4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
8 * demand-loading started 01.12.91 - seems it is high on the list of
9 * things wanted, and it should be easy to implement. - Linus
13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14 * pages started 02.12.91, seems to work. - Linus.
16 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
17 * would have taken more than the 6M I have free, but it worked well as
20 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
24 * Real VM (paging to/from disk) started 18.12.91. Much more work and
25 * thought has to go into this. Oh, well..
26 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
27 * Found it. Everything seems to work now.
28 * 20.12.91 - Ok, making the swap-device changeable like the root.
32 * 05.04.94 - Multi-page memory management added for v1.1.
33 * Idea by Alex Bligh (alex@cconcepts.co.uk)
35 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
36 * (Gerhard.Wichert@pdb.siemens.de)
38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
41 #include <linux/kernel_stat.h>
43 #include <linux/sched/mm.h>
44 #include <linux/sched/coredump.h>
45 #include <linux/sched/numa_balancing.h>
46 #include <linux/sched/task.h>
47 #include <linux/hugetlb.h>
48 #include <linux/mman.h>
49 #include <linux/swap.h>
50 #include <linux/highmem.h>
51 #include <linux/pagemap.h>
52 #include <linux/memremap.h>
53 #include <linux/ksm.h>
54 #include <linux/rmap.h>
55 #include <linux/export.h>
56 #include <linux/delayacct.h>
57 #include <linux/init.h>
58 #include <linux/pfn_t.h>
59 #include <linux/writeback.h>
60 #include <linux/memcontrol.h>
61 #include <linux/mmu_notifier.h>
62 #include <linux/swapops.h>
63 #include <linux/elf.h>
64 #include <linux/gfp.h>
65 #include <linux/migrate.h>
66 #include <linux/string.h>
67 #include <linux/dma-debug.h>
68 #include <linux/debugfs.h>
69 #include <linux/userfaultfd_k.h>
70 #include <linux/dax.h>
71 #include <linux/oom.h>
74 #include <asm/mmu_context.h>
75 #include <asm/pgalloc.h>
76 #include <linux/uaccess.h>
78 #include <asm/tlbflush.h>
79 #include <asm/pgtable.h>
83 #if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST)
84 #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
87 #ifndef CONFIG_NEED_MULTIPLE_NODES
88 /* use the per-pgdat data instead for discontigmem - mbligh */
89 unsigned long max_mapnr;
90 EXPORT_SYMBOL(max_mapnr);
93 EXPORT_SYMBOL(mem_map);
97 * A number of key systems in x86 including ioremap() rely on the assumption
98 * that high_memory defines the upper bound on direct map memory, then end
99 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
100 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
104 EXPORT_SYMBOL(high_memory);
107 * Randomize the address space (stacks, mmaps, brk, etc.).
109 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
110 * as ancient (libc5 based) binaries can segfault. )
112 int randomize_va_space __read_mostly =
113 #ifdef CONFIG_COMPAT_BRK
119 #ifndef arch_faults_on_old_pte
120 static inline bool arch_faults_on_old_pte(void)
123 * Those arches which don't have hw access flag feature need to
124 * implement their own helper. By default, "true" means pagefault
125 * will be hit on old pte.
131 static int __init disable_randmaps(char *s)
133 randomize_va_space = 0;
136 __setup("norandmaps", disable_randmaps);
138 unsigned long zero_pfn __read_mostly;
139 EXPORT_SYMBOL(zero_pfn);
141 unsigned long highest_memmap_pfn __read_mostly;
144 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
146 static int __init init_zero_pfn(void)
148 zero_pfn = page_to_pfn(ZERO_PAGE(0));
151 early_initcall(init_zero_pfn);
154 #if defined(SPLIT_RSS_COUNTING)
156 void sync_mm_rss(struct mm_struct *mm)
160 for (i = 0; i < NR_MM_COUNTERS; i++) {
161 if (current->rss_stat.count[i]) {
162 add_mm_counter(mm, i, current->rss_stat.count[i]);
163 current->rss_stat.count[i] = 0;
166 current->rss_stat.events = 0;
169 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
171 struct task_struct *task = current;
173 if (likely(task->mm == mm))
174 task->rss_stat.count[member] += val;
176 add_mm_counter(mm, member, val);
178 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
179 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
181 /* sync counter once per 64 page faults */
182 #define TASK_RSS_EVENTS_THRESH (64)
183 static void check_sync_rss_stat(struct task_struct *task)
185 if (unlikely(task != current))
187 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
188 sync_mm_rss(task->mm);
190 #else /* SPLIT_RSS_COUNTING */
192 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
193 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
195 static void check_sync_rss_stat(struct task_struct *task)
199 #endif /* SPLIT_RSS_COUNTING */
201 #ifdef HAVE_GENERIC_MMU_GATHER
203 static bool tlb_next_batch(struct mmu_gather *tlb)
205 struct mmu_gather_batch *batch;
209 tlb->active = batch->next;
213 if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
216 batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
223 batch->max = MAX_GATHER_BATCH;
225 tlb->active->next = batch;
231 void arch_tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
232 unsigned long start, unsigned long end)
236 /* Is it from 0 to ~0? */
237 tlb->fullmm = !(start | (end+1));
238 tlb->need_flush_all = 0;
239 tlb->local.next = NULL;
241 tlb->local.max = ARRAY_SIZE(tlb->__pages);
242 tlb->active = &tlb->local;
243 tlb->batch_count = 0;
245 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
250 __tlb_reset_range(tlb);
253 static void tlb_flush_mmu_free(struct mmu_gather *tlb)
255 struct mmu_gather_batch *batch;
257 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
258 tlb_table_flush(tlb);
260 for (batch = &tlb->local; batch && batch->nr; batch = batch->next) {
261 free_pages_and_swap_cache(batch->pages, batch->nr);
264 tlb->active = &tlb->local;
267 void tlb_flush_mmu(struct mmu_gather *tlb)
269 tlb_flush_mmu_tlbonly(tlb);
270 tlb_flush_mmu_free(tlb);
274 * Called at the end of the shootdown operation to free up any resources
275 * that were required.
277 void arch_tlb_finish_mmu(struct mmu_gather *tlb,
278 unsigned long start, unsigned long end, bool force)
280 struct mmu_gather_batch *batch, *next;
283 __tlb_adjust_range(tlb, start, end - start);
287 /* keep the page table cache within bounds */
290 for (batch = tlb->local.next; batch; batch = next) {
292 free_pages((unsigned long)batch, 0);
294 tlb->local.next = NULL;
298 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
299 * handling the additional races in SMP caused by other CPUs caching valid
300 * mappings in their TLBs. Returns the number of free page slots left.
301 * When out of page slots we must call tlb_flush_mmu().
302 *returns true if the caller should flush.
304 bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_size)
306 struct mmu_gather_batch *batch;
308 VM_BUG_ON(!tlb->end);
309 VM_WARN_ON(tlb->page_size != page_size);
313 * Add the page and check if we are full. If so
316 batch->pages[batch->nr++] = page;
317 if (batch->nr == batch->max) {
318 if (!tlb_next_batch(tlb))
322 VM_BUG_ON_PAGE(batch->nr > batch->max, page);
327 void tlb_flush_pmd_range(struct mmu_gather *tlb, unsigned long address,
330 if (tlb->page_size != 0 && tlb->page_size != PMD_SIZE)
333 tlb->page_size = PMD_SIZE;
334 tlb->start = min(tlb->start, address);
335 tlb->end = max(tlb->end, address + size);
337 #endif /* HAVE_GENERIC_MMU_GATHER */
339 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
342 * See the comment near struct mmu_table_batch.
346 * If we want tlb_remove_table() to imply TLB invalidates.
348 static inline void tlb_table_invalidate(struct mmu_gather *tlb)
350 #ifdef CONFIG_HAVE_RCU_TABLE_INVALIDATE
352 * Invalidate page-table caches used by hardware walkers. Then we still
353 * need to RCU-sched wait while freeing the pages because software
354 * walkers can still be in-flight.
356 tlb_flush_mmu_tlbonly(tlb);
360 static void tlb_remove_table_smp_sync(void *arg)
362 /* Simply deliver the interrupt */
365 static void tlb_remove_table_one(void *table)
368 * This isn't an RCU grace period and hence the page-tables cannot be
369 * assumed to be actually RCU-freed.
371 * It is however sufficient for software page-table walkers that rely on
372 * IRQ disabling. See the comment near struct mmu_table_batch.
374 smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
375 __tlb_remove_table(table);
378 static void tlb_remove_table_rcu(struct rcu_head *head)
380 struct mmu_table_batch *batch;
383 batch = container_of(head, struct mmu_table_batch, rcu);
385 for (i = 0; i < batch->nr; i++)
386 __tlb_remove_table(batch->tables[i]);
388 free_page((unsigned long)batch);
391 void tlb_table_flush(struct mmu_gather *tlb)
393 struct mmu_table_batch **batch = &tlb->batch;
396 tlb_table_invalidate(tlb);
397 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
402 void tlb_remove_table(struct mmu_gather *tlb, void *table)
404 struct mmu_table_batch **batch = &tlb->batch;
406 if (*batch == NULL) {
407 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
408 if (*batch == NULL) {
409 tlb_table_invalidate(tlb);
410 tlb_remove_table_one(table);
416 (*batch)->tables[(*batch)->nr++] = table;
417 if ((*batch)->nr == MAX_TABLE_BATCH)
418 tlb_table_flush(tlb);
421 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */
424 * tlb_gather_mmu - initialize an mmu_gather structure for page-table tear-down
425 * @tlb: the mmu_gather structure to initialize
426 * @mm: the mm_struct of the target address space
427 * @start: start of the region that will be removed from the page-table
428 * @end: end of the region that will be removed from the page-table
430 * Called to initialize an (on-stack) mmu_gather structure for page-table
431 * tear-down from @mm. The @start and @end are set to 0 and -1
432 * respectively when @mm is without users and we're going to destroy
433 * the full address space (exit/execve).
435 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
436 unsigned long start, unsigned long end)
438 arch_tlb_gather_mmu(tlb, mm, start, end);
439 inc_tlb_flush_pending(tlb->mm);
442 void tlb_finish_mmu(struct mmu_gather *tlb,
443 unsigned long start, unsigned long end)
446 * If there are parallel threads are doing PTE changes on same range
447 * under non-exclusive lock(e.g., mmap_sem read-side) but defer TLB
448 * flush by batching, a thread has stable TLB entry can fail to flush
449 * the TLB by observing pte_none|!pte_dirty, for example so flush TLB
450 * forcefully if we detect parallel PTE batching threads.
452 bool force = mm_tlb_flush_nested(tlb->mm);
454 arch_tlb_finish_mmu(tlb, start, end, force);
455 dec_tlb_flush_pending(tlb->mm);
459 * Note: this doesn't free the actual pages themselves. That
460 * has been handled earlier when unmapping all the memory regions.
462 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
465 pgtable_t token = pmd_pgtable(*pmd);
467 pte_free_tlb(tlb, token, addr);
468 mm_dec_nr_ptes(tlb->mm);
471 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
472 unsigned long addr, unsigned long end,
473 unsigned long floor, unsigned long ceiling)
480 pmd = pmd_offset(pud, addr);
482 next = pmd_addr_end(addr, end);
483 if (pmd_none_or_clear_bad(pmd))
485 free_pte_range(tlb, pmd, addr);
486 } while (pmd++, addr = next, addr != end);
496 if (end - 1 > ceiling - 1)
499 pmd = pmd_offset(pud, start);
501 pmd_free_tlb(tlb, pmd, start);
502 mm_dec_nr_pmds(tlb->mm);
505 static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
506 unsigned long addr, unsigned long end,
507 unsigned long floor, unsigned long ceiling)
514 pud = pud_offset(p4d, addr);
516 next = pud_addr_end(addr, end);
517 if (pud_none_or_clear_bad(pud))
519 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
520 } while (pud++, addr = next, addr != end);
530 if (end - 1 > ceiling - 1)
533 pud = pud_offset(p4d, start);
535 pud_free_tlb(tlb, pud, start);
536 mm_dec_nr_puds(tlb->mm);
539 static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
540 unsigned long addr, unsigned long end,
541 unsigned long floor, unsigned long ceiling)
548 p4d = p4d_offset(pgd, addr);
550 next = p4d_addr_end(addr, end);
551 if (p4d_none_or_clear_bad(p4d))
553 free_pud_range(tlb, p4d, addr, next, floor, ceiling);
554 } while (p4d++, addr = next, addr != end);
560 ceiling &= PGDIR_MASK;
564 if (end - 1 > ceiling - 1)
567 p4d = p4d_offset(pgd, start);
569 p4d_free_tlb(tlb, p4d, start);
573 * This function frees user-level page tables of a process.
575 void free_pgd_range(struct mmu_gather *tlb,
576 unsigned long addr, unsigned long end,
577 unsigned long floor, unsigned long ceiling)
583 * The next few lines have given us lots of grief...
585 * Why are we testing PMD* at this top level? Because often
586 * there will be no work to do at all, and we'd prefer not to
587 * go all the way down to the bottom just to discover that.
589 * Why all these "- 1"s? Because 0 represents both the bottom
590 * of the address space and the top of it (using -1 for the
591 * top wouldn't help much: the masks would do the wrong thing).
592 * The rule is that addr 0 and floor 0 refer to the bottom of
593 * the address space, but end 0 and ceiling 0 refer to the top
594 * Comparisons need to use "end - 1" and "ceiling - 1" (though
595 * that end 0 case should be mythical).
597 * Wherever addr is brought up or ceiling brought down, we must
598 * be careful to reject "the opposite 0" before it confuses the
599 * subsequent tests. But what about where end is brought down
600 * by PMD_SIZE below? no, end can't go down to 0 there.
602 * Whereas we round start (addr) and ceiling down, by different
603 * masks at different levels, in order to test whether a table
604 * now has no other vmas using it, so can be freed, we don't
605 * bother to round floor or end up - the tests don't need that.
619 if (end - 1 > ceiling - 1)
624 * We add page table cache pages with PAGE_SIZE,
625 * (see pte_free_tlb()), flush the tlb if we need
627 tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
628 pgd = pgd_offset(tlb->mm, addr);
630 next = pgd_addr_end(addr, end);
631 if (pgd_none_or_clear_bad(pgd))
633 free_p4d_range(tlb, pgd, addr, next, floor, ceiling);
634 } while (pgd++, addr = next, addr != end);
637 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
638 unsigned long floor, unsigned long ceiling)
641 struct vm_area_struct *next = vma->vm_next;
642 unsigned long addr = vma->vm_start;
645 * Hide vma from rmap and truncate_pagecache before freeing
648 unlink_anon_vmas(vma);
649 unlink_file_vma(vma);
651 if (is_vm_hugetlb_page(vma)) {
652 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
653 floor, next ? next->vm_start : ceiling);
656 * Optimization: gather nearby vmas into one call down
658 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
659 && !is_vm_hugetlb_page(next)) {
662 unlink_anon_vmas(vma);
663 unlink_file_vma(vma);
665 free_pgd_range(tlb, addr, vma->vm_end,
666 floor, next ? next->vm_start : ceiling);
672 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
675 pgtable_t new = pte_alloc_one(mm, address);
680 * Ensure all pte setup (eg. pte page lock and page clearing) are
681 * visible before the pte is made visible to other CPUs by being
682 * put into page tables.
