fn_t fn
, void *data
)
2362 spinlock_t
*uninitialized_var(ptl
);
2364 pte
= (mm
== &init_mm
) ?
2365 pte_alloc_kernel(pmd
, addr
) :
2366 pte_alloc_map_lock(mm
, pmd
, addr
, &ptl
);
2370 BUG_ON(pmd_huge(*pmd
));
2372 arch_enter_lazy_mmu_mode();
2374 token
= pmd_pgtable(*pmd
);
2377 err
= fn(pte
++, token
, addr
, data
);
2380 } while (addr
+= PAGE_SIZE
, addr
!= end
);
2382 arch_leave_lazy_mmu_mode();
2385 pte_unmap_unlock(pte
-1, ptl
);
2389 static int apply_to_pmd_range(struct mm_struct
*mm
, pud_t
*pud
,
2390 unsigned long addr
, unsigned long end
,
2391 pte_fn_t fn
, void *data
)
2397 BUG_ON(pud_huge(*pud
));
2399 pmd
= pmd_alloc(mm
, pud
, addr
);
2403 next
= pmd_addr_end(addr
, end
);
2404 err
= apply_to_pte_range(mm
, pmd
, addr
, next
, fn
, data
);
2407 } while (pmd
++, addr
= next
, addr
!= end
);
2411 static int apply_to_pud_range(struct mm_struct
*mm
, pgd_t
*pgd
,
2412 unsigned long addr
, unsigned long end
,
2413 pte_fn_t fn
, void *data
)
2419 pud
= pud_alloc(mm
, pgd
, addr
);
2423 next
= pud_addr_end(addr
, end
);
2424 err
= apply_to_pmd_range(mm
, pud
, addr
, next
, fn
, data
);
2427 } while (pud
++, addr
= next
, addr
!= end
);
2432 * Scan a region of virtual memory, filling in page tables as necessary
2433 * and calling a provided function on each leaf page table.
2435 int apply_to_page_range(struct mm_struct
*mm
, unsigned long addr
,
2436 unsigned long size
, pte_fn_t fn
, void *data
)
2440 unsigned long end
= addr
+ size
;
2443 BUG_ON(addr
>= end
);
2444 pgd
= pgd_offset(mm
, addr
);
2446 next
= pgd_addr_end(addr
, end
);
2447 err
= apply_to_pud_range(mm
, pgd
, addr
, next
, fn
, data
);
2450 } while (pgd
++, addr
= next
, addr
!= end
);
2454 EXPORT_SYMBOL_GPL(apply_to_page_range
);
2457 * handle_pte_fault chooses page fault handler according to an entry
2458 * which was read non-atomically. Before making any commitment, on
2459 * those architectures or configurations (e.g. i386 with PAE) which
2460 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
2461 * must check under lock before unmapping the pte and proceeding
2462 * (but do_wp_page is only called after already making such a check;
2463 * and do_anonymous_page can safely check later on).
2465 static inline int pte_unmap_same(struct mm_struct
*mm
, pmd_t
*pmd
,
2466 pte_t
*page_table
, pte_t orig_pte
)
2469 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2470 if (sizeof(pte_t
) > sizeof(unsigned long)) {
2471 spinlock_t
*ptl
= pte_lockptr(mm
, pmd
);
2473 same
= pte_same(*page_table
, orig_pte
);
2477 pte_unmap(page_table
);
2481 static inline void cow_user_page(struct page
*dst
, struct page
*src
, unsigned long va
, struct vm_area_struct
*vma
)
2484 * If the source page was a PFN mapping, we don't have
2485 * a "struct page" for it. We do a best-effort copy by
2486 * just copying from the original user address. If that
2487 * fails, we just zero-fill it. Live with it.
2489 if (unlikely(!src
)) {
2490 void *kaddr
= kmap_atomic(dst
);
2491 void __user
*uaddr
= (void __user
*)(va
& PAGE_MASK
);
2494 * This really shouldn't fail, because the page is there
2495 * in the page tables. But it might just be unreadable,
2496 * in which case we just give up and fill the result with
2499 if (__copy_from_user_inatomic(kaddr
, uaddr
, PAGE_SIZE
))
2501 kunmap_atomic(kaddr
);
2502 flush_dcache_page(dst
);
2504 copy_user_highpage(dst
, src
, va
, vma
);
2508 * This routine handles present pages, when users try to write
2509 * to a shared page. It is done by copying the page to a new address
2510 * and decrementing the shared-page counter for the old page.
2512 * Note that this routine assumes that the protection checks have been
2513 * done by the caller (the low-level page fault routine in most cases).
2514 * Thus we can safely just mark it writable once we've done any necessary
2517 * We also mark the page dirty at this point even though the page will
2518 * change only once the write actually happens. This avoids a few races,
2519 * and potentially makes it more efficient.
2521 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2522 * but allow concurrent faults), with pte both mapped and locked.
2523 * We return with mmap_sem still held, but pte unmapped and unlocked.
2525 static int do_wp_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
2526 unsigned long address
, pte_t
*page_table
, pmd_t
*pmd
,
2527 spinlock_t
*ptl
, pte_t orig_pte
)
2530 struct page
*old_page
, *new_page
= NULL
;
2533 int page_mkwrite
= 0;
2534 struct page
*dirty_page
= NULL
;
2535 unsigned long mmun_start
= 0; /* For mmu_notifiers */
2536 unsigned long mmun_end
= 0; /* For mmu_notifiers */
2538 old_page
= vm_normal_page(vma
, address
, orig_pte
);
2541 * VM_MIXEDMAP !pfn_valid() case
2543 * We should not cow pages in a shared writeable mapping.
2544 * Just mark the pages writable as we can't do any dirty
2545 * accounting on raw pfn maps.
2547 if ((vma
->vm_flags
& (VM_WRITE
|VM_SHARED
)) ==
2548 (VM_WRITE
|VM_SHARED
))
2554 * Take out anonymous pages first, anonymous shared vmas are
2555 * not dirty accountable.
2557 if (PageAnon(old_page
) && !PageKsm(old_page
)) {
2558 if (!trylock_page(old_page
)) {
2559 page_cache_get(old_page
);
2560 pte_unmap_unlock(page_table
, ptl
);
2561 lock_page(old_page
);
2562 page_table
= pte_offset_map_lock(mm
, pmd
, address
,
2564 if (!pte_same(*page_table
, orig_pte
)) {
2565 unlock_page(old_page
);
2568 page_cache_release(old_page
);
2570 if (reuse_swap_page(old_page
)) {
2572 * The page is all ours. Move it to our anon_vma so
2573 * the rmap code will not search our parent or siblings.
2574 * Protected against the rmap code by the page lock.
2576 page_move_anon_rmap(old_page
, vma
, address
);
2577 unlock_page(old_page
);
2580 unlock_page(old_page
);
2581 } else if (unlikely((vma
->vm_flags
& (VM_WRITE
|VM_SHARED
)) ==
2582 (VM_WRITE
|VM_SHARED
))) {
2584 * Only catch write-faults on shared writable pages,
2585 * read-only shared pages can get COWed by
2586 * get_user_pages(.write=1, .force=1).
