1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
9 * demand-loading started 01.12.91 - seems it is high on the list of
10 * things wanted, and it should be easy to implement. - Linus
14 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
15 * pages started 02.12.91, seems to work. - Linus.
17 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
18 * would have taken more than the 6M I have free, but it worked well as
21 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
25 * Real VM (paging to/from disk) started 18.12.91. Much more work and
26 * thought has to go into this. Oh, well..
27 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
28 * Found it. Everything seems to work now.
29 * 20.12.91 - Ok, making the swap-device changeable like the root.
33 * 05.04.94 - Multi-page memory management added for v1.1.
34 * Idea by Alex Bligh (alex@cconcepts.co.uk)
36 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
37 * (Gerhard.Wichert@pdb.siemens.de)
39 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
42 #include <linux/kernel_stat.h>
44 #include <linux/sched/mm.h>
45 #include <linux/sched/coredump.h>
46 #include <linux/sched/numa_balancing.h>
47 #include <linux/sched/task.h>
48 #include <linux/hugetlb.h>
49 #include <linux/mman.h>
50 #include <linux/swap.h>
51 #include <linux/highmem.h>
52 #include <linux/pagemap.h>
53 #include <linux/memremap.h>
54 #include <linux/ksm.h>
55 #include <linux/rmap.h>
56 #include <linux/export.h>
57 #include <linux/delayacct.h>
58 #include <linux/init.h>
59 #include <linux/pfn_t.h>
60 #include <linux/writeback.h>
61 #include <linux/memcontrol.h>
62 #include <linux/mmu_notifier.h>
63 #include <linux/swapops.h>
64 #include <linux/elf.h>
65 #include <linux/gfp.h>
66 #include <linux/migrate.h>
67 #include <linux/string.h>
68 #include <linux/debugfs.h>
69 #include <linux/userfaultfd_k.h>
70 #include <linux/dax.h>
71 #include <linux/oom.h>
72 #include <linux/numa.h>
73 #include <linux/perf_event.h>
74 #include <linux/ptrace.h>
75 #include <linux/vmalloc.h>
77 #include <trace/events/kmem.h>
80 #include <asm/mmu_context.h>
81 #include <asm/pgalloc.h>
82 #include <linux/uaccess.h>
84 #include <asm/tlbflush.h>
86 #include "pgalloc-track.h"
89 #if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST)
90 #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
93 #ifndef CONFIG_NEED_MULTIPLE_NODES
94 /* use the per-pgdat data instead for discontigmem - mbligh */
95 unsigned long max_mapnr
;
96 EXPORT_SYMBOL(max_mapnr
);
99 EXPORT_SYMBOL(mem_map
);
103 * A number of key systems in x86 including ioremap() rely on the assumption
104 * that high_memory defines the upper bound on direct map memory, then end
105 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
106 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
110 EXPORT_SYMBOL(high_memory
);
113 * Randomize the address space (stacks, mmaps, brk, etc.).
115 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
116 * as ancient (libc5 based) binaries can segfault. )
118 int randomize_va_space __read_mostly
=
119 #ifdef CONFIG_COMPAT_BRK
125 #ifndef arch_faults_on_old_pte
126 static inline bool arch_faults_on_old_pte(void)
129 * Those arches which don't have hw access flag feature need to
130 * implement their own helper. By default, "true" means pagefault
131 * will be hit on old pte.
137 #ifndef arch_wants_old_prefaulted_pte
138 static inline bool arch_wants_old_prefaulted_pte(void)
141 * Transitioning a PTE from 'old' to 'young' can be expensive on
142 * some architectures, even if it's performed in hardware. By
143 * default, "false" means prefaulted entries will be 'young'.
149 static int __init
disable_randmaps(char *s
)
151 randomize_va_space
= 0;
154 __setup("norandmaps", disable_randmaps
);
156 unsigned long zero_pfn __read_mostly
;
157 EXPORT_SYMBOL(zero_pfn
);
159 unsigned long highest_memmap_pfn __read_mostly
;
162 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
164 static int __init
init_zero_pfn(void)
166 zero_pfn
= page_to_pfn(ZERO_PAGE(0));
169 core_initcall(init_zero_pfn
);
171 void mm_trace_rss_stat(struct mm_struct
*mm
, int member
, long count
)
173 trace_rss_stat(mm
, member
, count
);
176 #if defined(SPLIT_RSS_COUNTING)
178 void sync_mm_rss(struct mm_struct
*mm
)
182 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
183 if (current
->rss_stat
.count
[i
]) {
184 add_mm_counter(mm
, i
, current
->rss_stat
.count
[i
]);
185 current
->rss_stat
.count
[i
] = 0;
188 current
->rss_stat
.events
= 0;
191 static void add_mm_counter_fast(struct mm_struct
*mm
, int member
, int val
)
193 struct task_struct
*task
= current
;
195 if (likely(task
->mm
== mm
))
196 task
->rss_stat
.count
[member
] += val
;
198 add_mm_counter(mm
, member
, val
);
200 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
201 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
203 /* sync counter once per 64 page faults */
204 #define TASK_RSS_EVENTS_THRESH (64)
205 static void check_sync_rss_stat(struct task_struct
*task
)
207 if (unlikely(task
!= current
))
209 if (unlikely(task
->rss_stat
.events
++ > TASK_RSS_EVENTS_THRESH
))
210 sync_mm_rss(task
->mm
);
212 #else /* SPLIT_RSS_COUNTING */
214 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
215 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
217 static void check_sync_rss_stat(struct task_struct
*task
)
221 #endif /* SPLIT_RSS_COUNTING */
224 * Note: this doesn't free the actual pages themselves. That
225 * has been handled earlier when unmapping all the memory regions.
227 static void free_pte_range(struct mmu_gather
*tlb
, pmd_t
*pmd
,
230 pgtable_t token
= pmd_pgtable(*pmd
);
232 pte_free_tlb(tlb
, token
, addr
);
233 mm_dec_nr_ptes(tlb
->mm
);
236 static inline void free_pmd_range(struct mmu_gather
*tlb
, pud_t
*pud
,
237 unsigned long addr
, unsigned long end
,
238 unsigned long floor
, unsigned long ceiling
)
245 pmd
= pmd_offset(pud
, addr
);
247 next
= pmd_addr_end(addr
, end
);
248 if (pmd_none_or_clear_bad(pmd
))
250 free_pte_range(tlb
, pmd
, addr
);
251 } while (pmd
++, addr
= next
, addr
!= end
);
261 if (end
- 1 > ceiling
- 1)
264 pmd
= pmd_offset(pud
, start
);
266 pmd_free_tlb(tlb
, pmd
, start
);
267 mm_dec_nr_pmds(tlb
->mm
);
270 static inline void free_pud_range(struct mmu_gather
*tlb
, p4d_t
*p4d
,
271 unsigned long addr
, unsigned long end
,
272 unsigned long floor
, unsigned long ceiling
)
279 pud
= pud_offset(p4d
, addr
);
281 next
= pud_addr_end(addr
, end
);
282 if (pud_none_or_clear_bad(pud
))
284 free_pmd_range(tlb
, pud
, addr
, next
, floor
, ceiling
);
285 } while (pud
++, addr
= next
, addr
!= end
);
295 if (end
- 1 > ceiling
- 1)
298 pud
= pud_offset(p4d
, start
);
300 pud_free_tlb(tlb
, pud
, start
);
301 mm_dec_nr_puds(tlb
->mm
);
304 static inline void free_p4d_range(struct mmu_gather
*tlb
, pgd_t
*pgd
,
305 unsigned long addr
, unsigned long end
,
306 unsigned long floor
, unsigned long ceiling
)
313 p4d
= p4d_offset(pgd
, addr
);
315 next
= p4d_addr_end(addr
, end
);
316 if (p4d_none_or_clear_bad(p4d
))
318 free_pud_range(tlb
, p4d
, addr
, next
, floor
, ceiling
);
319 } while (p4d
++, addr
= next
, addr
!= end
);
325 ceiling
&= PGDIR_MASK
;
329 if (end
- 1 > ceiling
- 1)
332 p4d
= p4d_offset(pgd
, start
);
334 p4d_free_tlb(tlb
, p4d
, start
);
338 * This function frees user-level page tables of a process.
340 void free_pgd_range(struct mmu_gather
*tlb
,
341 unsigned long addr
, unsigned long end
,
342 unsigned long floor
, unsigned long ceiling
)
348 * The next few lines have given us lots of grief...
350 * Why are we testing PMD* at this top level? Because often
351 * there will be no work to do at all, and we'd prefer not to
352 * go all the way down to the bottom just to discover that.
354 * Why all these "- 1"s? Because 0 represents both the bottom
355 * of the address space and the top of it (using -1 for the
356 * top wouldn't help much: the masks would do the wrong thing).
357 * The rule is that addr 0 and floor 0 refer to the bottom of
358 * the address space, but end 0 and ceiling 0 refer to the top
359 * Comparisons need to use "end - 1" and "ceiling - 1" (though
360 * that end 0 case should be mythical).
362 * Wherever addr is brought up or ceiling brought down, we must
363 * be careful to reject "the opposite 0" before it confuses the
364 * subsequent tests. But what about where end is brought down
365 * by PMD_SIZE below? no, end can't go down to 0 there.
367 * Whereas we round start (addr) and ceiling down, by different
368 * masks at different levels, in order to test whether a table
369 * now has no other vmas using it, so can be freed, we don't
370 * bother to round floor or end up - the tests don't need that.
384 if (end
- 1 > ceiling
- 1)
389 * We add page table cache pages with PAGE_SIZE,
390 * (see pte_free_tlb()), flush the tlb if we need
392 tlb_change_page_size(tlb
, PAGE_SIZE
);
393 pgd
= pgd_offset(tlb
->mm
, addr
);
395 next
= pgd_addr_end(addr
, end
);
396 if (pgd_none_or_clear_bad(pgd
))
398 free_p4d_range(tlb
, pgd
, addr
, next
, floor
, ceiling
);
399 } while (pgd
++, addr
= next
, addr
!= end
);
402 void free_pgtables(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
403 unsigned long floor
, unsigned long ceiling
)
406 struct vm_area_struct
*next
= vma
->vm_next
;
407 unsigned long addr
= vma
->vm_start
;
410 * Hide vma from rmap and truncate_pagecache before freeing
413 unlink_anon_vmas(vma
);
414 unlink_file_vma(vma
);
416 if (is_vm_hugetlb_page(vma
)) {
417 hugetlb_free_pgd_range(tlb
, addr
, vma
->vm_end
,
418 floor
, next
? next
->vm_start
: ceiling
);
421 * Optimization: gather nearby vmas into one call down
423 while (next
&& next
->vm_start
<= vma
->vm_end
+ PMD_SIZE
424 && !is_vm_hugetlb_page(next
)) {
427 unlink_anon_vmas(vma
);
428 unlink_file_vma(vma
);
430 free_pgd_range(tlb
, addr
, vma
->vm_end
,
431 floor
, next
? next
->vm_start
: ceiling
);
437 int __pte_alloc(struct mm_struct
*mm
, pmd_t
*pmd
)
440 pgtable_t
new = pte_alloc_one(mm
);
445 * Ensure all pte setup (eg. pte page lock and page clearing) are
446 * visible before the pte is made visible to other CPUs by being
447 * put into page tables.
449 * The other side of the story is the pointer chasing in the page
450 * table walking code (when walking the page table without locking;
451 * ie. most of the time). Fortunately, these data accesses consist
452 * of a chain of data-dependent loads, meaning most CPUs (alpha
453 * being the notable exception) will already guarantee loads are
454 * seen in-order. See the alpha page table accessors for the
455 * smp_rmb() barriers in page table walking code.
457 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
459 ptl
= pmd_lock(mm
, pmd
);
460 if (likely(pmd_none(*pmd
))) { /* Has another populated it ? */
462 pmd_populate(mm
, pmd
, new);
471 int __pte_alloc_kernel(pmd_t
*pmd
)
473 pte_t
*new = pte_alloc_one_kernel(&init_mm
);
477 smp_wmb(); /* See comment in __pte_alloc */
479 spin_lock(&init_mm
.page_table_lock
);
480 if (likely(pmd_none(*pmd
))) { /* Has another populated it ? */
481 pmd_populate_kernel(&init_mm
, pmd
, new);
484 spin_unlock(&init_mm
.page_table_lock
);
486 pte_free_kernel(&init_mm
, new);
490 static inline void init_rss_vec(int *rss
)
492 memset(rss
, 0, sizeof(int) * NR_MM_COUNTERS
);
495 static inline void add_mm_rss_vec(struct mm_struct
*mm
, int *rss
)
499 if (current
->mm
== mm
)
501 for (i
= 0; i
< NR_MM_COUNTERS
; i
++)
503 add_mm_counter(mm
, i
, rss
[i
]);
507 * This function is called to print an error when a bad pte
508 * is found. For example, we might have a PFN-mapped pte in
509 * a region that doesn't allow it.
511 * The calling function must still handle the error.
513 static void print_bad_pte(struct vm_area_struct
*vma
, unsigned long addr
,
514 pte_t pte
, struct page
*page
)
516 pgd_t
*pgd
= pgd_offset(vma
->vm_mm
, addr
);
517 p4d_t
*p4d
= p4d_offset(pgd
, addr
);
518 pud_t
*pud
= pud_offset(p4d
, addr
);
519 pmd_t
*pmd
= pmd_offset(pud
, addr
);
520 struct address_space
*mapping
;
522 static unsigned long resume
;
523 static unsigned long nr_shown
;
524 static unsigned long nr_unshown
;
527 * Allow a burst of 60 reports, then keep quiet for that minute;
528 * or allow a steady drip of one report per second.
530 if (nr_shown
== 60) {
531 if (time_before(jiffies
, resume
)) {
536 pr_alert("BUG: Bad page map: %lu messages suppressed\n",
543 resume
= jiffies
+ 60 * HZ
;
545 mapping
= vma
->vm_file
? vma
->vm_file
->f_mapping
: NULL
;
546 index
= linear_page_index(vma
, addr
);
548 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
550 (long long)pte_val(pte
), (long long)pmd_val(*pmd
));
552 dump_page(page
, "bad pte");
553 pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n",
554 (void *)addr
, vma
->vm_flags
, vma
->anon_vma
, mapping
, index
);
555 pr_alert("file:%pD fault:%ps mmap:%ps readpage:%ps\n",
557 vma
->vm_ops
? vma
->vm_ops
->fault
: NULL
,
558 vma
->vm_file
? vma
->vm_file
->f_op
->mmap
: NULL
,
559 mapping
? mapping
->a_ops
->readpage
: NULL
);
561 add_taint(TAINT_BAD_PAGE
, LOCKDEP_NOW_UNRELIABLE
);
565 * vm_normal_page -- This function gets the "struct page" associated with a pte.
567 * "Special" mappings do not wish to be associated with a "struct page" (either
568 * it doesn't exist, or it exists but they don't want to touch it). In this
569 * case, NULL is returned here. "Normal" mappings do have a struct page.
571 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
572 * pte bit, in which case this function is trivial. Secondly, an architecture
573 * may not have a spare pte bit, which requires a more complicated scheme,
576 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
577 * special mapping (even if there are underlying and valid "struct pages").
578 * COWed pages of a VM_PFNMAP are always normal.
580 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
581 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
582 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
583 * mapping will always honor the rule
585 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
587 * And for normal mappings this is false.
589 * This restricts such mappings to be a linear translation from virtual address
590 * to pfn. To get around this restriction, we allow arbitrary mappings so long
591 * as the vma is not a COW mapping; in that case, we know that all ptes are
592 * special (because none can have been COWed).
595 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
597 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
598 * page" backing, however the difference is that _all_ pages with a struct
599 * page (that is, those where pfn_valid is true) are refcounted and considered
600 * normal pages by the VM. The disadvantage is that pages are refcounted
601 * (which can be slower and simply not an option for some PFNMAP users). The
602 * advantage is that we don't have to follow the strict linearity rule of
603 * PFNMAP mappings in order to support COWable mappings.
606 struct page
*vm_normal_page(struct vm_area_struct
*vma
, unsigned long addr
,
609 unsigned long pfn
= pte_pfn(pte
);
611 if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL
)) {
612 if (likely(!pte_special(pte
)))
614 if (vma
->vm_ops
&& vma
->vm_ops
->find_special_page
)
615 return vma
->vm_ops
->find_special_page(vma
, addr
);
616 if (vma
->vm_flags
& (VM_PFNMAP
| VM_MIXEDMAP
))
618 if (is_zero_pfn(pfn
))
623 print_bad_pte(vma
, addr
, pte
, NULL
);
627 /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */
629 if (unlikely(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
))) {
630 if (vma
->vm_flags
& VM_MIXEDMAP
) {
636 off
= (addr
- vma
->vm_start
) >> PAGE_SHIFT
;
637 if (pfn
== vma
->vm_pgoff
+ off
)
639 if (!is_cow_mapping(vma
->vm_flags
))
644 if (is_zero_pfn(pfn
))
648 if (unlikely(pfn
> highest_memmap_pfn
)) {
649 print_bad_pte(vma
, addr
, pte
, NULL
);
654 * NOTE! We still have PageReserved() pages in the page tables.
655 * eg. VDSO mappings can cause them to exist.
658 return pfn_to_page(pfn
);
661 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
662 struct page
*vm_normal_page_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
665 unsigned long pfn
= pmd_pfn(pmd
);
668 * There is no pmd_special() but there may be special pmds, e.g.
669 * in a direct-access (dax) mapping, so let's just replicate the
670 * !CONFIG_ARCH_HAS_PTE_SPECIAL case from vm_normal_page() here.
672 if (unlikely(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
))) {
673 if (vma
->vm_flags
& VM_MIXEDMAP
) {
679 off
= (addr
- vma
->vm_start
) >> PAGE_SHIFT
;
680 if (pfn
== vma
->vm_pgoff
+ off
)
682 if (!is_cow_mapping(vma
->vm_flags
))
689 if (is_huge_zero_pmd(pmd
))
691 if (unlikely(pfn
> highest_memmap_pfn
))
695 * NOTE! We still have PageReserved() pages in the page tables.
696 * eg. VDSO mappings can cause them to exist.
699 return pfn_to_page(pfn
);
704 * copy one vm_area from one task to the other. Assumes the page tables
705 * already present in the new task to be cleared in the whole range
706 * covered by this vma.
710 copy_nonpresent_pte(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
711 pte_t
*dst_pte
, pte_t
*src_pte
, struct vm_area_struct
*vma
,
712 unsigned long addr
, int *rss
)
714 unsigned long vm_flags
= vma
->vm_flags
;
715 pte_t pte
= *src_pte
;
717 swp_entry_t entry
= pte_to_swp_entry(pte
);
719 if (likely(!non_swap_entry(entry
))) {
720 if (swap_duplicate(entry
) < 0)
723 /* make sure dst_mm is on swapoff's mmlist. */
724 if (unlikely(list_empty(&dst_mm
->mmlist
))) {
725 spin_lock(&mmlist_lock
);
726 if (list_empty(&dst_mm
->mmlist
))
727 list_add(&dst_mm
->mmlist
,
729 spin_unlock(&mmlist_lock
);
732 } else if (is_migration_entry(entry
)) {
733 page
= migration_entry_to_page(entry
);
735 rss
[mm_counter(page
)]++;
737 if (is_write_migration_entry(entry
) &&
738 is_cow_mapping(vm_flags
)) {
740 * COW mappings require pages in both
741 * parent and child to be set to read.
743 make_migration_entry_read(&entry
);
744 pte
= swp_entry_to_pte(entry
);
745 if (pte_swp_soft_dirty(*src_pte
))
746 pte
= pte_swp_mksoft_dirty(pte
);
747 if (pte_swp_uffd_wp(*src_pte
))
748 pte
= pte_swp_mkuffd_wp(pte
);
749 set_pte_at(src_mm
, addr
, src_pte
, pte
);
751 } else if (is_device_private_entry(entry
)) {
752 page
= device_private_entry_to_page(entry
);
755 * Update rss count even for unaddressable pages, as
756 * they should treated just like normal pages in this
759 * We will likely want to have some new rss counters
760 * for unaddressable pages, at some point. But for now
761 * keep things as they are.
764 rss
[mm_counter(page
)]++;
765 page_dup_rmap(page
, false);
768 * We do not preserve soft-dirty information, because so
769 * far, checkpoint/restore is the only feature that
770 * requires that. And checkpoint/restore does not work
771 * when a device driver is involved (you cannot easily
772 * save and restore device driver state).