684 * The other side of the story is the pointer chasing in the page
685 * table walking code (when walking the page table without locking;
686 * ie. most of the time). Fortunately, these data accesses consist
687 * of a chain of data-dependent loads, meaning most CPUs (alpha
688 * being the notable exception) will already guarantee loads are
689 * seen in-order. See the alpha page table accessors for the
690 * smp_read_barrier_depends() barriers in page table walking code.
692 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
694 ptl = pmd_lock(mm, pmd);
695 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
697 pmd_populate(mm, pmd, new);
706 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
708 pte_t *new = pte_alloc_one_kernel(&init_mm, address);
712 smp_wmb(); /* See comment in __pte_alloc */
714 spin_lock(&init_mm.page_table_lock);
715 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
716 pmd_populate_kernel(&init_mm, pmd, new);
719 spin_unlock(&init_mm.page_table_lock);
721 pte_free_kernel(&init_mm, new);
725 static inline void init_rss_vec(int *rss)
727 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
730 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
734 if (current->mm == mm)
736 for (i = 0; i < NR_MM_COUNTERS; i++)
738 add_mm_counter(mm, i, rss[i]);
742 * This function is called to print an error when a bad pte
743 * is found. For example, we might have a PFN-mapped pte in
744 * a region that doesn't allow it.
746 * The calling function must still handle the error.
748 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
749 pte_t pte, struct page *page)
751 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
752 p4d_t *p4d = p4d_offset(pgd, addr);
753 pud_t *pud = pud_offset(p4d, addr);
754 pmd_t *pmd = pmd_offset(pud, addr);
755 struct address_space *mapping;
757 static unsigned long resume;
758 static unsigned long nr_shown;
759 static unsigned long nr_unshown;
762 * Allow a burst of 60 reports, then keep quiet for that minute;
763 * or allow a steady drip of one report per second.
765 if (nr_shown == 60) {
766 if (time_before(jiffies, resume)) {
771 pr_alert("BUG: Bad page map: %lu messages suppressed\n",
778 resume = jiffies + 60 * HZ;
780 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
781 index = linear_page_index(vma, addr);
783 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
785 (long long)pte_val(pte), (long long)pmd_val(*pmd));
787 dump_page(page, "bad pte");
788 pr_alert("addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
789 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
790 pr_alert("file:%pD fault:%pf mmap:%pf readpage:%pf\n",
792 vma->vm_ops ? vma->vm_ops->fault : NULL,
793 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
794 mapping ? mapping->a_ops->readpage : NULL);
796 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
800 * vm_normal_page -- This function gets the "struct page" associated with a pte.
802 * "Special" mappings do not wish to be associated with a "struct page" (either
803 * it doesn't exist, or it exists but they don't want to touch it). In this
804 * case, NULL is returned here. "Normal" mappings do have a struct page.
806 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
807 * pte bit, in which case this function is trivial. Secondly, an architecture
808 * may not have a spare pte bit, which requires a more complicated scheme,
811 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
812 * special mapping (even if there are underlying and valid "struct pages").
813 * COWed pages of a VM_PFNMAP are always normal.
815 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
816 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
817 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
818 * mapping will always honor the rule
820 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
822 * And for normal mappings this is false.
824 * This restricts such mappings to be a linear translation from virtual address
825 * to pfn. To get around this restriction, we allow arbitrary mappings so long
826 * as the vma is not a COW mapping; in that case, we know that all ptes are
827 * special (because none can have been COWed).
830 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
832 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
833 * page" backing, however the difference is that _all_ pages with a struct
834 * page (that is, those where pfn_valid is true) are refcounted and considered
835 * normal pages by the VM. The disadvantage is that pages are refcounted
836 * (which can be slower and simply not an option for some PFNMAP users). The
837 * advantage is that we don't have to follow the strict linearity rule of
838 * PFNMAP mappings in order to support COWable mappings.
841 struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
842 pte_t pte, bool with_public_device)
844 unsigned long pfn = pte_pfn(pte);
846 if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) {
847 if (likely(!pte_special(pte)))
849 if (vma->vm_ops && vma->vm_ops->find_special_page)
850 return vma->vm_ops->find_special_page(vma, addr);
851 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
853 if (is_zero_pfn(pfn))
857 * Device public pages are special pages (they are ZONE_DEVICE
858 * pages but different from persistent memory). They behave
859 * allmost like normal pages. The difference is that they are
860 * not on the lru and thus should never be involve with any-
861 * thing that involve lru manipulation (mlock, numa balancing,
864 * This is why we still want to return NULL for such page from
865 * vm_normal_page() so that we do not have to special case all
866 * call site of vm_normal_page().
868 if (likely(pfn <= highest_memmap_pfn)) {
869 struct page *page = pfn_to_page(pfn);
871 if (is_device_public_page(page)) {
872 if (with_public_device)
881 print_bad_pte(vma, addr, pte, NULL);
885 /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */
887 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
888 if (vma->vm_flags & VM_MIXEDMAP) {
894 off = (addr - vma->vm_start) >> PAGE_SHIFT;
895 if (pfn == vma->vm_pgoff + off)
897 if (!is_cow_mapping(vma->vm_flags))
902 if (is_zero_pfn(pfn))
906 if (unlikely(pfn > highest_memmap_pfn)) {
907 print_bad_pte(vma, addr, pte, NULL);
912 * NOTE! We still have PageReserved() pages in the page tables.
913 * eg. VDSO mappings can cause them to exist.
916 return pfn_to_page(pfn);
919 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
920 struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
923 unsigned long pfn = pmd_pfn(pmd);
926 * There is no pmd_special() but there may be special pmds, e.g.
927 * in a direct-access (dax) mapping, so let's just replicate the
928 * !CONFIG_ARCH_HAS_PTE_SPECIAL case from vm_normal_page() here.
930 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
931 if (vma->vm_flags & VM_MIXEDMAP) {
937 off = (addr - vma->vm_start) >> PAGE_SHIFT;
938 if (pfn == vma->vm_pgoff + off)
940 if (!is_cow_mapping(vma->vm_flags))
947 if (is_zero_pfn(pfn))
949 if (unlikely(pfn > highest_memmap_pfn))
953 * NOTE! We still have PageReserved() pages in the page tables.
954 * eg. VDSO mappings can cause them to exist.
957 return pfn_to_page(pfn);
962 * copy one vm_area from one task to the other. Assumes the page tables
963 * already present in the new task to be cleared in the whole range
964 * covered by this vma.
967 static inline unsigned long
968 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
969 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
970 unsigned long addr, int *rss)
972 unsigned long vm_flags = vma->vm_flags;
973 pte_t pte = *src_pte;
976 /* pte contains position in swap or file, so copy. */
977 if (unlikely(!pte_present(pte))) {
978 swp_entry_t entry = pte_to_swp_entry(pte);
980 if (likely(!non_swap_entry(entry))) {
981 if (swap_duplicate(entry) < 0)
984 /* make sure dst_mm is on swapoff's mmlist. */
985 if (unlikely(list_empty(&dst_mm->mmlist))) {
986 spin_lock(&mmlist_lock);
987 if (list_empty(&dst_mm->mmlist))
988 list_add(&dst_mm->mmlist,
990 spin_unlock(&mmlist_lock);
993 } else if (is_migration_entry(entry)) {
994 page = migration_entry_to_page(entry);
996 rss[mm_counter(page)]++;
998 if (is_write_migration_entry(entry) &&
999 is_cow_mapping(vm_flags)) {
1001 * COW mappings require pages in both
1002 * parent and child to be set to read.
1004 make_migration_entry_read(&entry);
1005 pte = swp_entry_to_pte(entry);
1006 if (pte_swp_soft_dirty(*src_pte))
1007 pte = pte_swp_mksoft_dirty(pte);
1008 set_pte_at(src_mm, addr, src_pte, pte);
1010 } else if (is_device_private_entry(entry)) {
1011 page = device_private_entry_to_page(entry);
1014 * Update rss count even for unaddressable pages, as
1015 * they should treated just like normal pages in this
1018 * We will likely want to have some new rss counters
1019 * for unaddressable pages, at some point. But for now
1020 * keep things as they are.
1023 rss[mm_counter(page)]++;
1024 page_dup_rmap(page, false);
1027 * We do not preserve soft-dirty information, because so
1028 * far, checkpoint/restore is the only feature that
1029 * requires that. And checkpoint/restore does not work
1030 * when a device driver is involved (you cannot easily
1031 * save and restore device driver state).
1033 if (is_write_device_private_entry(entry) &&
1034 is_cow_mapping(vm_flags)) {
1035 make_device_private_entry_read(&entry);
1036 pte = swp_entry_to_pte(entry);
1037 set_pte_at(src_mm, addr, src_pte, pte);
1044 * If it's a COW mapping, write protect it both
1045 * in the parent and the child
1047 if (is_cow_mapping(vm_flags) && pte_write(pte)) {
1048 ptep_set_wrprotect(src_mm, addr, src_pte);
1049 pte = pte_wrprotect(pte);
1053 * If it's a shared mapping, mark it clean in
1056 if (vm_flags & VM_SHARED)
1057 pte = pte_mkclean(pte);
1058 pte = pte_mkold(pte);
1060 page = vm_normal_page(vma, addr, pte);
1063 page_dup_rmap(page, false);
1064 rss[mm_counter(page)]++;
1065 } else if (pte_devmap(pte)) {
1066 page = pte_page(pte);
1069 * Cache coherent device memory behave like regular page and
1070 * not like persistent memory page. For more informations see
1071 * MEMORY_DEVICE_CACHE_COHERENT in memory_hotplug.h
1073 if (is_device_public_page(page)) {
1075 page_dup_rmap(page, false);
1076 rss[mm_counter(page)]++;
1081 set_pte_at(dst_mm, addr, dst_pte, pte);
1085 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1086 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
1087 unsigned long addr, unsigned long end)
1089 pte_t *orig_src_pte, *orig_dst_pte;
1090 pte_t *src_pte, *dst_pte;
1091 spinlock_t *src_ptl, *dst_ptl;
1093 int rss[NR_MM_COUNTERS];
1094 swp_entry_t entry = (swp_entry_t){0};
1099 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
1102 src_pte = pte_offset_map(src_pmd, addr);
1103 src_ptl = pte_lockptr(src_mm, src_pmd);
1104 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1105 orig_src_pte = src_pte;
1106 orig_dst_pte = dst_pte;
1107 arch_enter_lazy_mmu_mode();
1111 * We are holding two locks at this point - either of them
1112 * could generate latencies in another task on another CPU.
1114 if (progress >= 32) {
1116 if (need_resched() ||
1117 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
1120 if (pte_none(*src_pte)) {
1124 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
1129 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
1131 arch_leave_lazy_mmu_mode();
1132 spin_unlock(src_ptl);
1133 pte_unmap(orig_src_pte);
1134 add_mm_rss_vec(dst_mm, rss);
1135 pte_unmap_unlock(orig_dst_pte, dst_ptl);
1139 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
1148 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1149 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
1150 unsigned long addr, unsigned long end)
1152 pmd_t *src_pmd, *dst_pmd;
1155 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
1158 src_pmd = pmd_offset(src_pud, addr);
1160 next = pmd_addr_end(addr, end);
1161 if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
1162 || pmd_devmap(*src_pmd)) {
1164 VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, vma);
1165 err = copy_huge_pmd(dst_mm, src_mm,
1166 dst_pmd, src_pmd, addr, vma);
1173 if (pmd_none_or_clear_bad(src_pmd))
1175 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1178 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1182 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1183 p4d_t *dst_p4d, p4d_t *src_p4d, struct vm_area_struct *vma,
1184 unsigned long addr, unsigned long end)
1186 pud_t *src_pud, *dst_pud;
1189 dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
1192 src_pud = pud_offset(src_p4d, addr);
1194 next = pud_addr_end(addr, end);
1195 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
1198 VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, vma);
1199 err = copy_huge_pud(dst_mm, src_mm,
1200 dst_pud, src_pud, addr, vma);
1207 if (pud_none_or_clear_bad(src_pud))
1209 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1212 } while (dst_pud++, src_pud++, addr = next, addr != end);
1216 static inline int copy_p4d_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1217 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1218 unsigned long addr, unsigned long end)
1220 p4d_t *src_p4d, *dst_p4d;
1223 dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
1226 src_p4d = p4d_offset(src_pgd, addr);
1228 next = p4d_addr_end(addr, end);
1229 if (p4d_none_or_clear_bad(src_p4d))
1231 if (copy_pud_range(dst_mm, src_mm, dst_p4d, src_p4d,
1234 } while (dst_p4d++, src_p4d++, addr = next, addr != end);
1238 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1239 struct vm_area_struct *vma)
1241 pgd_t *src_pgd, *dst_pgd;
1243 unsigned long addr = vma->vm_start;
1244 unsigned long end = vma->vm_end;
1245 unsigned long mmun_start; /* For mmu_notifiers */
1246 unsigned long mmun_end; /* For mmu_notifiers */
1251 * Don't copy ptes where a page fault will fill them correctly.
1252 * Fork becomes much lighter when there are big shared or private
1253 * readonly mappings. The tradeoff is that copy_page_range is more
1254 * efficient than faulting.
1256 if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
1260 if (is_vm_hugetlb_page(vma))
1261 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1263 if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1265 * We do not free on error cases below as remove_vma
1266 * gets called on error from higher level routine
1268 ret = track_pfn_copy(vma);
1274 * We need to invalidate the secondary MMU mappings only when
1275 * there could be a permission downgrade on the ptes of the
1276 * parent mm. And a permission downgrade will only happen if
1277 * is_cow_mapping() returns true.
1279 is_cow = is_cow_mapping(vma->vm_flags);
1283 mmu_notifier_invalidate_range_start(src_mm, mmun_start,
1287 dst_pgd = pgd_offset(dst_mm, addr);
1288 src_pgd = pgd_offset(src_mm, addr);
1290 next = pgd_addr_end(addr, end);
1291 if (pgd_none_or_clear_bad(src_pgd))
1293 if (unlikely(copy_p4d_range(dst_mm, src_mm, dst_pgd, src_pgd,
1294 vma, addr, next))) {
1298 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1301 mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
1305 static unsigned long zap_pte_range(struct mmu_gather *tlb,
1306 struct vm_area_struct *vma, pmd_t *pmd,
1307 unsigned long addr, unsigned long end,
1308 struct zap_details *details)
1310 struct mm_struct *mm = tlb->mm;
1311 int force_flush = 0;
1312 int rss[NR_MM_COUNTERS];
1318 tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
1321 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1323 flush_tlb_batched_pending(mm);
1324 arch_enter_lazy_mmu_mode();
1327 if (pte_none(ptent))
1330 if (pte_present(ptent)) {
1333 page = _vm_normal_page(vma, addr, ptent, true);
1334 if (unlikely(details) && page) {
1336 * unmap_shared_mapping_pages() wants to
1337 * invalidate cache without truncating:
1338 * unmap shared but keep private pages.