2588 if (vma
->vm_ops
&& vma
->vm_ops
->page_mkwrite
) {
2589 struct vm_fault vmf
;
2592 vmf
.virtual_address
= (void __user
*)(address
&
2594 vmf
.pgoff
= old_page
->index
;
2595 vmf
.flags
= FAULT_FLAG_WRITE
|FAULT_FLAG_MKWRITE
;
2596 vmf
.page
= old_page
;
2599 * Notify the address space that the page is about to
2600 * become writable so that it can prohibit this or wait
2601 * for the page to get into an appropriate state.
2603 * We do this without the lock held, so that it can
2604 * sleep if it needs to.
2606 page_cache_get(old_page
);
2607 pte_unmap_unlock(page_table
, ptl
);
2609 tmp
= vma
->vm_ops
->page_mkwrite(vma
, &vmf
);
2611 (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
))) {
2613 goto unwritable_page
;
2615 if (unlikely(!(tmp
& VM_FAULT_LOCKED
))) {
2616 lock_page(old_page
);
2617 if (!old_page
->mapping
) {
2618 ret
= 0; /* retry the fault */
2619 unlock_page(old_page
);
2620 goto unwritable_page
;
2623 VM_BUG_ON(!PageLocked(old_page
));
2626 * Since we dropped the lock we need to revalidate
2627 * the PTE as someone else may have changed it. If
2628 * they did, we just return, as we can count on the
2629 * MMU to tell us if they didn't also make it writable.
2631 page_table
= pte_offset_map_lock(mm
, pmd
, address
,
2633 if (!pte_same(*page_table
, orig_pte
)) {
2634 unlock_page(old_page
);
2640 dirty_page
= old_page
;
2641 get_page(dirty_page
);
2644 flush_cache_page(vma
, address
, pte_pfn(orig_pte
));
2645 entry
= pte_mkyoung(orig_pte
);
2646 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
2647 if (ptep_set_access_flags(vma
, address
, page_table
, entry
,1))
2648 update_mmu_cache(vma
, address
, page_table
);
2649 pte_unmap_unlock(page_table
, ptl
);
2650 ret
|= VM_FAULT_WRITE
;
2656 * Yes, Virginia, this is actually required to prevent a race
2657 * with clear_page_dirty_for_io() from clearing the page dirty
2658 * bit after it clear all dirty ptes, but before a racing
2659 * do_wp_page installs a dirty pte.
2661 * __do_fault is protected similarly.
2663 if (!page_mkwrite
) {
2664 wait_on_page_locked(dirty_page
);
2665 set_page_dirty_balance(dirty_page
, page_mkwrite
);
2666 /* file_update_time outside page_lock */
2668 file_update_time(vma
->vm_file
);
2670 put_page(dirty_page
);
2672 struct address_space
*mapping
= dirty_page
->mapping
;
2674 set_page_dirty(dirty_page
);
2675 unlock_page(dirty_page
);
2676 page_cache_release(dirty_page
);
2679 * Some device drivers do not set page.mapping
2680 * but still dirty their pages
2682 balance_dirty_pages_ratelimited(mapping
);
2690 * Ok, we need to copy. Oh, well..
2692 page_cache_get(old_page
);
2694 pte_unmap_unlock(page_table
, ptl
);
2696 if (unlikely(anon_vma_prepare(vma
)))
2699 if (is_zero_pfn(pte_pfn(orig_pte
))) {
2700 new_page
= alloc_zeroed_user_highpage_movable(vma
, address
);
2704 new_page
= alloc_page_vma(GFP_HIGHUSER_MOVABLE
, vma
, address
);
2707 cow_user_page(new_page
, old_page
, address
, vma
);
2709 __SetPageUptodate(new_page
);
2711 if (mem_cgroup_newpage_charge(new_page
, mm
, GFP_KERNEL
))
2714 mmun_start
= address
& PAGE_MASK
;
2715 mmun_end
= mmun_start
+ PAGE_SIZE
;
2716 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2719 * Re-check the pte - we dropped the lock
2721 page_table
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2722 if (likely(pte_same(*page_table
, orig_pte
))) {
2724 if (!PageAnon(old_page
)) {
2725 dec_mm_counter_fast(mm
, MM_FILEPAGES
);
2726 inc_mm_counter_fast(mm
, MM_ANONPAGES
);
2729 inc_mm_counter_fast(mm
, MM_ANONPAGES
);
2730 flush_cache_page(vma
, address
, pte_pfn(orig_pte
));
2731 entry
= mk_pte(new_page
, vma
->vm_page_prot
);
2732 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
2734 * Clear the pte entry and flush it first, before updating the
2735 * pte with the new entry. This will avoid a race condition
2736 * seen in the presence of one thread doing SMC and another
2739 ptep_clear_flush(vma
, address
, page_table
);
2740 page_add_new_anon_rmap(new_page
, vma
, address
);
2742 * We call the notify macro here because, when using secondary
2743 * mmu page tables (such as kvm shadow page tables), we want the
2744 * new page to be mapped directly into the secondary page table.
2746 set_pte_at_notify(mm
, address
, page_table
, entry
);
2747 update_mmu_cache(vma
, address
, page_table
);
2750 * Only after switching the pte to the new page may
2751 * we remove the mapcount here. Otherwise another
2752 * process may come and find the rmap count decremented
2753 * before the pte is switched to the new page, and
2754 * "reuse" the old page writing into it while our pte
2755 * here still points into it and can be read by other
2758 * The critical issue is to order this
2759 * page_remove_rmap with the ptp_clear_flush above.
2760 * Those stores are ordered by (if nothing else,)
2761 * the barrier present in the atomic_add_negative
2762 * in page_remove_rmap.
2764 * Then the TLB flush in ptep_clear_flush ensures that
2765 * no process can access the old page before the
2766 * decremented mapcount is visible. And the old page
2767 * cannot be reused until after the decremented
2768 * mapcount is visible. So transitively, TLBs to
2769 * old page will be flushed before it can be reused.
2771 page_remove_rmap(old_page
);
2774 /* Free the old page.. */
2775 new_page
= old_page
;
2776 ret
|= VM_FAULT_WRITE
;
2778 mem_cgroup_uncharge_page(new_page
);
2781 page_cache_release(new_page
);
2783 pte_unmap_unlock(page_table
, ptl
);
2784 if (mmun_end
> mmun_start
)
2785 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2788 * Don't let another task, with possibly unlocked vma,
2789 * keep the mlocked page.