774 if (is_write_device_private_entry(entry
) &&
775 is_cow_mapping(vm_flags
)) {
776 make_device_private_entry_read(&entry
);
777 pte
= swp_entry_to_pte(entry
);
778 if (pte_swp_uffd_wp(*src_pte
))
779 pte
= pte_swp_mkuffd_wp(pte
);
780 set_pte_at(src_mm
, addr
, src_pte
, pte
);
783 set_pte_at(dst_mm
, addr
, dst_pte
, pte
);
788 * Copy a present and normal page if necessary.
790 * NOTE! The usual case is that this doesn't need to do
791 * anything, and can just return a positive value. That
792 * will let the caller know that it can just increase
793 * the page refcount and re-use the pte the traditional
796 * But _if_ we need to copy it because it needs to be
797 * pinned in the parent (and the child should get its own
798 * copy rather than just a reference to the same page),
799 * we'll do that here and return zero to let the caller
802 * And if we need a pre-allocated page but don't yet have
803 * one, return a negative error to let the preallocation
804 * code know so that it can do so outside the page table
808 copy_present_page(struct vm_area_struct
*dst_vma
, struct vm_area_struct
*src_vma
,
809 pte_t
*dst_pte
, pte_t
*src_pte
, unsigned long addr
, int *rss
,
810 struct page
**prealloc
, pte_t pte
, struct page
*page
)
812 struct page
*new_page
;
815 * What we want to do is to check whether this page may
816 * have been pinned by the parent process. If so,
817 * instead of wrprotect the pte on both sides, we copy
818 * the page immediately so that we'll always guarantee
819 * the pinned page won't be randomly replaced in the
822 * The page pinning checks are just "has this mm ever
823 * seen pinning", along with the (inexact) check of
824 * the page count. That might give false positives for
825 * for pinning, but it will work correctly.
827 if (likely(!page_needs_cow_for_dma(src_vma
, page
)))
830 new_page
= *prealloc
;
835 * We have a prealloc page, all good! Take it
836 * over and copy the page & arm it.
839 copy_user_highpage(new_page
, page
, addr
, src_vma
);
840 __SetPageUptodate(new_page
);
841 page_add_new_anon_rmap(new_page
, dst_vma
, addr
, false);
842 lru_cache_add_inactive_or_unevictable(new_page
, dst_vma
);
843 rss
[mm_counter(new_page
)]++;
845 /* All done, just insert the new page copy in the child */
846 pte
= mk_pte(new_page
, dst_vma
->vm_page_prot
);
847 pte
= maybe_mkwrite(pte_mkdirty(pte
), dst_vma
);
848 set_pte_at(dst_vma
->vm_mm
, addr
, dst_pte
, pte
);
853 * Copy one pte. Returns 0 if succeeded, or -EAGAIN if one preallocated page
854 * is required to copy this pte.
857 copy_present_pte(struct vm_area_struct
*dst_vma
, struct vm_area_struct
*src_vma
,
858 pte_t
*dst_pte
, pte_t
*src_pte
, unsigned long addr
, int *rss
,
859 struct page
**prealloc
)
861 struct mm_struct
*src_mm
= src_vma
->vm_mm
;
862 unsigned long vm_flags
= src_vma
->vm_flags
;
863 pte_t pte
= *src_pte
;
866 page
= vm_normal_page(src_vma
, addr
, pte
);
870 retval
= copy_present_page(dst_vma
, src_vma
, dst_pte
, src_pte
,
871 addr
, rss
, prealloc
, pte
, page
);
876 page_dup_rmap(page
, false);
877 rss
[mm_counter(page
)]++;
881 * If it's a COW mapping, write protect it both
882 * in the parent and the child
884 if (is_cow_mapping(vm_flags
) && pte_write(pte
)) {
885 ptep_set_wrprotect(src_mm
, addr
, src_pte
);
886 pte
= pte_wrprotect(pte
);
890 * If it's a shared mapping, mark it clean in
893 if (vm_flags
& VM_SHARED
)
894 pte
= pte_mkclean(pte
);
895 pte
= pte_mkold(pte
);
898 * Make sure the _PAGE_UFFD_WP bit is cleared if the new VMA
899 * does not have the VM_UFFD_WP, which means that the uffd
900 * fork event is not enabled.
902 if (!(vm_flags
& VM_UFFD_WP
))
903 pte
= pte_clear_uffd_wp(pte
);
905 set_pte_at(dst_vma
->vm_mm
, addr
, dst_pte
, pte
);
909 static inline struct page
*
910 page_copy_prealloc(struct mm_struct
*src_mm
, struct vm_area_struct
*vma
,
913 struct page
*new_page
;
915 new_page
= alloc_page_vma(GFP_HIGHUSER_MOVABLE
, vma
, addr
);
919 if (mem_cgroup_charge(new_page
, src_mm
, GFP_KERNEL
)) {
923 cgroup_throttle_swaprate(new_page
, GFP_KERNEL
);
929 copy_pte_range(struct vm_area_struct
*dst_vma
, struct vm_area_struct
*src_vma
,
930 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
933 struct mm_struct
*dst_mm
= dst_vma
->vm_mm
;
934 struct mm_struct
*src_mm
= src_vma
->vm_mm
;
935 pte_t
*orig_src_pte
, *orig_dst_pte
;
936 pte_t
*src_pte
, *dst_pte
;
937 spinlock_t
*src_ptl
, *dst_ptl
;
938 int progress
, ret
= 0;
939 int rss
[NR_MM_COUNTERS
];
940 swp_entry_t entry
= (swp_entry_t
){0};
941 struct page
*prealloc
= NULL
;
947 dst_pte
= pte_alloc_map_lock(dst_mm
, dst_pmd
, addr
, &dst_ptl
);
952 src_pte
= pte_offset_map(src_pmd
, addr
);
953 src_ptl
= pte_lockptr(src_mm
, src_pmd
);
954 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
955 orig_src_pte
= src_pte
;
956 orig_dst_pte
= dst_pte
;
957 arch_enter_lazy_mmu_mode();
961 * We are holding two locks at this point - either of them
962 * could generate latencies in another task on another CPU.
964 if (progress
>= 32) {
966 if (need_resched() ||
967 spin_needbreak(src_ptl
) || spin_needbreak(dst_ptl
))
970 if (pte_none(*src_pte
)) {
974 if (unlikely(!pte_present(*src_pte
))) {
975 entry
.val
= copy_nonpresent_pte(dst_mm
, src_mm
,
983 /* copy_present_pte() will clear `*prealloc' if consumed */
984 ret
= copy_present_pte(dst_vma
, src_vma
, dst_pte
, src_pte
,
985 addr
, rss
, &prealloc
);
987 * If we need a pre-allocated page for this pte, drop the
988 * locks, allocate, and try again.
990 if (unlikely(ret
== -EAGAIN
))
992 if (unlikely(prealloc
)) {
994 * pre-alloc page cannot be reused by next time so as
995 * to strictly follow mempolicy (e.g., alloc_page_vma()
996 * will allocate page according to address). This
997 * could only happen if one pinned pte changed.
1003 } while (dst_pte
++, src_pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
1005 arch_leave_lazy_mmu_mode();
1006 spin_unlock(src_ptl
);
1007 pte_unmap(orig_src_pte
);
1008 add_mm_rss_vec(dst_mm
, rss
);
1009 pte_unmap_unlock(orig_dst_pte
, dst_ptl
);
1013 if (add_swap_count_continuation(entry
, GFP_KERNEL
) < 0) {
1019 WARN_ON_ONCE(ret
!= -EAGAIN
);
1020 prealloc
= page_copy_prealloc(src_mm
, src_vma
, addr
);
1023 /* We've captured and resolved the error. Reset, try again. */
1029 if (unlikely(prealloc
))
1035 copy_pmd_range(struct vm_area_struct
*dst_vma
, struct vm_area_struct
*src_vma
,
1036 pud_t
*dst_pud
, pud_t
*src_pud
, unsigned long addr
,
1039 struct mm_struct
*dst_mm
= dst_vma
->vm_mm
;
1040 struct mm_struct
*src_mm
= src_vma
->vm_mm
;
1041 pmd_t
*src_pmd
, *dst_pmd
;
1044 dst_pmd
= pmd_alloc(dst_mm
, dst_pud
, addr
);
1047 src_pmd
= pmd_offset(src_pud
, addr
);
1049 next
= pmd_addr_end(addr
, end
);
1050 if (is_swap_pmd(*src_pmd
) || pmd_trans_huge(*src_pmd
)
1051 || pmd_devmap(*src_pmd
)) {
1053 VM_BUG_ON_VMA(next
-addr
!= HPAGE_PMD_SIZE
, src_vma
);
1054 err
= copy_huge_pmd(dst_mm
, src_mm
,
1055 dst_pmd
, src_pmd
, addr
, src_vma
);
1062 if (pmd_none_or_clear_bad(src_pmd
))
1064 if (copy_pte_range(dst_vma
, src_vma
, dst_pmd
, src_pmd
,
1067 } while (dst_pmd
++, src_pmd
++, addr
= next
, addr
!= end
);
1072 copy_pud_range(struct vm_area_struct
*dst_vma
, struct vm_area_struct
*src_vma
,
1073 p4d_t
*dst_p4d
, p4d_t
*src_p4d
, unsigned long addr
,
1076 struct mm_struct
*dst_mm
= dst_vma
->vm_mm
;
1077 struct mm_struct
*src_mm
= src_vma
->vm_mm
;
1078 pud_t
*src_pud
, *dst_pud
;
1081 dst_pud
= pud_alloc(dst_mm
, dst_p4d
, addr
);
1084 src_pud
= pud_offset(src_p4d
, addr
);
1086 next
= pud_addr_end(addr
, end
);
1087 if (pud_trans_huge(*src_pud
) || pud_devmap(*src_pud
)) {
1090 VM_BUG_ON_VMA(next
-addr
!= HPAGE_PUD_SIZE
, src_vma
);
1091 err
= copy_huge_pud(dst_mm
, src_mm
,
1092 dst_pud
, src_pud
, addr
, src_vma
);
1099 if (pud_none_or_clear_bad(src_pud
))
1101 if (copy_pmd_range(dst_vma
, src_vma
, dst_pud
, src_pud
,
1104 } while (dst_pud
++, src_pud
++, addr
= next
, addr
!= end
);
1109 copy_p4d_range(struct vm_area_struct
*dst_vma
, struct vm_area_struct
*src_vma
,
1110 pgd_t
*dst_pgd
, pgd_t
*src_pgd
, unsigned long addr
,
1113 struct mm_struct
*dst_mm
= dst_vma
->vm_mm
;
1114 p4d_t
*src_p4d
, *dst_p4d
;
1117 dst_p4d
= p4d_alloc(dst_mm
, dst_pgd
, addr
);
1120 src_p4d
= p4d_offset(src_pgd
, addr
);
1122 next
= p4d_addr_end(addr
, end
);
1123 if (p4d_none_or_clear_bad(src_p4d
))
1125 if (copy_pud_range(dst_vma
, src_vma
, dst_p4d
, src_p4d
,
1128 } while (dst_p4d
++, src_p4d
++, addr
= next
, addr
!= end
);
1133 copy_page_range(struct vm_area_struct
*dst_vma
, struct vm_area_struct
*src_vma
)
1135 pgd_t
*src_pgd
, *dst_pgd
;
1137 unsigned long addr
= src_vma
->vm_start
;
1138 unsigned long end
= src_vma
->vm_end
;
1139 struct mm_struct
*dst_mm
= dst_vma
->vm_mm
;
1140 struct mm_struct
*src_mm
= src_vma
->vm_mm
;
1141 struct mmu_notifier_range range
;
1146 * Don't copy ptes where a page fault will fill them correctly.
1147 * Fork becomes much lighter when there are big shared or private
1148 * readonly mappings. The tradeoff is that copy_page_range is more
1149 * efficient than faulting.
1151 if (!(src_vma
->vm_flags
& (VM_HUGETLB
| VM_PFNMAP
| VM_MIXEDMAP
)) &&
1155 if (is_vm_hugetlb_page(src_vma
))
1156 return copy_hugetlb_page_range(dst_mm
, src_mm
, src_vma
);
1158 if (unlikely(src_vma
->vm_flags
& VM_PFNMAP
)) {
1160 * We do not free on error cases below as remove_vma
1161 * gets called on error from higher level routine
1163 ret
= track_pfn_copy(src_vma
);
1169 * We need to invalidate the secondary MMU mappings only when
1170 * there could be a permission downgrade on the ptes of the
1171 * parent mm. And a permission downgrade will only happen if
1172 * is_cow_mapping() returns true.
1174 is_cow
= is_cow_mapping(src_vma
->vm_flags
);
1177 mmu_notifier_range_init(&range
, MMU_NOTIFY_PROTECTION_PAGE
,
1178 0, src_vma
, src_mm
, addr
, end
);
1179 mmu_notifier_invalidate_range_start(&range
);
1181 * Disabling preemption is not needed for the write side, as
1182 * the read side doesn't spin, but goes to the mmap_lock.
1184 * Use the raw variant of the seqcount_t write API to avoid
1185 * lockdep complaining about preemptibility.
1187 mmap_assert_write_locked(src_mm
);
1188 raw_write_seqcount_begin(&src_mm
->write_protect_seq
);
1192 dst_pgd
= pgd_offset(dst_mm
, addr
);
1193 src_pgd
= pgd_offset(src_mm
, addr
);
1195 next
= pgd_addr_end(addr
, end
);
1196 if (pgd_none_or_clear_bad(src_pgd
))
1198 if (unlikely(copy_p4d_range(dst_vma
, src_vma
, dst_pgd
, src_pgd
,
1203 } while (dst_pgd
++, src_pgd
++, addr
= next
, addr
!= end
);
1206 raw_write_seqcount_end(&src_mm
->write_protect_seq
);
1207 mmu_notifier_invalidate_range_end(&range
);
1212 static unsigned long zap_pte_range(struct mmu_gather
*tlb
,
1213 struct vm_area_struct
*vma
, pmd_t
*pmd
,
1214 unsigned long addr
, unsigned long end
,
1215 struct zap_details
*details
)
1217 struct mm_struct
*mm
= tlb
->mm
;
1218 int force_flush
= 0;
1219 int rss
[NR_MM_COUNTERS
];
1225 tlb_change_page_size(tlb
, PAGE_SIZE
);
1228 start_pte
= pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
1230 flush_tlb_batched_pending(mm
);
1231 arch_enter_lazy_mmu_mode();
1234 if (pte_none(ptent
))
1240 if (pte_present(ptent
)) {
1243 page
= vm_normal_page(vma
, addr
, ptent
);
1244 if (unlikely(details
) && page
) {
1246 * unmap_shared_mapping_pages() wants to
1247 * invalidate cache without truncating:
1248 * unmap shared but keep private pages.
1250 if (details
->check_mapping
&&
1251 details
->check_mapping
!= page_rmapping(page
))
1254 ptent
= ptep_get_and_clear_full(mm
, addr
, pte
,
1256 tlb_remove_tlb_entry(tlb
, pte
, addr
);
1257 if (unlikely(!page
))
1260 if (!PageAnon(page
)) {
1261 if (pte_dirty(ptent
)) {
1263 set_page_dirty(page
);
1265 if (pte_young(ptent
) &&
1266 likely(!(vma
->vm_flags
& VM_SEQ_READ
)))
1267 mark_page_accessed(page
);
1269 rss
[mm_counter(page
)]--;
1270 page_remove_rmap(page
, false);
1271 if (unlikely(page_mapcount(page
) < 0))
1272 print_bad_pte(vma
, addr
, ptent
, page
);
1273 if (unlikely(__tlb_remove_page(tlb
, page
))) {
1281 entry
= pte_to_swp_entry(ptent
);
1282 if (is_device_private_entry(entry
)) {
1283 struct page
*page
= device_private_entry_to_page(entry
);
1285 if (unlikely(details
&& details
->check_mapping
)) {
1287 * unmap_shared_mapping_pages() wants to
1288 * invalidate cache without truncating:
1289 * unmap shared but keep private pages.
1291 if (details
->check_mapping
!=
1292 page_rmapping(page
))
1296 pte_clear_not_present_full(mm
, addr
, pte
, tlb
->fullmm
);
1297 rss
[mm_counter(page
)]--;
1298 page_remove_rmap(page
, false);
1303 /* If details->check_mapping, we leave swap entries. */
1304 if (unlikely(details
))
1307 if (!non_swap_entry(entry
))
1309 else if (is_migration_entry(entry
)) {
1312 page
= migration_entry_to_page(entry
);
1313 rss
[mm_counter(page
)]--;
1315 if (unlikely(!free_swap_and_cache(entry
)))
1316 print_bad_pte(vma
, addr
, ptent
, NULL
);
1317 pte_clear_not_present_full(mm
, addr
, pte
, tlb
->fullmm
);
1318 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
1320 add_mm_rss_vec(mm
, rss
);
1321 arch_leave_lazy_mmu_mode();
1323 /* Do the actual TLB flush before dropping ptl */
1325 tlb_flush_mmu_tlbonly(tlb
);
1326 pte_unmap_unlock(start_pte
, ptl
);
1329 * If we forced a TLB flush (either due to running out of
1330 * batch buffers or because we needed to flush dirty TLB
1331 * entries before releasing the ptl), free the batched
1332 * memory too. Restart if we didn't do everything.
1347 static inline unsigned long zap_pmd_range(struct mmu_gather
*tlb
,
1348 struct vm_area_struct
*vma
, pud_t
*pud
,
1349 unsigned long addr
, unsigned long end
,
1350 struct zap_details
*details
)
1355 pmd
= pmd_offset(pud
, addr
);
1357 next
= pmd_addr_end(addr
, end
);
1358 if (is_swap_pmd(*pmd
) || pmd_trans_huge(*pmd
) || pmd_devmap(*pmd
)) {
1359 if (next
- addr
!= HPAGE_PMD_SIZE
)
1360 __split_huge_pmd(vma
, pmd
, addr
, false, NULL
);
1361 else if (zap_huge_pmd(tlb
, vma
, pmd
, addr
))
1366 * Here there can be other concurrent MADV_DONTNEED or
1367 * trans huge page faults running, and if the pmd is
1368 * none or trans huge it can change under us. This is
1369 * because MADV_DONTNEED holds the mmap_lock in read
1372 if (pmd_none_or_trans_huge_or_clear_bad(pmd
))
1374 next
= zap_pte_range(tlb
, vma
, pmd
, addr
, next
, details
);
1377 } while (pmd
++, addr
= next
, addr
!= end
);
1382 static inline unsigned long zap_pud_range(struct mmu_gather
*tlb
,
1383 struct vm_area_struct
*vma
, p4d_t
*p4d
,
1384 unsigned long addr
, unsigned long end
,
1385 struct zap_details
*details
)
1390 pud
= pud_offset(p4d
, addr
);
1392 next
= pud_addr_end(addr
, end
);
1393 if (pud_trans_huge(*pud
) || pud_devmap(*pud
)) {
1394 if (next
- addr
!= HPAGE_PUD_SIZE
) {
1395 mmap_assert_locked(tlb
->mm
);
1396 split_huge_pud(vma
, pud
, addr
);
1397 } else if (zap_huge_pud(tlb
, vma
, pud
, addr
))
1401 if (pud_none_or_clear_bad(pud
))
1403 next
= zap_pmd_range(tlb
, vma
, pud
, addr
, next
, details
);
1406 } while (pud
++, addr
= next
, addr
!= end
);
1411 static inline unsigned long zap_p4d_range(struct mmu_gather
*tlb
,
1412 struct vm_area_struct
*vma
, pgd_t
*pgd
,
1413 unsigned long addr
, unsigned long end
,
1414 struct zap_details
*details
)
1419 p4d
= p4d_offset(pgd
, addr
);
1421 next
= p4d_addr_end(addr
, end
);
1422 if (p4d_none_or_clear_bad(p4d
))
1424 next
= zap_pud_range(tlb
, vma
, p4d
, addr
, next
, details
);
1425 } while (p4d
++, addr
= next
, addr
!= end
);
1430 void unmap_page_range(struct mmu_gather
*tlb
,
1431 struct vm_area_struct
*vma
,
1432 unsigned long addr
, unsigned long end
,
1433 struct zap_details
*details
)
1438 BUG_ON(addr
>= end
);
1439 tlb_start_vma(tlb
, vma
);
1440 pgd
= pgd_offset(vma
->vm_mm
, addr
);
1442 next
= pgd_addr_end(addr
, end
);
1443 if (pgd_none_or_clear_bad(pgd
))
1445 next
= zap_p4d_range(tlb
, vma
, pgd
, addr
, next
, details
);
1446 } while (pgd
++, addr
= next
, addr
!= end
);
1447 tlb_end_vma(tlb
, vma
);
1451 static void unmap_single_vma(struct mmu_gather
*tlb
,
1452 struct vm_area_struct
*vma
, unsigned long start_addr
,
1453 unsigned long end_addr
,
1454 struct zap_details
*details
)
1456 unsigned long start
= max(vma
->vm_start
, start_addr
);
1459 if (start
>= vma
->vm_end
)
1461 end
= min(vma
->vm_end
, end_addr
);
1462 if (end
<= vma
->vm_start
)
1466 uprobe_munmap(vma
, start
, end
);
1468 if (unlikely(vma
->vm_flags
& VM_PFNMAP
))
1469 untrack_pfn(vma
, 0, 0);
1472 if (unlikely(is_vm_hugetlb_page(vma
))) {
1474 * It is undesirable to test vma->vm_file as it
1475 * should be non-null for valid hugetlb area.