1340 if (details->check_mapping &&
1341 details->check_mapping != page_rmapping(page))
1344 ptent = ptep_get_and_clear_full(mm, addr, pte,
1346 tlb_remove_tlb_entry(tlb, pte, addr);
1347 if (unlikely(!page))
1350 if (!PageAnon(page)) {
1351 if (pte_dirty(ptent)) {
1353 set_page_dirty(page);
1355 if (pte_young(ptent) &&
1356 likely(!(vma->vm_flags & VM_SEQ_READ)))
1357 mark_page_accessed(page);
1359 rss[mm_counter(page)]--;
1360 page_remove_rmap(page, false);
1361 if (unlikely(page_mapcount(page) < 0))
1362 print_bad_pte(vma, addr, ptent, page);
1363 if (unlikely(__tlb_remove_page(tlb, page))) {
1371 entry = pte_to_swp_entry(ptent);
1372 if (non_swap_entry(entry) && is_device_private_entry(entry)) {
1373 struct page *page = device_private_entry_to_page(entry);
1375 if (unlikely(details && details->check_mapping)) {
1377 * unmap_shared_mapping_pages() wants to
1378 * invalidate cache without truncating:
1379 * unmap shared but keep private pages.
1381 if (details->check_mapping !=
1382 page_rmapping(page))
1386 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1387 rss[mm_counter(page)]--;
1388 page_remove_rmap(page, false);
1393 /* If details->check_mapping, we leave swap entries. */
1394 if (unlikely(details))
1397 entry = pte_to_swp_entry(ptent);
1398 if (!non_swap_entry(entry))
1400 else if (is_migration_entry(entry)) {
1403 page = migration_entry_to_page(entry);
1404 rss[mm_counter(page)]--;
1406 if (unlikely(!free_swap_and_cache(entry)))
1407 print_bad_pte(vma, addr, ptent, NULL);
1408 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1409 } while (pte++, addr += PAGE_SIZE, addr != end);
1411 add_mm_rss_vec(mm, rss);
1412 arch_leave_lazy_mmu_mode();
1414 /* Do the actual TLB flush before dropping ptl */
1416 tlb_flush_mmu_tlbonly(tlb);
1417 pte_unmap_unlock(start_pte, ptl);
1420 * If we forced a TLB flush (either due to running out of
1421 * batch buffers or because we needed to flush dirty TLB
1422 * entries before releasing the ptl), free the batched
1423 * memory too. Restart if we didn't do everything.
1427 tlb_flush_mmu_free(tlb);
1435 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1436 struct vm_area_struct *vma, pud_t *pud,
1437 unsigned long addr, unsigned long end,
1438 struct zap_details *details)
1443 pmd = pmd_offset(pud, addr);
1445 next = pmd_addr_end(addr, end);
1446 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1447 if (next - addr != HPAGE_PMD_SIZE)
1448 __split_huge_pmd(vma, pmd, addr, false, NULL);
1449 else if (zap_huge_pmd(tlb, vma, pmd, addr))
1452 } else if (details && details->single_page &&
1453 PageTransCompound(details->single_page) &&
1454 next - addr == HPAGE_PMD_SIZE && pmd_none(*pmd)) {
1455 spinlock_t *ptl = pmd_lock(tlb->mm, pmd);
1457 * Take and drop THP pmd lock so that we cannot return
1458 * prematurely, while zap_huge_pmd() has cleared *pmd,
1459 * but not yet decremented compound_mapcount().
1465 * Here there can be other concurrent MADV_DONTNEED or
1466 * trans huge page faults running, and if the pmd is
1467 * none or trans huge it can change under us. This is
1468 * because MADV_DONTNEED holds the mmap_sem in read
1471 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1473 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1476 } while (pmd++, addr = next, addr != end);
1481 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1482 struct vm_area_struct *vma, p4d_t *p4d,
1483 unsigned long addr, unsigned long end,
1484 struct zap_details *details)
1489 pud = pud_offset(p4d, addr);
1491 next = pud_addr_end(addr, end);
1492 if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1493 if (next - addr != HPAGE_PUD_SIZE) {
1494 VM_BUG_ON_VMA(!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1495 split_huge_pud(vma, pud, addr);
1496 } else if (zap_huge_pud(tlb, vma, pud, addr))
1500 if (pud_none_or_clear_bad(pud))
1502 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1505 } while (pud++, addr = next, addr != end);
1510 static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
1511 struct vm_area_struct *vma, pgd_t *pgd,
1512 unsigned long addr, unsigned long end,
1513 struct zap_details *details)
1518 p4d = p4d_offset(pgd, addr);
1520 next = p4d_addr_end(addr, end);
1521 if (p4d_none_or_clear_bad(p4d))
1523 next = zap_pud_range(tlb, vma, p4d, addr, next, details);
1524 } while (p4d++, addr = next, addr != end);
1529 void unmap_page_range(struct mmu_gather *tlb,
1530 struct vm_area_struct *vma,
1531 unsigned long addr, unsigned long end,
1532 struct zap_details *details)
1537 BUG_ON(addr >= end);
1538 tlb_start_vma(tlb, vma);
1539 pgd = pgd_offset(vma->vm_mm, addr);
1541 next = pgd_addr_end(addr, end);
1542 if (pgd_none_or_clear_bad(pgd))
1544 next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
1545 } while (pgd++, addr = next, addr != end);
1546 tlb_end_vma(tlb, vma);
1550 static void unmap_single_vma(struct mmu_gather *tlb,
1551 struct vm_area_struct *vma, unsigned long start_addr,
1552 unsigned long end_addr,
1553 struct zap_details *details)
1555 unsigned long start = max(vma->vm_start, start_addr);
1558 if (start >= vma->vm_end)
1560 end = min(vma->vm_end, end_addr);
1561 if (end <= vma->vm_start)
1565 uprobe_munmap(vma, start, end);
1567 if (unlikely(vma->vm_flags & VM_PFNMAP))
1568 untrack_pfn(vma, 0, 0);
1571 if (unlikely(is_vm_hugetlb_page(vma))) {
1573 * It is undesirable to test vma->vm_file as it
1574 * should be non-null for valid hugetlb area.
1575 * However, vm_file will be NULL in the error
1576 * cleanup path of mmap_region. When
1577 * hugetlbfs ->mmap method fails,
1578 * mmap_region() nullifies vma->vm_file
1579 * before calling this function to clean up.
1580 * Since no pte has actually been setup, it is
1581 * safe to do nothing in this case.
1584 i_mmap_lock_write(vma->vm_file->f_mapping);
1585 __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1586 i_mmap_unlock_write(vma->vm_file->f_mapping);
1589 unmap_page_range(tlb, vma, start, end, details);
1594 * unmap_vmas - unmap a range of memory covered by a list of vma's
1595 * @tlb: address of the caller's struct mmu_gather
1596 * @vma: the starting vma
1597 * @start_addr: virtual address at which to start unmapping
1598 * @end_addr: virtual address at which to end unmapping
1600 * Unmap all pages in the vma list.
1602 * Only addresses between `start' and `end' will be unmapped.
1604 * The VMA list must be sorted in ascending virtual address order.
1606 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1607 * range after unmap_vmas() returns. So the only responsibility here is to
1608 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1609 * drops the lock and schedules.
1611 void unmap_vmas(struct mmu_gather *tlb,
1612 struct vm_area_struct *vma, unsigned long start_addr,
1613 unsigned long end_addr)
1615 struct mm_struct *mm = vma->vm_mm;
1617 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1618 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1619 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1620 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1624 * zap_page_range - remove user pages in a given range
1625 * @vma: vm_area_struct holding the applicable pages
1626 * @start: starting address of pages to zap
1627 * @size: number of bytes to zap
1629 * Caller must protect the VMA list
1631 void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1634 struct mm_struct *mm = vma->vm_mm;
1635 struct mmu_gather tlb;
1636 unsigned long end = start + size;
1639 tlb_gather_mmu(&tlb, mm, start, end);
1640 update_hiwater_rss(mm);
1641 mmu_notifier_invalidate_range_start(mm, start, end);
1642 for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1643 unmap_single_vma(&tlb, vma, start, end, NULL);
1644 mmu_notifier_invalidate_range_end(mm, start, end);
1645 tlb_finish_mmu(&tlb, start, end);
1649 * zap_page_range_single - remove user pages in a given range
1650 * @vma: vm_area_struct holding the applicable pages
1651 * @address: starting address of pages to zap
1652 * @size: number of bytes to zap
1653 * @details: details of shared cache invalidation
1655 * The range must fit into one VMA.
1657 static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1658 unsigned long size, struct zap_details *details)
1660 struct mm_struct *mm = vma->vm_mm;
1661 struct mmu_gather tlb;
1662 unsigned long end = address + size;
1665 tlb_gather_mmu(&tlb, mm, address, end);
1666 update_hiwater_rss(mm);
1667 mmu_notifier_invalidate_range_start(mm, address, end);
1668 unmap_single_vma(&tlb, vma, address, end, details);
1669 mmu_notifier_invalidate_range_end(mm, address, end);
1670 tlb_finish_mmu(&tlb, address, end);
1674 * zap_vma_ptes - remove ptes mapping the vma
1675 * @vma: vm_area_struct holding ptes to be zapped
1676 * @address: starting address of pages to zap
1677 * @size: number of bytes to zap
1679 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1681 * The entire address range must be fully contained within the vma.
1684 void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1687 if (address < vma->vm_start || address + size > vma->vm_end ||
1688 !(vma->vm_flags & VM_PFNMAP))
1691 zap_page_range_single(vma, address, size, NULL);
1693 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1695 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1703 pgd = pgd_offset(mm, addr);
1704 p4d = p4d_alloc(mm, pgd, addr);
1707 pud = pud_alloc(mm, p4d, addr);
1710 pmd = pmd_alloc(mm, pud, addr);
1714 VM_BUG_ON(pmd_trans_huge(*pmd));
1715 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1719 * This is the old fallback for page remapping.
1721 * For historical reasons, it only allows reserved pages. Only
1722 * old drivers should use this, and they needed to mark their
1723 * pages reserved for the old functions anyway.
1725 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1726 struct page *page, pgprot_t prot)
1728 struct mm_struct *mm = vma->vm_mm;
1737 flush_dcache_page(page);
1738 pte = get_locked_pte(mm, addr, &ptl);
1742 if (!pte_none(*pte))
1745 /* Ok, finally just insert the thing.. */
1747 inc_mm_counter_fast(mm, mm_counter_file(page));
1748 page_add_file_rmap(page, false);
1749 set_pte_at(mm, addr, pte, mk_pte(page, prot));
1752 pte_unmap_unlock(pte, ptl);
1755 pte_unmap_unlock(pte, ptl);
1761 * vm_insert_page - insert single page into user vma
1762 * @vma: user vma to map to
1763 * @addr: target user address of this page
1764 * @page: source kernel page
1766 * This allows drivers to insert individual pages they've allocated
1769 * The page has to be a nice clean _individual_ kernel allocation.
1770 * If you allocate a compound page, you need to have marked it as
1771 * such (__GFP_COMP), or manually just split the page up yourself
1772 * (see split_page()).
1774 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1775 * took an arbitrary page protection parameter. This doesn't allow
1776 * that. Your vma protection will have to be set up correctly, which
1777 * means that if you want a shared writable mapping, you'd better
1778 * ask for a shared writable mapping!
1780 * The page does not need to be reserved.
1782 * Usually this function is called from f_op->mmap() handler
1783 * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
1784 * Caller must set VM_MIXEDMAP on vma if it wants to call this
1785 * function from other places, for example from page-fault handler.
1787 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1790 if (addr < vma->vm_start || addr >= vma->vm_end)
1792 if (!page_count(page))
1794 if (!(vma->vm_flags & VM_MIXEDMAP)) {
1795 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
1796 BUG_ON(vma->vm_flags & VM_PFNMAP);
1797 vma->vm_flags |= VM_MIXEDMAP;
1799 return insert_page(vma, addr, page, vma->vm_page_prot);
1801 EXPORT_SYMBOL(vm_insert_page);
1803 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1804 pfn_t pfn, pgprot_t prot, bool mkwrite)
1806 struct mm_struct *mm = vma->vm_mm;
1812 pte = get_locked_pte(mm, addr, &ptl);
1816 if (!pte_none(*pte)) {
1819 * For read faults on private mappings the PFN passed
1820 * in may not match the PFN we have mapped if the
1821 * mapped PFN is a writeable COW page. In the mkwrite
1822 * case we are creating a writable PTE for a shared
1823 * mapping and we expect the PFNs to match. If they
1824 * don't match, we are likely racing with block
1825 * allocation and mapping invalidation so just skip the
1828 if (pte_pfn(*pte) != pfn_t_to_pfn(pfn)) {
1829 WARN_ON_ONCE(!is_zero_pfn(pte_pfn(*pte)));
1832 entry = pte_mkyoung(*pte);
1833 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1834 if (ptep_set_access_flags(vma, addr, pte, entry, 1))
1835 update_mmu_cache(vma, addr, pte);
1840 /* Ok, finally just insert the thing.. */
1841 if (pfn_t_devmap(pfn))
1842 entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
1844 entry = pte_mkspecial(pfn_t_pte(pfn, prot));
1847 entry = pte_mkyoung(entry);
1848 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1851 set_pte_at(mm, addr, pte, entry);
1852 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1856 pte_unmap_unlock(pte, ptl);
1862 * vm_insert_pfn - insert single pfn into user vma
1863 * @vma: user vma to map to
1864 * @addr: target user address of this page
1865 * @pfn: source kernel pfn
1867 * Similar to vm_insert_page, this allows drivers to insert individual pages
1868 * they've allocated into a user vma. Same comments apply.
1870 * This function should only be called from a vm_ops->fault handler, and
1871 * in that case the handler should return NULL.
1873 * vma cannot be a COW mapping.
1875 * As this is called only for pages that do not currently exist, we
1876 * do not need to flush old virtual caches or the TLB.
1878 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1881 return vm_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
1883 EXPORT_SYMBOL(vm_insert_pfn);
1886 * vm_insert_pfn_prot - insert single pfn into user vma with specified pgprot
1887 * @vma: user vma to map to
1888 * @addr: target user address of this page
1889 * @pfn: source kernel pfn
1890 * @pgprot: pgprot flags for the inserted page
1892 * This is exactly like vm_insert_pfn, except that it allows drivers to
1893 * to override pgprot on a per-page basis.
1895 * This only makes sense for IO mappings, and it makes no sense for
1896 * cow mappings. In general, using multiple vmas is preferable;
1897 * vm_insert_pfn_prot should only be used if using multiple VMAs is
1900 int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
1901 unsigned long pfn, pgprot_t pgprot)
1905 * Technically, architectures with pte_special can avoid all these
1906 * restrictions (same for remap_pfn_range). However we would like
1907 * consistency in testing and feature parity among all, so we should
1908 * try to keep these invariants in place for everybody.
1910 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1911 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1912 (VM_PFNMAP|VM_MIXEDMAP));
1913 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1914 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1916 if (addr < vma->vm_start || addr >= vma->vm_end)
1919 if (!pfn_modify_allowed(pfn, pgprot))
1922 track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
1924 ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
1929 EXPORT_SYMBOL(vm_insert_pfn_prot);
1931 static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
1933 /* these checks mirror the abort conditions in vm_normal_page */
1934 if (vma->vm_flags & VM_MIXEDMAP)
1936 if (pfn_t_devmap(pfn))
1938 if (pfn_t_special(pfn))
1940 if (is_zero_pfn(pfn_t_to_pfn(pfn)))
1945 static int __vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1946 pfn_t pfn, bool mkwrite)
1948 pgprot_t pgprot = vma->vm_page_prot;
1950 BUG_ON(!vm_mixed_ok(vma, pfn));
1952 if (addr < vma->vm_start || addr >= vma->vm_end)
1955 track_pfn_insert(vma, &pgprot, pfn);
1957 if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot))
1961 * If we don't have pte special, then we have to use the pfn_valid()
1962 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1963 * refcount the page if pfn_valid is true (hence insert_page rather
1964 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
1965 * without pte special, it would there be refcounted as a normal page.