2791 if ((ret
& VM_FAULT_WRITE
) && (vma
->vm_flags
& VM_LOCKED
)) {
2792 lock_page(old_page
); /* LRU manipulation */
2793 munlock_vma_page(old_page
);
2794 unlock_page(old_page
);
2796 page_cache_release(old_page
);
2800 page_cache_release(new_page
);
2803 page_cache_release(old_page
);
2804 return VM_FAULT_OOM
;
2807 page_cache_release(old_page
);
2811 static void unmap_mapping_range_vma(struct vm_area_struct
*vma
,
2812 unsigned long start_addr
, unsigned long end_addr
,
2813 struct zap_details
*details
)
2815 zap_page_range_single(vma
, start_addr
, end_addr
- start_addr
, details
);
2818 static inline void unmap_mapping_range_tree(struct rb_root
*root
,
2819 struct zap_details
*details
)
2821 struct vm_area_struct
*vma
;
2822 pgoff_t vba
, vea
, zba
, zea
;
2824 vma_interval_tree_foreach(vma
, root
,
2825 details
->first_index
, details
->last_index
) {
2827 vba
= vma
->vm_pgoff
;
2828 vea
= vba
+ ((vma
->vm_end
- vma
->vm_start
) >> PAGE_SHIFT
) - 1;
2829 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2830 zba
= details
->first_index
;
2833 zea
= details
->last_index
;
2837 unmap_mapping_range_vma(vma
,
2838 ((zba
- vba
) << PAGE_SHIFT
) + vma
->vm_start
,
2839 ((zea
- vba
+ 1) << PAGE_SHIFT
) + vma
->vm_start
,
2844 static inline void unmap_mapping_range_list(struct list_head
*head
,
2845 struct zap_details
*details
)
2847 struct vm_area_struct
*vma
;
2850 * In nonlinear VMAs there is no correspondence between virtual address
2851 * offset and file offset. So we must perform an exhaustive search
2852 * across *all* the pages in each nonlinear VMA, not just the pages
2853 * whose virtual address lies outside the file truncation point.
2855 list_for_each_entry(vma
, head
, shared
.nonlinear
) {
2856 details
->nonlinear_vma
= vma
;
2857 unmap_mapping_range_vma(vma
, vma
->vm_start
, vma
->vm_end
, details
);
2862 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2863 * @mapping: the address space containing mmaps to be unmapped.
2864 * @holebegin: byte in first page to unmap, relative to the start of
2865 * the underlying file. This will be rounded down to a PAGE_SIZE
2866 * boundary. Note that this is different from truncate_pagecache(), which
2867 * must keep the partial page. In contrast, we must get rid of
2869 * @holelen: size of prospective hole in bytes. This will be rounded
2870 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2872 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2873 * but 0 when invalidating pagecache, don't throw away private data.
2875 void unmap_mapping_range(struct address_space
*mapping
,
2876 loff_t
const holebegin
, loff_t
const holelen
, int even_cows
)
2878 struct zap_details details
;
2879 pgoff_t hba
= holebegin
>> PAGE_SHIFT
;
2880 pgoff_t hlen
= (holelen
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
2882 /* Check for overflow. */
2883 if (sizeof(holelen
) > sizeof(hlen
)) {
2885 (holebegin
+ holelen
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
2886 if (holeend
& ~(long long)ULONG_MAX
)
2887 hlen
= ULONG_MAX
- hba
+ 1;
2890 details
.check_mapping
= even_cows
? NULL
: mapping
;
2891 details
.nonlinear_vma
= NULL
;
2892 details
.first_index
= hba
;
2893 details
.last_index
= hba
+ hlen
- 1;
2894 if (details
.last_index
< details
.first_index
)
2895 details
.last_index
= ULONG_MAX
;
2898 mutex_lock(&mapping
->i_mmap_mutex
);
2899 if (unlikely(!RB_EMPTY_ROOT(&mapping
->i_mmap
)))
2900 unmap_mapping_range_tree(&mapping
->i_mmap
, &details
);
2901 if (unlikely(!list_empty(&mapping
->i_mmap_nonlinear
)))
2902 unmap_mapping_range_list(&mapping
->i_mmap_nonlinear
, &details
);
2903 mutex_unlock(&mapping
->i_mmap_mutex
);
2905 EXPORT_SYMBOL(unmap_mapping_range
);
2908 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2909 * but allow concurrent faults), and pte mapped but not yet locked.
2910 * We return with mmap_sem still held, but pte unmapped and unlocked.
2912 static int do_swap_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
2913 unsigned long address
, pte_t
*page_table
, pmd_t
*pmd
,
2914 unsigned int flags
, pte_t orig_pte
)
2917 struct page
*page
, *swapcache
= NULL
;
2921 struct mem_cgroup
*ptr
;
2925 if (!pte_unmap_same(mm
, pmd
, page_table
, orig_pte
))
2928 entry
= pte_to_swp_entry(orig_pte
);
2929 if (unlikely(non_swap_entry(entry
))) {
2930 if (is_migration_entry(entry
)) {
2931 migration_entry_wait(mm
, pmd
, address
);
2932 } else if (is_hwpoison_entry(entry
)) {
2933 ret
= VM_FAULT_HWPOISON
;
2935 print_bad_pte(vma
, address
, orig_pte
, NULL
);
2936 ret
= VM_FAULT_SIGBUS
;
2940 delayacct_set_flag(DELAYACCT_PF_SWAPIN
);
2941 page
= lookup_swap_cache(entry
);
2943 page
= swapin_readahead(entry
,
2944 GFP_HIGHUSER_MOVABLE
, vma
, address
);
2947 * Back out if somebody else faulted in this pte
2948 * while we released the pte lock.
2950 page_table
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2951 if (likely(pte_same(*page_table
, orig_pte
)))
2953 delayacct_clear_flag(DELAYACCT_PF_SWAPIN
);
2957 /* Had to read the page from swap area: Major fault */
2958 ret
= VM_FAULT_MAJOR
;
2959 count_vm_event(PGMAJFAULT
);
2960 mem_cgroup_count_vm_event(mm
, PGMAJFAULT
);
2961 } else if (PageHWPoison(page
)) {
2963 * hwpoisoned dirty swapcache pages are kept for killing
2964 * owner processes (which may be unknown at hwpoison time)
2966 ret
= VM_FAULT_HWPOISON
;
2967 delayacct_clear_flag(DELAYACCT_PF_SWAPIN
);
2971 locked
= lock_page_or_retry(page
, mm
, flags
);
2973 delayacct_clear_flag(DELAYACCT_PF_SWAPIN
);
2975 ret
|= VM_FAULT_RETRY
;
2980 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2981 * release the swapcache from under us. The page pin, and pte_same
2982 * test below, are not enough to exclude that. Even if it is still
2983 * swapcache, we need to check that the page's swap has not changed.
2985 if (unlikely(!PageSwapCache(page
) || page_private(page
) != entry
.val
))
2988 if (ksm_might_need_to_copy(page
, vma
, address
)) {
2990 page
= ksm_does_need_to_copy(page
, vma
, address
);
2992 if (unlikely(!page
)) {
3000 if (mem_cgroup_try_charge_swapin(mm
, page
, GFP_KERNEL
, &ptr
)) {
3006 * Back out if somebody else already faulted in this pte.
3008 page_table
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
3009 if (unlikely(!pte_same(*page_table
, orig_pte
)))
3012 if (unlikely(!PageUptodate(page
))) {
3013 ret
= VM_FAULT_SIGBUS
;
3018 * The page isn't present yet, go ahead with the fault.
3020 * Be careful about the sequence of operations here.
3021 * To get its accounting right, reuse_swap_page() must be called
3022 * while the page is counted on swap but not yet in mapcount i.e.
3023 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
3024 * must be called after the swap_free(), or it will never succeed.
3025 * Because delete_from_swap_page() may be called by reuse_swap_page(),
3026 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
3027 * in page->private. In this case, a record in swap_cgroup is silently
3028 * discarded at swap_free().