1476 * However, vm_file will be NULL in the error
1477 * cleanup path of mmap_region. When
1478 * hugetlbfs ->mmap method fails,
1479 * mmap_region() nullifies vma->vm_file
1480 * before calling this function to clean up.
1481 * Since no pte has actually been setup, it is
1482 * safe to do nothing in this case.
1485 i_mmap_lock_write(vma
->vm_file
->f_mapping
);
1486 __unmap_hugepage_range_final(tlb
, vma
, start
, end
, NULL
);
1487 i_mmap_unlock_write(vma
->vm_file
->f_mapping
);
1490 unmap_page_range(tlb
, vma
, start
, end
, details
);
1495 * unmap_vmas - unmap a range of memory covered by a list of vma's
1496 * @tlb: address of the caller's struct mmu_gather
1497 * @vma: the starting vma
1498 * @start_addr: virtual address at which to start unmapping
1499 * @end_addr: virtual address at which to end unmapping
1501 * Unmap all pages in the vma list.
1503 * Only addresses between `start' and `end' will be unmapped.
1505 * The VMA list must be sorted in ascending virtual address order.
1507 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1508 * range after unmap_vmas() returns. So the only responsibility here is to
1509 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1510 * drops the lock and schedules.
1512 void unmap_vmas(struct mmu_gather
*tlb
,
1513 struct vm_area_struct
*vma
, unsigned long start_addr
,
1514 unsigned long end_addr
)
1516 struct mmu_notifier_range range
;
1518 mmu_notifier_range_init(&range
, MMU_NOTIFY_UNMAP
, 0, vma
, vma
->vm_mm
,
1519 start_addr
, end_addr
);
1520 mmu_notifier_invalidate_range_start(&range
);
1521 for ( ; vma
&& vma
->vm_start
< end_addr
; vma
= vma
->vm_next
)
1522 unmap_single_vma(tlb
, vma
, start_addr
, end_addr
, NULL
);
1523 mmu_notifier_invalidate_range_end(&range
);
1527 * zap_page_range - remove user pages in a given range
1528 * @vma: vm_area_struct holding the applicable pages
1529 * @start: starting address of pages to zap
1530 * @size: number of bytes to zap
1532 * Caller must protect the VMA list
1534 void zap_page_range(struct vm_area_struct
*vma
, unsigned long start
,
1537 struct mmu_notifier_range range
;
1538 struct mmu_gather tlb
;
1541 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, vma
, vma
->vm_mm
,
1542 start
, start
+ size
);
1543 tlb_gather_mmu(&tlb
, vma
->vm_mm
);
1544 update_hiwater_rss(vma
->vm_mm
);
1545 mmu_notifier_invalidate_range_start(&range
);
1546 for ( ; vma
&& vma
->vm_start
< range
.end
; vma
= vma
->vm_next
)
1547 unmap_single_vma(&tlb
, vma
, start
, range
.end
, NULL
);
1548 mmu_notifier_invalidate_range_end(&range
);
1549 tlb_finish_mmu(&tlb
);
1553 * zap_page_range_single - remove user pages in a given range
1554 * @vma: vm_area_struct holding the applicable pages
1555 * @address: starting address of pages to zap
1556 * @size: number of bytes to zap
1557 * @details: details of shared cache invalidation
1559 * The range must fit into one VMA.
1561 static void zap_page_range_single(struct vm_area_struct
*vma
, unsigned long address
,
1562 unsigned long size
, struct zap_details
*details
)
1564 struct mmu_notifier_range range
;
1565 struct mmu_gather tlb
;
1568 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, vma
, vma
->vm_mm
,
1569 address
, address
+ size
);
1570 tlb_gather_mmu(&tlb
, vma
->vm_mm
);
1571 update_hiwater_rss(vma
->vm_mm
);
1572 mmu_notifier_invalidate_range_start(&range
);
1573 unmap_single_vma(&tlb
, vma
, address
, range
.end
, details
);
1574 mmu_notifier_invalidate_range_end(&range
);
1575 tlb_finish_mmu(&tlb
);
1579 * zap_vma_ptes - remove ptes mapping the vma
1580 * @vma: vm_area_struct holding ptes to be zapped
1581 * @address: starting address of pages to zap
1582 * @size: number of bytes to zap
1584 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1586 * The entire address range must be fully contained within the vma.
1589 void zap_vma_ptes(struct vm_area_struct
*vma
, unsigned long address
,
1592 if (address
< vma
->vm_start
|| address
+ size
> vma
->vm_end
||
1593 !(vma
->vm_flags
& VM_PFNMAP
))
1596 zap_page_range_single(vma
, address
, size
, NULL
);
1598 EXPORT_SYMBOL_GPL(zap_vma_ptes
);
1600 static pmd_t
*walk_to_pmd(struct mm_struct
*mm
, unsigned long addr
)
1607 pgd
= pgd_offset(mm
, addr
);
1608 p4d
= p4d_alloc(mm
, pgd
, addr
);
1611 pud
= pud_alloc(mm
, p4d
, addr
);
1614 pmd
= pmd_alloc(mm
, pud
, addr
);
1618 VM_BUG_ON(pmd_trans_huge(*pmd
));
1622 pte_t
*__get_locked_pte(struct mm_struct
*mm
, unsigned long addr
,
1625 pmd_t
*pmd
= walk_to_pmd(mm
, addr
);
1629 return pte_alloc_map_lock(mm
, pmd
, addr
, ptl
);
1632 static int validate_page_before_insert(struct page
*page
)
1634 if (PageAnon(page
) || PageSlab(page
) || page_has_type(page
))
1636 flush_dcache_page(page
);
1640 static int insert_page_into_pte_locked(struct mm_struct
*mm
, pte_t
*pte
,
1641 unsigned long addr
, struct page
*page
, pgprot_t prot
)
1643 if (!pte_none(*pte
))
1645 /* Ok, finally just insert the thing.. */
1647 inc_mm_counter_fast(mm
, mm_counter_file(page
));
1648 page_add_file_rmap(page
, false);
1649 set_pte_at(mm
, addr
, pte
, mk_pte(page
, prot
));
1654 * This is the old fallback for page remapping.
1656 * For historical reasons, it only allows reserved pages. Only
1657 * old drivers should use this, and they needed to mark their
1658 * pages reserved for the old functions anyway.
1660 static int insert_page(struct vm_area_struct
*vma
, unsigned long addr
,
1661 struct page
*page
, pgprot_t prot
)
1663 struct mm_struct
*mm
= vma
->vm_mm
;
1668 retval
= validate_page_before_insert(page
);
1672 pte
= get_locked_pte(mm
, addr
, &ptl
);
1675 retval
= insert_page_into_pte_locked(mm
, pte
, addr
, page
, prot
);
1676 pte_unmap_unlock(pte
, ptl
);
1682 static int insert_page_in_batch_locked(struct mm_struct
*mm
, pte_t
*pte
,
1683 unsigned long addr
, struct page
*page
, pgprot_t prot
)
1687 if (!page_count(page
))
1689 err
= validate_page_before_insert(page
);
1692 return insert_page_into_pte_locked(mm
, pte
, addr
, page
, prot
);
1695 /* insert_pages() amortizes the cost of spinlock operations
1696 * when inserting pages in a loop. Arch *must* define pte_index.
1698 static int insert_pages(struct vm_area_struct
*vma
, unsigned long addr
,
1699 struct page
**pages
, unsigned long *num
, pgprot_t prot
)
1702 pte_t
*start_pte
, *pte
;
1703 spinlock_t
*pte_lock
;
1704 struct mm_struct
*const mm
= vma
->vm_mm
;
1705 unsigned long curr_page_idx
= 0;
1706 unsigned long remaining_pages_total
= *num
;
1707 unsigned long pages_to_write_in_pmd
;
1711 pmd
= walk_to_pmd(mm
, addr
);
1715 pages_to_write_in_pmd
= min_t(unsigned long,
1716 remaining_pages_total
, PTRS_PER_PTE
- pte_index(addr
));
1718 /* Allocate the PTE if necessary; takes PMD lock once only. */
1720 if (pte_alloc(mm
, pmd
))
1723 while (pages_to_write_in_pmd
) {
1725 const int batch_size
= min_t(int, pages_to_write_in_pmd
, 8);
1727 start_pte
= pte_offset_map_lock(mm
, pmd
, addr
, &pte_lock
);
1728 for (pte
= start_pte
; pte_idx
< batch_size
; ++pte
, ++pte_idx
) {
1729 int err
= insert_page_in_batch_locked(mm
, pte
,
1730 addr
, pages
[curr_page_idx
], prot
);
1731 if (unlikely(err
)) {
1732 pte_unmap_unlock(start_pte
, pte_lock
);
1734 remaining_pages_total
-= pte_idx
;
1740 pte_unmap_unlock(start_pte
, pte_lock
);
1741 pages_to_write_in_pmd
-= batch_size
;
1742 remaining_pages_total
-= batch_size
;
1744 if (remaining_pages_total
)
1748 *num
= remaining_pages_total
;
1751 #endif /* ifdef pte_index */
1754 * vm_insert_pages - insert multiple pages into user vma, batching the pmd lock.
1755 * @vma: user vma to map to
1756 * @addr: target start user address of these pages
1757 * @pages: source kernel pages
1758 * @num: in: number of pages to map. out: number of pages that were *not*
1759 * mapped. (0 means all pages were successfully mapped).
1761 * Preferred over vm_insert_page() when inserting multiple pages.
1763 * In case of error, we may have mapped a subset of the provided
1764 * pages. It is the caller's responsibility to account for this case.
1766 * The same restrictions apply as in vm_insert_page().
1768 int vm_insert_pages(struct vm_area_struct
*vma
, unsigned long addr
,
1769 struct page
**pages
, unsigned long *num
)
1772 const unsigned long end_addr
= addr
+ (*num
* PAGE_SIZE
) - 1;
1774 if (addr
< vma
->vm_start
|| end_addr
>= vma
->vm_end
)
1776 if (!(vma
->vm_flags
& VM_MIXEDMAP
)) {
1777 BUG_ON(mmap_read_trylock(vma
->vm_mm
));
1778 BUG_ON(vma
->vm_flags
& VM_PFNMAP
);
1779 vma
->vm_flags
|= VM_MIXEDMAP
;
1781 /* Defer page refcount checking till we're about to map that page. */
1782 return insert_pages(vma
, addr
, pages
, num
, vma
->vm_page_prot
);
1784 unsigned long idx
= 0, pgcount
= *num
;
1787 for (; idx
< pgcount
; ++idx
) {
1788 err
= vm_insert_page(vma
, addr
+ (PAGE_SIZE
* idx
), pages
[idx
]);
1792 *num
= pgcount
- idx
;
1794 #endif /* ifdef pte_index */
1796 EXPORT_SYMBOL(vm_insert_pages
);
1799 * vm_insert_page - insert single page into user vma
1800 * @vma: user vma to map to
1801 * @addr: target user address of this page
1802 * @page: source kernel page
1804 * This allows drivers to insert individual pages they've allocated
1807 * The page has to be a nice clean _individual_ kernel allocation.
1808 * If you allocate a compound page, you need to have marked it as
1809 * such (__GFP_COMP), or manually just split the page up yourself
1810 * (see split_page()).
1812 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1813 * took an arbitrary page protection parameter. This doesn't allow
1814 * that. Your vma protection will have to be set up correctly, which
1815 * means that if you want a shared writable mapping, you'd better
1816 * ask for a shared writable mapping!
1818 * The page does not need to be reserved.
1820 * Usually this function is called from f_op->mmap() handler
1821 * under mm->mmap_lock write-lock, so it can change vma->vm_flags.
1822 * Caller must set VM_MIXEDMAP on vma if it wants to call this
1823 * function from other places, for example from page-fault handler.
1825 * Return: %0 on success, negative error code otherwise.
1827 int vm_insert_page(struct vm_area_struct
*vma
, unsigned long addr
,
1830 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
1832 if (!page_count(page
))
1834 if (!(vma
->vm_flags
& VM_MIXEDMAP
)) {
1835 BUG_ON(mmap_read_trylock(vma
->vm_mm
));
1836 BUG_ON(vma
->vm_flags
& VM_PFNMAP
);
1837 vma
->vm_flags
|= VM_MIXEDMAP
;
1839 return insert_page(vma
, addr
, page
, vma
->vm_page_prot
);
1841 EXPORT_SYMBOL(vm_insert_page
);
1844 * __vm_map_pages - maps range of kernel pages into user vma
1845 * @vma: user vma to map to
1846 * @pages: pointer to array of source kernel pages
1847 * @num: number of pages in page array
1848 * @offset: user's requested vm_pgoff
1850 * This allows drivers to map range of kernel pages into a user vma.
1852 * Return: 0 on success and error code otherwise.
1854 static int __vm_map_pages(struct vm_area_struct
*vma
, struct page
**pages
,
1855 unsigned long num
, unsigned long offset
)
1857 unsigned long count
= vma_pages(vma
);
1858 unsigned long uaddr
= vma
->vm_start
;
1861 /* Fail if the user requested offset is beyond the end of the object */
1865 /* Fail if the user requested size exceeds available object size */
1866 if (count
> num
- offset
)
1869 for (i
= 0; i
< count
; i
++) {
1870 ret
= vm_insert_page(vma
, uaddr
, pages
[offset
+ i
]);
1880 * vm_map_pages - maps range of kernel pages starts with non zero offset
1881 * @vma: user vma to map to
1882 * @pages: pointer to array of source kernel pages
1883 * @num: number of pages in page array
1885 * Maps an object consisting of @num pages, catering for the user's
1886 * requested vm_pgoff
1888 * If we fail to insert any page into the vma, the function will return
1889 * immediately leaving any previously inserted pages present. Callers
1890 * from the mmap handler may immediately return the error as their caller
1891 * will destroy the vma, removing any successfully inserted pages. Other
1892 * callers should make their own arrangements for calling unmap_region().
1894 * Context: Process context. Called by mmap handlers.
1895 * Return: 0 on success and error code otherwise.
1897 int vm_map_pages(struct vm_area_struct
*vma
, struct page
**pages
,
1900 return __vm_map_pages(vma
, pages
, num
, vma
->vm_pgoff
);
1902 EXPORT_SYMBOL(vm_map_pages
);
1905 * vm_map_pages_zero - map range of kernel pages starts with zero offset
1906 * @vma: user vma to map to
1907 * @pages: pointer to array of source kernel pages
1908 * @num: number of pages in page array
1910 * Similar to vm_map_pages(), except that it explicitly sets the offset
1911 * to 0. This function is intended for the drivers that did not consider
1914 * Context: Process context. Called by mmap handlers.
1915 * Return: 0 on success and error code otherwise.
1917 int vm_map_pages_zero(struct vm_area_struct
*vma
, struct page
**pages
,
1920 return __vm_map_pages(vma
, pages
, num
, 0);
1922 EXPORT_SYMBOL(vm_map_pages_zero
);
1924 static vm_fault_t
insert_pfn(struct vm_area_struct
*vma
, unsigned long addr
,
1925 pfn_t pfn
, pgprot_t prot
, bool mkwrite
)
1927 struct mm_struct
*mm
= vma
->vm_mm
;
1931 pte
= get_locked_pte(mm
, addr
, &ptl
);
1933 return VM_FAULT_OOM
;
1934 if (!pte_none(*pte
)) {
1937 * For read faults on private mappings the PFN passed
1938 * in may not match the PFN we have mapped if the
1939 * mapped PFN is a writeable COW page. In the mkwrite
1940 * case we are creating a writable PTE for a shared
1941 * mapping and we expect the PFNs to match. If they
1942 * don't match, we are likely racing with block
1943 * allocation and mapping invalidation so just skip the
1946 if (pte_pfn(*pte
) != pfn_t_to_pfn(pfn
)) {
1947 WARN_ON_ONCE(!is_zero_pfn(pte_pfn(*pte
)));
1950 entry
= pte_mkyoung(*pte
);
1951 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1952 if (ptep_set_access_flags(vma
, addr
, pte
, entry
, 1))
1953 update_mmu_cache(vma
, addr
, pte
);
1958 /* Ok, finally just insert the thing.. */
1959 if (pfn_t_devmap(pfn
))
1960 entry
= pte_mkdevmap(pfn_t_pte(pfn
, prot
));
1962 entry
= pte_mkspecial(pfn_t_pte(pfn
, prot
));
1965 entry
= pte_mkyoung(entry
);
1966 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1969 set_pte_at(mm
, addr
, pte
, entry
);
1970 update_mmu_cache(vma
, addr
, pte
); /* XXX: why not for insert_page? */
1973 pte_unmap_unlock(pte
, ptl
);
1974 return VM_FAULT_NOPAGE
;
1978 * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot
1979 * @vma: user vma to map to
1980 * @addr: target user address of this page
1981 * @pfn: source kernel pfn
1982 * @pgprot: pgprot flags for the inserted page
1984 * This is exactly like vmf_insert_pfn(), except that it allows drivers
1985 * to override pgprot on a per-page basis.
1987 * This only makes sense for IO mappings, and it makes no sense for
1988 * COW mappings. In general, using multiple vmas is preferable;
1989 * vmf_insert_pfn_prot should only be used if using multiple VMAs is
1992 * See vmf_insert_mixed_prot() for a discussion of the implication of using
1993 * a value of @pgprot different from that of @vma->vm_page_prot.
1995 * Context: Process context. May allocate using %GFP_KERNEL.
1996 * Return: vm_fault_t value.
1998 vm_fault_t
vmf_insert_pfn_prot(struct vm_area_struct
*vma
, unsigned long addr
,
1999 unsigned long pfn
, pgprot_t pgprot
)
2002 * Technically, architectures with pte_special can avoid all these
2003 * restrictions (same for remap_pfn_range). However we would like
2004 * consistency in testing and feature parity among all, so we should
2005 * try to keep these invariants in place for everybody.
2007 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)));
2008 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
2009 (VM_PFNMAP
|VM_MIXEDMAP
));
2010 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
2011 BUG_ON((vma
->vm_flags
& VM_MIXEDMAP
) && pfn_valid(pfn
));
2013 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
2014 return VM_FAULT_SIGBUS
;
2016 if (!pfn_modify_allowed(pfn
, pgprot
))
2017 return VM_FAULT_SIGBUS
;
2019 track_pfn_insert(vma
, &pgprot
, __pfn_to_pfn_t(pfn
, PFN_DEV
));
2021 return insert_pfn(vma
, addr
, __pfn_to_pfn_t(pfn
, PFN_DEV
), pgprot
,
2024 EXPORT_SYMBOL(vmf_insert_pfn_prot
);
2027 * vmf_insert_pfn - insert single pfn into user vma
2028 * @vma: user vma to map to
2029 * @addr: target user address of this page
2030 * @pfn: source kernel pfn
2032 * Similar to vm_insert_page, this allows drivers to insert individual pages
2033 * they've allocated into a user vma. Same comments apply.
2035 * This function should only be called from a vm_ops->fault handler, and
2036 * in that case the handler should return the result of this function.
2038 * vma cannot be a COW mapping.
2040 * As this is called only for pages that do not currently exist, we
2041 * do not need to flush old virtual caches or the TLB.
2043 * Context: Process context. May allocate using %GFP_KERNEL.
2044 * Return: vm_fault_t value.