1967 if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) &&
1968 !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
1972 * At this point we are committed to insert_page()
1973 * regardless of whether the caller specified flags that
1974 * result in pfn_t_has_page() == false.
1976 page = pfn_to_page(pfn_t_to_pfn(pfn));
1977 return insert_page(vma, addr, page, pgprot);
1979 return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
1982 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1985 return __vm_insert_mixed(vma, addr, pfn, false);
1988 EXPORT_SYMBOL(vm_insert_mixed);
1991 * If the insertion of PTE failed because someone else already added a
1992 * different entry in the mean time, we treat that as success as we assume
1993 * the same entry was actually inserted.
1996 vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
1997 unsigned long addr, pfn_t pfn)
2001 err = __vm_insert_mixed(vma, addr, pfn, true);
2003 return VM_FAULT_OOM;
2004 if (err < 0 && err != -EBUSY)
2005 return VM_FAULT_SIGBUS;
2006 return VM_FAULT_NOPAGE;
2008 EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);
2011 * maps a range of physical memory into the requested pages. the old
2012 * mappings are removed. any references to nonexistent pages results
2013 * in null mappings (currently treated as "copy-on-access")
2015 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2016 unsigned long addr, unsigned long end,
2017 unsigned long pfn, pgprot_t prot)
2019 pte_t *pte, *mapped_pte;
2023 mapped_pte = pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2026 arch_enter_lazy_mmu_mode();
2028 BUG_ON(!pte_none(*pte));
2029 if (!pfn_modify_allowed(pfn, prot)) {
2033 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2035 } while (pte++, addr += PAGE_SIZE, addr != end);
2036 arch_leave_lazy_mmu_mode();
2037 pte_unmap_unlock(mapped_pte, ptl);
2041 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2042 unsigned long addr, unsigned long end,
2043 unsigned long pfn, pgprot_t prot)
2049 pfn -= addr >> PAGE_SHIFT;
2050 pmd = pmd_alloc(mm, pud, addr);
2053 VM_BUG_ON(pmd_trans_huge(*pmd));
2055 next = pmd_addr_end(addr, end);
2056 err = remap_pte_range(mm, pmd, addr, next,
2057 pfn + (addr >> PAGE_SHIFT), prot);
2060 } while (pmd++, addr = next, addr != end);
2064 static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
2065 unsigned long addr, unsigned long end,
2066 unsigned long pfn, pgprot_t prot)
2072 pfn -= addr >> PAGE_SHIFT;
2073 pud = pud_alloc(mm, p4d, addr);
2077 next = pud_addr_end(addr, end);
2078 err = remap_pmd_range(mm, pud, addr, next,
2079 pfn + (addr >> PAGE_SHIFT), prot);
2082 } while (pud++, addr = next, addr != end);
2086 static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2087 unsigned long addr, unsigned long end,
2088 unsigned long pfn, pgprot_t prot)
2094 pfn -= addr >> PAGE_SHIFT;
2095 p4d = p4d_alloc(mm, pgd, addr);
2099 next = p4d_addr_end(addr, end);
2100 err = remap_pud_range(mm, p4d, addr, next,
2101 pfn + (addr >> PAGE_SHIFT), prot);
2104 } while (p4d++, addr = next, addr != end);
2109 * remap_pfn_range - remap kernel memory to userspace
2110 * @vma: user vma to map to
2111 * @addr: target user address to start at
2112 * @pfn: physical address of kernel memory
2113 * @size: size of map area
2114 * @prot: page protection flags for this mapping
2116 * Note: this is only safe if the mm semaphore is held when called.
2118 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2119 unsigned long pfn, unsigned long size, pgprot_t prot)
2123 unsigned long end = addr + PAGE_ALIGN(size);
2124 struct mm_struct *mm = vma->vm_mm;
2125 unsigned long remap_pfn = pfn;
2129 * Physically remapped pages are special. Tell the
2130 * rest of the world about it:
2131 * VM_IO tells people not to look at these pages
2132 * (accesses can have side effects).
2133 * VM_PFNMAP tells the core MM that the base pages are just
2134 * raw PFN mappings, and do not have a "struct page" associated
2137 * Disable vma merging and expanding with mremap().
2139 * Omit vma from core dump, even when VM_IO turned off.
2141 * There's a horrible special case to handle copy-on-write
2142 * behaviour that some programs depend on. We mark the "original"
2143 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2144 * See vm_normal_page() for details.
2146 if (is_cow_mapping(vma->vm_flags)) {
2147 if (addr != vma->vm_start || end != vma->vm_end)
2149 vma->vm_pgoff = pfn;
2152 err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
2156 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
2158 BUG_ON(addr >= end);
2159 pfn -= addr >> PAGE_SHIFT;
2160 pgd = pgd_offset(mm, addr);
2161 flush_cache_range(vma, addr, end);
2163 next = pgd_addr_end(addr, end);
2164 err = remap_p4d_range(mm, pgd, addr, next,
2165 pfn + (addr >> PAGE_SHIFT), prot);
2168 } while (pgd++, addr = next, addr != end);
2171 untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
2175 EXPORT_SYMBOL(remap_pfn_range);
2178 * vm_iomap_memory - remap memory to userspace
2179 * @vma: user vma to map to
2180 * @start: start of area
2181 * @len: size of area
2183 * This is a simplified io_remap_pfn_range() for common driver use. The
2184 * driver just needs to give us the physical memory range to be mapped,
2185 * we'll figure out the rest from the vma information.
2187 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2188 * whatever write-combining details or similar.
2190 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2192 unsigned long vm_len, pfn, pages;
2194 /* Check that the physical memory area passed in looks valid */
2195 if (start + len < start)
2198 * You *really* shouldn't map things that aren't page-aligned,
2199 * but we've historically allowed it because IO memory might
2200 * just have smaller alignment.
2202 len += start & ~PAGE_MASK;
2203 pfn = start >> PAGE_SHIFT;
2204 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2205 if (pfn + pages < pfn)
2208 /* We start the mapping 'vm_pgoff' pages into the area */
2209 if (vma->vm_pgoff > pages)
2211 pfn += vma->vm_pgoff;
2212 pages -= vma->vm_pgoff;
2214 /* Can we fit all of the mapping? */
2215 vm_len = vma->vm_end - vma->vm_start;
2216 if (vm_len >> PAGE_SHIFT > pages)
2219 /* Ok, let it rip */
2220 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2222 EXPORT_SYMBOL(vm_iomap_memory);
2224 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2225 unsigned long addr, unsigned long end,
2226 pte_fn_t fn, void *data)
2231 spinlock_t *uninitialized_var(ptl);
2233 pte = (mm == &init_mm) ?
2234 pte_alloc_kernel(pmd, addr) :
2235 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2239 BUG_ON(pmd_huge(*pmd));
2241 arch_enter_lazy_mmu_mode();
2243 token = pmd_pgtable(*pmd);
2246 err = fn(pte++, token, addr, data);
2249 } while (addr += PAGE_SIZE, addr != end);
2251 arch_leave_lazy_mmu_mode();
2254 pte_unmap_unlock(pte-1, ptl);
2258 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2259 unsigned long addr, unsigned long end,
2260 pte_fn_t fn, void *data)
2266 BUG_ON(pud_huge(*pud));
2268 pmd = pmd_alloc(mm, pud, addr);
2272 next = pmd_addr_end(addr, end);
2273 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2276 } while (pmd++, addr = next, addr != end);
2280 static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
2281 unsigned long addr, unsigned long end,
2282 pte_fn_t fn, void *data)
2288 pud = pud_alloc(mm, p4d, addr);
2292 next = pud_addr_end(addr, end);
2293 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2296 } while (pud++, addr = next, addr != end);
2300 static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2301 unsigned long addr, unsigned long end,
2302 pte_fn_t fn, void *data)
2308 p4d = p4d_alloc(mm, pgd, addr);
2312 next = p4d_addr_end(addr, end);
2313 err = apply_to_pud_range(mm, p4d, addr, next, fn, data);
2316 } while (p4d++, addr = next, addr != end);
2321 * Scan a region of virtual memory, filling in page tables as necessary
2322 * and calling a provided function on each leaf page table.
2324 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2325 unsigned long size, pte_fn_t fn, void *data)
2329 unsigned long end = addr + size;
2332 if (WARN_ON(addr >= end))
2335 pgd = pgd_offset(mm, addr);
2337 next = pgd_addr_end(addr, end);
2338 err = apply_to_p4d_range(mm, pgd, addr, next, fn, data);
2341 } while (pgd++, addr = next, addr != end);
2345 EXPORT_SYMBOL_GPL(apply_to_page_range);
2348 * handle_pte_fault chooses page fault handler according to an entry which was
2349 * read non-atomically. Before making any commitment, on those architectures
2350 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
2351 * parts, do_swap_page must check under lock before unmapping the pte and
2352 * proceeding (but do_wp_page is only called after already making such a check;
2353 * and do_anonymous_page can safely check later on).
2355 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2356 pte_t *page_table, pte_t orig_pte)
2359 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2360 if (sizeof(pte_t) > sizeof(unsigned long)) {
2361 spinlock_t *ptl = pte_lockptr(mm, pmd);
2363 same = pte_same(*page_table, orig_pte);
2367 pte_unmap(page_table);
2371 static inline bool cow_user_page(struct page *dst, struct page *src,
2372 struct vm_fault *vmf)
2377 bool locked = false;
2378 struct vm_area_struct *vma = vmf->vma;
2379 struct mm_struct *mm = vma->vm_mm;
2380 unsigned long addr = vmf->address;
2382 debug_dma_assert_idle(src);
2385 copy_user_highpage(dst, src, addr, vma);
2390 * If the source page was a PFN mapping, we don't have
2391 * a "struct page" for it. We do a best-effort copy by
2392 * just copying from the original user address. If that
2393 * fails, we just zero-fill it. Live with it.
2395 kaddr = kmap_atomic(dst);
2396 uaddr = (void __user *)(addr & PAGE_MASK);
2399 * On architectures with software "accessed" bits, we would
2400 * take a double page fault, so mark it accessed here.
2402 if (arch_faults_on_old_pte() && !pte_young(vmf->orig_pte)) {
2405 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
2407 if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2409 * Other thread has already handled the fault
2410 * and we don't need to do anything. If it's
2411 * not the case, the fault will be triggered
2412 * again on the same address.
2418 entry = pte_mkyoung(vmf->orig_pte);
2419 if (ptep_set_access_flags(vma, addr, vmf->pte, entry, 0))
2420 update_mmu_cache(vma, addr, vmf->pte);
2424 * This really shouldn't fail, because the page is there
2425 * in the page tables. But it might just be unreadable,
2426 * in which case we just give up and fill the result with
2429 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
2433 /* Re-validate under PTL if the page is still mapped */
2434 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
2436 if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2437 /* The PTE changed under us. Retry page fault. */
2443 * The same page can be mapped back since last copy attampt.
2444 * Try to copy again under PTL.
2446 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
2448 * Give a warn in case there can be some obscure
2461 pte_unmap_unlock(vmf->pte, vmf->ptl);
2462 kunmap_atomic(kaddr);
2463 flush_dcache_page(dst);
2468 static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2470 struct file *vm_file = vma->vm_file;
2473 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2476 * Special mappings (e.g. VDSO) do not have any file so fake
2477 * a default GFP_KERNEL for them.
2483 * Notify the address space that the page is about to become writable so that
2484 * it can prohibit this or wait for the page to get into an appropriate state.
2486 * We do this without the lock held, so that it can sleep if it needs to.
2488 static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
2491 struct page *page = vmf->page;
2492 unsigned int old_flags = vmf->flags;
2494 vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2496 ret = vmf->vma->vm_ops->page_mkwrite(vmf);
2497 /* Restore original flags so that caller is not surprised */
2498 vmf->flags = old_flags;
2499 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2501 if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2503 if (!page->mapping) {
2505 return 0; /* retry */
2507 ret |= VM_FAULT_LOCKED;
2509 VM_BUG_ON_PAGE(!PageLocked(page), page);
2514 * Handle dirtying of a page in shared file mapping on a write fault.
2516 * The function expects the page to be locked and unlocks it.
2518 static void fault_dirty_shared_page(struct vm_area_struct *vma,
2521 struct address_space *mapping;
2523 bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
2525 dirtied = set_page_dirty(page);
2526 VM_BUG_ON_PAGE(PageAnon(page), page);
2528 * Take a local copy of the address_space - page.mapping may be zeroed
2529 * by truncate after unlock_page(). The address_space itself remains
2530 * pinned by vma->vm_file's reference. We rely on unlock_page()'s
2531 * release semantics to prevent the compiler from undoing this copying.
2533 mapping = page_rmapping(page);
2536 if ((dirtied || page_mkwrite) && mapping) {
2538 * Some device drivers do not set page.mapping
2539 * but still dirty their pages
2541 balance_dirty_pages_ratelimited(mapping);
2545 file_update_time(vma->vm_file);
2549 * Handle write page faults for pages that can be reused in the current vma
2551 * This can happen either due to the mapping being with the VM_SHARED flag,
2552 * or due to us being the last reference standing to the page. In either
2553 * case, all we need to do here is to mark the page as writable and update
2554 * any related book-keeping.
2556 static inline void wp_page_reuse(struct vm_fault *vmf)
2557 __releases(vmf->ptl)
2559 struct vm_area_struct *vma = vmf->vma;
2560 struct page *page = vmf->page;
2563 * Clear the pages cpupid information as the existing
2564 * information potentially belongs to a now completely
2565 * unrelated process.
2568 page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
2570 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2571 entry = pte_mkyoung(vmf->orig_pte);
2572 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2573 if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
2574 update_mmu_cache(vma, vmf->address, vmf->pte);
2575 pte_unmap_unlock(vmf->pte, vmf->ptl);
2579 * Handle the case of a page which we actually need to copy to a new page.
2581 * Called with mmap_sem locked and the old page referenced, but
2582 * without the ptl held.
2584 * High level logic flow:
2586 * - Allocate a page, copy the content of the old page to the new one.
2587 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2588 * - Take the PTL. If the pte changed, bail out and release the allocated page
2589 * - If the pte is still the way we remember it, update the page table and all
2590 * relevant references. This includes dropping the reference the page-table
2591 * held to the old page, as well as updating the rmap.
2592 * - In any case, unlock the PTL and drop the reference we took to the old page.
2594 static vm_fault_t wp_page_copy(struct vm_fault *vmf)
2596 struct vm_area_struct *vma = vmf->vma;
2597 struct mm_struct *mm = vma->vm_mm;
2598 struct page *old_page = vmf->page;
2599 struct page *new_page = NULL;
2601 int page_copied = 0;
2602 const unsigned long mmun_start = vmf->address & PAGE_MASK;
2603 const unsigned long mmun_end = mmun_start + PAGE_SIZE;
2604 struct mem_cgroup *memcg;
2606 if (unlikely(anon_vma_prepare(vma)))
2609 if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
2610 new_page = alloc_zeroed_user_highpage_movable(vma,
2615 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
2620 if (!cow_user_page(new_page, old_page, vmf)) {
2622 * COW failed, if the fault was solved by other,
2623 * it's fine. If not, userspace would re-fault on
2624 * the same address and we will handle the fault
2625 * from the second attempt.