3031 inc_mm_counter_fast(mm
, MM_ANONPAGES
);
3032 dec_mm_counter_fast(mm
, MM_SWAPENTS
);
3033 pte
= mk_pte(page
, vma
->vm_page_prot
);
3034 if ((flags
& FAULT_FLAG_WRITE
) && reuse_swap_page(page
)) {
3035 pte
= maybe_mkwrite(pte_mkdirty(pte
), vma
);
3036 flags
&= ~FAULT_FLAG_WRITE
;
3037 ret
|= VM_FAULT_WRITE
;
3040 flush_icache_page(vma
, page
);
3041 set_pte_at(mm
, address
, page_table
, pte
);
3042 do_page_add_anon_rmap(page
, vma
, address
, exclusive
);
3043 /* It's better to call commit-charge after rmap is established */
3044 mem_cgroup_commit_charge_swapin(page
, ptr
);
3047 if (vm_swap_full() || (vma
->vm_flags
& VM_LOCKED
) || PageMlocked(page
))
3048 try_to_free_swap(page
);
3052 * Hold the lock to avoid the swap entry to be reused
3053 * until we take the PT lock for the pte_same() check
3054 * (to avoid false positives from pte_same). For
3055 * further safety release the lock after the swap_free
3056 * so that the swap count won't change under a
3057 * parallel locked swapcache.
3059 unlock_page(swapcache
);
3060 page_cache_release(swapcache
);
3063 if (flags
& FAULT_FLAG_WRITE
) {
3064 ret
|= do_wp_page(mm
, vma
, address
, page_table
, pmd
, ptl
, pte
);
3065 if (ret
& VM_FAULT_ERROR
)
3066 ret
&= VM_FAULT_ERROR
;
3070 /* No need to invalidate - it was non-present before */
3071 update_mmu_cache(vma
, address
, page_table
);
3073 pte_unmap_unlock(page_table
, ptl
);
3077 mem_cgroup_cancel_charge_swapin(ptr
);
3078 pte_unmap_unlock(page_table
, ptl
);
3082 page_cache_release(page
);
3084 unlock_page(swapcache
);
3085 page_cache_release(swapcache
);
3091 * This is like a special single-page "expand_{down|up}wards()",
3092 * except we must first make sure that 'address{-|+}PAGE_SIZE'
3093 * doesn't hit another vma.
3095 static inline int check_stack_guard_page(struct vm_area_struct
*vma
, unsigned long address
)
3097 address
&= PAGE_MASK
;
3098 if ((vma
->vm_flags
& VM_GROWSDOWN
) && address
== vma
->vm_start
) {
3099 struct vm_area_struct
*prev
= vma
->vm_prev
;
3102 * Is there a mapping abutting this one below?
3104 * That's only ok if it's the same stack mapping
3105 * that has gotten split..
3107 if (prev
&& prev
->vm_end
== address
)
3108 return prev
->vm_flags
& VM_GROWSDOWN
? 0 : -ENOMEM
;
3110 expand_downwards(vma
, address
- PAGE_SIZE
);
3112 if ((vma
->vm_flags
& VM_GROWSUP
) && address
+ PAGE_SIZE
== vma
->vm_end
) {
3113 struct vm_area_struct
*next
= vma
->vm_next
;
3115 /* As VM_GROWSDOWN but s/below/above/ */
3116 if (next
&& next
->vm_start
== address
+ PAGE_SIZE
)
3117 return next
->vm_flags
& VM_GROWSUP
? 0 : -ENOMEM
;
3119 expand_upwards(vma
, address
+ PAGE_SIZE
);
3125 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3126 * but allow concurrent faults), and pte mapped but not yet locked.
3127 * We return with mmap_sem still held, but pte unmapped and unlocked.
3129 static int do_anonymous_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
3130 unsigned long address
, pte_t
*page_table
, pmd_t
*pmd
,
3137 pte_unmap(page_table
);
3139 /* Check if we need to add a guard page to the stack */
3140 if (check_stack_guard_page(vma
, address
) < 0)
3141 return VM_FAULT_SIGBUS
;
3143 /* Use the zero-page for reads */
3144 if (!(flags
& FAULT_FLAG_WRITE
)) {
3145 entry
= pte_mkspecial(pfn_pte(my_zero_pfn(address
),
3146 vma
->vm_page_prot
));
3147 page_table
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
3148 if (!pte_none(*page_table
))
3153 /* Allocate our own private page. */
3154 if (unlikely(anon_vma_prepare(vma
)))
3156 page
= alloc_zeroed_user_highpage_movable(vma
, address
);
3159 __SetPageUptodate(page
);
3161 if (mem_cgroup_newpage_charge(page
, mm
, GFP_KERNEL
))
3164 entry
= mk_pte(page
, vma
->vm_page_prot
);
3165 if (vma
->vm_flags
& VM_WRITE
)
3166 entry
= pte_mkwrite(pte_mkdirty(entry
));
3168 page_table
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
3169 if (!pte_none(*page_table
))
3172 inc_mm_counter_fast(mm
, MM_ANONPAGES
);
3173 page_add_new_anon_rmap(page
, vma
, address
);
3175 set_pte_at(mm
, address
, page_table
, entry
);
3177 /* No need to invalidate - it was non-present before */
3178 update_mmu_cache(vma
, address
, page_table
);
3180 pte_unmap_unlock(page_table
, ptl
);
3183 mem_cgroup_uncharge_page(page
);
3184 page_cache_release(page
);
3187 page_cache_release(page
);
3189 return VM_FAULT_OOM
;
3193 * __do_fault() tries to create a new page mapping. It aggressively
3194 * tries to share with existing pages, but makes a separate copy if
3195 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
3196 * the next page fault.
3198 * As this is called only for pages that do not currently exist, we
3199 * do not need to flush old virtual caches or the TLB.
3201 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3202 * but allow concurrent faults), and pte neither mapped nor locked.
3203 * We return with mmap_sem still held, but pte unmapped and unlocked.
3205 static int __do_fault(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
3206 unsigned long address
, pmd_t
*pmd
,
3207 pgoff_t pgoff
, unsigned int flags
, pte_t orig_pte
)
3212 struct page
*cow_page
;
3215 struct page
*dirty_page
= NULL
;
3216 struct vm_fault vmf
;
3218 int page_mkwrite
= 0;
3221 * If we do COW later, allocate page befor taking lock_page()
3222 * on the file cache page. This will reduce lock holding time.
3224 if ((flags
& FAULT_FLAG_WRITE
) && !(vma
->vm_flags
& VM_SHARED
)) {
3226 if (unlikely(anon_vma_prepare(vma
)))
3227 return VM_FAULT_OOM
;
3229 cow_page
= alloc_page_vma(GFP_HIGHUSER_MOVABLE
, vma
, address
);
3231 return VM_FAULT_OOM
;
3233 if (mem_cgroup_newpage_charge(cow_page
, mm
, GFP_KERNEL
)) {
3234 page_cache_release(cow_page
);
3235 return VM_FAULT_OOM
;
3240 vmf
.virtual_address
= (void __user
*)(address
& PAGE_MASK
);
3245 ret
= vma
->vm_ops
->fault(vma
, &vmf
);
3246 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
|
3250 if (unlikely(PageHWPoison(vmf
.page
))) {
3251 if (ret
& VM_FAULT_LOCKED
)
3252 unlock_page(vmf
.page
);
3253 ret
= VM_FAULT_HWPOISON
;
3258 * For consistency in subsequent calls, make the faulted page always
3261 if (unlikely(!(ret
& VM_FAULT_LOCKED
)))
3262 lock_page(vmf
.page
);
3264 VM_BUG_ON(!PageLocked(vmf
.page
));
3267 * Should we do an early C-O-W break?