2046 vm_fault_t
vmf_insert_pfn(struct vm_area_struct
*vma
, unsigned long addr
,
2049 return vmf_insert_pfn_prot(vma
, addr
, pfn
, vma
->vm_page_prot
);
2051 EXPORT_SYMBOL(vmf_insert_pfn
);
2053 static bool vm_mixed_ok(struct vm_area_struct
*vma
, pfn_t pfn
)
2055 /* these checks mirror the abort conditions in vm_normal_page */
2056 if (vma
->vm_flags
& VM_MIXEDMAP
)
2058 if (pfn_t_devmap(pfn
))
2060 if (pfn_t_special(pfn
))
2062 if (is_zero_pfn(pfn_t_to_pfn(pfn
)))
2067 static vm_fault_t
__vm_insert_mixed(struct vm_area_struct
*vma
,
2068 unsigned long addr
, pfn_t pfn
, pgprot_t pgprot
,
2073 BUG_ON(!vm_mixed_ok(vma
, pfn
));
2075 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
2076 return VM_FAULT_SIGBUS
;
2078 track_pfn_insert(vma
, &pgprot
, pfn
);
2080 if (!pfn_modify_allowed(pfn_t_to_pfn(pfn
), pgprot
))
2081 return VM_FAULT_SIGBUS
;
2084 * If we don't have pte special, then we have to use the pfn_valid()
2085 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2086 * refcount the page if pfn_valid is true (hence insert_page rather
2087 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
2088 * without pte special, it would there be refcounted as a normal page.
2090 if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL
) &&
2091 !pfn_t_devmap(pfn
) && pfn_t_valid(pfn
)) {
2095 * At this point we are committed to insert_page()
2096 * regardless of whether the caller specified flags that
2097 * result in pfn_t_has_page() == false.
2099 page
= pfn_to_page(pfn_t_to_pfn(pfn
));
2100 err
= insert_page(vma
, addr
, page
, pgprot
);
2102 return insert_pfn(vma
, addr
, pfn
, pgprot
, mkwrite
);
2106 return VM_FAULT_OOM
;
2107 if (err
< 0 && err
!= -EBUSY
)
2108 return VM_FAULT_SIGBUS
;
2110 return VM_FAULT_NOPAGE
;
2114 * vmf_insert_mixed_prot - insert single pfn into user vma with specified pgprot
2115 * @vma: user vma to map to
2116 * @addr: target user address of this page
2117 * @pfn: source kernel pfn
2118 * @pgprot: pgprot flags for the inserted page
2120 * This is exactly like vmf_insert_mixed(), except that it allows drivers
2121 * to override pgprot on a per-page basis.
2123 * Typically this function should be used by drivers to set caching- and
2124 * encryption bits different than those of @vma->vm_page_prot, because
2125 * the caching- or encryption mode may not be known at mmap() time.
2126 * This is ok as long as @vma->vm_page_prot is not used by the core vm
2127 * to set caching and encryption bits for those vmas (except for COW pages).
2128 * This is ensured by core vm only modifying these page table entries using
2129 * functions that don't touch caching- or encryption bits, using pte_modify()
2130 * if needed. (See for example mprotect()).
2131 * Also when new page-table entries are created, this is only done using the
2132 * fault() callback, and never using the value of vma->vm_page_prot,
2133 * except for page-table entries that point to anonymous pages as the result
2136 * Context: Process context. May allocate using %GFP_KERNEL.
2137 * Return: vm_fault_t value.
2139 vm_fault_t
vmf_insert_mixed_prot(struct vm_area_struct
*vma
, unsigned long addr
,
2140 pfn_t pfn
, pgprot_t pgprot
)
2142 return __vm_insert_mixed(vma
, addr
, pfn
, pgprot
, false);
2144 EXPORT_SYMBOL(vmf_insert_mixed_prot
);
2146 vm_fault_t
vmf_insert_mixed(struct vm_area_struct
*vma
, unsigned long addr
,
2149 return __vm_insert_mixed(vma
, addr
, pfn
, vma
->vm_page_prot
, false);
2151 EXPORT_SYMBOL(vmf_insert_mixed
);
2154 * If the insertion of PTE failed because someone else already added a
2155 * different entry in the mean time, we treat that as success as we assume
2156 * the same entry was actually inserted.
2158 vm_fault_t
vmf_insert_mixed_mkwrite(struct vm_area_struct
*vma
,
2159 unsigned long addr
, pfn_t pfn
)
2161 return __vm_insert_mixed(vma
, addr
, pfn
, vma
->vm_page_prot
, true);
2163 EXPORT_SYMBOL(vmf_insert_mixed_mkwrite
);
2166 * maps a range of physical memory into the requested pages. the old
2167 * mappings are removed. any references to nonexistent pages results
2168 * in null mappings (currently treated as "copy-on-access")
2170 static int remap_pte_range(struct mm_struct
*mm
, pmd_t
*pmd
,
2171 unsigned long addr
, unsigned long end
,
2172 unsigned long pfn
, pgprot_t prot
)
2174 pte_t
*pte
, *mapped_pte
;
2178 mapped_pte
= pte
= pte_alloc_map_lock(mm
, pmd
, addr
, &ptl
);
2181 arch_enter_lazy_mmu_mode();
2183 BUG_ON(!pte_none(*pte
));
2184 if (!pfn_modify_allowed(pfn
, prot
)) {
2188 set_pte_at(mm
, addr
, pte
, pte_mkspecial(pfn_pte(pfn
, prot
)));
2190 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
2191 arch_leave_lazy_mmu_mode();
2192 pte_unmap_unlock(mapped_pte
, ptl
);
2196 static inline int remap_pmd_range(struct mm_struct
*mm
, pud_t
*pud
,
2197 unsigned long addr
, unsigned long end
,
2198 unsigned long pfn
, pgprot_t prot
)
2204 pfn
-= addr
>> PAGE_SHIFT
;
2205 pmd
= pmd_alloc(mm
, pud
, addr
);
2208 VM_BUG_ON(pmd_trans_huge(*pmd
));
2210 next
= pmd_addr_end(addr
, end
);
2211 err
= remap_pte_range(mm
, pmd
, addr
, next
,
2212 pfn
+ (addr
>> PAGE_SHIFT
), prot
);
2215 } while (pmd
++, addr
= next
, addr
!= end
);
2219 static inline int remap_pud_range(struct mm_struct
*mm
, p4d_t
*p4d
,
2220 unsigned long addr
, unsigned long end
,
2221 unsigned long pfn
, pgprot_t prot
)
2227 pfn
-= addr
>> PAGE_SHIFT
;
2228 pud
= pud_alloc(mm
, p4d
, addr
);
2232 next
= pud_addr_end(addr
, end
);
2233 err
= remap_pmd_range(mm
, pud
, addr
, next
,
2234 pfn
+ (addr
>> PAGE_SHIFT
), prot
);
2237 } while (pud
++, addr
= next
, addr
!= end
);
2241 static inline int remap_p4d_range(struct mm_struct
*mm
, pgd_t
*pgd
,
2242 unsigned long addr
, unsigned long end
,
2243 unsigned long pfn
, pgprot_t prot
)
2249 pfn
-= addr
>> PAGE_SHIFT
;
2250 p4d
= p4d_alloc(mm
, pgd
, addr
);
2254 next
= p4d_addr_end(addr
, end
);
2255 err
= remap_pud_range(mm
, p4d
, addr
, next
,
2256 pfn
+ (addr
>> PAGE_SHIFT
), prot
);
2259 } while (p4d
++, addr
= next
, addr
!= end
);
2264 * remap_pfn_range - remap kernel memory to userspace
2265 * @vma: user vma to map to
2266 * @addr: target page aligned user address to start at
2267 * @pfn: page frame number of kernel physical memory address
2268 * @size: size of mapping area
2269 * @prot: page protection flags for this mapping
2271 * Note: this is only safe if the mm semaphore is held when called.
2273 * Return: %0 on success, negative error code otherwise.
2275 int remap_pfn_range(struct vm_area_struct
*vma
, unsigned long addr
,
2276 unsigned long pfn
, unsigned long size
, pgprot_t prot
)
2280 unsigned long end
= addr
+ PAGE_ALIGN(size
);
2281 struct mm_struct
*mm
= vma
->vm_mm
;
2282 unsigned long remap_pfn
= pfn
;
2285 if (WARN_ON_ONCE(!PAGE_ALIGNED(addr
)))
2289 * Physically remapped pages are special. Tell the
2290 * rest of the world about it:
2291 * VM_IO tells people not to look at these pages
2292 * (accesses can have side effects).
2293 * VM_PFNMAP tells the core MM that the base pages are just
2294 * raw PFN mappings, and do not have a "struct page" associated
2297 * Disable vma merging and expanding with mremap().
2299 * Omit vma from core dump, even when VM_IO turned off.
2301 * There's a horrible special case to handle copy-on-write
2302 * behaviour that some programs depend on. We mark the "original"
2303 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2304 * See vm_normal_page() for details.
2306 if (is_cow_mapping(vma
->vm_flags
)) {
2307 if (addr
!= vma
->vm_start
|| end
!= vma
->vm_end
)
2309 vma
->vm_pgoff
= pfn
;
2312 err
= track_pfn_remap(vma
, &prot
, remap_pfn
, addr
, PAGE_ALIGN(size
));
2316 vma
->vm_flags
|= VM_IO
| VM_PFNMAP
| VM_DONTEXPAND
| VM_DONTDUMP
;
2318 BUG_ON(addr
>= end
);
2319 pfn
-= addr
>> PAGE_SHIFT
;
2320 pgd
= pgd_offset(mm
, addr
);
2321 flush_cache_range(vma
, addr
, end
);
2323 next
= pgd_addr_end(addr
, end
);
2324 err
= remap_p4d_range(mm
, pgd
, addr
, next
,
2325 pfn
+ (addr
>> PAGE_SHIFT
), prot
);
2328 } while (pgd
++, addr
= next
, addr
!= end
);
2331 untrack_pfn(vma
, remap_pfn
, PAGE_ALIGN(size
));
2335 EXPORT_SYMBOL(remap_pfn_range
);
2338 * vm_iomap_memory - remap memory to userspace
2339 * @vma: user vma to map to
2340 * @start: start of the physical memory to be mapped
2341 * @len: size of area
2343 * This is a simplified io_remap_pfn_range() for common driver use. The
2344 * driver just needs to give us the physical memory range to be mapped,
2345 * we'll figure out the rest from the vma information.
2347 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2348 * whatever write-combining details or similar.
2350 * Return: %0 on success, negative error code otherwise.
2352 int vm_iomap_memory(struct vm_area_struct
*vma
, phys_addr_t start
, unsigned long len
)
2354 unsigned long vm_len
, pfn
, pages
;
2356 /* Check that the physical memory area passed in looks valid */
2357 if (start
+ len
< start
)
2360 * You *really* shouldn't map things that aren't page-aligned,
2361 * but we've historically allowed it because IO memory might
2362 * just have smaller alignment.
2364 len
+= start
& ~PAGE_MASK
;
2365 pfn
= start
>> PAGE_SHIFT
;
2366 pages
= (len
+ ~PAGE_MASK
) >> PAGE_SHIFT
;
2367 if (pfn
+ pages
< pfn
)
2370 /* We start the mapping 'vm_pgoff' pages into the area */
2371 if (vma
->vm_pgoff
> pages
)
2373 pfn
+= vma
->vm_pgoff
;
2374 pages
-= vma
->vm_pgoff
;
2376 /* Can we fit all of the mapping? */
2377 vm_len
= vma
->vm_end
- vma
->vm_start
;
2378 if (vm_len
>> PAGE_SHIFT
> pages
)
2381 /* Ok, let it rip */
2382 return io_remap_pfn_range(vma
, vma
->vm_start
, pfn
, vm_len
, vma
->vm_page_prot
);
2384 EXPORT_SYMBOL(vm_iomap_memory
);
2386 static int apply_to_pte_range(struct mm_struct
*mm
, pmd_t
*pmd
,
2387 unsigned long addr
, unsigned long end
,
2388 pte_fn_t fn
, void *data
, bool create
,
2389 pgtbl_mod_mask
*mask
)
2391 pte_t
*pte
, *mapped_pte
;
2396 mapped_pte
= pte
= (mm
== &init_mm
) ?
2397 pte_alloc_kernel_track(pmd
, addr
, mask
) :
2398 pte_alloc_map_lock(mm
, pmd
, addr
, &ptl
);
2402 mapped_pte
= pte
= (mm
== &init_mm
) ?
2403 pte_offset_kernel(pmd
, addr
) :
2404 pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
2407 BUG_ON(pmd_huge(*pmd
));
2409 arch_enter_lazy_mmu_mode();
2413 if (create
|| !pte_none(*pte
)) {
2414 err
= fn(pte
++, addr
, data
);
2418 } while (addr
+= PAGE_SIZE
, addr
!= end
);
2420 *mask
|= PGTBL_PTE_MODIFIED
;
2422 arch_leave_lazy_mmu_mode();
2425 pte_unmap_unlock(mapped_pte
, ptl
);
2429 static int apply_to_pmd_range(struct mm_struct
*mm
, pud_t
*pud
,
2430 unsigned long addr
, unsigned long end
,
2431 pte_fn_t fn
, void *data
, bool create
,
2432 pgtbl_mod_mask
*mask
)
2438 BUG_ON(pud_huge(*pud
));
2441 pmd
= pmd_alloc_track(mm
, pud
, addr
, mask
);
2445 pmd
= pmd_offset(pud
, addr
);
2448 next
= pmd_addr_end(addr
, end
);
2449 if (create
|| !pmd_none_or_clear_bad(pmd
)) {
2450 err
= apply_to_pte_range(mm
, pmd
, addr
, next
, fn
, data
,
2455 } while (pmd
++, addr
= next
, addr
!= end
);
2459 static int apply_to_pud_range(struct mm_struct
*mm
, p4d_t
*p4d
,
2460 unsigned long addr
, unsigned long end
,
2461 pte_fn_t fn
, void *data
, bool create
,
2462 pgtbl_mod_mask
*mask
)
2469 pud
= pud_alloc_track(mm
, p4d
, addr
, mask
);
2473 pud
= pud_offset(p4d
, addr
);
2476 next
= pud_addr_end(addr
, end
);
2477 if (create
|| !pud_none_or_clear_bad(pud
)) {
2478 err
= apply_to_pmd_range(mm
, pud
, addr
, next
, fn
, data
,
2483 } while (pud
++, addr
= next
, addr
!= end
);
2487 static int apply_to_p4d_range(struct mm_struct
*mm
, pgd_t
*pgd
,
2488 unsigned long addr
, unsigned long end
,
2489 pte_fn_t fn
, void *data
, bool create
,
2490 pgtbl_mod_mask
*mask
)
2497 p4d
= p4d_alloc_track(mm
, pgd
, addr
, mask
);
2501 p4d
= p4d_offset(pgd
, addr
);
2504 next
= p4d_addr_end(addr
, end
);
2505 if (create
|| !p4d_none_or_clear_bad(p4d
)) {
2506 err
= apply_to_pud_range(mm
, p4d
, addr
, next
, fn
, data
,
2511 } while (p4d
++, addr
= next
, addr
!= end
);
2515 static int __apply_to_page_range(struct mm_struct
*mm
, unsigned long addr
,
2516 unsigned long size
, pte_fn_t fn
,
2517 void *data
, bool create
)
2520 unsigned long start
= addr
, next
;
2521 unsigned long end
= addr
+ size
;
2522 pgtbl_mod_mask mask
= 0;
2525 if (WARN_ON(addr
>= end
))
2528 pgd
= pgd_offset(mm
, addr
);
2530 next
= pgd_addr_end(addr
, end
);
2531 if (!create
&& pgd_none_or_clear_bad(pgd
))
2533 err
= apply_to_p4d_range(mm
, pgd
, addr
, next
, fn
, data
, create
, &mask
);
2536 } while (pgd
++, addr
= next
, addr
!= end
);
2538 if (mask
& ARCH_PAGE_TABLE_SYNC_MASK
)
2539 arch_sync_kernel_mappings(start
, start
+ size
);
2545 * Scan a region of virtual memory, filling in page tables as necessary
2546 * and calling a provided function on each leaf page table.
2548 int apply_to_page_range(struct mm_struct
*mm
, unsigned long addr
,
2549 unsigned long size
, pte_fn_t fn
, void *data
)
2551 return __apply_to_page_range(mm
, addr
, size
, fn
, data
, true);
2553 EXPORT_SYMBOL_GPL(apply_to_page_range
);
2556 * Scan a region of virtual memory, calling a provided function on
2557 * each leaf page table where it exists.
2559 * Unlike apply_to_page_range, this does _not_ fill in page tables
2560 * where they are absent.
2562 int apply_to_existing_page_range(struct mm_struct
*mm
, unsigned long addr
,
2563 unsigned long size
, pte_fn_t fn
, void *data
)
2565 return __apply_to_page_range(mm
, addr
, size
, fn
, data
, false);
2567 EXPORT_SYMBOL_GPL(apply_to_existing_page_range
);
2570 * handle_pte_fault chooses page fault handler according to an entry which was
2571 * read non-atomically. Before making any commitment, on those architectures
2572 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
2573 * parts, do_swap_page must check under lock before unmapping the pte and
2574 * proceeding (but do_wp_page is only called after already making such a check;
2575 * and do_anonymous_page can safely check later on).
2577 static inline int pte_unmap_same(struct mm_struct
*mm
, pmd_t
*pmd
,
2578 pte_t
*page_table
, pte_t orig_pte
)
2581 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPTION)
2582 if (sizeof(pte_t
) > sizeof(unsigned long)) {
2583 spinlock_t
*ptl
= pte_lockptr(mm
, pmd
);
2585 same
= pte_same(*page_table
, orig_pte
);
2589 pte_unmap(page_table
);
2593 static inline bool cow_user_page(struct page
*dst
, struct page
*src
,
2594 struct vm_fault
*vmf
)
2599 bool locked
= false;
2600 struct vm_area_struct
*vma
= vmf
->vma
;
2601 struct mm_struct
*mm
= vma
->vm_mm
;
2602 unsigned long addr
= vmf
->address
;
2605 copy_user_highpage(dst
, src
, addr
, vma
);
2610 * If the source page was a PFN mapping, we don't have
2611 * a "struct page" for it. We do a best-effort copy by
2612 * just copying from the original user address. If that
2613 * fails, we just zero-fill it. Live with it.
2615 kaddr
= kmap_atomic(dst
);
2616 uaddr
= (void __user
*)(addr
& PAGE_MASK
);
2619 * On architectures with software "accessed" bits, we would
2620 * take a double page fault, so mark it accessed here.
2622 if (arch_faults_on_old_pte() && !pte_young(vmf
->orig_pte
)) {
2625 vmf
->pte
= pte_offset_map_lock(mm
, vmf
->pmd
, addr
, &vmf
->ptl
);
2627 if (!likely(pte_same(*vmf
->pte
, vmf
->orig_pte
))) {
2629 * Other thread has already handled the fault
2630 * and update local tlb only
2632 update_mmu_tlb(vma
, addr
, vmf
->pte
);
2637 entry
= pte_mkyoung(vmf
->orig_pte
);
2638 if (ptep_set_access_flags(vma
, addr
, vmf
->pte
, entry
, 0))
2639 update_mmu_cache(vma
, addr
, vmf
->pte
);
2643 * This really shouldn't fail, because the page is there
2644 * in the page tables. But it might just be unreadable,
2645 * in which case we just give up and fill the result with
2648 if (__copy_from_user_inatomic(kaddr
, uaddr
, PAGE_SIZE
)) {
2652 /* Re-validate under PTL if the page is still mapped */
2653 vmf
->pte
= pte_offset_map_lock(mm
, vmf
->pmd
, addr
, &vmf
->ptl
);
2655 if (!likely(pte_same(*vmf
->pte
, vmf
->orig_pte
))) {
2656 /* The PTE changed under us, update local tlb */
2657 update_mmu_tlb(vma
, addr
, vmf
->pte
);
2663 * The same page can be mapped back since last copy attempt.
2664 * Try to copy again under PTL.
2666 if (__copy_from_user_inatomic(kaddr
, uaddr
, PAGE_SIZE
)) {
2668 * Give a warn in case there can be some obscure
2681 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
2682 kunmap_atomic(kaddr
);
2683 flush_dcache_page(dst
);
2688 static gfp_t
__get_fault_gfp_mask(struct vm_area_struct
*vma
)
2690 struct file
*vm_file
= vma
->vm_file
;
2693 return mapping_gfp_mask(vm_file
->f_mapping
) | __GFP_FS
| __GFP_IO
;
2696 * Special mappings (e.g. VDSO) do not have any file so fake
2697 * a default GFP_KERNEL for them.
2703 * Notify the address space that the page is about to become writable so that
2704 * it can prohibit this or wait for the page to get into an appropriate state.
2706 * We do this without the lock held, so that it can sleep if it needs to.
2708 static vm_fault_t
do_page_mkwrite(struct vm_fault
*vmf
)
2711 struct page
*page
= vmf
->page
;
2712 unsigned int old_flags
= vmf
->flags
;
2714 vmf
->flags
= FAULT_FLAG_WRITE
|FAULT_FLAG_MKWRITE
;
2716 if (vmf
->vma
->vm_file
&&
2717 IS_SWAPFILE(vmf
->vma
->vm_file
->f_mapping
->host
))
2718 return VM_FAULT_SIGBUS
;
2720 ret
= vmf
->vma
->vm_ops
->page_mkwrite(vmf
);
2721 /* Restore original flags so that caller is not surprised */
2722 vmf
->flags
= old_flags
;
2723 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
)))
2725 if (unlikely(!(ret
& VM_FAULT_LOCKED
))) {
2727 if (!page
->mapping
) {
2729 return 0; /* retry */
2731 ret
|= VM_FAULT_LOCKED
;
2733 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
2738 * Handle dirtying of a page in shared file mapping on a write fault.
2740 * The function expects the page to be locked and unlocks it.
2742 static vm_fault_t
fault_dirty_shared_page(struct vm_fault
*vmf
)
2744 struct vm_area_struct
*vma
= vmf
->vma
;
2745 struct address_space
*mapping
;
2746 struct page
*page
= vmf
->page
;
2748 bool page_mkwrite
= vma
->vm_ops
&& vma
->vm_ops
->page_mkwrite
;
2750 dirtied
= set_page_dirty(page
);
2751 VM_BUG_ON_PAGE(PageAnon(page
), page
);
2753 * Take a local copy of the address_space - page.mapping may be zeroed
2754 * by truncate after unlock_page(). The address_space itself remains
2755 * pinned by vma->vm_file's reference. We rely on unlock_page()'s
2756 * release semantics to prevent the compiler from undoing this copying.
2758 mapping
= page_rmapping(page
);
2762 file_update_time(vma
->vm_file
);
2765 * Throttle page dirtying rate down to writeback speed.
2767 * mapping may be NULL here because some device drivers do not
2768 * set page.mapping but still dirty their pages
2770 * Drop the mmap_lock before waiting on IO, if we can. The file
2771 * is pinning the mapping, as per above.
2773 if ((dirtied
|| page_mkwrite
) && mapping
) {
2776 fpin
= maybe_unlock_mmap_for_io(vmf
, NULL
);
2777 balance_dirty_pages_ratelimited(mapping
);
2780 return VM_FAULT_RETRY
;
2788 * Handle write page faults for pages that can be reused in the current vma
2790 * This can happen either due to the mapping being with the VM_SHARED flag,
2791 * or due to us being the last reference standing to the page. In either
2792 * case, all we need to do here is to mark the page as writable and update
2793 * any related book-keeping.
2795 static inline void wp_page_reuse(struct vm_fault
*vmf
)
2796 __releases(vmf
->ptl
)
2798 struct vm_area_struct
*vma
= vmf
->vma
;
2799 struct page
*page
= vmf
->page
;
2802 * Clear the pages cpupid information as the existing
2803 * information potentially belongs to a now completely
2804 * unrelated process.
2807 page_cpupid_xchg_last(page
, (1 << LAST_CPUPID_SHIFT
) - 1);
2809 flush_cache_page(vma
, vmf
->address
, pte_pfn(vmf
->orig_pte
));
2810 entry
= pte_mkyoung(vmf
->orig_pte
);
2811 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
2812 if (ptep_set_access_flags(vma
, vmf
->address
, vmf
->pte
, entry
, 1))
2813 update_mmu_cache(vma
, vmf
->address
, vmf
->pte
);
2814 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
2815 count_vm_event(PGREUSE
);
2819 * Handle the case of a page which we actually need to copy to a new page.
2821 * Called with mmap_lock locked and the old page referenced, but
2822 * without the ptl held.
2824 * High level logic flow:
2826 * - Allocate a page, copy the content of the old page to the new one.
2827 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2828 * - Take the PTL. If the pte changed, bail out and release the allocated page
2829 * - If the pte is still the way we remember it, update the page table and all
2830 * relevant references. This includes dropping the reference the page-table
2831 * held to the old page, as well as updating the rmap.
2832 * - In any case, unlock the PTL and drop the reference we took to the old page.
2834 static vm_fault_t
wp_page_copy(struct vm_fault
*vmf
)
2836 struct vm_area_struct
*vma
= vmf
->vma
;
2837 struct mm_struct
*mm
= vma
->vm_mm
;
2838 struct page
*old_page
= vmf
->page
;
2839 struct page
*new_page
= NULL
;
2841 int page_copied
= 0;
2842 struct mmu_notifier_range range
;
2844 if (unlikely(anon_vma_prepare(vma
)))
2847 if (is_zero_pfn(pte_pfn(vmf
->orig_pte
))) {
2848 new_page
= alloc_zeroed_user_highpage_movable(vma
,
2853 new_page
= alloc_page_vma(GFP_HIGHUSER_MOVABLE
, vma
,
2858 if (!cow_user_page(new_page
, old_page
, vmf
)) {
2860 * COW failed, if the fault was solved by other,
2861 * it's fine. If not, userspace would re-fault on
2862 * the same address and we will handle the fault
2863 * from the second attempt.
2872 if (mem_cgroup_charge(new_page
, mm
, GFP_KERNEL
))
2874 cgroup_throttle_swaprate(new_page
, GFP_KERNEL
);
2876 __SetPageUptodate(new_page
);
2878 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, vma
, mm
,
2879 vmf
->address
& PAGE_MASK
,
2880 (vmf
->address
& PAGE_MASK
) + PAGE_SIZE
);
2881 mmu_notifier_invalidate_range_start(&range
);
2884 * Re-check the pte - we dropped the lock
2886 vmf
->pte
= pte_offset_map_lock(mm
, vmf
->pmd
, vmf
->address
, &vmf
->ptl
);
2887 if (likely(pte_same(*vmf
->pte
, vmf
->orig_pte
))) {
2889 if (!PageAnon(old_page
)) {
2890 dec_mm_counter_fast(mm
,
2891 mm_counter_file(old_page
));
2892 inc_mm_counter_fast(mm
, MM_ANONPAGES
);
2895 inc_mm_counter_fast(mm
, MM_ANONPAGES
);
2897 flush_cache_page(vma
, vmf
->address
, pte_pfn(vmf
->orig_pte
));
2898 entry
= mk_pte(new_page
, vma
->vm_page_prot
);
2899 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
2902 * Clear the pte entry and flush it first, before updating the
2903 * pte with the new entry, to keep TLBs on different CPUs in
2904 * sync. This code used to set the new PTE then flush TLBs, but
2905 * that left a window where the new PTE could be loaded into
2906 * some TLBs while the old PTE remains in others.
2908 ptep_clear_flush_notify(vma
, vmf
->address
, vmf
->pte
);
2909 page_add_new_anon_rmap(new_page
, vma
, vmf
->address
, false);
2910 lru_cache_add_inactive_or_unevictable(new_page
, vma
);
2912 * We call the notify macro here because, when using secondary
2913 * mmu page tables (such as kvm shadow page tables), we want the
2914 * new page to be mapped directly into the secondary page table.
2916 set_pte_at_notify(mm
, vmf
->address
, vmf
->pte
, entry
);
2917 update_mmu_cache(vma
, vmf
->address
, vmf
->pte
);
2920 * Only after switching the pte to the new page may
2921 * we remove the mapcount here. Otherwise another
2922 * process may come and find the rmap count decremented
2923 * before the pte is switched to the new page, and
2924 * "reuse" the old page writing into it while our pte
2925 * here still points into it and can be read by other
2928 * The critical issue is to order this
2929 * page_remove_rmap with the ptp_clear_flush above.
2930 * Those stores are ordered by (if nothing else,)
2931 * the barrier present in the atomic_add_negative
2932 * in page_remove_rmap.
2934 * Then the TLB flush in ptep_clear_flush ensures that
2935 * no process can access the old page before the
2936 * decremented mapcount is visible. And the old page
2937 * cannot be reused until after the decremented
2938 * mapcount is visible. So transitively, TLBs to
2939 * old page will be flushed before it can be reused.
2941 page_remove_rmap(old_page
, false);
2944 /* Free the old page.. */
2945 new_page
= old_page
;
2948 update_mmu_tlb(vma
, vmf
->address
, vmf
->pte
);
2954 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
2956 * No need to double call mmu_notifier->invalidate_range() callback as
2957 * the above ptep_clear_flush_notify() did already call it.
2959 mmu_notifier_invalidate_range_only_end(&range
);
2962 * Don't let another task, with possibly unlocked vma,
2963 * keep the mlocked page.
2965 if (page_copied
&& (vma
->vm_flags
& VM_LOCKED
)) {
2966 lock_page(old_page
); /* LRU manipulation */
2967 if (PageMlocked(old_page
))
2968 munlock_vma_page(old_page
);
2969 unlock_page(old_page
);
2973 return page_copied
? VM_FAULT_WRITE
: 0;
2979 return VM_FAULT_OOM
;
2983 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
2984 * writeable once the page is prepared
2986 * @vmf: structure describing the fault
2988 * This function handles all that is needed to finish a write page fault in a
2989 * shared mapping due to PTE being read-only once the mapped page is prepared.
2990 * It handles locking of PTE and modifying it.
2992 * The function expects the page to be locked or other protection against
2993 * concurrent faults / writeback (such as DAX radix tree locks).
2995 * Return: %VM_FAULT_WRITE on success, %0 when PTE got changed before
2996 * we acquired PTE lock.
2998 vm_fault_t
finish_mkwrite_fault(struct vm_fault
*vmf
)
3000 WARN_ON_ONCE(!(vmf
->vma
->vm_flags
& VM_SHARED
));
3001 vmf
->pte
= pte_offset_map_lock(vmf
->vma
->vm_mm
, vmf
->pmd
, vmf
->address
,
3004 * We might have raced with another page fault while we released the
3005 * pte_offset_map_lock.
3007 if (!pte_same(*vmf
->pte
, vmf
->orig_pte
)) {
3008 update_mmu_tlb(vmf
->vma
, vmf
->address
, vmf
->pte
);
3009 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
3010 return VM_FAULT_NOPAGE
;
3017 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
3020 static vm_fault_t
wp_pfn_shared(struct vm_fault
*vmf
)
3022 struct vm_area_struct
*vma
= vmf
->vma
;
3024 if (vma
->vm_ops
&& vma
->vm_ops
->pfn_mkwrite
) {
3027 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
3028 vmf
->flags
|= FAULT_FLAG_MKWRITE
;
3029 ret
= vma
->vm_ops
->pfn_mkwrite(vmf
);
3030 if (ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
))
3032 return finish_mkwrite_fault(vmf
);
3035 return VM_FAULT_WRITE
;
3038 static vm_fault_t
wp_page_shared(struct vm_fault
*vmf
)
3039 __releases(vmf
->ptl
)
3041 struct vm_area_struct
*vma
= vmf
->vma
;
3042 vm_fault_t ret
= VM_FAULT_WRITE
;
3044 get_page(vmf
->page
);
3046 if (vma
->vm_ops
&& vma
->vm_ops
->page_mkwrite
) {
3049 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
3050 tmp
= do_page_mkwrite(vmf
);
3051 if (unlikely(!tmp
|| (tmp
&
3052 (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
)))) {
3053 put_page(vmf
->page
);
3056 tmp
= finish_mkwrite_fault(vmf
);
3057 if (unlikely(tmp
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
))) {
3058 unlock_page(vmf
->page
);
3059 put_page(vmf
->page
);
3064 lock_page(vmf
->page
);
3066 ret
|= fault_dirty_shared_page(vmf
);
3067 put_page(vmf
->page
);
3073 * This routine handles present pages, when users try to write
3074 * to a shared page. It is done by copying the page to a new address
3075 * and decrementing the shared-page counter for the old page.
3077 * Note that this routine assumes that the protection checks have been
3078 * done by the caller (the low-level page fault routine in most cases).
3079 * Thus we can safely just mark it writable once we've done any necessary
3082 * We also mark the page dirty at this point even though the page will
3083 * change only once the write actually happens. This avoids a few races,
3084 * and potentially makes it more efficient.
3086 * We enter with non-exclusive mmap_lock (to exclude vma changes,
3087 * but allow concurrent faults), with pte both mapped and locked.
3088 * We return with mmap_lock still held, but pte unmapped and unlocked.
3090 static vm_fault_t
do_wp_page(struct vm_fault
*vmf
)
3091 __releases(vmf
->ptl
)
3093 struct vm_area_struct
*vma
= vmf
->vma
;
3095 if (userfaultfd_pte_wp(vma
, *vmf
->pte
)) {
3096 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
3097 return handle_userfault(vmf
, VM_UFFD_WP
);
3101 * Userfaultfd write-protect can defer flushes. Ensure the TLB
3102 * is flushed in this case before copying.
3104 if (unlikely(userfaultfd_wp(vmf
->vma
) &&
3105 mm_tlb_flush_pending(vmf
->vma
->vm_mm
)))
3106 flush_tlb_page(vmf
->vma
, vmf
->address
);
3108 vmf
->page
= vm_normal_page(vma
, vmf
->address
, vmf
->orig_pte
);
3111 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
3114 * We should not cow pages in a shared writeable mapping.
3115 * Just mark the pages writable and/or call ops->pfn_mkwrite.
3117 if ((vma
->vm_flags
& (VM_WRITE
|VM_SHARED
)) ==
3118 (VM_WRITE
|VM_SHARED
))
3119 return wp_pfn_shared(vmf
);
3121 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
3122 return wp_page_copy(vmf
);
3126 * Take out anonymous pages first, anonymous shared vmas are
3127 * not dirty accountable.
3129 if (PageAnon(vmf
->page
)) {
3130 struct page
*page
= vmf
->page
;
3132 /* PageKsm() doesn't necessarily raise the page refcount */
3133 if (PageKsm(page
) || page_count(page
) != 1)
3135 if (!trylock_page(page
))
3137 if (PageKsm(page
) || page_mapcount(page
) != 1 || page_count(page
) != 1) {
3142 * Ok, we've got the only map reference, and the only
3143 * page count reference, and the page is locked,
3144 * it's dark out, and we're wearing sunglasses. Hit it.
3148 return VM_FAULT_WRITE
;
3149 } else if (unlikely((vma
->vm_flags
& (VM_WRITE
|VM_SHARED
)) ==
3150 (VM_WRITE
|VM_SHARED
))) {
3151 return wp_page_shared(vmf
);
3155 * Ok, we need to copy. Oh, well..
3157 get_page(vmf
->page
);
3159 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
3160 return wp_page_copy(vmf
);
3163 static void unmap_mapping_range_vma(struct vm_area_struct
*vma
,
3164 unsigned long start_addr
, unsigned long end_addr
,
3165 struct zap_details
*details
)
3167 zap_page_range_single(vma
, start_addr
, end_addr
- start_addr
, details
);
3170 static inline void unmap_mapping_range_tree(struct rb_root_cached
*root
,
3171 struct zap_details
*details
)
3173 struct vm_area_struct
*vma
;
3174 pgoff_t vba
, vea
, zba
, zea
;
3176 vma_interval_tree_foreach(vma
, root
,
3177 details
->first_index
, details
->last_index
) {
3179 vba
= vma
->vm_pgoff
;
3180 vea
= vba
+ vma_pages(vma
) - 1;
3181 zba
= details
->first_index
;
3184 zea
= details
->last_index
;
3188 unmap_mapping_range_vma(vma
,
3189 ((zba
- vba
) << PAGE_SHIFT
) + vma
->vm_start
,
3190 ((zea
- vba
+ 1) << PAGE_SHIFT
) + vma
->vm_start
,
3196 * unmap_mapping_pages() - Unmap pages from processes.
3197 * @mapping: The address space containing pages to be unmapped.
3198 * @start: Index of first page to be unmapped.
3199 * @nr: Number of pages to be unmapped. 0 to unmap to end of file.
3200 * @even_cows: Whether to unmap even private COWed pages.
3202 * Unmap the pages in this address space from any userspace process which
3203 * has them mmaped. Generally, you want to remove COWed pages as well when
3204 * a file is being truncated, but not when invalidating pages from the page
3207 void unmap_mapping_pages(struct address_space
*mapping
, pgoff_t start
,
3208 pgoff_t nr
, bool even_cows
)
3210 struct zap_details details
= { };
3212 details
.check_mapping
= even_cows
? NULL
: mapping
;
3213 details
.first_index
= start
;
3214 details
.last_index
= start
+ nr
- 1;
3215 if (details
.last_index
< details
.first_index
)
3216 details
.last_index
= ULONG_MAX
;
3218 i_mmap_lock_write(mapping
);
3219 if (unlikely(!RB_EMPTY_ROOT(&mapping
->i_mmap
.rb_root
)))
3220 unmap_mapping_range_tree(&mapping
->i_mmap
, &details
);
3221 i_mmap_unlock_write(mapping
);
3225 * unmap_mapping_range - unmap the portion of all mmaps in the specified
3226 * address_space corresponding to the specified byte range in the underlying
3229 * @mapping: the address space containing mmaps to be unmapped.
3230 * @holebegin: byte in first page to unmap, relative to the start of
3231 * the underlying file. This will be rounded down to a PAGE_SIZE
3232 * boundary. Note that this is different from truncate_pagecache(), which
3233 * must keep the partial page. In contrast, we must get rid of
3235 * @holelen: size of prospective hole in bytes. This will be rounded
3236 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
3238 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
3239 * but 0 when invalidating pagecache, don't throw away private data.
3241 void unmap_mapping_range(struct address_space
*mapping
,
3242 loff_t
const holebegin
, loff_t
const holelen
, int even_cows
)
3244 pgoff_t hba
= holebegin
>> PAGE_SHIFT
;
3245 pgoff_t hlen
= (holelen
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
3247 /* Check for overflow. */
3248 if (sizeof(holelen
) > sizeof(hlen
)) {
3250 (holebegin
+ holelen
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
3251 if (holeend
& ~(long long)ULONG_MAX
)
3252 hlen
= ULONG_MAX
- hba
+ 1;
3255 unmap_mapping_pages(mapping
, hba
, hlen
, even_cows
);
3257 EXPORT_SYMBOL(unmap_mapping_range
);
3260 * We enter with non-exclusive mmap_lock (to exclude vma changes,
3261 * but allow concurrent faults), and pte mapped but not yet locked.
3262 * We return with pte unmapped and unlocked.
3264 * We return with the mmap_lock locked or unlocked in the same cases
3265 * as does filemap_fault().
3267 vm_fault_t
do_swap_page(struct vm_fault
*vmf
)
3269 struct vm_area_struct
*vma
= vmf
->vma
;
3270 struct page
*page
= NULL
, *swapcache
;
3276 void *shadow
= NULL
;
3278 if (!pte_unmap_same(vma
->vm_mm
, vmf
->pmd
, vmf
->pte
, vmf
->orig_pte
))
3281 entry
= pte_to_swp_entry(vmf
->orig_pte
);
3282 if (unlikely(non_swap_entry(entry
))) {
3283 if (is_migration_entry(entry
)) {
3284 migration_entry_wait(vma
->vm_mm
, vmf
->pmd
,
3286 } else if (is_device_private_entry(entry
)) {
3287 vmf
->page
= device_private_entry_to_page(entry
);
3288 ret
= vmf
->page
->pgmap
->ops
->migrate_to_ram(vmf
);
3289 } else if (is_hwpoison_entry(entry
)) {
3290 ret
= VM_FAULT_HWPOISON
;
3292 print_bad_pte(vma
, vmf
->address
, vmf
->orig_pte
, NULL
);
3293 ret
= VM_FAULT_SIGBUS
;
3299 delayacct_set_flag(DELAYACCT_PF_SWAPIN
);
3300 page
= lookup_swap_cache(entry
, vma
, vmf
->address
);
3304 struct swap_info_struct
*si
= swp_swap_info(entry
);
3306 if (data_race(si
->flags
& SWP_SYNCHRONOUS_IO
) &&
3307 __swap_count(entry
) == 1) {
3308 /* skip swapcache */
3309 page
= alloc_page_vma(GFP_HIGHUSER_MOVABLE
, vma
,
3314 __SetPageLocked(page
);
3315 __SetPageSwapBacked(page
);
3316 set_page_private(page
, entry
.val
);
3318 /* Tell memcg to use swap ownership records */
3319 SetPageSwapCache(page
);
3320 err
= mem_cgroup_charge(page
, vma
->vm_mm
,
3322 ClearPageSwapCache(page
);
3328 shadow
= get_shadow_from_swap_cache(entry
);
3330 workingset_refault(page
, shadow
);
3332 lru_cache_add(page
);
3333 swap_readpage(page
, true);
3336 page
= swapin_readahead(entry
, GFP_HIGHUSER_MOVABLE
,
3343 * Back out if somebody else faulted in this pte
3344 * while we released the pte lock.
3346 vmf
->pte
= pte_offset_map_lock(vma
->vm_mm
, vmf
->pmd
,
3347 vmf
->address
, &vmf
->ptl
);
3348 if (likely(pte_same(*vmf
->pte
, vmf
->orig_pte
)))
3350 delayacct_clear_flag(DELAYACCT_PF_SWAPIN
);
3354 /* Had to read the page from swap area: Major fault */
3355 ret
= VM_FAULT_MAJOR
;
3356 count_vm_event(PGMAJFAULT
);
3357 count_memcg_event_mm(vma
->vm_mm
, PGMAJFAULT
);
3358 } else if (PageHWPoison(page
)) {
3360 * hwpoisoned dirty swapcache pages are kept for killing
3361 * owner processes (which may be unknown at hwpoison time)
3363 ret
= VM_FAULT_HWPOISON
;
3364 delayacct_clear_flag(DELAYACCT_PF_SWAPIN
);
3368 locked
= lock_page_or_retry(page
, vma
->vm_mm
, vmf
->flags
);
3370 delayacct_clear_flag(DELAYACCT_PF_SWAPIN
);
3372 ret
|= VM_FAULT_RETRY
;
3377 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
3378 * release the swapcache from under us. The page pin, and pte_same
3379 * test below, are not enough to exclude that. Even if it is still
3380 * swapcache, we need to check that the page's swap has not changed.
3382 if (unlikely((!PageSwapCache(page
) ||
3383 page_private(page
) != entry
.val
)) && swapcache
)
3386 page
= ksm_might_need_to_copy(page
, vma
, vmf
->address
);
3387 if (unlikely(!page
)) {
3393 cgroup_throttle_swaprate(page
, GFP_KERNEL
);
3396 * Back out if somebody else already faulted in this pte.
3398 vmf
->pte
= pte_offset_map_lock(vma
->vm_mm
, vmf
->pmd
, vmf
->address
,
3400 if (unlikely(!pte_same(*vmf
->pte
, vmf
->orig_pte
)))
3403 if (unlikely(!PageUptodate(page
))) {
3404 ret
= VM_FAULT_SIGBUS
;
3409 * The page isn't present yet, go ahead with the fault.
3411 * Be careful about the sequence of operations here.
3412 * To get its accounting right, reuse_swap_page() must be called
3413 * while the page is counted on swap but not yet in mapcount i.e.
3414 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
3415 * must be called after the swap_free(), or it will never succeed.
3418 inc_mm_counter_fast(vma
->vm_mm
, MM_ANONPAGES
);
3419 dec_mm_counter_fast(vma
->vm_mm
, MM_SWAPENTS
);
3420 pte
= mk_pte(page
, vma
->vm_page_prot
);
3421 if ((vmf
->flags
& FAULT_FLAG_WRITE
) && reuse_swap_page(page
, NULL
)) {
3422 pte
= maybe_mkwrite(pte_mkdirty(pte
), vma
);
3423 vmf
->flags
&= ~FAULT_FLAG_WRITE
;
3424 ret
|= VM_FAULT_WRITE
;
3425 exclusive
= RMAP_EXCLUSIVE
;
3427 flush_icache_page(vma
, page
);
3428 if (pte_swp_soft_dirty(vmf
->orig_pte
))
3429 pte
= pte_mksoft_dirty(pte
);
3430 if (pte_swp_uffd_wp(vmf
->orig_pte
)) {
3431 pte
= pte_mkuffd_wp(pte
);
3432 pte
= pte_wrprotect(pte
);
3434 set_pte_at(vma
->vm_mm
, vmf
->address
, vmf
->pte
, pte
);
3435 arch_do_swap_page(vma
->vm_mm
, vma
, vmf
->address
, pte
, vmf
->orig_pte
);
3436 vmf
->orig_pte
= pte
;
3438 /* ksm created a completely new copy */
3439 if (unlikely(page
!= swapcache
&& swapcache
)) {
3440 page_add_new_anon_rmap(page
, vma
, vmf
->address
, false);
3441 lru_cache_add_inactive_or_unevictable(page
, vma
);
3443 do_page_add_anon_rmap(page
, vma
, vmf
->address
, exclusive
);
3447 if (mem_cgroup_swap_full(page
) ||
3448 (vma
->vm_flags
& VM_LOCKED
) || PageMlocked(page
))
3449 try_to_free_swap(page
);
3451 if (page
!= swapcache
&& swapcache
) {
3453 * Hold the lock to avoid the swap entry to be reused
3454 * until we take the PT lock for the pte_same() check
3455 * (to avoid false positives from pte_same). For
3456 * further safety release the lock after the swap_free
3457 * so that the swap count won't change under a
3458 * parallel locked swapcache.
3460 unlock_page(swapcache
);
3461 put_page(swapcache
);
3464 if (vmf
->flags
& FAULT_FLAG_WRITE
) {
3465 ret
|= do_wp_page(vmf
);
3466 if (ret
& VM_FAULT_ERROR
)
3467 ret
&= VM_FAULT_ERROR
;
3471 /* No need to invalidate - it was non-present before */
3472 update_mmu_cache(vma
, vmf
->address
, vmf
->pte
);
3474 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
3478 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
3483 if (page
!= swapcache
&& swapcache
) {
3484 unlock_page(swapcache
);
3485 put_page(swapcache
);
3491 * We enter with non-exclusive mmap_lock (to exclude vma changes,
3492 * but allow concurrent faults), and pte mapped but not yet locked.
3493 * We return with mmap_lock still held, but pte unmapped and unlocked.
3495 static vm_fault_t
do_anonymous_page(struct vm_fault
*vmf
)
3497 struct vm_area_struct
*vma
= vmf
->vma
;
3502 /* File mapping without ->vm_ops ? */
3503 if (vma
->vm_flags
& VM_SHARED
)
3504 return VM_FAULT_SIGBUS
;
3507 * Use pte_alloc() instead of pte_alloc_map(). We can't run
3508 * pte_offset_map() on pmds where a huge pmd might be created
3509 * from a different thread.
3511 * pte_alloc_map() is safe to use under mmap_write_lock(mm) or when
3512 * parallel threads are excluded by other means.
3514 * Here we only have mmap_read_lock(mm).
3516 if (pte_alloc(vma
->vm_mm
, vmf
->pmd
))
3517 return VM_FAULT_OOM
;
3519 /* See comment in handle_pte_fault() */
3520 if (unlikely(pmd_trans_unstable(vmf
->pmd
)))
3523 /* Use the zero-page for reads */
3524 if (!(vmf
->flags
& FAULT_FLAG_WRITE
) &&
3525 !mm_forbids_zeropage(vma
->vm_mm
)) {
3526 entry
= pte_mkspecial(pfn_pte(my_zero_pfn(vmf
->address
),
3527 vma
->vm_page_prot
));
3528 vmf
->pte
= pte_offset_map_lock(vma
->vm_mm
, vmf
->pmd
,
3529 vmf
->address
, &vmf
->ptl
);
3530 if (!pte_none(*vmf
->pte
)) {
3531 update_mmu_tlb(vma
, vmf
->address
, vmf
->pte
);
3534 ret
= check_stable_address_space(vma
->vm_mm
);
3537 /* Deliver the page fault to userland, check inside PT lock */
3538 if (userfaultfd_missing(vma
)) {
3539 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
3540 return handle_userfault(vmf
, VM_UFFD_MISSING
);
3545 /* Allocate our own private page. */
3546 if (unlikely(anon_vma_prepare(vma
)))
3548 page
= alloc_zeroed_user_highpage_movable(vma
, vmf
->address
);
3552 if (mem_cgroup_charge(page
, vma
->vm_mm
, GFP_KERNEL
))
3554 cgroup_throttle_swaprate(page
, GFP_KERNEL
);
3557 * The memory barrier inside __SetPageUptodate makes sure that
3558 * preceding stores to the page contents become visible before
3559 * the set_pte_at() write.
3561 __SetPageUptodate(page
);
3563 entry
= mk_pte(page
, vma
->vm_page_prot
);
3564 if (vma
->vm_flags
& VM_WRITE
)
3565 entry
= pte_mkwrite(pte_mkdirty(entry
));
3567 vmf
->pte
= pte_offset_map_lock(vma
->vm_mm
, vmf
->pmd
, vmf
->address
,
3569 if (!pte_none(*vmf
->pte
)) {
3570 update_mmu_cache(vma
, vmf
->address
, vmf
->pte
);
3574 ret
= check_stable_address_space(vma
->vm_mm
);
3578 /* Deliver the page fault to userland, check inside PT lock */
3579 if (userfaultfd_missing(vma
)) {
3580 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
3582 return handle_userfault(vmf
, VM_UFFD_MISSING
);
3585 inc_mm_counter_fast(vma
->vm_mm
, MM_ANONPAGES
);
3586 page_add_new_anon_rmap(page
, vma
, vmf
->address
, false);
3587 lru_cache_add_inactive_or_unevictable(page
, vma
);
3589 set_pte_at(vma
->vm_mm
, vmf
->address
, vmf
->pte
, entry
);
3591 /* No need to invalidate - it was non-present before */
3592 update_mmu_cache(vma
, vmf
->address
, vmf
->pte
);
3594 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
3602 return VM_FAULT_OOM
;
3606 * The mmap_lock must have been held on entry, and may have been
3607 * released depending on flags and vma->vm_ops->fault() return value.
3608 * See filemap_fault() and __lock_page_retry().
3610 static vm_fault_t
__do_fault(struct vm_fault
*vmf
)
3612 struct vm_area_struct
*vma
= vmf
->vma
;
3616 * Preallocate pte before we take page_lock because this might lead to
3617 * deadlocks for memcg reclaim which waits for pages under writeback:
3619 * SetPageWriteback(A)
3625 * wait_on_page_writeback(A)
3626 * SetPageWriteback(B)
3628 * # flush A, B to clear the writeback
3630 if (pmd_none(*vmf
->pmd
) && !vmf
->prealloc_pte
) {
3631 vmf
->prealloc_pte
= pte_alloc_one(vma
->vm_mm
);
3632 if (!vmf
->prealloc_pte
)
3633 return VM_FAULT_OOM
;
3634 smp_wmb(); /* See comment in __pte_alloc() */
3637 ret
= vma
->vm_ops
->fault(vmf
);
3638 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
| VM_FAULT_RETRY
|
3639 VM_FAULT_DONE_COW
)))
3642 if (unlikely(PageHWPoison(vmf
->page
))) {
3643 if (ret
& VM_FAULT_LOCKED
)
3644 unlock_page(vmf
->page
);
3645 put_page(vmf
->page
);
3647 return VM_FAULT_HWPOISON
;
3650 if (unlikely(!(ret
& VM_FAULT_LOCKED
)))
3651 lock_page(vmf
->page
);
3653 VM_BUG_ON_PAGE(!PageLocked(vmf
->page
), vmf
->page
);
3658 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3659 static void deposit_prealloc_pte(struct vm_fault
*vmf
)
3661 struct vm_area_struct
*vma
= vmf
->vma
;
3663 pgtable_trans_huge_deposit(vma
->vm_mm
, vmf
->pmd
, vmf
->prealloc_pte
);
3665 * We are going to consume the prealloc table,
3666 * count that as nr_ptes.
3668 mm_inc_nr_ptes(vma
->vm_mm
);
3669 vmf
->prealloc_pte
= NULL
;
3672 vm_fault_t
do_set_pmd(struct vm_fault
*vmf
, struct page
*page
)
3674 struct vm_area_struct
*vma
= vmf
->vma
;
3675 bool write
= vmf
->flags
& FAULT_FLAG_WRITE
;
3676 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
3679 vm_fault_t ret
= VM_FAULT_FALLBACK
;
3681 if (!transhuge_vma_suitable(vma
, haddr
))
3684 page
= compound_head(page
);
3685 if (compound_order(page
) != HPAGE_PMD_ORDER
)
3689 * Archs like ppc64 need additonal space to store information
3690 * related to pte entry. Use the preallocated table for that.
3692 if (arch_needs_pgtable_deposit() && !vmf
->prealloc_pte
) {
3693 vmf
->prealloc_pte
= pte_alloc_one(vma
->vm_mm
);
3694 if (!vmf
->prealloc_pte
)
3695 return VM_FAULT_OOM
;
3696 smp_wmb(); /* See comment in __pte_alloc() */
3699 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
3700 if (unlikely(!pmd_none(*vmf
->pmd
)))
3703 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
3704 flush_icache_page(vma
, page
+ i
);
3706 entry
= mk_huge_pmd(page
, vma
->vm_page_prot
);
3708 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
3710 add_mm_counter(vma
->vm_mm
, mm_counter_file(page
), HPAGE_PMD_NR
);
3711 page_add_file_rmap(page
, true);
3713 * deposit and withdraw with pmd lock held
3715 if (arch_needs_pgtable_deposit())
3716 deposit_prealloc_pte(vmf
);
3718 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, entry
);
3720 update_mmu_cache_pmd(vma
, haddr
, vmf
->pmd
);
3722 /* fault is handled */
3724 count_vm_event(THP_FILE_MAPPED
);
3726 spin_unlock(vmf
->ptl
);
3730 vm_fault_t
do_set_pmd(struct vm_fault
*vmf
, struct page
*page
)
3732 return VM_FAULT_FALLBACK
;
3736 void do_set_pte(struct vm_fault
*vmf
, struct page
*page
, unsigned long addr
)
3738 struct vm_area_struct
*vma
= vmf
->vma
;
3739 bool write
= vmf
->flags
& FAULT_FLAG_WRITE
;
3740 bool prefault
= vmf
->address
!= addr
;
3743 flush_icache_page(vma
, page
);
3744 entry
= mk_pte(page
, vma
->vm_page_prot
);
3746 if (prefault
&& arch_wants_old_prefaulted_pte())
3747 entry
= pte_mkold(entry
);
3750 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
3751 /* copy-on-write page */
3752 if (write
&& !(vma
->vm_flags
& VM_SHARED
)) {
3753 inc_mm_counter_fast(vma
->vm_mm
, MM_ANONPAGES
);
3754 page_add_new_anon_rmap(page
, vma
, addr
, false);
3755 lru_cache_add_inactive_or_unevictable(page
, vma
);
3757 inc_mm_counter_fast(vma
->vm_mm
, mm_counter_file(page
));
3758 page_add_file_rmap(page
, false);
3760 set_pte_at(vma
->vm_mm
, addr
, vmf
->pte
, entry
);
3764 * finish_fault - finish page fault once we have prepared the page to fault
3766 * @vmf: structure describing the fault
3768 * This function handles all that is needed to finish a page fault once the
3769 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
3770 * given page, adds reverse page mapping, handles memcg charges and LRU
3773 * The function expects the page to be locked and on success it consumes a
3774 * reference of a page being mapped (for the PTE which maps it).
3776 * Return: %0 on success, %VM_FAULT_ code in case of error.
3778 vm_fault_t
finish_fault(struct vm_fault
*vmf
)
3780 struct vm_area_struct
*vma
= vmf
->vma
;
3784 /* Did we COW the page? */
3785 if ((vmf
->flags
& FAULT_FLAG_WRITE
) && !(vma
->vm_flags
& VM_SHARED
))
3786 page
= vmf
->cow_page
;
3791 * check even for read faults because we might have lost our CoWed
3794 if (!(vma
->vm_flags
& VM_SHARED
)) {
3795 ret
= check_stable_address_space(vma
->vm_mm
);
3800 if (pmd_none(*vmf
->pmd
)) {
3801 if (PageTransCompound(page
)) {
3802 ret
= do_set_pmd(vmf
, page
);
3803 if (ret
!= VM_FAULT_FALLBACK
)
3807 if (unlikely(pte_alloc(vma
->vm_mm
, vmf
->pmd
)))
3808 return VM_FAULT_OOM
;
3811 /* See comment in handle_pte_fault() */
3812 if (pmd_devmap_trans_unstable(vmf
->pmd
))
3815 vmf
->pte
= pte_offset_map_lock(vma
->vm_mm
, vmf
->pmd
,
3816 vmf
->address
, &vmf
->ptl
);
3818 /* Re-check under ptl */
3819 if (likely(pte_none(*vmf
->pte
)))
3820 do_set_pte(vmf
, page
, vmf
->address
);
3822 ret
= VM_FAULT_NOPAGE
;
3824 update_mmu_tlb(vma
, vmf
->address
, vmf
->pte
);
3825 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
3829 static unsigned long fault_around_bytes __read_mostly
=
3830 rounddown_pow_of_two(65536);
3832 #ifdef CONFIG_DEBUG_FS
3833 static int fault_around_bytes_get(void *data
, u64
*val
)
3835 *val
= fault_around_bytes
;
3840 * fault_around_bytes must be rounded down to the nearest page order as it's
3841 * what do_fault_around() expects to see.
3843 static int fault_around_bytes_set(void *data
, u64 val
)
3845 if (val
/ PAGE_SIZE
> PTRS_PER_PTE
)
3847 if (val
> PAGE_SIZE
)
3848 fault_around_bytes
= rounddown_pow_of_two(val
);
3850 fault_around_bytes
= PAGE_SIZE
; /* rounddown_pow_of_two(0) is undefined */
3853 DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops
,
3854 fault_around_bytes_get
, fault_around_bytes_set
, "%llu\n");
3856 static int __init
fault_around_debugfs(void)
3858 debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL
, NULL
,
3859 &fault_around_bytes_fops
);
3862 late_initcall(fault_around_debugfs
);
3866 * do_fault_around() tries to map few pages around the fault address. The hope
3867 * is that the pages will be needed soon and this will lower the number of
3870 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
3871 * not ready to be mapped: not up-to-date, locked, etc.
3873 * This function is called with the page table lock taken. In the split ptlock
3874 * case the page table lock only protects only those entries which belong to
3875 * the page table corresponding to the fault address.
3877 * This function doesn't cross the VMA boundaries, in order to call map_pages()
3880 * fault_around_bytes defines how many bytes we'll try to map.
3881 * do_fault_around() expects it to be set to a power of two less than or equal
3884 * The virtual address of the area that we map is naturally aligned to
3885 * fault_around_bytes rounded down to the machine page size
3886 * (and therefore to page order). This way it's easier to guarantee
3887 * that we don't cross page table boundaries.
3889 static vm_fault_t
do_fault_around(struct vm_fault
*vmf
)
3891 unsigned long address
= vmf
->address
, nr_pages
, mask
;
3892 pgoff_t start_pgoff
= vmf
->pgoff
;
3896 nr_pages
= READ_ONCE(fault_around_bytes
) >> PAGE_SHIFT
;
3897 mask
= ~(nr_pages
* PAGE_SIZE
- 1) & PAGE_MASK
;
3899 address
= max(address
& mask
, vmf
->vma
->vm_start
);
3900 off
= ((vmf
->address
- address
) >> PAGE_SHIFT
) & (PTRS_PER_PTE
- 1);
3904 * end_pgoff is either the end of the page table, the end of
3905 * the vma or nr_pages from start_pgoff, depending what is nearest.
3907 end_pgoff
= start_pgoff
-
3908 ((address
>> PAGE_SHIFT
) & (PTRS_PER_PTE
- 1)) +
3910 end_pgoff
= min3(end_pgoff
, vma_pages(vmf
->vma
) + vmf
->vma
->vm_pgoff
- 1,
3911 start_pgoff
+ nr_pages
- 1);
3913 if (pmd_none(*vmf
->pmd
)) {
3914 vmf
->prealloc_pte
= pte_alloc_one(vmf
->vma
->vm_mm
);
3915 if (!vmf
->prealloc_pte
)
3916 return VM_FAULT_OOM
;
3917 smp_wmb(); /* See comment in __pte_alloc() */
3920 return vmf
->vma
->vm_ops
->map_pages(vmf
, start_pgoff
, end_pgoff
);
3923 static vm_fault_t
do_read_fault(struct vm_fault
*vmf
)
3925 struct vm_area_struct
*vma
= vmf
->vma
;
3929 * Let's call ->map_pages() first and use ->fault() as fallback
3930 * if page by the offset is not ready to be mapped (cold cache or
3933 if (vma
->vm_ops
->map_pages
&& fault_around_bytes
>> PAGE_SHIFT
> 1) {
3934 ret
= do_fault_around(vmf
);
3939 ret
= __do_fault(vmf
);
3940 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
| VM_FAULT_RETRY
)))
3943 ret
|= finish_fault(vmf
);
3944 unlock_page(vmf
->page
);
3945 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
| VM_FAULT_RETRY
)))
3946 put_page(vmf
->page
);
3950 static vm_fault_t
do_cow_fault(struct vm_fault
*vmf
)
3952 struct vm_area_struct
*vma
= vmf
->vma
;
3955 if (unlikely(anon_vma_prepare(vma
)))
3956 return VM_FAULT_OOM
;
3958 vmf
->cow_page
= alloc_page_vma(GFP_HIGHUSER_MOVABLE
, vma
, vmf
->address
);
3960 return VM_FAULT_OOM
;
3962 if (mem_cgroup_charge(vmf
->cow_page
, vma
->vm_mm
, GFP_KERNEL
)) {
3963 put_page(vmf
->cow_page
);
3964 return VM_FAULT_OOM
;
3966 cgroup_throttle_swaprate(vmf
->cow_page
, GFP_KERNEL
);
3968 ret
= __do_fault(vmf
);
3969 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
| VM_FAULT_RETRY
)))
3971 if (ret
& VM_FAULT_DONE_COW
)
3974 copy_user_highpage(vmf
->cow_page
, vmf
->page
, vmf
->address
, vma
);
3975 __SetPageUptodate(vmf
->cow_page
);
3977 ret
|= finish_fault(vmf
);
3978 unlock_page(vmf
->page
);
3979 put_page(vmf
->page
);
3980 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
| VM_FAULT_RETRY
)))
3984 put_page(vmf
->cow_page
);
3988 static vm_fault_t
do_shared_fault(struct vm_fault
*vmf
)
3990 struct vm_area_struct
*vma
= vmf
->vma
;
3991 vm_fault_t ret
, tmp
;
3993 ret
= __do_fault(vmf
);
3994 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
| VM_FAULT_RETRY
)))
3998 * Check if the backing address space wants to know that the page is
3999 * about to become writable
4001 if (vma
->vm_ops
->page_mkwrite
) {
4002 unlock_page(vmf
->page
);
4003 tmp
= do_page_mkwrite(vmf
);
4004 if (unlikely(!tmp
||
4005 (tmp
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
)))) {
4006 put_page(vmf
->page
);
4011 ret
|= finish_fault(vmf
);
4012 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
|
4014 unlock_page(vmf
->page
);
4015 put_page(vmf
->page
);
4019 ret
|= fault_dirty_shared_page(vmf
);
4024 * We enter with non-exclusive mmap_lock (to exclude vma changes,
4025 * but allow concurrent faults).
4026 * The mmap_lock may have been released depending on flags and our
4027 * return value. See filemap_fault() and __lock_page_or_retry().
4028 * If mmap_lock is released, vma may become invalid (for example
4029 * by other thread calling munmap()).
4031 static vm_fault_t
do_fault(struct vm_fault
*vmf
)
4033 struct vm_area_struct
*vma
= vmf
->vma
;
4034 struct mm_struct
*vm_mm
= vma
->vm_mm
;
4038 * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND
4040 if (!vma
->vm_ops
->fault
) {
4042 * If we find a migration pmd entry or a none pmd entry, which
4043 * should never happen, return SIGBUS
4045 if (unlikely(!pmd_present(*vmf
->pmd
)))
4046 ret
= VM_FAULT_SIGBUS
;
4048 vmf
->pte
= pte_offset_map_lock(vmf
->vma
->vm_mm
,
4053 * Make sure this is not a temporary clearing of pte
4054 * by holding ptl and checking again. A R/M/W update
4055 * of pte involves: take ptl, clearing the pte so that
4056 * we don't have concurrent modification by hardware
4057 * followed by an update.
4059 if (unlikely(pte_none(*vmf
->pte
)))
4060 ret
= VM_FAULT_SIGBUS
;
4062 ret
= VM_FAULT_NOPAGE
;
4064 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
4066 } else if (!(vmf
->flags
& FAULT_FLAG_WRITE
))
4067 ret
= do_read_fault(vmf
);
4068 else if (!(vma
->vm_flags
& VM_SHARED
))
4069 ret
= do_cow_fault(vmf
);
4071 ret
= do_shared_fault(vmf
);
4073 /* preallocated pagetable is unused: free it */
4074 if (vmf
->prealloc_pte
) {
4075 pte_free(vm_mm
, vmf
->prealloc_pte
);
4076 vmf
->prealloc_pte
= NULL
;
4081 static int numa_migrate_prep(struct page
*page
, struct vm_area_struct
*vma
,
4082 unsigned long addr
, int page_nid
,
4087 count_vm_numa_event(NUMA_HINT_FAULTS
);
4088 if (page_nid
== numa_node_id()) {
4089 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL
);
4090 *flags
|= TNF_FAULT_LOCAL
;
4093 return mpol_misplaced(page
, vma
, addr
);
4096 static vm_fault_t
do_numa_page(struct vm_fault
*vmf
)
4098 struct vm_area_struct
*vma
= vmf
->vma
;
4099 struct page
*page
= NULL
;
4100 int page_nid
= NUMA_NO_NODE
;
4103 bool migrated
= false;
4105 bool was_writable
= pte_savedwrite(vmf
->orig_pte
);
4109 * The "pte" at this point cannot be used safely without
4110 * validation through pte_unmap_same(). It's of NUMA type but
4111 * the pfn may be screwed if the read is non atomic.
4113 vmf
->ptl
= pte_lockptr(vma
->vm_mm
, vmf
->pmd
);
4114 spin_lock(vmf
->ptl
);
4115 if (unlikely(!pte_same(*vmf
->pte
, vmf
->orig_pte
))) {
4116 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
4121 * Make it present again, Depending on how arch implementes non
4122 * accessible ptes, some can allow access by kernel mode.
4124 old_pte
= ptep_modify_prot_start(vma
, vmf
->address
, vmf
->pte
);
4125 pte
= pte_modify(old_pte
, vma
->vm_page_prot
);
4126 pte
= pte_mkyoung(pte
);
4128 pte
= pte_mkwrite(pte
);
4129 ptep_modify_prot_commit(vma
, vmf
->address
, vmf
->pte
, old_pte
, pte
);
4130 update_mmu_cache(vma
, vmf
->address
, vmf
->pte
);
4132 page
= vm_normal_page(vma
, vmf
->address
, pte
);
4134 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
4138 /* TODO: handle PTE-mapped THP */
4139 if (PageCompound(page
)) {
4140 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
4145 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
4146 * much anyway since they can be in shared cache state. This misses
4147 * the case where a mapping is writable but the process never writes
4148 * to it but pte_write gets cleared during protection updates and
4149 * pte_dirty has unpredictable behaviour between PTE scan updates,
4150 * background writeback, dirty balancing and application behaviour.
4152 if (!pte_write(pte
))
4153 flags
|= TNF_NO_GROUP
;
4156 * Flag if the page is shared between multiple address spaces. This
4157 * is later used when determining whether to group tasks together
4159 if (page_mapcount(page
) > 1 && (vma
->vm_flags
& VM_SHARED
))
4160 flags
|= TNF_SHARED
;
4162 last_cpupid
= page_cpupid_last(page
);
4163 page_nid
= page_to_nid(page
);
4164 target_nid
= numa_migrate_prep(page
, vma
, vmf
->address
, page_nid
,
4166 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
4167 if (target_nid
== NUMA_NO_NODE
) {
4172 /* Migrate to the requested node */
4173 migrated
= migrate_misplaced_page(page
, vma
, target_nid
);
4175 page_nid
= target_nid
;
4176 flags
|= TNF_MIGRATED
;
4178 flags
|= TNF_MIGRATE_FAIL
;
4181 if (page_nid
!= NUMA_NO_NODE
)
4182 task_numa_fault(last_cpupid
, page_nid
, 1, flags
);
4186 static inline vm_fault_t
create_huge_pmd(struct vm_fault
*vmf
)
4188 if (vma_is_anonymous(vmf
->vma
))
4189 return do_huge_pmd_anonymous_page(vmf
);
4190 if (vmf
->vma
->vm_ops
->huge_fault
)
4191 return vmf
->vma
->vm_ops
->huge_fault(vmf
, PE_SIZE_PMD
);
4192 return VM_FAULT_FALLBACK
;
4195 /* `inline' is required to avoid gcc 4.1.2 build error */
4196 static inline vm_fault_t
wp_huge_pmd(struct vm_fault
*vmf
, pmd_t orig_pmd
)
4198 if (vma_is_anonymous(vmf
->vma
)) {
4199 if (userfaultfd_huge_pmd_wp(vmf
->vma
, orig_pmd
))
4200 return handle_userfault(vmf
, VM_UFFD_WP
);
4201 return do_huge_pmd_wp_page(vmf
, orig_pmd
);
4203 if (vmf
->vma
->vm_ops
->huge_fault
) {
4204 vm_fault_t ret
= vmf
->vma
->vm_ops
->huge_fault(vmf
, PE_SIZE_PMD
);
4206 if (!(ret
& VM_FAULT_FALLBACK
))
4210 /* COW or write-notify handled on pte level: split pmd. */
4211 __split_huge_pmd(vmf
->vma
, vmf
->pmd
, vmf
->address
, false, NULL
);
4213 return VM_FAULT_FALLBACK
;
4216 static vm_fault_t
create_huge_pud(struct vm_fault
*vmf
)
4218 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
4219 defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
4220 /* No support for anonymous transparent PUD pages yet */
4221 if (vma_is_anonymous(vmf
->vma
))
4223 if (vmf
->vma
->vm_ops
->huge_fault
) {
4224 vm_fault_t ret
= vmf
->vma
->vm_ops
->huge_fault(vmf
, PE_SIZE_PUD
);
4226 if (!(ret
& VM_FAULT_FALLBACK
))
4230 /* COW or write-notify not handled on PUD level: split pud.*/
4231 __split_huge_pud(vmf
->vma
, vmf
->pud
, vmf
->address
);
4232 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
4233 return VM_FAULT_FALLBACK
;
4236 static vm_fault_t
wp_huge_pud(struct vm_fault
*vmf
, pud_t orig_pud
)
4238 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
4239 /* No support for anonymous transparent PUD pages yet */
4240 if (vma_is_anonymous(vmf
->vma
))
4241 return VM_FAULT_FALLBACK
;
4242 if (vmf
->vma
->vm_ops
->huge_fault
)
4243 return vmf
->vma
->vm_ops
->huge_fault(vmf
, PE_SIZE_PUD
);
4244 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
4245 return VM_FAULT_FALLBACK
;
4249 * These routines also need to handle stuff like marking pages dirty
4250 * and/or accessed for architectures that don't do it in hardware (most
4251 * RISC architectures). The early dirtying is also good on the i386.
4253 * There is also a hook called "update_mmu_cache()" that architectures
4254 * with external mmu caches can use to update those (ie the Sparc or
4255 * PowerPC hashed page tables that act as extended TLBs).
4257 * We enter with non-exclusive mmap_lock (to exclude vma changes, but allow
4258 * concurrent faults).
4260 * The mmap_lock may have been released depending on flags and our return value.
4261 * See filemap_fault() and __lock_page_or_retry().
4263 static vm_fault_t
handle_pte_fault(struct vm_fault
*vmf
)
4267 if (unlikely(pmd_none(*vmf
->pmd
))) {
4269 * Leave __pte_alloc() until later: because vm_ops->fault may
4270 * want to allocate huge page, and if we expose page table
4271 * for an instant, it will be difficult to retract from
4272 * concurrent faults and from rmap lookups.
4277 * If a huge pmd materialized under us just retry later. Use
4278 * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead
4279 * of pmd_trans_huge() to ensure the pmd didn't become
4280 * pmd_trans_huge under us and then back to pmd_none, as a
4281 * result of MADV_DONTNEED running immediately after a huge pmd
4282 * fault in a different thread of this mm, in turn leading to a
4283 * misleading pmd_trans_huge() retval. All we have to ensure is
4284 * that it is a regular pmd that we can walk with
4285 * pte_offset_map() and we can do that through an atomic read
4286 * in C, which is what pmd_trans_unstable() provides.
4288 if (pmd_devmap_trans_unstable(vmf
->pmd
))
4291 * A regular pmd is established and it can't morph into a huge
4292 * pmd from under us anymore at this point because we hold the
4293 * mmap_lock read mode and khugepaged takes it in write mode.
4294 * So now it's safe to run pte_offset_map().
4296 vmf
->pte
= pte_offset_map(vmf
->pmd
, vmf
->address
);
4297 vmf
->orig_pte
= *vmf
->pte
;
4300 * some architectures can have larger ptes than wordsize,
4301 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
4302 * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic
4303 * accesses. The code below just needs a consistent view
4304 * for the ifs and we later double check anyway with the
4305 * ptl lock held. So here a barrier will do.
4308 if (pte_none(vmf
->orig_pte
)) {
4309 pte_unmap(vmf
->pte
);
4315 if (vma_is_anonymous(vmf
->vma
))
4316 return do_anonymous_page(vmf
);
4318 return do_fault(vmf
);
4321 if (!pte_present(vmf
->orig_pte
))
4322 return do_swap_page(vmf
);
4324 if (pte_protnone(vmf
->orig_pte
) && vma_is_accessible(vmf
->vma
))
4325 return do_numa_page(vmf
);
4327 vmf
->ptl
= pte_lockptr(vmf
->vma
->vm_mm
, vmf
->pmd
);
4328 spin_lock(vmf
->ptl
);
4329 entry
= vmf
->orig_pte
;
4330 if (unlikely(!pte_same(*vmf
->pte
, entry
))) {
4331 update_mmu_tlb(vmf
->vma
, vmf
->address
, vmf
->pte
);
4334 if (vmf
->flags
& FAULT_FLAG_WRITE
) {
4335 if (!pte_write(entry
))
4336 return do_wp_page(vmf
);
4337 entry
= pte_mkdirty(entry
);
4339 entry
= pte_mkyoung(entry
);
4340 if (ptep_set_access_flags(vmf
->vma
, vmf
->address
, vmf
->pte
, entry
,
4341 vmf
->flags
& FAULT_FLAG_WRITE
)) {
4342 update_mmu_cache(vmf
->vma
, vmf
->address
, vmf
->pte
);
4344 /* Skip spurious TLB flush for retried page fault */
4345 if (vmf
->flags
& FAULT_FLAG_TRIED
)
4348 * This is needed only for protection faults but the arch code
4349 * is not yet telling us if this is a protection fault or not.
4350 * This still avoids useless tlb flushes for .text page faults
4353 if (vmf
->flags
& FAULT_FLAG_WRITE
)
4354 flush_tlb_fix_spurious_fault(vmf
->vma
, vmf
->address
);
4357 pte_unmap_unlock(vmf
->pte
, vmf
->ptl
);
4362 * By the time we get here, we already hold the mm semaphore
4364 * The mmap_lock may have been released depending on flags and our
4365 * return value. See filemap_fault() and __lock_page_or_retry().
4367 static vm_fault_t
__handle_mm_fault(struct vm_area_struct
*vma
,
4368 unsigned long address
, unsigned int flags
)
4370 struct vm_fault vmf
= {
4372 .address
= address
& PAGE_MASK
,
4374 .pgoff
= linear_page_index(vma
, address
),
4375 .gfp_mask
= __get_fault_gfp_mask(vma
),
4377 unsigned int dirty
= flags
& FAULT_FLAG_WRITE
;
4378 struct mm_struct
*mm
= vma
->vm_mm
;
4383 pgd
= pgd_offset(mm
, address
);
4384 p4d
= p4d_alloc(mm
, pgd
, address
);
4386 return VM_FAULT_OOM
;
4388 vmf
.pud
= pud_alloc(mm
, p4d
, address
);
4390 return VM_FAULT_OOM
;
4392 if (pud_none(*vmf
.pud
) && __transparent_hugepage_enabled(vma
)) {
4393 ret
= create_huge_pud(&vmf
);
4394 if (!(ret
& VM_FAULT_FALLBACK
))
4397 pud_t orig_pud
= *vmf
.pud
;
4400 if (pud_trans_huge(orig_pud
) || pud_devmap(orig_pud
)) {
4402 /* NUMA case for anonymous PUDs would go here */
4404 if (dirty
&& !pud_write(orig_pud
)) {
4405 ret
= wp_huge_pud(&vmf
, orig_pud
);
4406 if (!(ret
& VM_FAULT_FALLBACK
))
4409 huge_pud_set_accessed(&vmf
, orig_pud
);
4415 vmf
.pmd
= pmd_alloc(mm
, vmf
.pud
, address
);
4417 return VM_FAULT_OOM
;
4419 /* Huge pud page fault raced with pmd_alloc? */
4420 if (pud_trans_unstable(vmf
.pud
))
4423 if (pmd_none(*vmf
.pmd
) && __transparent_hugepage_enabled(vma
)) {
4424 ret
= create_huge_pmd(&vmf
);
4425 if (!(ret
& VM_FAULT_FALLBACK
))
4428 pmd_t orig_pmd
= *vmf
.pmd
;
4431 if (unlikely(is_swap_pmd(orig_pmd
))) {
4432 VM_BUG_ON(thp_migration_supported() &&
4433 !is_pmd_migration_entry(orig_pmd
));
4434 if (is_pmd_migration_entry(orig_pmd
))
4435 pmd_migration_entry_wait(mm
, vmf
.pmd
);
4438 if (pmd_trans_huge(orig_pmd
) || pmd_devmap(orig_pmd
)) {
4439 if (pmd_protnone(orig_pmd
) && vma_is_accessible(vma
))
4440 return do_huge_pmd_numa_page(&vmf
, orig_pmd
);
4442 if (dirty
&& !pmd_write(orig_pmd
)) {
4443 ret
= wp_huge_pmd(&vmf
, orig_pmd
);
4444 if (!(ret
& VM_FAULT_FALLBACK
))
4447 huge_pmd_set_accessed(&vmf
, orig_pmd
);
4453 return handle_pte_fault(&vmf
);
4457 * mm_account_fault - Do page fault accountings
4459 * @regs: the pt_regs struct pointer. When set to NULL, will skip accounting
4460 * of perf event counters, but we'll still do the per-task accounting to
4461 * the task who triggered this page fault.
4462 * @address: the faulted address.
4463 * @flags: the fault flags.
4464 * @ret: the fault retcode.
4466 * This will take care of most of the page fault accountings. Meanwhile, it
4467 * will also include the PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN] perf counter
4468 * updates. However note that the handling of PERF_COUNT_SW_PAGE_FAULTS should
4469 * still be in per-arch page fault handlers at the entry of page fault.
4471 static inline void mm_account_fault(struct pt_regs
*regs
,
4472 unsigned long address
, unsigned int flags
,
4478 * We don't do accounting for some specific faults:
4480 * - Unsuccessful faults (e.g. when the address wasn't valid). That
4481 * includes arch_vma_access_permitted() failing before reaching here.
4482 * So this is not a "this many hardware page faults" counter. We
4483 * should use the hw profiling for that.
4485 * - Incomplete faults (VM_FAULT_RETRY). They will only be counted
4486 * once they're completed.
4488 if (ret
& (VM_FAULT_ERROR
| VM_FAULT_RETRY
))
4492 * We define the fault as a major fault when the final successful fault
4493 * is VM_FAULT_MAJOR, or if it retried (which implies that we couldn't
4494 * handle it immediately previously).
4496 major
= (ret
& VM_FAULT_MAJOR
) || (flags
& FAULT_FLAG_TRIED
);
4504 * If the fault is done for GUP, regs will be NULL. We only do the
4505 * accounting for the per thread fault counters who triggered the
4506 * fault, and we skip the perf event updates.
4512 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ
, 1, regs
, address
);
4514 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN
, 1, regs
, address
);
4518 * By the time we get here, we already hold the mm semaphore
4520 * The mmap_lock may have been released depending on flags and our
4521 * return value. See filemap_fault() and __lock_page_or_retry().
4523 vm_fault_t
handle_mm_fault(struct vm_area_struct
*vma
, unsigned long address
,
4524 unsigned int flags
, struct pt_regs
*regs
)
4528 __set_current_state(TASK_RUNNING
);
4530 count_vm_event(PGFAULT
);
4531 count_memcg_event_mm(vma
->vm_mm
, PGFAULT
);
4533 /* do counter updates before entering really critical section. */
4534 check_sync_rss_stat(current
);
4536 if (!arch_vma_access_permitted(vma
, flags
& FAULT_FLAG_WRITE
,
4537 flags
& FAULT_FLAG_INSTRUCTION
,
4538 flags
& FAULT_FLAG_REMOTE
))
4539 return VM_FAULT_SIGSEGV
;
4542 * Enable the memcg OOM handling for faults triggered in user
4543 * space. Kernel faults are handled more gracefully.
4545 if (flags
& FAULT_FLAG_USER
)
4546 mem_cgroup_enter_user_fault();
4548 if (unlikely(is_vm_hugetlb_page(vma
)))
4549 ret
= hugetlb_fault(vma
->vm_mm
, vma
, address
, flags
);
4551 ret
= __handle_mm_fault(vma
, address
, flags
);
4553 if (flags
& FAULT_FLAG_USER
) {
4554 mem_cgroup_exit_user_fault();
4556 * The task may have entered a memcg OOM situation but
4557 * if the allocation error was handled gracefully (no
4558 * VM_FAULT_OOM), there is no need to kill anything.
4559 * Just clean up the OOM state peacefully.
4561 if (task_in_memcg_oom(current
) && !(ret
& VM_FAULT_OOM
))
4562 mem_cgroup_oom_synchronize(false);
4565 mm_account_fault(regs
, address
, flags
, ret
);
4569 EXPORT_SYMBOL_GPL(handle_mm_fault
);
4571 #ifndef __PAGETABLE_P4D_FOLDED
4573 * Allocate p4d page table.
4574 * We've already handled the fast-path in-line.
4576 int __p4d_alloc(struct mm_struct
*mm
, pgd_t
*pgd
, unsigned long address
)
4578 p4d_t
*new = p4d_alloc_one(mm
, address
);
4582 smp_wmb(); /* See comment in __pte_alloc */
4584 spin_lock(&mm
->page_table_lock
);
4585 if (pgd_present(*pgd
)) /* Another has populated it */
4588 pgd_populate(mm
, pgd
, new);
4589 spin_unlock(&mm
->page_table_lock
);
4592 #endif /* __PAGETABLE_P4D_FOLDED */
4594 #ifndef __PAGETABLE_PUD_FOLDED
4596 * Allocate page upper directory.
4597 * We've already handled the fast-path in-line.
4599 int __pud_alloc(struct mm_struct
*mm
, p4d_t
*p4d
, unsigned long address
)
4601 pud_t
*new = pud_alloc_one(mm
, address
);
4605 smp_wmb(); /* See comment in __pte_alloc */
4607 spin_lock(&mm
->page_table_lock
);
4608 if (!p4d_present(*p4d
)) {
4610 p4d_populate(mm
, p4d
, new);
4611 } else /* Another has populated it */
4613 spin_unlock(&mm
->page_table_lock
);
4616 #endif /* __PAGETABLE_PUD_FOLDED */
4618 #ifndef __PAGETABLE_PMD_FOLDED
4620 * Allocate page middle directory.
4621 * We've already handled the fast-path in-line.
4623 int __pmd_alloc(struct mm_struct
*mm
, pud_t
*pud
, unsigned long address
)
4626 pmd_t
*new = pmd_alloc_one(mm
, address
);
4630 smp_wmb(); /* See comment in __pte_alloc */
4632 ptl
= pud_lock(mm
, pud
);
4633 if (!pud_present(*pud
)) {
4635 pud_populate(mm
, pud
, new);
4636 } else /* Another has populated it */
4641 #endif /* __PAGETABLE_PMD_FOLDED */
4643 int follow_invalidate_pte(struct mm_struct
*mm
, unsigned long address
,
4644 struct mmu_notifier_range
*range
, pte_t
**ptepp
,
4645 pmd_t
**pmdpp
, spinlock_t
**ptlp
)
4653 pgd
= pgd_offset(mm
, address
);
4654 if (pgd_none(*pgd
) || unlikely(pgd_bad(*pgd
)))
4657 p4d
= p4d_offset(pgd
, address
);
4658 if (p4d_none(*p4d
) || unlikely(p4d_bad(*p4d
)))
4661 pud
= pud_offset(p4d
, address
);
4662 if (pud_none(*pud
) || unlikely(pud_bad(*pud
)))
4665 pmd
= pmd_offset(pud
, address
);
4666 VM_BUG_ON(pmd_trans_huge(*pmd
));
4668 if (pmd_huge(*pmd
)) {
4673 mmu_notifier_range_init(range
, MMU_NOTIFY_CLEAR
, 0,
4674 NULL
, mm
, address
& PMD_MASK
,
4675 (address
& PMD_MASK
) + PMD_SIZE
);
4676 mmu_notifier_invalidate_range_start(range
);
4678 *ptlp
= pmd_lock(mm
, pmd
);
4679 if (pmd_huge(*pmd
)) {
4685 mmu_notifier_invalidate_range_end(range
);
4688 if (pmd_none(*pmd
) || unlikely(pmd_bad(*pmd
)))
4692 mmu_notifier_range_init(range
, MMU_NOTIFY_CLEAR
, 0, NULL
, mm
,
4693 address
& PAGE_MASK
,
4694 (address
& PAGE_MASK
) + PAGE_SIZE
);
4695 mmu_notifier_invalidate_range_start(range
);
4697 ptep
= pte_offset_map_lock(mm
, pmd
, address
, ptlp
);
4698 if (!pte_present(*ptep
))
4703 pte_unmap_unlock(ptep
, *ptlp
);
4705 mmu_notifier_invalidate_range_end(range
);
4711 * follow_pte - look up PTE at a user virtual address
4712 * @mm: the mm_struct of the target address space
4713 * @address: user virtual address
4714 * @ptepp: location to store found PTE
4715 * @ptlp: location to store the lock for the PTE
4717 * On a successful return, the pointer to the PTE is stored in @ptepp;
4718 * the corresponding lock is taken and its location is stored in @ptlp.
4719 * The contents of the PTE are only stable until @ptlp is released;
4720 * any further use, if any, must be protected against invalidation
4721 * with MMU notifiers.
4723 * Only IO mappings and raw PFN mappings are allowed. The mmap semaphore
4724 * should be taken for read.
4726 * KVM uses this function. While it is arguably less bad than ``follow_pfn``,
4727 * it is not a good general-purpose API.
4729 * Return: zero on success, -ve otherwise.
4731 int follow_pte(struct mm_struct
*mm
, unsigned long address
,
4732 pte_t
**ptepp
, spinlock_t
**ptlp
)
4734 return follow_invalidate_pte(mm
, address
, NULL
, ptepp
, NULL
, ptlp
);
4736 EXPORT_SYMBOL_GPL(follow_pte
);
4739 * follow_pfn - look up PFN at a user virtual address
4740 * @vma: memory mapping
4741 * @address: user virtual address
4742 * @pfn: location to store found PFN
4744 * Only IO mappings and raw PFN mappings are allowed.
4746 * This function does not allow the caller to read the permissions
4747 * of the PTE. Do not use it.
4749 * Return: zero and the pfn at @pfn on success, -ve otherwise.
4751 int follow_pfn(struct vm_area_struct
*vma
, unsigned long address
,
4758 if (!(vma
->vm_flags
& (VM_IO
| VM_PFNMAP
)))
4761 ret
= follow_pte(vma
->vm_mm
, address
, &ptep
, &ptl
);
4764 *pfn
= pte_pfn(*ptep
);
4765 pte_unmap_unlock(ptep
, ptl
);
4768 EXPORT_SYMBOL(follow_pfn
);
4770 #ifdef CONFIG_HAVE_IOREMAP_PROT
4771 int follow_phys(struct vm_area_struct
*vma
,
4772 unsigned long address
, unsigned int flags
,
4773 unsigned long *prot
, resource_size_t
*phys
)
4779 if (!(vma
->vm_flags
& (VM_IO
| VM_PFNMAP
)))
4782 if (follow_pte(vma
->vm_mm
, address
, &ptep
, &ptl
))
4786 if ((flags
& FOLL_WRITE
) && !pte_write(pte
))
4789 *prot
= pgprot_val(pte_pgprot(pte
));
4790 *phys
= (resource_size_t
)pte_pfn(pte
) << PAGE_SHIFT
;
4794 pte_unmap_unlock(ptep
, ptl
);
4800 * generic_access_phys - generic implementation for iomem mmap access
4801 * @vma: the vma to access
4802 * @addr: userspace addres, not relative offset within @vma
4803 * @buf: buffer to read/write
4804 * @len: length of transfer
4805 * @write: set to FOLL_WRITE when writing, otherwise reading
4807 * This is a generic implementation for &vm_operations_struct.access for an
4808 * iomem mapping. This callback is used by access_process_vm() when the @vma is
4811 int generic_access_phys(struct vm_area_struct
*vma
, unsigned long addr
,
4812 void *buf
, int len
, int write
)
4814 resource_size_t phys_addr
;
4815 unsigned long prot
= 0;
4816 void __iomem
*maddr
;
4819 int offset
= offset_in_page(addr
);
4822 if (!(vma
->vm_flags
& (VM_IO
| VM_PFNMAP
)))
4826 if (follow_pte(vma
->vm_mm
, addr
, &ptep
, &ptl
))
4829 pte_unmap_unlock(ptep
, ptl
);
4831 prot
= pgprot_val(pte_pgprot(pte
));
4832 phys_addr
= (resource_size_t
)pte_pfn(pte
) << PAGE_SHIFT
;
4834 if ((write
& FOLL_WRITE
) && !pte_write(pte
))
4837 maddr
= ioremap_prot(phys_addr
, PAGE_ALIGN(len
+ offset
), prot
);
4841 if (follow_pte(vma
->vm_mm
, addr
, &ptep
, &ptl
))
4844 if (!pte_same(pte
, *ptep
)) {
4845 pte_unmap_unlock(ptep
, ptl
);
4852 memcpy_toio(maddr
+ offset
, buf
, len
);
4854 memcpy_fromio(buf
, maddr
+ offset
, len
);
4856 pte_unmap_unlock(ptep
, ptl
);
4862 EXPORT_SYMBOL_GPL(generic_access_phys
);
4866 * Access another process' address space as given in mm.
4868 int __access_remote_vm(struct mm_struct
*mm
, unsigned long addr
, void *buf
,
4869 int len
, unsigned int gup_flags
)
4871 struct vm_area_struct
*vma
;
4872 void *old_buf
= buf
;
4873 int write
= gup_flags
& FOLL_WRITE
;
4875 if (mmap_read_lock_killable(mm
))
4878 /* ignore errors, just check how much was successfully transferred */
4880 int bytes
, ret
, offset
;
4882 struct page
*page
= NULL
;
4884 ret
= get_user_pages_remote(mm
, addr
, 1,
4885 gup_flags
, &page
, &vma
, NULL
);
4887 #ifndef CONFIG_HAVE_IOREMAP_PROT
4891 * Check if this is a VM_IO | VM_PFNMAP VMA, which
4892 * we can access using slightly different code.
4894 vma
= find_vma(mm
, addr
);
4895 if (!vma
|| vma
->vm_start
> addr
)
4897 if (vma
->vm_ops
&& vma
->vm_ops
->access
)
4898 ret
= vma
->vm_ops
->access(vma
, addr
, buf
,
4906 offset
= addr
& (PAGE_SIZE
-1);
4907 if (bytes
> PAGE_SIZE
-offset
)
4908 bytes
= PAGE_SIZE
-offset
;
4912 copy_to_user_page(vma
, page
, addr
,
4913 maddr
+ offset
, buf
, bytes
);
4914 set_page_dirty_lock(page
);
4916 copy_from_user_page(vma
, page
, addr
,
4917 buf
, maddr
+ offset
, bytes
);
4926 mmap_read_unlock(mm
);
4928 return buf
- old_buf
;
4932 * access_remote_vm - access another process' address space
4933 * @mm: the mm_struct of the target address space
4934 * @addr: start address to access
4935 * @buf: source or destination buffer
4936 * @len: number of bytes to transfer
4937 * @gup_flags: flags modifying lookup behaviour
4939 * The caller must hold a reference on @mm.
4941 * Return: number of bytes copied from source to destination.
4943 int access_remote_vm(struct mm_struct
*mm
, unsigned long addr
,
4944 void *buf
, int len
, unsigned int gup_flags
)
4946 return __access_remote_vm(mm
, addr
, buf
, len
, gup_flags
);
4950 * Access another process' address space.
4951 * Source/target buffer must be kernel space,
4952 * Do not walk the page table directly, use get_user_pages
4954 int access_process_vm(struct task_struct
*tsk
, unsigned long addr
,
4955 void *buf
, int len
, unsigned int gup_flags
)
4957 struct mm_struct
*mm
;
4960 mm
= get_task_mm(tsk
);
4964 ret
= __access_remote_vm(mm
, addr
, buf
, len
, gup_flags
);
4970 EXPORT_SYMBOL_GPL(access_process_vm
);
4973 * Print the name of a VMA.
4975 void print_vma_addr(char *prefix
, unsigned long ip
)
4977 struct mm_struct
*mm
= current
->mm
;
4978 struct vm_area_struct
*vma
;
4981 * we might be running from an atomic context so we cannot sleep
4983 if (!mmap_read_trylock(mm
))
4986 vma
= find_vma(mm
, ip
);
4987 if (vma
&& vma
->vm_file
) {
4988 struct file
*f
= vma
->vm_file
;
4989 char *buf
= (char *)__get_free_page(GFP_NOWAIT
);
4993 p
= file_path(f
, buf
, PAGE_SIZE
);
4996 printk("%s%s[%lx+%lx]", prefix
, kbasename(p
),
4998 vma
->vm_end
- vma
->vm_start
);
4999 free_page((unsigned long)buf
);
5002 mmap_read_unlock(mm
);
5005 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
5006 void __might_fault(const char *file
, int line
)
5009 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
5010 * holding the mmap_lock, this is safe because kernel memory doesn't
5011 * get paged out, therefore we'll never actually fault, and the
5012 * below annotations will generate false positives.
5014 if (uaccess_kernel())
5016 if (pagefault_disabled())
5018 __might_sleep(file
, line
, 0);
5019 #if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
5021 might_lock_read(¤t
->mm
->mmap_lock
);
5024 EXPORT_SYMBOL(__might_fault
);
5027 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
5029 * Process all subpages of the specified huge page with the specified
5030 * operation. The target subpage will be processed last to keep its
5033 static inline void process_huge_page(
5034 unsigned long addr_hint
, unsigned int pages_per_huge_page
,
5035 void (*process_subpage
)(unsigned long addr
, int idx
, void *arg
),
5039 unsigned long addr
= addr_hint
&
5040 ~(((unsigned long)pages_per_huge_page
<< PAGE_SHIFT
) - 1);
5042 /* Process target subpage last to keep its cache lines hot */
5044 n
= (addr_hint
- addr
) / PAGE_SIZE
;
5045 if (2 * n
<= pages_per_huge_page
) {
5046 /* If target subpage in first half of huge page */
5049 /* Process subpages at the end of huge page */
5050 for (i
= pages_per_huge_page
- 1; i
>= 2 * n
; i
--) {
5052 process_subpage(addr
+ i
* PAGE_SIZE
, i
, arg
);
5055 /* If target subpage in second half of huge page */
5056 base
= pages_per_huge_page
- 2 * (pages_per_huge_page
- n
);
5057 l
= pages_per_huge_page
- n
;
5058 /* Process subpages at the begin of huge page */
5059 for (i
= 0; i
< base
; i
++) {
5061 process_subpage(addr
+ i
* PAGE_SIZE
, i
, arg
);
5065 * Process remaining subpages in left-right-left-right pattern
5066 * towards the target subpage
5068 for (i
= 0; i
< l
; i
++) {
5069 int left_idx
= base
+ i
;
5070 int right_idx
= base
+ 2 * l
- 1 - i
;
5073 process_subpage(addr
+ left_idx
* PAGE_SIZE
, left_idx
, arg
);
5075 process_subpage(addr
+ right_idx
* PAGE_SIZE
, right_idx
, arg
);
5079 static void clear_gigantic_page(struct page
*page
,
5081 unsigned int pages_per_huge_page
)
5084 struct page
*p
= page
;
5087 for (i
= 0; i
< pages_per_huge_page
;
5088 i
++, p
= mem_map_next(p
, page
, i
)) {
5090 clear_user_highpage(p
, addr
+ i
* PAGE_SIZE
);
5094 static void clear_subpage(unsigned long addr
, int idx
, void *arg
)
5096 struct page
*page
= arg
;
5098 clear_user_highpage(page
+ idx
, addr
);
5101 void clear_huge_page(struct page
*page
,
5102 unsigned long addr_hint
, unsigned int pages_per_huge_page
)
5104 unsigned long addr
= addr_hint
&
5105 ~(((unsigned long)pages_per_huge_page
<< PAGE_SHIFT
) - 1);
5107 if (unlikely(pages_per_huge_page
> MAX_ORDER_NR_PAGES
)) {
5108 clear_gigantic_page(page
, addr
, pages_per_huge_page
);
5112 process_huge_page(addr_hint
, pages_per_huge_page
, clear_subpage
, page
);
5115 static void copy_user_gigantic_page(struct page
*dst
, struct page
*src
,
5117 struct vm_area_struct
*vma
,
5118 unsigned int pages_per_huge_page
)
5121 struct page
*dst_base
= dst
;
5122 struct page
*src_base
= src
;
5124 for (i
= 0; i
< pages_per_huge_page
; ) {
5126 copy_user_highpage(dst
, src
, addr
+ i
*PAGE_SIZE
, vma
);
5129 dst
= mem_map_next(dst
, dst_base
, i
);
5130 src
= mem_map_next(src
, src_base
, i
);
5134 struct copy_subpage_arg
{
5137 struct vm_area_struct
*vma
;
5140 static void copy_subpage(unsigned long addr
, int idx
, void *arg
)
5142 struct copy_subpage_arg
*copy_arg
= arg
;
5144 copy_user_highpage(copy_arg
->dst
+ idx
, copy_arg
->src
+ idx
,
5145 addr
, copy_arg
->vma
);
5148 void copy_user_huge_page(struct page
*dst
, struct page
*src
,
5149 unsigned long addr_hint
, struct vm_area_struct
*vma
,
5150 unsigned int pages_per_huge_page
)
5152 unsigned long addr
= addr_hint
&
5153 ~(((unsigned long)pages_per_huge_page
<< PAGE_SHIFT
) - 1);
5154 struct copy_subpage_arg arg
= {
5160 if (unlikely(pages_per_huge_page
> MAX_ORDER_NR_PAGES
)) {
5161 copy_user_gigantic_page(dst
, src
, addr
, vma
,
5162 pages_per_huge_page
);
5166 process_huge_page(addr_hint
, pages_per_huge_page
, copy_subpage
, &arg
);
5169 long copy_huge_page_from_user(struct page
*dst_page
,
5170 const void __user
*usr_src
,
5171 unsigned int pages_per_huge_page
,
5172 bool allow_pagefault
)
5174 void *src
= (void *)usr_src
;
5176 unsigned long i
, rc
= 0;
5177 unsigned long ret_val
= pages_per_huge_page
* PAGE_SIZE
;
5178 struct page
*subpage
= dst_page
;
5180 for (i
= 0; i
< pages_per_huge_page
;
5181 i
++, subpage
= mem_map_next(subpage
, dst_page
, i
)) {
5182 if (allow_pagefault
)
5183 page_kaddr
= kmap(subpage
);
5185 page_kaddr
= kmap_atomic(subpage
);
5186 rc
= copy_from_user(page_kaddr
,
5187 (const void __user
*)(src
+ i
* PAGE_SIZE
),
5189 if (allow_pagefault
)
5192 kunmap_atomic(page_kaddr
);
5194 ret_val
-= (PAGE_SIZE
- rc
);
5202 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
5204 #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
5206 static struct kmem_cache
*page_ptl_cachep
;
5208 void __init
ptlock_cache_init(void)
5210 page_ptl_cachep
= kmem_cache_create("page->ptl", sizeof(spinlock_t
), 0,
5214 bool ptlock_alloc(struct page
*page
)
5218 ptl
= kmem_cache_alloc(page_ptl_cachep
, GFP_KERNEL
);
5225 void ptlock_free(struct page
*page
)
5227 kmem_cache_free(page_ptl_cachep
, page
->ptl
);