2634 if (mem_cgroup_try_charge_delay(new_page, mm, GFP_KERNEL, &memcg, false))
2637 __SetPageUptodate(new_page);
2639 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2642 * Re-check the pte - we dropped the lock
2644 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
2645 if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2647 if (!PageAnon(old_page)) {
2648 dec_mm_counter_fast(mm,
2649 mm_counter_file(old_page));
2650 inc_mm_counter_fast(mm, MM_ANONPAGES);
2653 inc_mm_counter_fast(mm, MM_ANONPAGES);
2655 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2656 entry = mk_pte(new_page, vma->vm_page_prot);
2657 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2659 * Clear the pte entry and flush it first, before updating the
2660 * pte with the new entry. This will avoid a race condition
2661 * seen in the presence of one thread doing SMC and another
2664 ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
2665 page_add_new_anon_rmap(new_page, vma, vmf->address, false);
2666 mem_cgroup_commit_charge(new_page, memcg, false, false);
2667 lru_cache_add_active_or_unevictable(new_page, vma);
2669 * We call the notify macro here because, when using secondary
2670 * mmu page tables (such as kvm shadow page tables), we want the
2671 * new page to be mapped directly into the secondary page table.
2673 set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
2674 update_mmu_cache(vma, vmf->address, vmf->pte);
2677 * Only after switching the pte to the new page may
2678 * we remove the mapcount here. Otherwise another
2679 * process may come and find the rmap count decremented
2680 * before the pte is switched to the new page, and
2681 * "reuse" the old page writing into it while our pte
2682 * here still points into it and can be read by other
2685 * The critical issue is to order this
2686 * page_remove_rmap with the ptp_clear_flush above.
2687 * Those stores are ordered by (if nothing else,)
2688 * the barrier present in the atomic_add_negative
2689 * in page_remove_rmap.
2691 * Then the TLB flush in ptep_clear_flush ensures that
2692 * no process can access the old page before the
2693 * decremented mapcount is visible. And the old page
2694 * cannot be reused until after the decremented
2695 * mapcount is visible. So transitively, TLBs to
2696 * old page will be flushed before it can be reused.
2698 page_remove_rmap(old_page, false);
2701 /* Free the old page.. */
2702 new_page = old_page;
2705 mem_cgroup_cancel_charge(new_page, memcg, false);
2711 pte_unmap_unlock(vmf->pte, vmf->ptl);
2713 * No need to double call mmu_notifier->invalidate_range() callback as
2714 * the above ptep_clear_flush_notify() did already call it.
2716 mmu_notifier_invalidate_range_only_end(mm, mmun_start, mmun_end);
2719 * Don't let another task, with possibly unlocked vma,
2720 * keep the mlocked page.
2722 if (page_copied && (vma->vm_flags & VM_LOCKED)) {
2723 lock_page(old_page); /* LRU manipulation */
2724 if (PageMlocked(old_page))
2725 munlock_vma_page(old_page);
2726 unlock_page(old_page);
2730 return page_copied ? VM_FAULT_WRITE : 0;
2736 return VM_FAULT_OOM;
2740 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
2741 * writeable once the page is prepared
2743 * @vmf: structure describing the fault
2745 * This function handles all that is needed to finish a write page fault in a
2746 * shared mapping due to PTE being read-only once the mapped page is prepared.
2747 * It handles locking of PTE and modifying it. The function returns
2748 * VM_FAULT_WRITE on success, 0 when PTE got changed before we acquired PTE
2751 * The function expects the page to be locked or other protection against
2752 * concurrent faults / writeback (such as DAX radix tree locks).
2754 vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf)
2756 WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
2757 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
2760 * We might have raced with another page fault while we released the
2761 * pte_offset_map_lock.
2763 if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2764 pte_unmap_unlock(vmf->pte, vmf->ptl);
2765 return VM_FAULT_NOPAGE;
2772 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
2775 static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
2777 struct vm_area_struct *vma = vmf->vma;
2779 if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
2782 pte_unmap_unlock(vmf->pte, vmf->ptl);
2783 vmf->flags |= FAULT_FLAG_MKWRITE;
2784 ret = vma->vm_ops->pfn_mkwrite(vmf);
2785 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
2787 return finish_mkwrite_fault(vmf);
2790 return VM_FAULT_WRITE;
2793 static vm_fault_t wp_page_shared(struct vm_fault *vmf)
2794 __releases(vmf->ptl)
2796 struct vm_area_struct *vma = vmf->vma;
2798 get_page(vmf->page);
2800 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2803 pte_unmap_unlock(vmf->pte, vmf->ptl);
2804 tmp = do_page_mkwrite(vmf);
2805 if (unlikely(!tmp || (tmp &
2806 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2807 put_page(vmf->page);
2810 tmp = finish_mkwrite_fault(vmf);
2811 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2812 unlock_page(vmf->page);
2813 put_page(vmf->page);
2818 lock_page(vmf->page);
2820 fault_dirty_shared_page(vma, vmf->page);
2821 put_page(vmf->page);
2823 return VM_FAULT_WRITE;
2827 * This routine handles present pages, when users try to write
2828 * to a shared page. It is done by copying the page to a new address
2829 * and decrementing the shared-page counter for the old page.
2831 * Note that this routine assumes that the protection checks have been
2832 * done by the caller (the low-level page fault routine in most cases).
2833 * Thus we can safely just mark it writable once we've done any necessary
2836 * We also mark the page dirty at this point even though the page will
2837 * change only once the write actually happens. This avoids a few races,
2838 * and potentially makes it more efficient.
2840 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2841 * but allow concurrent faults), with pte both mapped and locked.
2842 * We return with mmap_sem still held, but pte unmapped and unlocked.
2844 static vm_fault_t do_wp_page(struct vm_fault *vmf)
2845 __releases(vmf->ptl)
2847 struct vm_area_struct *vma = vmf->vma;
2849 vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
2852 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
2855 * We should not cow pages in a shared writeable mapping.
2856 * Just mark the pages writable and/or call ops->pfn_mkwrite.
2858 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2859 (VM_WRITE|VM_SHARED))
2860 return wp_pfn_shared(vmf);
2862 pte_unmap_unlock(vmf->pte, vmf->ptl);
2863 return wp_page_copy(vmf);
2867 * Take out anonymous pages first, anonymous shared vmas are
2868 * not dirty accountable.
2870 if (PageAnon(vmf->page) && !PageKsm(vmf->page)) {
2871 int total_map_swapcount;
2872 if (!trylock_page(vmf->page)) {
2873 get_page(vmf->page);
2874 pte_unmap_unlock(vmf->pte, vmf->ptl);
2875 lock_page(vmf->page);
2876 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2877 vmf->address, &vmf->ptl);
2878 if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2879 unlock_page(vmf->page);
2880 pte_unmap_unlock(vmf->pte, vmf->ptl);
2881 put_page(vmf->page);
2884 put_page(vmf->page);
2886 if (reuse_swap_page(vmf->page, &total_map_swapcount)) {
2887 if (total_map_swapcount == 1) {
2889 * The page is all ours. Move it to
2890 * our anon_vma so the rmap code will
2891 * not search our parent or siblings.
2892 * Protected against the rmap code by
2895 page_move_anon_rmap(vmf->page, vma);
2897 unlock_page(vmf->page);
2899 return VM_FAULT_WRITE;
2901 unlock_page(vmf->page);
2902 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2903 (VM_WRITE|VM_SHARED))) {
2904 return wp_page_shared(vmf);
2908 * Ok, we need to copy. Oh, well..
2910 get_page(vmf->page);
2912 pte_unmap_unlock(vmf->pte, vmf->ptl);
2913 return wp_page_copy(vmf);
2916 static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2917 unsigned long start_addr, unsigned long end_addr,
2918 struct zap_details *details)
2920 zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2923 static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
2924 struct zap_details *details)
2926 struct vm_area_struct *vma;
2927 pgoff_t vba, vea, zba, zea;
2929 vma_interval_tree_foreach(vma, root,
2930 details->first_index, details->last_index) {
2932 vba = vma->vm_pgoff;
2933 vea = vba + vma_pages(vma) - 1;
2934 zba = details->first_index;
2937 zea = details->last_index;
2941 unmap_mapping_range_vma(vma,
2942 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2943 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2949 * unmap_mapping_page() - Unmap single page from processes.
2950 * @page: The locked page to be unmapped.
2952 * Unmap this page from any userspace process which still has it mmaped.
2953 * Typically, for efficiency, the range of nearby pages has already been
2954 * unmapped by unmap_mapping_pages() or unmap_mapping_range(). But once
2955 * truncation or invalidation holds the lock on a page, it may find that
2956 * the page has been remapped again: and then uses unmap_mapping_page()
2957 * to unmap it finally.
2959 void unmap_mapping_page(struct page *page)
2961 struct address_space *mapping = page->mapping;
2962 struct zap_details details = { };
2964 VM_BUG_ON(!PageLocked(page));
2965 VM_BUG_ON(PageTail(page));
2967 details.check_mapping = mapping;
2968 details.first_index = page->index;
2969 details.last_index = page->index + hpage_nr_pages(page) - 1;
2970 details.single_page = page;
2972 i_mmap_lock_write(mapping);
2973 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
2974 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2975 i_mmap_unlock_write(mapping);
2979 * unmap_mapping_pages() - Unmap pages from processes.
2980 * @mapping: The address space containing pages to be unmapped.
2981 * @start: Index of first page to be unmapped.
2982 * @nr: Number of pages to be unmapped. 0 to unmap to end of file.
2983 * @even_cows: Whether to unmap even private COWed pages.
2985 * Unmap the pages in this address space from any userspace process which
2986 * has them mmaped. Generally, you want to remove COWed pages as well when
2987 * a file is being truncated, but not when invalidating pages from the page
2990 void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
2991 pgoff_t nr, bool even_cows)
2993 struct zap_details details = { };
2995 details.check_mapping = even_cows ? NULL : mapping;
2996 details.first_index = start;
2997 details.last_index = start + nr - 1;
2998 if (details.last_index < details.first_index)
2999 details.last_index = ULONG_MAX;
3001 i_mmap_lock_write(mapping);
3002 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
3003 unmap_mapping_range_tree(&mapping->i_mmap, &details);
3004 i_mmap_unlock_write(mapping);
3008 * unmap_mapping_range - unmap the portion of all mmaps in the specified
3009 * address_space corresponding to the specified byte range in the underlying
3012 * @mapping: the address space containing mmaps to be unmapped.
3013 * @holebegin: byte in first page to unmap, relative to the start of
3014 * the underlying file. This will be rounded down to a PAGE_SIZE
3015 * boundary. Note that this is different from truncate_pagecache(), which
3016 * must keep the partial page. In contrast, we must get rid of
3018 * @holelen: size of prospective hole in bytes. This will be rounded
3019 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
3021 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
3022 * but 0 when invalidating pagecache, don't throw away private data.
3024 void unmap_mapping_range(struct address_space *mapping,
3025 loff_t const holebegin, loff_t const holelen, int even_cows)
3027 pgoff_t hba = holebegin >> PAGE_SHIFT;
3028 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
3030 /* Check for overflow. */
3031 if (sizeof(holelen) > sizeof(hlen)) {
3033 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
3034 if (holeend & ~(long long)ULONG_MAX)
3035 hlen = ULONG_MAX - hba + 1;
3038 unmap_mapping_pages(mapping, hba, hlen, even_cows);
3040 EXPORT_SYMBOL(unmap_mapping_range);
3043 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3044 * but allow concurrent faults), and pte mapped but not yet locked.
3045 * We return with pte unmapped and unlocked.
3047 * We return with the mmap_sem locked or unlocked in the same cases
3048 * as does filemap_fault().
3050 vm_fault_t do_swap_page(struct vm_fault *vmf)
3052 struct vm_area_struct *vma = vmf->vma;
3053 struct page *page = NULL, *swapcache;
3054 struct mem_cgroup *memcg;
3061 if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
3064 entry = pte_to_swp_entry(vmf->orig_pte);
3065 if (unlikely(non_swap_entry(entry))) {
3066 if (is_migration_entry(entry)) {
3067 migration_entry_wait(vma->vm_mm, vmf->pmd,
3069 } else if (is_device_private_entry(entry)) {
3071 * For un-addressable device memory we call the pgmap
3072 * fault handler callback. The callback must migrate
3073 * the page back to some CPU accessible page.
3075 ret = device_private_entry_fault(vma, vmf->address, entry,
3076 vmf->flags, vmf->pmd);
3077 } else if (is_hwpoison_entry(entry)) {
3078 ret = VM_FAULT_HWPOISON;
3080 print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
3081 ret = VM_FAULT_SIGBUS;
3087 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
3088 page = lookup_swap_cache(entry, vma, vmf->address);
3092 struct swap_info_struct *si = swp_swap_info(entry);
3094 if (si->flags & SWP_SYNCHRONOUS_IO &&
3095 __swap_count(si, entry) == 1) {
3096 /* skip swapcache */
3097 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
3100 __SetPageLocked(page);
3101 __SetPageSwapBacked(page);
3102 set_page_private(page, entry.val);
3103 lru_cache_add_anon(page);
3104 swap_readpage(page, true);
3107 page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
3114 * Back out if somebody else faulted in this pte
3115 * while we released the pte lock.
3117 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3118 vmf->address, &vmf->ptl);
3119 if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
3121 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3125 /* Had to read the page from swap area: Major fault */
3126 ret = VM_FAULT_MAJOR;
3127 count_vm_event(PGMAJFAULT);
3128 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
3129 } else if (PageHWPoison(page)) {
3131 * hwpoisoned dirty swapcache pages are kept for killing
3132 * owner processes (which may be unknown at hwpoison time)
3134 ret = VM_FAULT_HWPOISON;
3135 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3139 locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
3141 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3143 ret |= VM_FAULT_RETRY;
3148 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
3149 * release the swapcache from under us. The page pin, and pte_same
3150 * test below, are not enough to exclude that. Even if it is still
3151 * swapcache, we need to check that the page's swap has not changed.
3153 if (unlikely((!PageSwapCache(page) ||
3154 page_private(page) != entry.val)) && swapcache)
3157 page = ksm_might_need_to_copy(page, vma, vmf->address);
3158 if (unlikely(!page)) {
3164 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, GFP_KERNEL,
3171 * Back out if somebody else already faulted in this pte.
3173 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3175 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
3178 if (unlikely(!PageUptodate(page))) {
3179 ret = VM_FAULT_SIGBUS;
3184 * The page isn't present yet, go ahead with the fault.
3186 * Be careful about the sequence of operations here.
3187 * To get its accounting right, reuse_swap_page() must be called
3188 * while the page is counted on swap but not yet in mapcount i.e.
3189 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
3190 * must be called after the swap_free(), or it will never succeed.