3270 if (flags
& FAULT_FLAG_WRITE
) {
3271 if (!(vma
->vm_flags
& VM_SHARED
)) {
3274 copy_user_highpage(page
, vmf
.page
, address
, vma
);
3275 __SetPageUptodate(page
);
3278 * If the page will be shareable, see if the backing
3279 * address space wants to know that the page is about
3280 * to become writable
3282 if (vma
->vm_ops
->page_mkwrite
) {
3286 vmf
.flags
= FAULT_FLAG_WRITE
|FAULT_FLAG_MKWRITE
;
3287 tmp
= vma
->vm_ops
->page_mkwrite(vma
, &vmf
);
3289 (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
))) {
3291 goto unwritable_page
;
3293 if (unlikely(!(tmp
& VM_FAULT_LOCKED
))) {
3295 if (!page
->mapping
) {
3296 ret
= 0; /* retry the fault */
3298 goto unwritable_page
;
3301 VM_BUG_ON(!PageLocked(page
));
3308 page_table
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
3311 * This silly early PAGE_DIRTY setting removes a race
3312 * due to the bad i386 page protection. But it's valid
3313 * for other architectures too.
3315 * Note that if FAULT_FLAG_WRITE is set, we either now have
3316 * an exclusive copy of the page, or this is a shared mapping,
3317 * so we can make it writable and dirty to avoid having to
3318 * handle that later.
3320 /* Only go through if we didn't race with anybody else... */
3321 if (likely(pte_same(*page_table
, orig_pte
))) {
3322 flush_icache_page(vma
, page
);
3323 entry
= mk_pte(page
, vma
->vm_page_prot
);
3324 if (flags
& FAULT_FLAG_WRITE
)
3325 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
3327 inc_mm_counter_fast(mm
, MM_ANONPAGES
);
3328 page_add_new_anon_rmap(page
, vma
, address
);
3330 inc_mm_counter_fast(mm
, MM_FILEPAGES
);
3331 page_add_file_rmap(page
);
3332 if (flags
& FAULT_FLAG_WRITE
) {
3334 get_page(dirty_page
);
3337 set_pte_at(mm
, address
, page_table
, entry
);
3339 /* no need to invalidate: a not-present page won't be cached */
3340 update_mmu_cache(vma
, address
, page_table
);
3343 mem_cgroup_uncharge_page(cow_page
);
3345 page_cache_release(page
);
3347 anon
= 1; /* no anon but release faulted_page */
3350 pte_unmap_unlock(page_table
, ptl
);
3353 struct address_space
*mapping
= page
->mapping
;
3356 if (set_page_dirty(dirty_page
))
3358 unlock_page(dirty_page
);
3359 put_page(dirty_page
);
3360 if ((dirtied
|| page_mkwrite
) && mapping
) {
3362 * Some device drivers do not set page.mapping but still
3365 balance_dirty_pages_ratelimited(mapping
);
3368 /* file_update_time outside page_lock */
3369 if (vma
->vm_file
&& !page_mkwrite
)
3370 file_update_time(vma
->vm_file
);
3372 unlock_page(vmf
.page
);
3374 page_cache_release(vmf
.page
);
3380 page_cache_release(page
);
3383 /* fs's fault handler get error */
3385 mem_cgroup_uncharge_page(cow_page
);
3386 page_cache_release(cow_page
);
3391 static int do_linear_fault(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
3392 unsigned long address
, pte_t
*page_table
, pmd_t
*pmd
,
3393 unsigned int flags
, pte_t orig_pte
)
3395 pgoff_t pgoff
= (((address
& PAGE_MASK
)
3396 - vma
->vm_start
) >> PAGE_SHIFT
) + vma
->vm_pgoff
;
3398 pte_unmap(page_table
);
3399 return __do_fault(mm
, vma
, address
, pmd
, pgoff
, flags
, orig_pte
);
3403 * Fault of a previously existing named mapping. Repopulate the pte
3404 * from the encoded file_pte if possible. This enables swappable
3407 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3408 * but allow concurrent faults), and pte mapped but not yet locked.
3409 * We return with mmap_sem still held, but pte unmapped and unlocked.
3411 static int do_nonlinear_fault(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
3412 unsigned long address
, pte_t
*page_table
, pmd_t
*pmd
,
3413 unsigned int flags
, pte_t orig_pte
)
3417 flags
|= FAULT_FLAG_NONLINEAR
;
3419 if (!pte_unmap_same(mm
, pmd
, page_table
, orig_pte
))
3422 if (unlikely(!(vma
->vm_flags
& VM_NONLINEAR
))) {
3424 * Page table corrupted: show pte and kill process.
3426 print_bad_pte(vma
, address
, orig_pte
, NULL
);
3427 return VM_FAULT_SIGBUS
;
3430 pgoff
= pte_to_pgoff(orig_pte
);
3431 return __do_fault(mm
, vma
, address
, pmd
, pgoff
, flags
, orig_pte
);
3434 int numa_migrate_prep(struct page
*page
, struct vm_area_struct
*vma
,
3435 unsigned long addr
, int current_nid
)
3439 count_vm_numa_event(NUMA_HINT_FAULTS
);
3440 if (current_nid
== numa_node_id())
3441 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL
);
3443 return mpol_misplaced(page
, vma
, addr
);
3446 int do_numa_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
3447 unsigned long addr
, pte_t pte
, pte_t
*ptep
, pmd_t
*pmd
)
3449 struct page
*page
= NULL
;
3451 int current_nid
= -1;
3453 bool migrated
= false;
3456 * The "pte" at this point cannot be used safely without
3457 * validation through pte_unmap_same(). It's of NUMA type but
3458 * the pfn may be screwed if the read is non atomic.
3460 * ptep_modify_prot_start is not called as this is clearing
3461 * the _PAGE_NUMA bit and it is not really expected that there
3462 * would be concurrent hardware modifications to the PTE.
3464 ptl
= pte_lockptr(mm
, pmd
);
3466 if (unlikely(!pte_same(*ptep
, pte
))) {
3467 pte_unmap_unlock(ptep
, ptl
);
3471 pte
= pte_mknonnuma(pte
);
3472 set_pte_at(mm
, addr
, ptep
, pte
);
3473 update_mmu_cache(vma
, addr
, ptep
);
3475 page
= vm_normal_page(vma
, addr
, pte
);
3477 pte_unmap_unlock(ptep
, ptl
);
3481 current_nid
= page_to_nid(page
);
3482 target_nid
= numa_migrate_prep(page
, vma
, addr
, current_nid
);
3483 pte_unmap_unlock(ptep
, ptl
);
3484 if (target_nid
== -1) {
3486 * Account for the fault against the current node if it not
3487 * being replaced regardless of where the page is located.