3193 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3194 dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
3195 pte = mk_pte(page, vma->vm_page_prot);
3196 if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
3197 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
3198 vmf->flags &= ~FAULT_FLAG_WRITE;
3199 ret |= VM_FAULT_WRITE;
3200 exclusive = RMAP_EXCLUSIVE;
3202 flush_icache_page(vma, page);
3203 if (pte_swp_soft_dirty(vmf->orig_pte))
3204 pte = pte_mksoft_dirty(pte);
3205 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
3206 arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte);
3207 vmf->orig_pte = pte;
3209 /* ksm created a completely new copy */
3210 if (unlikely(page != swapcache && swapcache)) {
3211 page_add_new_anon_rmap(page, vma, vmf->address, false);
3212 mem_cgroup_commit_charge(page, memcg, false, false);
3213 lru_cache_add_active_or_unevictable(page, vma);
3215 do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
3216 mem_cgroup_commit_charge(page, memcg, true, false);
3217 activate_page(page);
3221 if (mem_cgroup_swap_full(page) ||
3222 (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
3223 try_to_free_swap(page);
3225 if (page != swapcache && swapcache) {
3227 * Hold the lock to avoid the swap entry to be reused
3228 * until we take the PT lock for the pte_same() check
3229 * (to avoid false positives from pte_same). For
3230 * further safety release the lock after the swap_free
3231 * so that the swap count won't change under a
3232 * parallel locked swapcache.
3234 unlock_page(swapcache);
3235 put_page(swapcache);
3238 if (vmf->flags & FAULT_FLAG_WRITE) {
3239 ret |= do_wp_page(vmf);
3240 if (ret & VM_FAULT_ERROR)
3241 ret &= VM_FAULT_ERROR;
3245 /* No need to invalidate - it was non-present before */
3246 update_mmu_cache(vma, vmf->address, vmf->pte);
3248 pte_unmap_unlock(vmf->pte, vmf->ptl);
3252 mem_cgroup_cancel_charge(page, memcg, false);
3253 pte_unmap_unlock(vmf->pte, vmf->ptl);
3258 if (page != swapcache && swapcache) {
3259 unlock_page(swapcache);
3260 put_page(swapcache);
3266 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3267 * but allow concurrent faults), and pte mapped but not yet locked.
3268 * We return with mmap_sem still held, but pte unmapped and unlocked.
3270 static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
3272 struct vm_area_struct *vma = vmf->vma;
3273 struct mem_cgroup *memcg;
3278 /* File mapping without ->vm_ops ? */
3279 if (vma->vm_flags & VM_SHARED)
3280 return VM_FAULT_SIGBUS;
3283 * Use pte_alloc() instead of pte_alloc_map(). We can't run
3284 * pte_offset_map() on pmds where a huge pmd might be created
3285 * from a different thread.
3287 * pte_alloc_map() is safe to use under down_write(mmap_sem) or when
3288 * parallel threads are excluded by other means.
3290 * Here we only have down_read(mmap_sem).
3292 if (pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))
3293 return VM_FAULT_OOM;
3295 /* See the comment in pte_alloc_one_map() */
3296 if (unlikely(pmd_trans_unstable(vmf->pmd)))
3299 /* Use the zero-page for reads */
3300 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
3301 !mm_forbids_zeropage(vma->vm_mm)) {
3302 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
3303 vma->vm_page_prot));
3304 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3305 vmf->address, &vmf->ptl);
3306 if (!pte_none(*vmf->pte))
3308 ret = check_stable_address_space(vma->vm_mm);
3311 /* Deliver the page fault to userland, check inside PT lock */
3312 if (userfaultfd_missing(vma)) {
3313 pte_unmap_unlock(vmf->pte, vmf->ptl);
3314 return handle_userfault(vmf, VM_UFFD_MISSING);
3319 /* Allocate our own private page. */
3320 if (unlikely(anon_vma_prepare(vma)))
3322 page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
3326 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, GFP_KERNEL, &memcg,
3331 * The memory barrier inside __SetPageUptodate makes sure that
3332 * preceeding stores to the page contents become visible before
3333 * the set_pte_at() write.
3335 __SetPageUptodate(page);
3337 entry = mk_pte(page, vma->vm_page_prot);
3338 if (vma->vm_flags & VM_WRITE)
3339 entry = pte_mkwrite(pte_mkdirty(entry));
3341 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3343 if (!pte_none(*vmf->pte))
3346 ret = check_stable_address_space(vma->vm_mm);
3350 /* Deliver the page fault to userland, check inside PT lock */
3351 if (userfaultfd_missing(vma)) {
3352 pte_unmap_unlock(vmf->pte, vmf->ptl);
3353 mem_cgroup_cancel_charge(page, memcg, false);
3355 return handle_userfault(vmf, VM_UFFD_MISSING);
3358 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3359 page_add_new_anon_rmap(page, vma, vmf->address, false);
3360 mem_cgroup_commit_charge(page, memcg, false, false);
3361 lru_cache_add_active_or_unevictable(page, vma);
3363 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3365 /* No need to invalidate - it was non-present before */
3366 update_mmu_cache(vma, vmf->address, vmf->pte);
3368 pte_unmap_unlock(vmf->pte, vmf->ptl);
3371 mem_cgroup_cancel_charge(page, memcg, false);
3377 return VM_FAULT_OOM;
3381 * The mmap_sem must have been held on entry, and may have been
3382 * released depending on flags and vma->vm_ops->fault() return value.
3383 * See filemap_fault() and __lock_page_retry().
3385 static vm_fault_t __do_fault(struct vm_fault *vmf)
3387 struct vm_area_struct *vma = vmf->vma;
3391 * Preallocate pte before we take page_lock because this might lead to
3392 * deadlocks for memcg reclaim which waits for pages under writeback:
3394 * SetPageWriteback(A)
3400 * wait_on_page_writeback(A)
3401 * SetPageWriteback(B)
3403 * # flush A, B to clear the writeback
3405 if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) {
3406 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm,
3408 if (!vmf->prealloc_pte)
3409 return VM_FAULT_OOM;
3410 smp_wmb(); /* See comment in __pte_alloc() */
3413 ret = vma->vm_ops->fault(vmf);
3414 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
3415 VM_FAULT_DONE_COW)))
3418 if (unlikely(PageHWPoison(vmf->page))) {
3419 if (ret & VM_FAULT_LOCKED)
3420 unlock_page(vmf->page);
3421 put_page(vmf->page);
3423 return VM_FAULT_HWPOISON;
3426 if (unlikely(!(ret & VM_FAULT_LOCKED)))
3427 lock_page(vmf->page);
3429 VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
3435 * The ordering of these checks is important for pmds with _PAGE_DEVMAP set.
3436 * If we check pmd_trans_unstable() first we will trip the bad_pmd() check
3437 * inside of pmd_none_or_trans_huge_or_clear_bad(). This will end up correctly
3438 * returning 1 but not before it spams dmesg with the pmd_clear_bad() output.
3440 static int pmd_devmap_trans_unstable(pmd_t *pmd)
3442 return pmd_devmap(*pmd) || pmd_trans_unstable(pmd);
3445 static vm_fault_t pte_alloc_one_map(struct vm_fault *vmf)
3447 struct vm_area_struct *vma = vmf->vma;
3449 if (!pmd_none(*vmf->pmd))
3451 if (vmf->prealloc_pte) {
3452 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3453 if (unlikely(!pmd_none(*vmf->pmd))) {
3454 spin_unlock(vmf->ptl);
3458 mm_inc_nr_ptes(vma->vm_mm);
3459 pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3460 spin_unlock(vmf->ptl);
3461 vmf->prealloc_pte = NULL;
3462 } else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))) {
3463 return VM_FAULT_OOM;
3467 * If a huge pmd materialized under us just retry later. Use
3468 * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead of
3469 * pmd_trans_huge() to ensure the pmd didn't become pmd_trans_huge
3470 * under us and then back to pmd_none, as a result of MADV_DONTNEED
3471 * running immediately after a huge pmd fault in a different thread of
3472 * this mm, in turn leading to a misleading pmd_trans_huge() retval.
3473 * All we have to ensure is that it is a regular pmd that we can walk
3474 * with pte_offset_map() and we can do that through an atomic read in
3475 * C, which is what pmd_trans_unstable() provides.
3477 if (pmd_devmap_trans_unstable(vmf->pmd))
3478 return VM_FAULT_NOPAGE;
3481 * At this point we know that our vmf->pmd points to a page of ptes
3482 * and it cannot become pmd_none(), pmd_devmap() or pmd_trans_huge()
3483 * for the duration of the fault. If a racing MADV_DONTNEED runs and
3484 * we zap the ptes pointed to by our vmf->pmd, the vmf->ptl will still
3485 * be valid and we will re-check to make sure the vmf->pte isn't
3486 * pte_none() under vmf->ptl protection when we return to
3489 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3494 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3496 #define HPAGE_CACHE_INDEX_MASK (HPAGE_PMD_NR - 1)
3497 static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
3498 unsigned long haddr)
3500 if (((vma->vm_start >> PAGE_SHIFT) & HPAGE_CACHE_INDEX_MASK) !=
3501 (vma->vm_pgoff & HPAGE_CACHE_INDEX_MASK))
3503 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
3508 static void deposit_prealloc_pte(struct vm_fault *vmf)
3510 struct vm_area_struct *vma = vmf->vma;
3512 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3514 * We are going to consume the prealloc table,
3515 * count that as nr_ptes.
3517 mm_inc_nr_ptes(vma->vm_mm);
3518 vmf->prealloc_pte = NULL;
3521 static vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
3523 struct vm_area_struct *vma = vmf->vma;
3524 bool write = vmf->flags & FAULT_FLAG_WRITE;
3525 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
3530 if (!transhuge_vma_suitable(vma, haddr))
3531 return VM_FAULT_FALLBACK;
3533 ret = VM_FAULT_FALLBACK;
3534 page = compound_head(page);
3537 * Archs like ppc64 need additonal space to store information
3538 * related to pte entry. Use the preallocated table for that.
3540 if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
3541 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm, vmf->address);
3542 if (!vmf->prealloc_pte)
3543 return VM_FAULT_OOM;
3544 smp_wmb(); /* See comment in __pte_alloc() */
3547 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3548 if (unlikely(!pmd_none(*vmf->pmd)))
3551 for (i = 0; i < HPAGE_PMD_NR; i++)
3552 flush_icache_page(vma, page + i);
3554 entry = mk_huge_pmd(page, vma->vm_page_prot);
3556 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
3558 add_mm_counter(vma->vm_mm, mm_counter_file(page), HPAGE_PMD_NR);
3559 page_add_file_rmap(page, true);
3561 * deposit and withdraw with pmd lock held
3563 if (arch_needs_pgtable_deposit())
3564 deposit_prealloc_pte(vmf);
3566 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
3568 update_mmu_cache_pmd(vma, haddr, vmf->pmd);
3570 /* fault is handled */
3572 count_vm_event(THP_FILE_MAPPED);
3574 spin_unlock(vmf->ptl);
3578 static vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
3586 * alloc_set_pte - setup new PTE entry for given page and add reverse page
3587 * mapping. If needed, the fucntion allocates page table or use pre-allocated.
3589 * @vmf: fault environment
3590 * @memcg: memcg to charge page (only for private mappings)
3591 * @page: page to map
3593 * Caller must take care of unlocking vmf->ptl, if vmf->pte is non-NULL on
3596 * Target users are page handler itself and implementations of
3597 * vm_ops->map_pages.
3599 vm_fault_t alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
3602 struct vm_area_struct *vma = vmf->vma;
3603 bool write = vmf->flags & FAULT_FLAG_WRITE;
3607 if (pmd_none(*vmf->pmd) && PageTransCompound(page) &&
3608 IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
3610 VM_BUG_ON_PAGE(memcg, page);
3612 ret = do_set_pmd(vmf, page);
3613 if (ret != VM_FAULT_FALLBACK)
3618 ret = pte_alloc_one_map(vmf);
3623 /* Re-check under ptl */
3624 if (unlikely(!pte_none(*vmf->pte)))
3625 return VM_FAULT_NOPAGE;
3627 flush_icache_page(vma, page);
3628 entry = mk_pte(page, vma->vm_page_prot);
3630 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3631 /* copy-on-write page */
3632 if (write && !(vma->vm_flags & VM_SHARED)) {
3633 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3634 page_add_new_anon_rmap(page, vma, vmf->address, false);
3635 mem_cgroup_commit_charge(page, memcg, false, false);
3636 lru_cache_add_active_or_unevictable(page, vma);
3638 inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
3639 page_add_file_rmap(page, false);
3641 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3643 /* no need to invalidate: a not-present page won't be cached */
3644 update_mmu_cache(vma, vmf->address, vmf->pte);
3651 * finish_fault - finish page fault once we have prepared the page to fault
3653 * @vmf: structure describing the fault
3655 * This function handles all that is needed to finish a page fault once the
3656 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
3657 * given page, adds reverse page mapping, handles memcg charges and LRU
3658 * addition. The function returns 0 on success, VM_FAULT_ code in case of
3661 * The function expects the page to be locked and on success it consumes a
3662 * reference of a page being mapped (for the PTE which maps it).
3664 vm_fault_t finish_fault(struct vm_fault *vmf)
3669 /* Did we COW the page? */
3670 if ((vmf->flags & FAULT_FLAG_WRITE) &&
3671 !(vmf->vma->vm_flags & VM_SHARED))
3672 page = vmf->cow_page;
3677 * check even for read faults because we might have lost our CoWed
3680 if (!(vmf->vma->vm_flags & VM_SHARED))
3681 ret = check_stable_address_space(vmf->vma->vm_mm);
3683 ret = alloc_set_pte(vmf, vmf->memcg, page);
3685 pte_unmap_unlock(vmf->pte, vmf->ptl);
3689 static unsigned long fault_around_bytes __read_mostly =
3690 rounddown_pow_of_two(65536);
3692 #ifdef CONFIG_DEBUG_FS
3693 static int fault_around_bytes_get(void *data, u64 *val)
3695 *val = fault_around_bytes;
3700 * fault_around_bytes must be rounded down to the nearest page order as it's
3701 * what do_fault_around() expects to see.
3703 static int fault_around_bytes_set(void *data, u64 val)
3705 if (val / PAGE_SIZE > PTRS_PER_PTE)
3707 if (val > PAGE_SIZE)
3708 fault_around_bytes = rounddown_pow_of_two(val);
3710 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
3713 DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
3714 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
3716 static int __init fault_around_debugfs(void)
3720 ret = debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
3721 &fault_around_bytes_fops);
3723 pr_warn("Failed to create fault_around_bytes in debugfs");
3726 late_initcall(fault_around_debugfs);
3730 * do_fault_around() tries to map few pages around the fault address. The hope
3731 * is that the pages will be needed soon and this will lower the number of
3734 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
3735 * not ready to be mapped: not up-to-date, locked, etc.
3737 * This function is called with the page table lock taken. In the split ptlock
3738 * case the page table lock only protects only those entries which belong to
3739 * the page table corresponding to the fault address.
3741 * This function doesn't cross the VMA boundaries, in order to call map_pages()
3744 * fault_around_bytes defines how many bytes we'll try to map.
3745 * do_fault_around() expects it to be set to a power of two less than or equal
3748 * The virtual address of the area that we map is naturally aligned to
3749 * fault_around_bytes rounded down to the machine page size
3750 * (and therefore to page order). This way it's easier to guarantee
3751 * that we don't cross page table boundaries.