3489 current_nid
= numa_node_id();
3494 /* Migrate to the requested node */
3495 migrated
= migrate_misplaced_page(page
, target_nid
);
3497 current_nid
= target_nid
;
3500 if (current_nid
!= -1)
3501 task_numa_fault(current_nid
, 1, migrated
);
3505 /* NUMA hinting page fault entry point for regular pmds */
3506 #ifdef CONFIG_NUMA_BALANCING
3507 static int do_pmd_numa_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
3508 unsigned long addr
, pmd_t
*pmdp
)
3511 pte_t
*pte
, *orig_pte
;
3512 unsigned long _addr
= addr
& PMD_MASK
;
3513 unsigned long offset
;
3516 int local_nid
= numa_node_id();
3518 spin_lock(&mm
->page_table_lock
);
3520 if (pmd_numa(pmd
)) {
3521 set_pmd_at(mm
, _addr
, pmdp
, pmd_mknonnuma(pmd
));
3524 spin_unlock(&mm
->page_table_lock
);
3529 /* we're in a page fault so some vma must be in the range */
3531 BUG_ON(vma
->vm_start
>= _addr
+ PMD_SIZE
);
3532 offset
= max(_addr
, vma
->vm_start
) & ~PMD_MASK
;
3533 VM_BUG_ON(offset
>= PMD_SIZE
);
3534 orig_pte
= pte
= pte_offset_map_lock(mm
, pmdp
, _addr
, &ptl
);
3535 pte
+= offset
>> PAGE_SHIFT
;
3536 for (addr
= _addr
+ offset
; addr
< _addr
+ PMD_SIZE
; pte
++, addr
+= PAGE_SIZE
) {
3537 pte_t pteval
= *pte
;
3539 int curr_nid
= local_nid
;
3542 if (!pte_present(pteval
))
3544 if (!pte_numa(pteval
))
3546 if (addr
>= vma
->vm_end
) {
3547 vma
= find_vma(mm
, addr
);
3548 /* there's a pte present so there must be a vma */
3550 BUG_ON(addr
< vma
->vm_start
);
3552 if (pte_numa(pteval
)) {
3553 pteval
= pte_mknonnuma(pteval
);
3554 set_pte_at(mm
, addr
, pte
, pteval
);
3556 page
= vm_normal_page(vma
, addr
, pteval
);
3557 if (unlikely(!page
))
3559 /* only check non-shared pages */
3560 if (unlikely(page_mapcount(page
) != 1))
3564 * Note that the NUMA fault is later accounted to either
3565 * the node that is currently running or where the page is
3568 curr_nid
= local_nid
;
3569 target_nid
= numa_migrate_prep(page
, vma
, addr
,
3571 if (target_nid
== -1) {
3576 /* Migrate to the requested node */
3577 pte_unmap_unlock(pte
, ptl
);
3578 migrated
= migrate_misplaced_page(page
, target_nid
);
3580 curr_nid
= target_nid
;
3581 task_numa_fault(curr_nid
, 1, migrated
);
3583 pte
= pte_offset_map_lock(mm
, pmdp
, addr
, &ptl
);
3585 pte_unmap_unlock(orig_pte
, ptl
);
3590 static int do_pmd_numa_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
3591 unsigned long addr
, pmd_t
*pmdp
)
3596 #endif /* CONFIG_NUMA_BALANCING */
3599 * These routines also need to handle stuff like marking pages dirty
3600 * and/or accessed for architectures that don't do it in hardware (most
3601 * RISC architectures). The early dirtying is also good on the i386.
3603 * There is also a hook called "update_mmu_cache()" that architectures
3604 * with external mmu caches can use to update those (ie the Sparc or
3605 * PowerPC hashed page tables that act as extended TLBs).
3607 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3608 * but allow concurrent faults), and pte mapped but not yet locked.
3609 * We return with mmap_sem still held, but pte unmapped and unlocked.
3611 int handle_pte_fault(struct mm_struct
*mm
,
3612 struct vm_area_struct
*vma
, unsigned long address
,
3613 pte_t
*pte
, pmd_t
*pmd
, unsigned int flags
)
3619 if (!pte_present(entry
)) {
3620 if (pte_none(entry
)) {
3622 if (likely(vma
->vm_ops
->fault
))
3623 return do_linear_fault(mm
, vma
, address
,
3624 pte
, pmd
, flags
, entry
);
3626 return do_anonymous_page(mm
, vma
, address
,
3629 if (pte_file(entry
))
3630 return do_nonlinear_fault(mm
, vma
, address
,
3631 pte
, pmd
, flags
, entry
);
3632 return do_swap_page(mm
, vma
, address
,
3633 pte
, pmd
, flags
, entry
);
3636 if (pte_numa(entry
))
3637 return do_numa_page(mm
, vma
, address
, entry
, pte
, pmd
);
3639 ptl
= pte_lockptr(mm
, pmd
);
3641 if (unlikely(!pte_same(*pte
, entry
)))
3643 if (flags
& FAULT_FLAG_WRITE
) {
3644 if (!pte_write(entry
))
3645 return do_wp_page(mm
, vma
, address
,
3646 pte
, pmd
, ptl
, entry
);
3647 entry
= pte_mkdirty(entry
);
3649 entry
= pte_mkyoung(entry
);
3650 if (ptep_set_access_flags(vma
, address
, pte
, entry
, flags
& FAULT_FLAG_WRITE
)) {
3651 update_mmu_cache(vma
, address
, pte
);
3654 * This is needed only for protection faults but the arch code
3655 * is not yet telling us if this is a protection fault or not.
3656 * This still avoids useless tlb flushes for .text page faults
3659 if (flags
& FAULT_FLAG_WRITE
)
3660 flush_tlb_fix_spurious_fault(vma
, address
);
3663 pte_unmap_unlock(pte
, ptl
);
3668 * By the time we get here, we already hold the mm semaphore
3670 int handle_mm_fault(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
3671 unsigned long address
, unsigned int flags
)
3678 __set_current_state(TASK_RUNNING
);
3680 count_vm_event(PGFAULT
);
3681 mem_cgroup_count_vm_event(mm
, PGFAULT
);
3683 /* do counter updates before entering really critical section. */
3684 check_sync_rss_stat(current
);
3686 if (unlikely(is_vm_hugetlb_page(vma
)))
3687 return hugetlb_fault(mm
, vma
, address
, flags
);
3690 pgd
= pgd_offset(mm
, address
);
3691 pud
= pud_alloc(mm
, pgd
, address
);
3693 return VM_FAULT_OOM
;
3694 pmd
= pmd_alloc(mm
, pud
, address
);
3696 return VM_FAULT_OOM
;
3697 if (pmd_none(*pmd
) && transparent_hugepage_enabled(vma
)) {
3699 return do_huge_pmd_anonymous_page(mm
, vma
, address
,
3702 pmd_t orig_pmd
= *pmd
;
3706 if (pmd_trans_huge(orig_pmd
)) {
3707 unsigned int dirty
= flags
& FAULT_FLAG_WRITE
;
3709 if (pmd_numa(orig_pmd
))
3710 return do_huge_pmd_numa_page(mm
, vma
, address
,
3713 if (dirty
&& !pmd_write(orig_pmd
)) {
3714 ret
= do_huge_pmd_wp_page(mm
, vma
, address
, pmd
,
3717 * If COW results in an oom, the huge pmd will
3718 * have been split, so retry the fault on the
3719 * pte for a smaller charge.
3721 if (unlikely(ret
& VM_FAULT_OOM
))
3725 huge_pmd_set_accessed(mm
, vma
, address
, pmd
,
3734 return do_pmd_numa_page(mm
, vma
, address
, pmd
);
3737 * Use __pte_alloc instead of pte_alloc_map, because we can't
3738 * run pte_offset_map on the pmd, if an huge pmd could
3739 * materialize from under us from a different thread.
3741 if (unlikely(pmd_none(*pmd
)) &&
3742 unlikely(__pte_alloc(mm
, vma
, pmd
, address
)))
3743 return VM_FAULT_OOM
;
3744 /* if an huge pmd materialized from under us just retry later */
3745 if (unlikely(pmd_trans_huge(*pmd
)))
3748 * A regular pmd is established and it can't morph into a huge pmd
3749 * from under us anymore at this point because we hold the mmap_sem
3750 * read mode and khugepaged takes it in write mode. So now it's
3751 * safe to run pte_offset_map().
3753 pte
= pte_offset_map(pmd
, address
);
3755 return handle_pte_fault(mm
, vma
, address
, pte
, pmd
, flags
);
3758 #ifndef __PAGETABLE_PUD_FOLDED
3760 * Allocate page upper directory.
3761 * We've already handled the fast-path in-line.
3763 int __pud_alloc(struct mm_struct
*mm
, pgd_t
*pgd
, unsigned long address
)
3765 pud_t
*new = pud_alloc_one(mm
, address
);
3769 smp_wmb(); /* See comment in __pte_alloc */
3771 spin_lock(&mm
->page_table_lock
);
3772 if (pgd_present(*pgd
)) /* Another has populated it */
3775 pgd_populate(mm
, pgd
, new);
3776 spin_unlock(&mm
->page_table_lock
);
3779 #endif /* __PAGETABLE_PUD_FOLDED */
3781 #ifndef __PAGETABLE_PMD_FOLDED
3783 * Allocate page middle directory.
3784 * We've already handled the fast-path in-line.
3786 int __pmd_alloc(struct mm_struct
*mm
, pud_t
*pud
, unsigned long address
)
3788 pmd_t
*new = pmd_alloc_one(mm
, address
);
3792 smp_wmb(); /* See comment in __pte_alloc */
3794 spin_lock(&mm
->page_table_lock
);
3795 #ifndef __ARCH_HAS_4LEVEL_HACK
3796 if (pud_present(*pud
)) /* Another has populated it */
3799 pud_populate(mm
, pud
, new);
3801 if (pgd_present(*pud
)) /* Another has populated it */
3804 pgd_populate(mm
, pud
, new);
3805 #endif /* __ARCH_HAS_4LEVEL_HACK */
3806 spin_unlock(&mm
->page_table_lock
);
3809 #endif /* __PAGETABLE_PMD_FOLDED */
3811 int make_pages_present(unsigned long addr
, unsigned long end
)
3813 int ret
, len
, write
;
3814 struct vm_area_struct
* vma
;
3816 vma
= find_vma(current
->mm
, addr
);
3820 * We want to touch writable mappings with a write fault in order
3821 * to break COW, except for shared mappings because these don't COW
3822 * and we would not want to dirty them for nothing.
3824 write
= (vma
->vm_flags
& (VM_WRITE
| VM_SHARED
)) == VM_WRITE
;
3825 BUG_ON(addr
>= end
);
3826 BUG_ON(end
> vma
->vm_end
);
3827 len
= DIV_ROUND_UP(end
, PAGE_SIZE
) - addr
/PAGE_SIZE
;
3828 ret
= get_user_pages(current
, current
->mm
, addr
,
3829 len
, write
, 0, NULL
, NULL
);
3832 return ret
== len
? 0 : -EFAULT
;
3835 #if !defined(__HAVE_ARCH_GATE_AREA)
3837 #if defined(AT_SYSINFO_EHDR)
3838 static struct vm_area_struct gate_vma
;
3840 static int __init
gate_vma_init(void)
3842 gate_vma
.vm_mm
= NULL
;
3843 gate_vma
.vm_start
= FIXADDR_USER_START
;
3844 gate_vma
.vm_end
= FIXADDR_USER_END
;
3845 gate_vma
.vm_flags
= VM_READ
| VM_MAYREAD
| VM_EXEC
| VM_MAYEXEC
;
3846 gate_vma
.vm_page_prot
= __P101
;
3850 __initcall(gate_vma_init
);
3853 struct vm_area_struct
*get_gate_vma(struct mm_struct
*mm
)
3855 #ifdef AT_SYSINFO_EHDR
3862 int in_gate_area_no_mm(unsigned long addr
)
3864 #ifdef AT_SYSINFO_EHDR
3865 if ((addr
>= FIXADDR_USER_START
) && (addr
< FIXADDR_USER_END
))
3871 #endif /* __HAVE_ARCH_GATE_AREA */
3873 static int __follow_pte(struct mm_struct
*mm
, unsigned long address
,
3874 pte_t
**ptepp
, spinlock_t
**ptlp
)
3881 pgd
= pgd_offset(mm
, address
);
3882 if (pgd_none(*pgd
) || unlikely(pgd_bad(*pgd
)))
3885 pud
= pud_offset(pgd
, address
);
3886 if (pud_none(*pud
) || unlikely(pud_bad(*pud
)))
3889 pmd
= pmd_offset(pud
, address
);
3890 VM_BUG_ON(pmd_trans_huge(*pmd
));
3891 if (pmd_none(*pmd
) || unlikely(pmd_bad(*pmd
)))
3894 /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3898 ptep
= pte_offset_map_lock(mm
, pmd
, address
, ptlp
);
3901 if (!pte_present(*ptep
))
3906 pte_unmap_unlock(ptep
, *ptlp
);
3911 static inline int follow_pte(struct mm_struct
*mm
, unsigned long address
,
3912 pte_t
**ptepp
, spinlock_t
**ptlp
)
3916 /* (void) is needed to make gcc happy */
3917 (void) __cond_lock(*ptlp
,
3918 !(res
= __follow_pte(mm
, address
, ptepp
, ptlp
)));
3923 * follow_pfn - look up PFN at a user virtual address
3924 * @vma: memory mapping
3925 * @address: user virtual address
3926 * @pfn: location to store found PFN
3928 * Only IO mappings and raw PFN mappings are allowed.
3930 * Returns zero and the pfn at @pfn on success, -ve otherwise.
3932 int follow_pfn(struct vm_area_struct
*vma
, unsigned long address
,
3939 if (!(vma
->vm_flags
& (VM_IO
| VM_PFNMAP
)))
3942 ret
= follow_pte(vma
->vm_mm
, address
, &ptep
, &ptl
);
3945 *pfn
= pte_pfn(*ptep
);
3946 pte_unmap_unlock(ptep
, ptl
);
3949 EXPORT_SYMBOL(follow_pfn
);
3951 #ifdef CONFIG_HAVE_IOREMAP_PROT
3952 int follow_phys(struct vm_area_struct
*vma
,
3953 unsigned long address
, unsigned int flags
,
3954 unsigned long *prot
, resource_size_t
*phys
)
3960 if (!(vma
->vm_flags
& (VM_IO
| VM_PFNMAP
)))
3963 if (follow_pte(vma
->vm_mm
, address
, &ptep
, &ptl
))
3967 if ((flags
& FOLL_WRITE
) && !pte_write(pte
))
3970 *prot
= pgprot_val(pte_pgprot(pte
));
3971 *phys
= (resource_size_t
)pte_pfn(pte
) << PAGE_SHIFT
;
3975 pte_unmap_unlock(ptep
, ptl
);
3980 int generic_access_phys(struct vm_area_struct
*vma
, unsigned long addr
,
3981 void *buf
, int len
, int write
)
3983 resource_size_t phys_addr
;
3984 unsigned long prot
= 0;
3985 void __iomem
*maddr
;
3986 int offset
= addr
& (PAGE_SIZE
-1);
3988 if (follow_phys(vma
, addr
, write
, &prot
, &phys_addr
))
3991 maddr
= ioremap_prot(phys_addr
, PAGE_SIZE
, prot
);
3993 memcpy_toio(maddr
+ offset
, buf
, len
);
3995 memcpy_fromio(buf
, maddr
+ offset
, len
);
4003 * Access another process' address space as given in mm. If non-NULL, use the
4004 * given task for page fault accounting.