3753 static vm_fault_t do_fault_around(struct vm_fault *vmf)
3755 unsigned long address = vmf->address, nr_pages, mask;
3756 pgoff_t start_pgoff = vmf->pgoff;
3761 nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
3762 mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
3764 vmf->address = max(address & mask, vmf->vma->vm_start);
3765 off = ((address - vmf->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
3769 * end_pgoff is either the end of the page table, the end of
3770 * the vma or nr_pages from start_pgoff, depending what is nearest.
3772 end_pgoff = start_pgoff -
3773 ((vmf->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
3775 end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
3776 start_pgoff + nr_pages - 1);
3778 if (pmd_none(*vmf->pmd)) {
3779 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm,
3781 if (!vmf->prealloc_pte)
3783 smp_wmb(); /* See comment in __pte_alloc() */
3786 vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
3788 /* Huge page is mapped? Page fault is solved */
3789 if (pmd_trans_huge(*vmf->pmd)) {
3790 ret = VM_FAULT_NOPAGE;
3794 /* ->map_pages() haven't done anything useful. Cold page cache? */
3798 /* check if the page fault is solved */
3799 vmf->pte -= (vmf->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT);
3800 if (!pte_none(*vmf->pte))
3801 ret = VM_FAULT_NOPAGE;
3802 pte_unmap_unlock(vmf->pte, vmf->ptl);
3804 vmf->address = address;
3809 static vm_fault_t do_read_fault(struct vm_fault *vmf)
3811 struct vm_area_struct *vma = vmf->vma;
3815 * Let's call ->map_pages() first and use ->fault() as fallback
3816 * if page by the offset is not ready to be mapped (cold cache or
3819 if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
3820 ret = do_fault_around(vmf);
3825 ret = __do_fault(vmf);
3826 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3829 ret |= finish_fault(vmf);
3830 unlock_page(vmf->page);
3831 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3832 put_page(vmf->page);
3836 static vm_fault_t do_cow_fault(struct vm_fault *vmf)
3838 struct vm_area_struct *vma = vmf->vma;
3841 if (unlikely(anon_vma_prepare(vma)))
3842 return VM_FAULT_OOM;
3844 vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
3846 return VM_FAULT_OOM;
3848 if (mem_cgroup_try_charge_delay(vmf->cow_page, vma->vm_mm, GFP_KERNEL,
3849 &vmf->memcg, false)) {
3850 put_page(vmf->cow_page);
3851 return VM_FAULT_OOM;
3854 ret = __do_fault(vmf);
3855 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3857 if (ret & VM_FAULT_DONE_COW)
3860 copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
3861 __SetPageUptodate(vmf->cow_page);
3863 ret |= finish_fault(vmf);
3864 unlock_page(vmf->page);
3865 put_page(vmf->page);
3866 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3870 mem_cgroup_cancel_charge(vmf->cow_page, vmf->memcg, false);
3871 put_page(vmf->cow_page);
3875 static vm_fault_t do_shared_fault(struct vm_fault *vmf)
3877 struct vm_area_struct *vma = vmf->vma;
3878 vm_fault_t ret, tmp;
3880 ret = __do_fault(vmf);
3881 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3885 * Check if the backing address space wants to know that the page is
3886 * about to become writable
3888 if (vma->vm_ops->page_mkwrite) {
3889 unlock_page(vmf->page);
3890 tmp = do_page_mkwrite(vmf);
3891 if (unlikely(!tmp ||
3892 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3893 put_page(vmf->page);
3898 ret |= finish_fault(vmf);
3899 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3901 unlock_page(vmf->page);
3902 put_page(vmf->page);
3906 fault_dirty_shared_page(vma, vmf->page);
3911 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3912 * but allow concurrent faults).
3913 * The mmap_sem may have been released depending on flags and our
3914 * return value. See filemap_fault() and __lock_page_or_retry().
3915 * If mmap_sem is released, vma may become invalid (for example
3916 * by other thread calling munmap()).
3918 static vm_fault_t do_fault(struct vm_fault *vmf)
3920 struct vm_area_struct *vma = vmf->vma;
3921 struct mm_struct *vm_mm = vma->vm_mm;
3925 * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND
3927 if (!vma->vm_ops->fault) {
3929 * If we find a migration pmd entry or a none pmd entry, which
3930 * should never happen, return SIGBUS
3932 if (unlikely(!pmd_present(*vmf->pmd)))
3933 ret = VM_FAULT_SIGBUS;
3935 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm,
3940 * Make sure this is not a temporary clearing of pte
3941 * by holding ptl and checking again. A R/M/W update
3942 * of pte involves: take ptl, clearing the pte so that
3943 * we don't have concurrent modification by hardware
3944 * followed by an update.
3946 if (unlikely(pte_none(*vmf->pte)))
3947 ret = VM_FAULT_SIGBUS;
3949 ret = VM_FAULT_NOPAGE;
3951 pte_unmap_unlock(vmf->pte, vmf->ptl);
3953 } else if (!(vmf->flags & FAULT_FLAG_WRITE))
3954 ret = do_read_fault(vmf);
3955 else if (!(vma->vm_flags & VM_SHARED))
3956 ret = do_cow_fault(vmf);
3958 ret = do_shared_fault(vmf);
3960 /* preallocated pagetable is unused: free it */
3961 if (vmf->prealloc_pte) {
3962 pte_free(vm_mm, vmf->prealloc_pte);
3963 vmf->prealloc_pte = NULL;
3968 static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3969 unsigned long addr, int page_nid,
3974 count_vm_numa_event(NUMA_HINT_FAULTS);
3975 if (page_nid == numa_node_id()) {
3976 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3977 *flags |= TNF_FAULT_LOCAL;
3980 return mpol_misplaced(page, vma, addr);
3983 static vm_fault_t do_numa_page(struct vm_fault *vmf)
3985 struct vm_area_struct *vma = vmf->vma;
3986 struct page *page = NULL;
3990 bool migrated = false;
3992 bool was_writable = pte_savedwrite(vmf->orig_pte);
3996 * The "pte" at this point cannot be used safely without
3997 * validation through pte_unmap_same(). It's of NUMA type but
3998 * the pfn may be screwed if the read is non atomic.
4000 vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
4001 spin_lock(vmf->ptl);
4002 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
4003 pte_unmap_unlock(vmf->pte, vmf->ptl);
4008 * Make it present again, Depending on how arch implementes non
4009 * accessible ptes, some can allow access by kernel mode.
4011 pte = ptep_modify_prot_start(vma->vm_mm, vmf->address, vmf->pte);
4012 pte = pte_modify(pte, vma->vm_page_prot);
4013 pte = pte_mkyoung(pte);
4015 pte = pte_mkwrite(pte);
4016 ptep_modify_prot_commit(vma->vm_mm, vmf->address, vmf->pte, pte);
4017 update_mmu_cache(vma, vmf->address, vmf->pte);
4019 page = vm_normal_page(vma, vmf->address, pte);
4021 pte_unmap_unlock(vmf->pte, vmf->ptl);
4025 /* TODO: handle PTE-mapped THP */
4026 if (PageCompound(page)) {
4027 pte_unmap_unlock(vmf->pte, vmf->ptl);
4032 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
4033 * much anyway since they can be in shared cache state. This misses
4034 * the case where a mapping is writable but the process never writes
4035 * to it but pte_write gets cleared during protection updates and
4036 * pte_dirty has unpredictable behaviour between PTE scan updates,
4037 * background writeback, dirty balancing and application behaviour.
4039 if (!pte_write(pte))
4040 flags |= TNF_NO_GROUP;
4043 * Flag if the page is shared between multiple address spaces. This
4044 * is later used when determining whether to group tasks together
4046 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
4047 flags |= TNF_SHARED;
4049 last_cpupid = page_cpupid_last(page);
4050 page_nid = page_to_nid(page);
4051 target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
4053 pte_unmap_unlock(vmf->pte, vmf->ptl);
4054 if (target_nid == -1) {
4059 /* Migrate to the requested node */
4060 migrated = migrate_misplaced_page(page, vma, target_nid);
4062 page_nid = target_nid;
4063 flags |= TNF_MIGRATED;
4065 flags |= TNF_MIGRATE_FAIL;
4069 task_numa_fault(last_cpupid, page_nid, 1, flags);
4073 static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf)
4075 if (vma_is_anonymous(vmf->vma))
4076 return do_huge_pmd_anonymous_page(vmf);
4077 if (vmf->vma->vm_ops->huge_fault)
4078 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
4079 return VM_FAULT_FALLBACK;
4082 /* `inline' is required to avoid gcc 4.1.2 build error */
4083 static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd)
4085 if (vma_is_anonymous(vmf->vma))
4086 return do_huge_pmd_wp_page(vmf, orig_pmd);
4087 if (vmf->vma->vm_ops->huge_fault)
4088 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
4090 /* COW handled on pte level: split pmd */
4091 VM_BUG_ON_VMA(vmf->vma->vm_flags & VM_SHARED, vmf->vma);
4092 __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
4094 return VM_FAULT_FALLBACK;
4097 static inline bool vma_is_accessible(struct vm_area_struct *vma)
4099 return vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE);
4102 static vm_fault_t create_huge_pud(struct vm_fault *vmf)
4104 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
4105 /* No support for anonymous transparent PUD pages yet */
4106 if (vma_is_anonymous(vmf->vma))
4107 return VM_FAULT_FALLBACK;
4108 if (vmf->vma->vm_ops->huge_fault)
4109 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
4110 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
4111 return VM_FAULT_FALLBACK;
4114 static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
4116 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
4117 /* No support for anonymous transparent PUD pages yet */
4118 if (vma_is_anonymous(vmf->vma))
4119 return VM_FAULT_FALLBACK;
4120 if (vmf->vma->vm_ops->huge_fault)
4121 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
4122 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
4123 return VM_FAULT_FALLBACK;
4127 * These routines also need to handle stuff like marking pages dirty
4128 * and/or accessed for architectures that don't do it in hardware (most
4129 * RISC architectures). The early dirtying is also good on the i386.
4131 * There is also a hook called "update_mmu_cache()" that architectures
4132 * with external mmu caches can use to update those (ie the Sparc or
4133 * PowerPC hashed page tables that act as extended TLBs).
4135 * We enter with non-exclusive mmap_sem (to exclude vma changes, but allow
4136 * concurrent faults).
4138 * The mmap_sem may have been released depending on flags and our return value.
4139 * See filemap_fault() and __lock_page_or_retry().
4141 static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
4145 if (unlikely(pmd_none(*vmf->pmd))) {
4147 * Leave __pte_alloc() until later: because vm_ops->fault may
4148 * want to allocate huge page, and if we expose page table
4149 * for an instant, it will be difficult to retract from
4150 * concurrent faults and from rmap lookups.
4154 /* See comment in pte_alloc_one_map() */
4155 if (pmd_devmap_trans_unstable(vmf->pmd))
4158 * A regular pmd is established and it can't morph into a huge
4159 * pmd from under us anymore at this point because we hold the
4160 * mmap_sem read mode and khugepaged takes it in write mode.
4161 * So now it's safe to run pte_offset_map().
4163 vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
4164 vmf->orig_pte = *vmf->pte;
4167 * some architectures can have larger ptes than wordsize,
4168 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
4169 * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic
4170 * accesses. The code below just needs a consistent view
4171 * for the ifs and we later double check anyway with the
4172 * ptl lock held. So here a barrier will do.
4175 if (pte_none(vmf->orig_pte)) {
4176 pte_unmap(vmf->pte);
4182 if (vma_is_anonymous(vmf->vma))
4183 return do_anonymous_page(vmf);
4185 return do_fault(vmf);
4188 if (!pte_present(vmf->orig_pte))
4189 return do_swap_page(vmf);
4191 if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
4192 return do_numa_page(vmf);
4194 vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
4195 spin_lock(vmf->ptl);
4196 entry = vmf->orig_pte;
4197 if (unlikely(!pte_same(*vmf->pte, entry)))
4199 if (vmf->flags & FAULT_FLAG_WRITE) {
4200 if (!pte_write(entry))
4201 return do_wp_page(vmf);
4202 entry = pte_mkdirty(entry);
4204 entry = pte_mkyoung(entry);
4205 if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
4206 vmf->flags & FAULT_FLAG_WRITE)) {
4207 update_mmu_cache(vmf->vma, vmf->address, vmf->pte);
4210 * This is needed only for protection faults but the arch code
4211 * is not yet telling us if this is a protection fault or not.
4212 * This still avoids useless tlb flushes for .text page faults
4215 if (vmf->flags & FAULT_FLAG_WRITE)
4216 flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
4219 pte_unmap_unlock(vmf->pte, vmf->ptl);
4224 * By the time we get here, we already hold the mm semaphore
4226 * The mmap_sem may have been released depending on flags and our
4227 * return value. See filemap_fault() and __lock_page_or_retry().
4229 static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
4230 unsigned long address, unsigned int flags)
4232 struct vm_fault vmf = {
4234 .address = address & PAGE_MASK,
4236 .pgoff = linear_page_index(vma, address),
4237 .gfp_mask = __get_fault_gfp_mask(vma),
4239 unsigned int dirty = flags & FAULT_FLAG_WRITE;
4240 struct mm_struct *mm = vma->vm_mm;
4245 pgd = pgd_offset(mm, address);
4246 p4d = p4d_alloc(mm, pgd, address);
4248 return VM_FAULT_OOM;
4250 vmf.pud = pud_alloc(mm, p4d, address);
4252 return VM_FAULT_OOM;
4253 if (pud_none(*vmf.pud) && __transparent_hugepage_enabled(vma)) {
4254 ret = create_huge_pud(&vmf);
4255 if (!(ret & VM_FAULT_FALLBACK))
4258 pud_t orig_pud = *vmf.pud;
4261 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
4263 /* NUMA case for anonymous PUDs would go here */
4265 if (dirty && !pud_write(orig_pud)) {
4266 ret = wp_huge_pud(&vmf, orig_pud);
4267 if (!(ret & VM_FAULT_FALLBACK))
4270 huge_pud_set_accessed(&vmf, orig_pud);
4276 vmf.pmd = pmd_alloc(mm, vmf.pud, address);
4278 return VM_FAULT_OOM;
4279 if (pmd_none(*vmf.pmd) && __transparent_hugepage_enabled(vma)) {
4280 ret = create_huge_pmd(&vmf);
4281 if (!(ret & VM_FAULT_FALLBACK))
4284 pmd_t orig_pmd = *vmf.pmd;
4287 if (unlikely(is_swap_pmd(orig_pmd))) {
4288 VM_BUG_ON(thp_migration_supported() &&
4289 !is_pmd_migration_entry(orig_pmd));
4290 if (is_pmd_migration_entry(orig_pmd))
4291 pmd_migration_entry_wait(mm, vmf.pmd);
4294 if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
4295 if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
4296 return do_huge_pmd_numa_page(&vmf, orig_pmd);
4298 if (dirty && !pmd_write(orig_pmd)) {
4299 ret = wp_huge_pmd(&vmf, orig_pmd);
4300 if (!(ret & VM_FAULT_FALLBACK))
4303 huge_pmd_set_accessed(&vmf, orig_pmd);
4309 return handle_pte_fault(&vmf);
4313 * By the time we get here, we already hold the mm semaphore
4315 * The mmap_sem may have been released depending on flags and our
4316 * return value. See filemap_fault() and __lock_page_or_retry().
4318 vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
4323 __set_current_state(TASK_RUNNING);
4325 count_vm_event(PGFAULT);
4326 count_memcg_event_mm(vma->vm_mm, PGFAULT);
4328 /* do counter updates before entering really critical section. */
4329 check_sync_rss_stat(current);
4331 if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
4332 flags & FAULT_FLAG_INSTRUCTION,
4333 flags & FAULT_FLAG_REMOTE))
4334 return VM_FAULT_SIGSEGV;
4337 * Enable the memcg OOM handling for faults triggered in user
4338 * space. Kernel faults are handled more gracefully.
4340 if (flags & FAULT_FLAG_USER)
4341 mem_cgroup_enter_user_fault();
4343 if (unlikely(is_vm_hugetlb_page(vma)))
4344 ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
4346 ret = __handle_mm_fault(vma, address, flags);
4348 if (flags & FAULT_FLAG_USER) {
4349 mem_cgroup_exit_user_fault();
4351 * The task may have entered a memcg OOM situation but
4352 * if the allocation error was handled gracefully (no
4353 * VM_FAULT_OOM), there is no need to kill anything.
4354 * Just clean up the OOM state peacefully.
4356 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
4357 mem_cgroup_oom_synchronize(false);
4362 EXPORT_SYMBOL_GPL(handle_mm_fault);
4364 #ifndef __PAGETABLE_P4D_FOLDED
4366 * Allocate p4d page table.
4367 * We've already handled the fast-path in-line.
4369 int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
4371 p4d_t *new = p4d_alloc_one(mm, address);
4375 smp_wmb(); /* See comment in __pte_alloc */
4377 spin_lock(&mm->page_table_lock);
4378 if (pgd_present(*pgd)) /* Another has populated it */
4381 pgd_populate(mm, pgd, new);
4382 spin_unlock(&mm->page_table_lock);
4385 #endif /* __PAGETABLE_P4D_FOLDED */
4387 #ifndef __PAGETABLE_PUD_FOLDED
4389 * Allocate page upper directory.
4390 * We've already handled the fast-path in-line.
4392 int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
4394 pud_t *new = pud_alloc_one(mm, address);
4398 smp_wmb(); /* See comment in __pte_alloc */
4400 spin_lock(&mm->page_table_lock);
4401 #ifndef __ARCH_HAS_5LEVEL_HACK
4402 if (!p4d_present(*p4d)) {
4404 p4d_populate(mm, p4d, new);
4405 } else /* Another has populated it */
4408 if (!pgd_present(*p4d)) {
4410 pgd_populate(mm, p4d, new);
4411 } else /* Another has populated it */
4413 #endif /* __ARCH_HAS_5LEVEL_HACK */
4414 spin_unlock(&mm->page_table_lock);
4417 #endif /* __PAGETABLE_PUD_FOLDED */
4419 #ifndef __PAGETABLE_PMD_FOLDED
4421 * Allocate page middle directory.
4422 * We've already handled the fast-path in-line.
4424 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
4427 pmd_t *new = pmd_alloc_one(mm, address);
4431 smp_wmb(); /* See comment in __pte_alloc */
4433 ptl = pud_lock(mm, pud);
4434 #ifndef __ARCH_HAS_4LEVEL_HACK
4435 if (!pud_present(*pud)) {
4437 pud_populate(mm, pud, new);
4438 } else /* Another has populated it */
4441 if (!pgd_present(*pud)) {
4443 pgd_populate(mm, pud, new);
4444 } else /* Another has populated it */
4446 #endif /* __ARCH_HAS_4LEVEL_HACK */
4450 #endif /* __PAGETABLE_PMD_FOLDED */
4452 static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4453 unsigned long *start, unsigned long *end,
4454 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4462 pgd = pgd_offset(mm, address);
4463 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
4466 p4d = p4d_offset(pgd, address);
4467 if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d)))
4470 pud = pud_offset(p4d, address);
4471 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
4474 pmd = pmd_offset(pud, address);
4475 VM_BUG_ON(pmd_trans_huge(*pmd));
4477 if (pmd_huge(*pmd)) {
4482 *start = address & PMD_MASK;
4483 *end = *start + PMD_SIZE;
4484 mmu_notifier_invalidate_range_start(mm, *start, *end);
4486 *ptlp = pmd_lock(mm, pmd);
4487 if (pmd_huge(*pmd)) {
4493 mmu_notifier_invalidate_range_end(mm, *start, *end);
4496 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
4500 *start = address & PAGE_MASK;
4501 *end = *start + PAGE_SIZE;
4502 mmu_notifier_invalidate_range_start(mm, *start, *end);
4504 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
4505 if (!pte_present(*ptep))
4510 pte_unmap_unlock(ptep, *ptlp);
4512 mmu_notifier_invalidate_range_end(mm, *start, *end);
4517 static inline int follow_pte(struct mm_struct *mm, unsigned long address,
4518 pte_t **ptepp, spinlock_t **ptlp)
4522 /* (void) is needed to make gcc happy */
4523 (void) __cond_lock(*ptlp,
4524 !(res = __follow_pte_pmd(mm, address, NULL, NULL,
4525 ptepp, NULL, ptlp)));
4529 int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4530 unsigned long *start, unsigned long *end,
4531 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4535 /* (void) is needed to make gcc happy */
4536 (void) __cond_lock(*ptlp,
4537 !(res = __follow_pte_pmd(mm, address, start, end,
4538 ptepp, pmdpp, ptlp)));
4541 EXPORT_SYMBOL(follow_pte_pmd);
4544 * follow_pfn - look up PFN at a user virtual address
4545 * @vma: memory mapping
4546 * @address: user virtual address
4547 * @pfn: location to store found PFN
4549 * Only IO mappings and raw PFN mappings are allowed.
4551 * Returns zero and the pfn at @pfn on success, -ve otherwise.
4553 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
4560 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4563 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
4566 *pfn = pte_pfn(*ptep);
4567 pte_unmap_unlock(ptep, ptl);
4570 EXPORT_SYMBOL(follow_pfn);
4572 #ifdef CONFIG_HAVE_IOREMAP_PROT
4573 int follow_phys(struct vm_area_struct *vma,
4574 unsigned long address, unsigned int flags,
4575 unsigned long *prot, resource_size_t *phys)
4581 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4584 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
4588 if ((flags & FOLL_WRITE) && !pte_write(pte))
4591 *prot = pgprot_val(pte_pgprot(pte));
4592 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
4596 pte_unmap_unlock(ptep, ptl);
4601 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
4602 void *buf, int len, int write)
4604 resource_size_t phys_addr;
4605 unsigned long prot = 0;
4606 void __iomem *maddr;
4607 int offset = addr & (PAGE_SIZE-1);
4609 if (follow_phys(vma, addr, write, &prot, &phys_addr))
4612 maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
4617 memcpy_toio(maddr + offset, buf, len);
4619 memcpy_fromio(buf, maddr + offset, len);
4624 EXPORT_SYMBOL_GPL(generic_access_phys);
4628 * Access another process' address space as given in mm. If non-NULL, use the
4629 * given task for page fault accounting.
4631 int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
4632 unsigned long addr, void *buf, int len, unsigned int gup_flags)
4634 struct vm_area_struct *vma;
4635 void *old_buf = buf;
4636 int write = gup_flags & FOLL_WRITE;
4638 if (down_read_killable(&mm->mmap_sem))
4641 /* ignore errors, just check how much was successfully transferred */
4643 int bytes, ret, offset;
4645 struct page *page = NULL;
4647 ret = get_user_pages_remote(tsk, mm, addr, 1,
4648 gup_flags, &page, &vma, NULL);
4650 #ifndef CONFIG_HAVE_IOREMAP_PROT
4654 * Check if this is a VM_IO | VM_PFNMAP VMA, which
4655 * we can access using slightly different code.
4657 vma = find_vma(mm, addr);
4658 if (!vma || vma->vm_start > addr)
4660 if (vma->vm_ops && vma->vm_ops->access)
4661 ret = vma->vm_ops->access(vma, addr, buf,
4669 offset = addr & (PAGE_SIZE-1);
4670 if (bytes > PAGE_SIZE-offset)
4671 bytes = PAGE_SIZE-offset;
4675 copy_to_user_page(vma, page, addr,
4676 maddr + offset, buf, bytes);
4677 set_page_dirty_lock(page);
4679 copy_from_user_page(vma, page, addr,
4680 buf, maddr + offset, bytes);
4689 up_read(&mm->mmap_sem);
4691 return buf - old_buf;
4695 * access_remote_vm - access another process' address space
4696 * @mm: the mm_struct of the target address space
4697 * @addr: start address to access
4698 * @buf: source or destination buffer
4699 * @len: number of bytes to transfer
4700 * @gup_flags: flags modifying lookup behaviour
4702 * The caller must hold a reference on @mm.
4704 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
4705 void *buf, int len, unsigned int gup_flags)
4707 return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
4711 * Access another process' address space.
4712 * Source/target buffer must be kernel space,
4713 * Do not walk the page table directly, use get_user_pages
4715 int access_process_vm(struct task_struct *tsk, unsigned long addr,
4716 void *buf, int len, unsigned int gup_flags)
4718 struct mm_struct *mm;
4721 mm = get_task_mm(tsk);
4725 ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
4731 EXPORT_SYMBOL_GPL(access_process_vm);
4734 * Print the name of a VMA.
4736 void print_vma_addr(char *prefix, unsigned long ip)
4738 struct mm_struct *mm = current->mm;
4739 struct vm_area_struct *vma;
4742 * we might be running from an atomic context so we cannot sleep
4744 if (!down_read_trylock(&mm->mmap_sem))
4747 vma = find_vma(mm, ip);
4748 if (vma && vma->vm_file) {
4749 struct file *f = vma->vm_file;
4750 char *buf = (char *)__get_free_page(GFP_NOWAIT);
4754 p = file_path(f, buf, PAGE_SIZE);
4757 printk("%s%s[%lx+%lx]", prefix, kbasename(p),
4759 vma->vm_end - vma->vm_start);
4760 free_page((unsigned long)buf);
4763 up_read(&mm->mmap_sem);
4766 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4767 void __might_fault(const char *file, int line)
4770 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
4771 * holding the mmap_sem, this is safe because kernel memory doesn't
4772 * get paged out, therefore we'll never actually fault, and the
4773 * below annotations will generate false positives.
4775 if (uaccess_kernel())
4777 if (pagefault_disabled())
4779 __might_sleep(file, line, 0);
4780 #if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4782 might_lock_read(¤t->mm->mmap_sem);
4785 EXPORT_SYMBOL(__might_fault);
4788 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
4790 * Process all subpages of the specified huge page with the specified
4791 * operation. The target subpage will be processed last to keep its
4794 static inline void process_huge_page(
4795 unsigned long addr_hint, unsigned int pages_per_huge_page,
4796 void (*process_subpage)(unsigned long addr, int idx, void *arg),
4800 unsigned long addr = addr_hint &
4801 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
4803 /* Process target subpage last to keep its cache lines hot */
4805 n = (addr_hint - addr) / PAGE_SIZE;
4806 if (2 * n <= pages_per_huge_page) {
4807 /* If target subpage in first half of huge page */
4810 /* Process subpages at the end of huge page */
4811 for (i = pages_per_huge_page - 1; i >= 2 * n; i--) {
4813 process_subpage(addr + i * PAGE_SIZE, i, arg);
4816 /* If target subpage in second half of huge page */
4817 base = pages_per_huge_page - 2 * (pages_per_huge_page - n);
4818 l = pages_per_huge_page - n;
4819 /* Process subpages at the begin of huge page */
4820 for (i = 0; i < base; i++) {
4822 process_subpage(addr + i * PAGE_SIZE, i, arg);
4826 * Process remaining subpages in left-right-left-right pattern
4827 * towards the target subpage
4829 for (i = 0; i < l; i++) {
4830 int left_idx = base + i;
4831 int right_idx = base + 2 * l - 1 - i;
4834 process_subpage(addr + left_idx * PAGE_SIZE, left_idx, arg);
4836 process_subpage(addr + right_idx * PAGE_SIZE, right_idx, arg);
4840 static void clear_gigantic_page(struct page *page,
4842 unsigned int pages_per_huge_page)
4845 struct page *p = page;
4848 for (i = 0; i < pages_per_huge_page;
4849 i++, p = mem_map_next(p, page, i)) {
4851 clear_user_highpage(p, addr + i * PAGE_SIZE);
4855 static void clear_subpage(unsigned long addr, int idx, void *arg)
4857 struct page *page = arg;
4859 clear_user_highpage(page + idx, addr);
4862 void clear_huge_page(struct page *page,
4863 unsigned long addr_hint, unsigned int pages_per_huge_page)
4865 unsigned long addr = addr_hint &
4866 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
4868 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4869 clear_gigantic_page(page, addr, pages_per_huge_page);
4873 process_huge_page(addr_hint, pages_per_huge_page, clear_subpage, page);
4876 static void copy_user_gigantic_page(struct page *dst, struct page *src,
4878 struct vm_area_struct *vma,
4879 unsigned int pages_per_huge_page)
4882 struct page *dst_base = dst;
4883 struct page *src_base = src;
4885 for (i = 0; i < pages_per_huge_page; ) {
4887 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
4890 dst = mem_map_next(dst, dst_base, i);
4891 src = mem_map_next(src, src_base, i);
4895 struct copy_subpage_arg {
4898 struct vm_area_struct *vma;
4901 static void copy_subpage(unsigned long addr, int idx, void *arg)
4903 struct copy_subpage_arg *copy_arg = arg;
4905 copy_user_highpage(copy_arg->dst + idx, copy_arg->src + idx,
4906 addr, copy_arg->vma);
4909 void copy_user_huge_page(struct page *dst, struct page *src,
4910 unsigned long addr_hint, struct vm_area_struct *vma,
4911 unsigned int pages_per_huge_page)
4913 unsigned long addr = addr_hint &
4914 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
4915 struct copy_subpage_arg arg = {
4921 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4922 copy_user_gigantic_page(dst, src, addr, vma,
4923 pages_per_huge_page);
4927 process_huge_page(addr_hint, pages_per_huge_page, copy_subpage, &arg);
4930 long copy_huge_page_from_user(struct page *dst_page,
4931 const void __user *usr_src,
4932 unsigned int pages_per_huge_page,
4933 bool allow_pagefault)
4935 void *src = (void *)usr_src;
4937 unsigned long i, rc = 0;
4938 unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
4939 struct page *subpage = dst_page;
4941 for (i = 0; i < pages_per_huge_page;
4942 i++, subpage = mem_map_next(subpage, dst_page, i)) {
4943 if (allow_pagefault)
4944 page_kaddr = kmap(subpage);
4946 page_kaddr = kmap_atomic(subpage);
4947 rc = copy_from_user(page_kaddr,
4948 (const void __user *)(src + i * PAGE_SIZE),
4950 if (allow_pagefault)
4953 kunmap_atomic(page_kaddr);
4955 ret_val -= (PAGE_SIZE - rc);
4963 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
4965 #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
4967 static struct kmem_cache *page_ptl_cachep;
4969 void __init ptlock_cache_init(void)
4971 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
4975 bool ptlock_alloc(struct page *page)
4979 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
4986 void ptlock_free(struct page *page)
4988 kmem_cache_free(page_ptl_cachep, page->ptl);