4006 static int __access_remote_vm(struct task_struct
*tsk
, struct mm_struct
*mm
,
4007 unsigned long addr
, void *buf
, int len
, int write
)
4009 struct vm_area_struct
*vma
;
4010 void *old_buf
= buf
;
4012 down_read(&mm
->mmap_sem
);
4013 /* ignore errors, just check how much was successfully transferred */
4015 int bytes
, ret
, offset
;
4017 struct page
*page
= NULL
;
4019 ret
= get_user_pages(tsk
, mm
, addr
, 1,
4020 write
, 1, &page
, &vma
);
4023 * Check if this is a VM_IO | VM_PFNMAP VMA, which
4024 * we can access using slightly different code.
4026 #ifdef CONFIG_HAVE_IOREMAP_PROT
4027 vma
= find_vma(mm
, addr
);
4028 if (!vma
|| vma
->vm_start
> addr
)
4030 if (vma
->vm_ops
&& vma
->vm_ops
->access
)
4031 ret
= vma
->vm_ops
->access(vma
, addr
, buf
,
4039 offset
= addr
& (PAGE_SIZE
-1);
4040 if (bytes
> PAGE_SIZE
-offset
)
4041 bytes
= PAGE_SIZE
-offset
;
4045 copy_to_user_page(vma
, page
, addr
,
4046 maddr
+ offset
, buf
, bytes
);
4047 set_page_dirty_lock(page
);
4049 copy_from_user_page(vma
, page
, addr
,
4050 buf
, maddr
+ offset
, bytes
);
4053 page_cache_release(page
);
4059 up_read(&mm
->mmap_sem
);
4061 return buf
- old_buf
;
4065 * access_remote_vm - access another process' address space
4066 * @mm: the mm_struct of the target address space
4067 * @addr: start address to access
4068 * @buf: source or destination buffer
4069 * @len: number of bytes to transfer
4070 * @write: whether the access is a write
4072 * The caller must hold a reference on @mm.
4074 int access_remote_vm(struct mm_struct
*mm
, unsigned long addr
,
4075 void *buf
, int len
, int write
)
4077 return __access_remote_vm(NULL
, mm
, addr
, buf
, len
, write
);
4081 * Access another process' address space.
4082 * Source/target buffer must be kernel space,
4083 * Do not walk the page table directly, use get_user_pages
4085 int access_process_vm(struct task_struct
*tsk
, unsigned long addr
,
4086 void *buf
, int len
, int write
)
4088 struct mm_struct
*mm
;
4091 mm
= get_task_mm(tsk
);
4095 ret
= __access_remote_vm(tsk
, mm
, addr
, buf
, len
, write
);
4102 * Print the name of a VMA.
4104 void print_vma_addr(char *prefix
, unsigned long ip
)
4106 struct mm_struct
*mm
= current
->mm
;
4107 struct vm_area_struct
*vma
;
4110 * Do not print if we are in atomic
4111 * contexts (in exception stacks, etc.):
4113 if (preempt_count())
4116 down_read(&mm
->mmap_sem
);
4117 vma
= find_vma(mm
, ip
);
4118 if (vma
&& vma
->vm_file
) {
4119 struct file
*f
= vma
->vm_file
;
4120 char *buf
= (char *)__get_free_page(GFP_KERNEL
);
4124 p
= d_path(&f
->f_path
, buf
, PAGE_SIZE
);
4127 printk("%s%s[%lx+%lx]", prefix
, kbasename(p
),
4129 vma
->vm_end
- vma
->vm_start
);
4130 free_page((unsigned long)buf
);
4133 up_read(&mm
->mmap_sem
);
4136 #ifdef CONFIG_PROVE_LOCKING
4137 void might_fault(void)
4140 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
4141 * holding the mmap_sem, this is safe because kernel memory doesn't
4142 * get paged out, therefore we'll never actually fault, and the
4143 * below annotations will generate false positives.
4145 if (segment_eq(get_fs(), KERNEL_DS
))
4150 * it would be nicer only to annotate paths which are not under
4151 * pagefault_disable, however that requires a larger audit and
4152 * providing helpers like get_user_atomic.
4154 if (!in_atomic() && current
->mm
)
4155 might_lock_read(¤t
->mm
->mmap_sem
);
4157 EXPORT_SYMBOL(might_fault
);
4160 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
4161 static void clear_gigantic_page(struct page
*page
,
4163 unsigned int pages_per_huge_page
)
4166 struct page
*p
= page
;
4169 for (i
= 0; i
< pages_per_huge_page
;
4170 i
++, p
= mem_map_next(p
, page
, i
)) {
4172 clear_user_highpage(p
, addr
+ i
* PAGE_SIZE
);
4175 void clear_huge_page(struct page
*page
,
4176 unsigned long addr
, unsigned int pages_per_huge_page
)
4180 if (unlikely(pages_per_huge_page
> MAX_ORDER_NR_PAGES
)) {
4181 clear_gigantic_page(page
, addr
, pages_per_huge_page
);
4186 for (i
= 0; i
< pages_per_huge_page
; i
++) {
4188 clear_user_highpage(page
+ i
, addr
+ i
* PAGE_SIZE
);
4192 static void copy_user_gigantic_page(struct page
*dst
, struct page
*src
,
4194 struct vm_area_struct
*vma
,
4195 unsigned int pages_per_huge_page
)
4198 struct page
*dst_base
= dst
;
4199 struct page
*src_base
= src
;
4201 for (i
= 0; i
< pages_per_huge_page
; ) {
4203 copy_user_highpage(dst
, src
, addr
+ i
*PAGE_SIZE
, vma
);
4206 dst
= mem_map_next(dst
, dst_base
, i
);
4207 src
= mem_map_next(src
, src_base
, i
);
4211 void copy_user_huge_page(struct page
*dst
, struct page
*src
,
4212 unsigned long addr
, struct vm_area_struct
*vma
,
4213 unsigned int pages_per_huge_page
)
4217 if (unlikely(pages_per_huge_page
> MAX_ORDER_NR_PAGES
)) {
4218 copy_user_gigantic_page(dst
, src
, addr
, vma
,
4219 pages_per_huge_page
);
4224 for (i
= 0; i
< pages_per_huge_page
; i
++) {
4226 copy_user_highpage(dst
+ i
, src
+ i
, addr
+ i
*PAGE_SIZE
, vma
);
4229 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */