4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
8 * demand-loading started 01.12.91 - seems it is high on the list of
9 * things wanted, and it should be easy to implement. - Linus
13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14 * pages started 02.12.91, seems to work. - Linus.
16 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
17 * would have taken more than the 6M I have free, but it worked well as
20 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
24 * Real VM (paging to/from disk) started 18.12.91. Much more work and
25 * thought has to go into this. Oh, well..
26 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
27 * Found it. Everything seems to work now.
28 * 20.12.91 - Ok, making the swap-device changeable like the root.
32 * 05.04.94 - Multi-page memory management added for v1.1.
33 * Idea by Alex Bligh (alex@cconcepts.co.uk)
35 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
36 * (Gerhard.Wichert@pdb.siemens.de)
38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
41 #include <linux/kernel_stat.h>
43 #include <linux/hugetlb.h>
44 #include <linux/mman.h>
45 #include <linux/swap.h>
46 #include <linux/highmem.h>
47 #include <linux/pagemap.h>
48 #include <linux/rmap.h>
49 #include <linux/module.h>
50 #include <linux/delayacct.h>
51 #include <linux/init.h>
53 #include <asm/pgalloc.h>
54 #include <asm/uaccess.h>
56 #include <asm/tlbflush.h>
57 #include <asm/pgtable.h>
59 #include <linux/swapops.h>
60 #include <linux/elf.h>
62 #ifndef CONFIG_NEED_MULTIPLE_NODES
63 /* use the per-pgdat data instead for discontigmem - mbligh */
64 unsigned long max_mapnr;
67 EXPORT_SYMBOL(max_mapnr);
68 EXPORT_SYMBOL(mem_map);
71 unsigned long num_physpages;
73 * A number of key systems in x86 including ioremap() rely on the assumption
74 * that high_memory defines the upper bound on direct map memory, then end
75 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
76 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
80 unsigned long vmalloc_earlyreserve;
82 EXPORT_SYMBOL(num_physpages);
83 EXPORT_SYMBOL(high_memory);
84 EXPORT_SYMBOL(vmalloc_earlyreserve);
86 int randomize_va_space __read_mostly = 1;
88 static int __init disable_randmaps(char *s)
90 randomize_va_space = 0;
93 __setup("norandmaps", disable_randmaps);
97 * If a p?d_bad entry is found while walking page tables, report
98 * the error, before resetting entry to p?d_none. Usually (but
99 * very seldom) called out from the p?d_none_or_clear_bad macros.
102 void pgd_clear_bad(pgd_t *pgd)
108 void pud_clear_bad(pud_t *pud)
114 void pmd_clear_bad(pmd_t *pmd)
121 * Note: this doesn't free the actual pages themselves. That
122 * has been handled earlier when unmapping all the memory regions.
124 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
126 struct page *page = pmd_page(*pmd);
128 pte_lock_deinit(page);
129 pte_free_tlb(tlb, page);
130 dec_zone_page_state(page, NR_PAGETABLE);
134 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
135 unsigned long addr, unsigned long end,
136 unsigned long floor, unsigned long ceiling)
143 pmd = pmd_offset(pud, addr);
145 next = pmd_addr_end(addr, end);
146 if (pmd_none_or_clear_bad(pmd))
148 free_pte_range(tlb, pmd);
149 } while (pmd++, addr = next, addr != end);
159 if (end - 1 > ceiling - 1)
162 pmd = pmd_offset(pud, start);
164 pmd_free_tlb(tlb, pmd);
167 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
168 unsigned long addr, unsigned long end,
169 unsigned long floor, unsigned long ceiling)
176 pud = pud_offset(pgd, addr);
178 next = pud_addr_end(addr, end);
179 if (pud_none_or_clear_bad(pud))
181 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
182 } while (pud++, addr = next, addr != end);
188 ceiling &= PGDIR_MASK;
192 if (end - 1 > ceiling - 1)
195 pud = pud_offset(pgd, start);
197 pud_free_tlb(tlb, pud);
201 * This function frees user-level page tables of a process.
203 * Must be called with pagetable lock held.
205 void free_pgd_range(struct mmu_gather **tlb,
206 unsigned long addr, unsigned long end,
207 unsigned long floor, unsigned long ceiling)
214 * The next few lines have given us lots of grief...
216 * Why are we testing PMD* at this top level? Because often
217 * there will be no work to do at all, and we'd prefer not to
218 * go all the way down to the bottom just to discover that.
220 * Why all these "- 1"s? Because 0 represents both the bottom
221 * of the address space and the top of it (using -1 for the
222 * top wouldn't help much: the masks would do the wrong thing).
223 * The rule is that addr 0 and floor 0 refer to the bottom of
224 * the address space, but end 0 and ceiling 0 refer to the top
225 * Comparisons need to use "end - 1" and "ceiling - 1" (though
226 * that end 0 case should be mythical).
228 * Wherever addr is brought up or ceiling brought down, we must
229 * be careful to reject "the opposite 0" before it confuses the
230 * subsequent tests. But what about where end is brought down
231 * by PMD_SIZE below? no, end can't go down to 0 there.
233 * Whereas we round start (addr) and ceiling down, by different
234 * masks at different levels, in order to test whether a table
235 * now has no other vmas using it, so can be freed, we don't
236 * bother to round floor or end up - the tests don't need that.
250 if (end - 1 > ceiling - 1)
256 pgd = pgd_offset((*tlb)->mm, addr);
258 next = pgd_addr_end(addr, end);
259 if (pgd_none_or_clear_bad(pgd))
261 free_pud_range(*tlb, pgd, addr, next, floor, ceiling);
262 } while (pgd++, addr = next, addr != end);
265 flush_tlb_pgtables((*tlb)->mm, start, end);
268 void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
269 unsigned long floor, unsigned long ceiling)
272 struct vm_area_struct *next = vma->vm_next;
273 unsigned long addr = vma->vm_start;
276 * Hide vma from rmap and vmtruncate before freeing pgtables
278 anon_vma_unlink(vma);
279 unlink_file_vma(vma);
281 if (is_vm_hugetlb_page(vma)) {
282 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
283 floor, next? next->vm_start: ceiling);
286 * Optimization: gather nearby vmas into one call down
288 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
289 && !is_vm_hugetlb_page(next)) {
292 anon_vma_unlink(vma);
293 unlink_file_vma(vma);
295 free_pgd_range(tlb, addr, vma->vm_end,
296 floor, next? next->vm_start: ceiling);
302 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
304 struct page *new = pte_alloc_one(mm, address);
309 spin_lock(&mm->page_table_lock);
310 if (pmd_present(*pmd)) { /* Another has populated it */
311 pte_lock_deinit(new);
315 inc_zone_page_state(new, NR_PAGETABLE);
316 pmd_populate(mm, pmd, new);
318 spin_unlock(&mm->page_table_lock);
322 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
324 pte_t *new = pte_alloc_one_kernel(&init_mm, address);
328 spin_lock(&init_mm.page_table_lock);
329 if (pmd_present(*pmd)) /* Another has populated it */
330 pte_free_kernel(new);
332 pmd_populate_kernel(&init_mm, pmd, new);
333 spin_unlock(&init_mm.page_table_lock);
337 static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
340 add_mm_counter(mm, file_rss, file_rss);
342 add_mm_counter(mm, anon_rss, anon_rss);
346 * This function is called to print an error when a bad pte
347 * is found. For example, we might have a PFN-mapped pte in
348 * a region that doesn't allow it.
350 * The calling function must still handle the error.
352 void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr)
354 printk(KERN_ERR "Bad pte = %08llx, process = %s, "
355 "vm_flags = %lx, vaddr = %lx\n",
356 (long long)pte_val(pte),
357 (vma->vm_mm == current->mm ? current->comm : "???"),
358 vma->vm_flags, vaddr);
362 static inline int is_cow_mapping(unsigned int flags)
364 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
368 * This function gets the "struct page" associated with a pte.
370 * NOTE! Some mappings do not have "struct pages". A raw PFN mapping
371 * will have each page table entry just pointing to a raw page frame
372 * number, and as far as the VM layer is concerned, those do not have
373 * pages associated with them - even if the PFN might point to memory
374 * that otherwise is perfectly fine and has a "struct page".
376 * The way we recognize those mappings is through the rules set up
377 * by "remap_pfn_range()": the vma will have the VM_PFNMAP bit set,
378 * and the vm_pgoff will point to the first PFN mapped: thus every
379 * page that is a raw mapping will always honor the rule
381 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
383 * and if that isn't true, the page has been COW'ed (in which case it
384 * _does_ have a "struct page" associated with it even if it is in a
387 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
389 unsigned long pfn = pte_pfn(pte);
391 if (unlikely(vma->vm_flags & VM_PFNMAP)) {
392 unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT;
393 if (pfn == vma->vm_pgoff + off)
395 if (!is_cow_mapping(vma->vm_flags))
400 * Add some anal sanity checks for now. Eventually,
401 * we should just do "return pfn_to_page(pfn)", but
402 * in the meantime we check that we get a valid pfn,
403 * and that the resulting page looks ok.
405 if (unlikely(!pfn_valid(pfn))) {
406 print_bad_pte(vma, pte, addr);
411 * NOTE! We still have PageReserved() pages in the page
414 * The PAGE_ZERO() pages and various VDSO mappings can
415 * cause them to exist.
417 return pfn_to_page(pfn);
421 * copy one vm_area from one task to the other. Assumes the page tables
422 * already present in the new task to be cleared in the whole range
423 * covered by this vma.
427 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
428 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
429 unsigned long addr, int *rss)
431 unsigned long vm_flags = vma->vm_flags;
432 pte_t pte = *src_pte;
435 /* pte contains position in swap or file, so copy. */
436 if (unlikely(!pte_present(pte))) {
437 if (!pte_file(pte)) {
438 swp_entry_t entry = pte_to_swp_entry(pte);
440 swap_duplicate(entry);
441 /* make sure dst_mm is on swapoff's mmlist. */
442 if (unlikely(list_empty(&dst_mm->mmlist))) {
443 spin_lock(&mmlist_lock);
444 if (list_empty(&dst_mm->mmlist))
445 list_add(&dst_mm->mmlist,
447 spin_unlock(&mmlist_lock);
449 if (is_write_migration_entry(entry) &&
450 is_cow_mapping(vm_flags)) {
452 * COW mappings require pages in both parent
453 * and child to be set to read.
455 make_migration_entry_read(&entry);
456 pte = swp_entry_to_pte(entry);
457 set_pte_at(src_mm, addr, src_pte, pte);
464 * If it's a COW mapping, write protect it both
465 * in the parent and the child
467 if (is_cow_mapping(vm_flags)) {
468 ptep_set_wrprotect(src_mm, addr, src_pte);
473 * If it's a shared mapping, mark it clean in
476 if (vm_flags & VM_SHARED)
477 pte = pte_mkclean(pte);
478 pte = pte_mkold(pte);
480 page = vm_normal_page(vma, addr, pte);
484 rss[!!PageAnon(page)]++;
488 set_pte_at(dst_mm, addr, dst_pte, pte);
491 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
492 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
493 unsigned long addr, unsigned long end)
495 pte_t *src_pte, *dst_pte;
496 spinlock_t *src_ptl, *dst_ptl;
502 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
505 src_pte = pte_offset_map_nested(src_pmd, addr);
506 src_ptl = pte_lockptr(src_mm, src_pmd);
507 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
511 * We are holding two locks at this point - either of them
512 * could generate latencies in another task on another CPU.
514 if (progress >= 32) {
516 if (need_resched() ||
517 need_lockbreak(src_ptl) ||
518 need_lockbreak(dst_ptl))
521 if (pte_none(*src_pte)) {
525 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
527 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
529 spin_unlock(src_ptl);
530 pte_unmap_nested(src_pte - 1);
531 add_mm_rss(dst_mm, rss[0], rss[1]);
532 pte_unmap_unlock(dst_pte - 1, dst_ptl);
539 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
540 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
541 unsigned long addr, unsigned long end)
543 pmd_t *src_pmd, *dst_pmd;
546 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
549 src_pmd = pmd_offset(src_pud, addr);
551 next = pmd_addr_end(addr, end);
552 if (pmd_none_or_clear_bad(src_pmd))
554 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
557 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
561 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
562 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
563 unsigned long addr, unsigned long end)
565 pud_t *src_pud, *dst_pud;
568 dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
571 src_pud = pud_offset(src_pgd, addr);
573 next = pud_addr_end(addr, end);
574 if (pud_none_or_clear_bad(src_pud))
576 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
579 } while (dst_pud++, src_pud++, addr = next, addr != end);
583 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
584 struct vm_area_struct *vma)
586 pgd_t *src_pgd, *dst_pgd;
588 unsigned long addr = vma->vm_start;
589 unsigned long end = vma->vm_end;
592 * Don't copy ptes where a page fault will fill them correctly.
593 * Fork becomes much lighter when there are big shared or private
594 * readonly mappings. The tradeoff is that copy_page_range is more
595 * efficient than faulting.
597 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
602 if (is_vm_hugetlb_page(vma))
603 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
605 dst_pgd = pgd_offset(dst_mm, addr);
606 src_pgd = pgd_offset(src_mm, addr);
608 next = pgd_addr_end(addr, end);
609 if (pgd_none_or_clear_bad(src_pgd))
611 if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
614 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
618 static unsigned long zap_pte_range(struct mmu_gather *tlb,
619 struct vm_area_struct *vma, pmd_t *pmd,
620 unsigned long addr, unsigned long end,
621 long *zap_work, struct zap_details *details)
623 struct mm_struct *mm = tlb->mm;
629 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
632 if (pte_none(ptent)) {
637 (*zap_work) -= PAGE_SIZE;
639 if (pte_present(ptent)) {
642 page = vm_normal_page(vma, addr, ptent);
643 if (unlikely(details) && page) {
645 * unmap_shared_mapping_pages() wants to
646 * invalidate cache without truncating:
647 * unmap shared but keep private pages.
649 if (details->check_mapping &&
650 details->check_mapping != page->mapping)
653 * Each page->index must be checked when
654 * invalidating or truncating nonlinear.
656 if (details->nonlinear_vma &&
657 (page->index < details->first_index ||
658 page->index > details->last_index))
661 ptent = ptep_get_and_clear_full(mm, addr, pte,
663 tlb_remove_tlb_entry(tlb, pte, addr);
666 if (unlikely(details) && details->nonlinear_vma
667 && linear_page_index(details->nonlinear_vma,
668 addr) != page->index)
669 set_pte_at(mm, addr, pte,
670 pgoff_to_pte(page->index));
674 if (pte_dirty(ptent))
675 set_page_dirty(page);
676 if (pte_young(ptent))
677 mark_page_accessed(page);
680 page_remove_rmap(page);
681 tlb_remove_page(tlb, page);
685 * If details->check_mapping, we leave swap entries;
686 * if details->nonlinear_vma, we leave file entries.
688 if (unlikely(details))
690 if (!pte_file(ptent))
691 free_swap_and_cache(pte_to_swp_entry(ptent));
692 pte_clear_full(mm, addr, pte, tlb->fullmm);
693 } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
695 add_mm_rss(mm, file_rss, anon_rss);
696 pte_unmap_unlock(pte - 1, ptl);
701 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
702 struct vm_area_struct *vma, pud_t *pud,
703 unsigned long addr, unsigned long end,
704 long *zap_work, struct zap_details *details)
709 pmd = pmd_offset(pud, addr);
711 next = pmd_addr_end(addr, end);
712 if (pmd_none_or_clear_bad(pmd)) {
716 next = zap_pte_range(tlb, vma, pmd, addr, next,
718 } while (pmd++, addr = next, (addr != end && *zap_work > 0));
723 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
724 struct vm_area_struct *vma, pgd_t *pgd,
725 unsigned long addr, unsigned long end,
726 long *zap_work, struct zap_details *details)
731 pud = pud_offset(pgd, addr);
733 next = pud_addr_end(addr, end);
734 if (pud_none_or_clear_bad(pud)) {
738 next = zap_pmd_range(tlb, vma, pud, addr, next,
740 } while (pud++, addr = next, (addr != end && *zap_work > 0));
745 static unsigned long unmap_page_range(struct mmu_gather *tlb,
746 struct vm_area_struct *vma,
747 unsigned long addr, unsigned long end,
748 long *zap_work, struct zap_details *details)
753 if (details && !details->check_mapping && !details->nonlinear_vma)
757 tlb_start_vma(tlb, vma);
758 pgd = pgd_offset(vma->vm_mm, addr);
760 next = pgd_addr_end(addr, end);
761 if (pgd_none_or_clear_bad(pgd)) {
765 next = zap_pud_range(tlb, vma, pgd, addr, next,
767 } while (pgd++, addr = next, (addr != end && *zap_work > 0));
768 tlb_end_vma(tlb, vma);
773 #ifdef CONFIG_PREEMPT
774 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
776 /* No preempt: go for improved straight-line efficiency */
777 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
781 * unmap_vmas - unmap a range of memory covered by a list of vma's
782 * @tlbp: address of the caller's struct mmu_gather
783 * @vma: the starting vma
784 * @start_addr: virtual address at which to start unmapping
785 * @end_addr: virtual address at which to end unmapping
786 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
787 * @details: details of nonlinear truncation or shared cache invalidation
789 * Returns the end address of the unmapping (restart addr if interrupted).
791 * Unmap all pages in the vma list.
793 * We aim to not hold locks for too long (for scheduling latency reasons).
794 * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to
795 * return the ending mmu_gather to the caller.
797 * Only addresses between `start' and `end' will be unmapped.
799 * The VMA list must be sorted in ascending virtual address order.
801 * unmap_vmas() assumes that the caller will flush the whole unmapped address
802 * range after unmap_vmas() returns. So the only responsibility here is to
803 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
804 * drops the lock and schedules.
806 unsigned long unmap_vmas(struct mmu_gather **tlbp,
807 struct vm_area_struct *vma, unsigned long start_addr,
808 unsigned long end_addr, unsigned long *nr_accounted,
809 struct zap_details *details)
811 long zap_work = ZAP_BLOCK_SIZE;
812 unsigned long tlb_start = 0; /* For tlb_finish_mmu */
813 int tlb_start_valid = 0;
814 unsigned long start = start_addr;
815 spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
816 int fullmm = (*tlbp)->fullmm;
818 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
821 start = max(vma->vm_start, start_addr);
822 if (start >= vma->vm_end)
824 end = min(vma->vm_end, end_addr);
825 if (end <= vma->vm_start)
828 if (vma->vm_flags & VM_ACCOUNT)
829 *nr_accounted += (end - start) >> PAGE_SHIFT;
831 while (start != end) {
832 if (!tlb_start_valid) {
837 if (unlikely(is_vm_hugetlb_page(vma))) {
838 unmap_hugepage_range(vma, start, end);
839 zap_work -= (end - start) /
840 (HPAGE_SIZE / PAGE_SIZE);
843 start = unmap_page_range(*tlbp, vma,
844 start, end, &zap_work, details);
847 BUG_ON(start != end);
851 tlb_finish_mmu(*tlbp, tlb_start, start);
853 if (need_resched() ||
854 (i_mmap_lock && need_lockbreak(i_mmap_lock))) {
862 *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
864 zap_work = ZAP_BLOCK_SIZE;
868 return start; /* which is now the end (or restart) address */
872 * zap_page_range - remove user pages in a given range
873 * @vma: vm_area_struct holding the applicable pages
874 * @address: starting address of pages to zap
875 * @size: number of bytes to zap
876 * @details: details of nonlinear truncation or shared cache invalidation
878 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
879 unsigned long size, struct zap_details *details)
881 struct mm_struct *mm = vma->vm_mm;
882 struct mmu_gather *tlb;
883 unsigned long end = address + size;
884 unsigned long nr_accounted = 0;
887 tlb = tlb_gather_mmu(mm, 0);
888 update_hiwater_rss(mm);
889 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
891 tlb_finish_mmu(tlb, address, end);
896 * Do a quick page-table lookup for a single page.
898 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
907 struct mm_struct *mm = vma->vm_mm;
909 page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
911 BUG_ON(flags & FOLL_GET);
916 pgd = pgd_offset(mm, address);
917 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
920 pud = pud_offset(pgd, address);
921 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
924 pmd = pmd_offset(pud, address);
925 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
928 if (pmd_huge(*pmd)) {
929 BUG_ON(flags & FOLL_GET);
930 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
934 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
939 if (!pte_present(pte))
941 if ((flags & FOLL_WRITE) && !pte_write(pte))
943 page = vm_normal_page(vma, address, pte);
947 if (flags & FOLL_GET)
949 if (flags & FOLL_TOUCH) {
950 if ((flags & FOLL_WRITE) &&
951 !pte_dirty(pte) && !PageDirty(page))
952 set_page_dirty(page);
953 mark_page_accessed(page);
956 pte_unmap_unlock(ptep, ptl);
962 * When core dumping an enormous anonymous area that nobody
963 * has touched so far, we don't want to allocate page tables.
965 if (flags & FOLL_ANON) {
966 page = ZERO_PAGE(address);
967 if (flags & FOLL_GET)
969 BUG_ON(flags & FOLL_WRITE);
974 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
975 unsigned long start, int len, int write, int force,
976 struct page **pages, struct vm_area_struct **vmas)
979 unsigned int vm_flags;
982 * Require read or write permissions.
983 * If 'force' is set, we only require the "MAY" flags.
985 vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
986 vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
990 struct vm_area_struct *vma;
991 unsigned int foll_flags;
993 vma = find_extend_vma(mm, start);
994 if (!vma && in_gate_area(tsk, start)) {
995 unsigned long pg = start & PAGE_MASK;
996 struct vm_area_struct *gate_vma = get_gate_vma(tsk);
1001 if (write) /* user gate pages are read-only */
1002 return i ? : -EFAULT;
1004 pgd = pgd_offset_k(pg);
1006 pgd = pgd_offset_gate(mm, pg);
1007 BUG_ON(pgd_none(*pgd));
1008 pud = pud_offset(pgd, pg);
1009 BUG_ON(pud_none(*pud));
1010 pmd = pmd_offset(pud, pg);
1012 return i ? : -EFAULT;
1013 pte = pte_offset_map(pmd, pg);
1014 if (pte_none(*pte)) {
1016 return i ? : -EFAULT;
1019 struct page *page = vm_normal_page(gate_vma, start, *pte);
1033 if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
1034 || !(vm_flags & vma->vm_flags))
1035 return i ? : -EFAULT;
1037 if (is_vm_hugetlb_page(vma)) {
1038 i = follow_hugetlb_page(mm, vma, pages, vmas,
1043 foll_flags = FOLL_TOUCH;
1045 foll_flags |= FOLL_GET;
1046 if (!write && !(vma->vm_flags & VM_LOCKED) &&
1047 (!vma->vm_ops || !vma->vm_ops->nopage))
1048 foll_flags |= FOLL_ANON;
1054 foll_flags |= FOLL_WRITE;
1057 while (!(page = follow_page(vma, start, foll_flags))) {
1059 ret = __handle_mm_fault(mm, vma, start,
1060 foll_flags & FOLL_WRITE);
1062 * The VM_FAULT_WRITE bit tells us that do_wp_page has
1063 * broken COW when necessary, even if maybe_mkwrite
1064 * decided not to set pte_write. We can thus safely do
1065 * subsequent page lookups as if they were reads.
1067 if (ret & VM_FAULT_WRITE)
1068 foll_flags &= ~FOLL_WRITE;
1070 switch (ret & ~VM_FAULT_WRITE) {
1071 case VM_FAULT_MINOR:
1074 case VM_FAULT_MAJOR:
1077 case VM_FAULT_SIGBUS:
1078 return i ? i : -EFAULT;
1080 return i ? i : -ENOMEM;
1088 flush_anon_page(page, start);
1089 flush_dcache_page(page);
1096 } while (len && start < vma->vm_end);
1100 EXPORT_SYMBOL(get_user_pages);
1102 static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1103 unsigned long addr, unsigned long end, pgprot_t prot)
1108 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1112 struct page *page = ZERO_PAGE(addr);
1113 pte_t zero_pte = pte_wrprotect(mk_pte(page, prot));
1114 page_cache_get(page);
1115 page_add_file_rmap(page);
1116 inc_mm_counter(mm, file_rss);
1117 BUG_ON(!pte_none(*pte));
1118 set_pte_at(mm, addr, pte, zero_pte);
1119 } while (pte++, addr += PAGE_SIZE, addr != end);
1120 pte_unmap_unlock(pte - 1, ptl);
1124 static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud,
1125 unsigned long addr, unsigned long end, pgprot_t prot)
1130 pmd = pmd_alloc(mm, pud, addr);
1134 next = pmd_addr_end(addr, end);
1135 if (zeromap_pte_range(mm, pmd, addr, next, prot))
1137 } while (pmd++, addr = next, addr != end);
1141 static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1142 unsigned long addr, unsigned long end, pgprot_t prot)
1147 pud = pud_alloc(mm, pgd, addr);
1151 next = pud_addr_end(addr, end);
1152 if (zeromap_pmd_range(mm, pud, addr, next, prot))
1154 } while (pud++, addr = next, addr != end);
1158 int zeromap_page_range(struct vm_area_struct *vma,
1159 unsigned long addr, unsigned long size, pgprot_t prot)
1163 unsigned long end = addr + size;
1164 struct mm_struct *mm = vma->vm_mm;
1167 BUG_ON(addr >= end);
1168 pgd = pgd_offset(mm, addr);
1169 flush_cache_range(vma, addr, end);
1171 next = pgd_addr_end(addr, end);
1172 err = zeromap_pud_range(mm, pgd, addr, next, prot);
1175 } while (pgd++, addr = next, addr != end);
1179 pte_t * fastcall get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl)
1181 pgd_t * pgd = pgd_offset(mm, addr);
1182 pud_t * pud = pud_alloc(mm, pgd, addr);
1184 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1186 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1192 * This is the old fallback for page remapping.
1194 * For historical reasons, it only allows reserved pages. Only
1195 * old drivers should use this, and they needed to mark their
1196 * pages reserved for the old functions anyway.
1198 static int insert_page(struct mm_struct *mm, unsigned long addr, struct page *page, pgprot_t prot)
1208 flush_dcache_page(page);
1209 pte = get_locked_pte(mm, addr, &ptl);
1213 if (!pte_none(*pte))
1216 /* Ok, finally just insert the thing.. */
1218 inc_mm_counter(mm, file_rss);
1219 page_add_file_rmap(page);
1220 set_pte_at(mm, addr, pte, mk_pte(page, prot));
1224 pte_unmap_unlock(pte, ptl);
1230 * This allows drivers to insert individual pages they've allocated
1233 * The page has to be a nice clean _individual_ kernel allocation.
1234 * If you allocate a compound page, you need to have marked it as
1235 * such (__GFP_COMP), or manually just split the page up yourself
1236 * (see split_page()).
1238 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1239 * took an arbitrary page protection parameter. This doesn't allow
1240 * that. Your vma protection will have to be set up correctly, which
1241 * means that if you want a shared writable mapping, you'd better
1242 * ask for a shared writable mapping!
1244 * The page does not need to be reserved.
1246 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page *page)
1248 if (addr < vma->vm_start || addr >= vma->vm_end)
1250 if (!page_count(page))
1252 vma->vm_flags |= VM_INSERTPAGE;
1253 return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
1255 EXPORT_SYMBOL(vm_insert_page);
1258 * maps a range of physical memory into the requested pages. the old
1259 * mappings are removed. any references to nonexistent pages results
1260 * in null mappings (currently treated as "copy-on-access")
1262 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1263 unsigned long addr, unsigned long end,
1264 unsigned long pfn, pgprot_t prot)
1269 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1273 BUG_ON(!pte_none(*pte));
1274 set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
1276 } while (pte++, addr += PAGE_SIZE, addr != end);
1277 pte_unmap_unlock(pte - 1, ptl);
1281 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1282 unsigned long addr, unsigned long end,
1283 unsigned long pfn, pgprot_t prot)
1288 pfn -= addr >> PAGE_SHIFT;
1289 pmd = pmd_alloc(mm, pud, addr);
1293 next = pmd_addr_end(addr, end);
1294 if (remap_pte_range(mm, pmd, addr, next,
1295 pfn + (addr >> PAGE_SHIFT), prot))
1297 } while (pmd++, addr = next, addr != end);
1301 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1302 unsigned long addr, unsigned long end,
1303 unsigned long pfn, pgprot_t prot)
1308 pfn -= addr >> PAGE_SHIFT;
1309 pud = pud_alloc(mm, pgd, addr);
1313 next = pud_addr_end(addr, end);
1314 if (remap_pmd_range(mm, pud, addr, next,
1315 pfn + (addr >> PAGE_SHIFT), prot))
1317 } while (pud++, addr = next, addr != end);
1321 /* Note: this is only safe if the mm semaphore is held when called. */
1322 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1323 unsigned long pfn, unsigned long size, pgprot_t prot)
1327 unsigned long end = addr + PAGE_ALIGN(size);
1328 struct mm_struct *mm = vma->vm_mm;
1332 * Physically remapped pages are special. Tell the
1333 * rest of the world about it:
1334 * VM_IO tells people not to look at these pages
1335 * (accesses can have side effects).
1336 * VM_RESERVED is specified all over the place, because
1337 * in 2.4 it kept swapout's vma scan off this vma; but
1338 * in 2.6 the LRU scan won't even find its pages, so this
1339 * flag means no more than count its pages in reserved_vm,
1340 * and omit it from core dump, even when VM_IO turned off.
1341 * VM_PFNMAP tells the core MM that the base pages are just
1342 * raw PFN mappings, and do not have a "struct page" associated
1345 * There's a horrible special case to handle copy-on-write
1346 * behaviour that some programs depend on. We mark the "original"
1347 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1349 if (is_cow_mapping(vma->vm_flags)) {
1350 if (addr != vma->vm_start || end != vma->vm_end)
1352 vma->vm_pgoff = pfn;
1355 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1357 BUG_ON(addr >= end);
1358 pfn -= addr >> PAGE_SHIFT;
1359 pgd = pgd_offset(mm, addr);
1360 flush_cache_range(vma, addr, end);
1362 next = pgd_addr_end(addr, end);
1363 err = remap_pud_range(mm, pgd, addr, next,
1364 pfn + (addr >> PAGE_SHIFT), prot);
1367 } while (pgd++, addr = next, addr != end);
1370 EXPORT_SYMBOL(remap_pfn_range);
1373 * handle_pte_fault chooses page fault handler according to an entry
1374 * which was read non-atomically. Before making any commitment, on
1375 * those architectures or configurations (e.g. i386 with PAE) which
1376 * might give a mix of unmatched parts, do_swap_page and do_file_page
1377 * must check under lock before unmapping the pte and proceeding
1378 * (but do_wp_page is only called after already making such a check;
1379 * and do_anonymous_page and do_no_page can safely check later on).
1381 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1382 pte_t *page_table, pte_t orig_pte)
1385 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1386 if (sizeof(pte_t) > sizeof(unsigned long)) {
1387 spinlock_t *ptl = pte_lockptr(mm, pmd);
1389 same = pte_same(*page_table, orig_pte);
1393 pte_unmap(page_table);
1398 * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when
1399 * servicing faults for write access. In the normal case, do always want
1400 * pte_mkwrite. But get_user_pages can cause write faults for mappings
1401 * that do not have writing enabled, when used by access_process_vm.
1403 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
1405 if (likely(vma->vm_flags & VM_WRITE))
1406 pte = pte_mkwrite(pte);
1410 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va)
1413 * If the source page was a PFN mapping, we don't have
1414 * a "struct page" for it. We do a best-effort copy by
1415 * just copying from the original user address. If that
1416 * fails, we just zero-fill it. Live with it.
1418 if (unlikely(!src)) {
1419 void *kaddr = kmap_atomic(dst, KM_USER0);
1420 void __user *uaddr = (void __user *)(va & PAGE_MASK);
1423 * This really shouldn't fail, because the page is there
1424 * in the page tables. But it might just be unreadable,
1425 * in which case we just give up and fill the result with
1428 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1429 memset(kaddr, 0, PAGE_SIZE);
1430 kunmap_atomic(kaddr, KM_USER0);
1434 copy_user_highpage(dst, src, va);
1438 * This routine handles present pages, when users try to write
1439 * to a shared page. It is done by copying the page to a new address
1440 * and decrementing the shared-page counter for the old page.
1442 * Note that this routine assumes that the protection checks have been
1443 * done by the caller (the low-level page fault routine in most cases).
1444 * Thus we can safely just mark it writable once we've done any necessary
1447 * We also mark the page dirty at this point even though the page will
1448 * change only once the write actually happens. This avoids a few races,
1449 * and potentially makes it more efficient.
1451 * We enter with non-exclusive mmap_sem (to exclude vma changes,
1452 * but allow concurrent faults), with pte both mapped and locked.
1453 * We return with mmap_sem still held, but pte unmapped and unlocked.
1455 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1456 unsigned long address, pte_t *page_table, pmd_t *pmd,
1457 spinlock_t *ptl, pte_t orig_pte)
1459 struct page *old_page, *new_page;
1461 int reuse = 0, ret = VM_FAULT_MINOR;
1462 struct page *dirty_page = NULL;
1464 old_page = vm_normal_page(vma, address, orig_pte);
1469 * Only catch write-faults on shared writable pages, read-only
1470 * shared pages can get COWed by get_user_pages(.write=1, .force=1).
1472 if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1473 (VM_WRITE|VM_SHARED))) {
1474 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
1476 * Notify the address space that the page is about to
1477 * become writable so that it can prohibit this or wait
1478 * for the page to get into an appropriate state.
1480 * We do this without the lock held, so that it can
1481 * sleep if it needs to.
1483 page_cache_get(old_page);
1484 pte_unmap_unlock(page_table, ptl);
1486 if (vma->vm_ops->page_mkwrite(vma, old_page) < 0)
1487 goto unwritable_page;
1489 page_cache_release(old_page);
1492 * Since we dropped the lock we need to revalidate
1493 * the PTE as someone else may have changed it. If
1494 * they did, we just return, as we can count on the
1495 * MMU to tell us if they didn't also make it writable.
1497 page_table = pte_offset_map_lock(mm, pmd, address,
1499 if (!pte_same(*page_table, orig_pte))
1502 dirty_page = old_page;
1503 get_page(dirty_page);
1505 } else if (PageAnon(old_page) && !TestSetPageLocked(old_page)) {
1506 reuse = can_share_swap_page(old_page);
1507 unlock_page(old_page);
1511 flush_cache_page(vma, address, pte_pfn(orig_pte));
1512 entry = pte_mkyoung(orig_pte);
1513 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1514 ptep_set_access_flags(vma, address, page_table, entry, 1);
1515 update_mmu_cache(vma, address, entry);
1516 lazy_mmu_prot_update(entry);
1517 ret |= VM_FAULT_WRITE;
1522 * Ok, we need to copy. Oh, well..
1524 page_cache_get(old_page);
1526 pte_unmap_unlock(page_table, ptl);
1528 if (unlikely(anon_vma_prepare(vma)))
1530 if (old_page == ZERO_PAGE(address)) {
1531 new_page = alloc_zeroed_user_highpage(vma, address);
1535 new_page = alloc_page_vma(GFP_HIGHUSER, vma, address);
1538 cow_user_page(new_page, old_page, address);
1542 * Re-check the pte - we dropped the lock
1544 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1545 if (likely(pte_same(*page_table, orig_pte))) {
1547 page_remove_rmap(old_page);
1548 if (!PageAnon(old_page)) {
1549 dec_mm_counter(mm, file_rss);
1550 inc_mm_counter(mm, anon_rss);
1553 inc_mm_counter(mm, anon_rss);
1554 flush_cache_page(vma, address, pte_pfn(orig_pte));
1555 entry = mk_pte(new_page, vma->vm_page_prot);
1556 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1557 lazy_mmu_prot_update(entry);
1558 ptep_establish(vma, address, page_table, entry);
1559 update_mmu_cache(vma, address, entry);
1560 lru_cache_add_active(new_page);
1561 page_add_new_anon_rmap(new_page, vma, address);
1563 /* Free the old page.. */
1564 new_page = old_page;
1565 ret |= VM_FAULT_WRITE;
1568 page_cache_release(new_page);
1570 page_cache_release(old_page);
1572 pte_unmap_unlock(page_table, ptl);
1574 set_page_dirty(dirty_page);
1575 put_page(dirty_page);
1580 page_cache_release(old_page);
1581 return VM_FAULT_OOM;
1584 page_cache_release(old_page);
1585 return VM_FAULT_SIGBUS;
1589 * Helper functions for unmap_mapping_range().
1591 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
1593 * We have to restart searching the prio_tree whenever we drop the lock,
1594 * since the iterator is only valid while the lock is held, and anyway
1595 * a later vma might be split and reinserted earlier while lock dropped.
1597 * The list of nonlinear vmas could be handled more efficiently, using
1598 * a placeholder, but handle it in the same way until a need is shown.
1599 * It is important to search the prio_tree before nonlinear list: a vma
1600 * may become nonlinear and be shifted from prio_tree to nonlinear list
1601 * while the lock is dropped; but never shifted from list to prio_tree.
1603 * In order to make forward progress despite restarting the search,
1604 * vm_truncate_count is used to mark a vma as now dealt with, so we can
1605 * quickly skip it next time around. Since the prio_tree search only
1606 * shows us those vmas affected by unmapping the range in question, we
1607 * can't efficiently keep all vmas in step with mapping->truncate_count:
1608 * so instead reset them all whenever it wraps back to 0 (then go to 1).
1609 * mapping->truncate_count and vma->vm_truncate_count are protected by
1612 * In order to make forward progress despite repeatedly restarting some
1613 * large vma, note the restart_addr from unmap_vmas when it breaks out:
1614 * and restart from that address when we reach that vma again. It might
1615 * have been split or merged, shrunk or extended, but never shifted: so
1616 * restart_addr remains valid so long as it remains in the vma's range.
1617 * unmap_mapping_range forces truncate_count to leap over page-aligned
1618 * values so we can save vma's restart_addr in its truncate_count field.
1620 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
1622 static void reset_vma_truncate_counts(struct address_space *mapping)
1624 struct vm_area_struct *vma;
1625 struct prio_tree_iter iter;
1627 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
1628 vma->vm_truncate_count = 0;
1629 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
1630 vma->vm_truncate_count = 0;
1633 static int unmap_mapping_range_vma(struct vm_area_struct *vma,
1634 unsigned long start_addr, unsigned long end_addr,
1635 struct zap_details *details)
1637 unsigned long restart_addr;
1641 restart_addr = vma->vm_truncate_count;
1642 if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
1643 start_addr = restart_addr;
1644 if (start_addr >= end_addr) {
1645 /* Top of vma has been split off since last time */
1646 vma->vm_truncate_count = details->truncate_count;
1651 restart_addr = zap_page_range(vma, start_addr,
1652 end_addr - start_addr, details);
1653 need_break = need_resched() ||
1654 need_lockbreak(details->i_mmap_lock);
1656 if (restart_addr >= end_addr) {
1657 /* We have now completed this vma: mark it so */
1658 vma->vm_truncate_count = details->truncate_count;
1662 /* Note restart_addr in vma's truncate_count field */
1663 vma->vm_truncate_count = restart_addr;
1668 spin_unlock(details->i_mmap_lock);
1670 spin_lock(details->i_mmap_lock);
1674 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
1675 struct zap_details *details)
1677 struct vm_area_struct *vma;
1678 struct prio_tree_iter iter;
1679 pgoff_t vba, vea, zba, zea;
1682 vma_prio_tree_foreach(vma, &iter, root,
1683 details->first_index, details->last_index) {
1684 /* Skip quickly over those we have already dealt with */
1685 if (vma->vm_truncate_count == details->truncate_count)
1688 vba = vma->vm_pgoff;
1689 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
1690 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
1691 zba = details->first_index;
1694 zea = details->last_index;
1698 if (unmap_mapping_range_vma(vma,
1699 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
1700 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
1706 static inline void unmap_mapping_range_list(struct list_head *head,
1707 struct zap_details *details)
1709 struct vm_area_struct *vma;
1712 * In nonlinear VMAs there is no correspondence between virtual address
1713 * offset and file offset. So we must perform an exhaustive search
1714 * across *all* the pages in each nonlinear VMA, not just the pages
1715 * whose virtual address lies outside the file truncation point.
1718 list_for_each_entry(vma, head, shared.vm_set.list) {
1719 /* Skip quickly over those we have already dealt with */
1720 if (vma->vm_truncate_count == details->truncate_count)
1722 details->nonlinear_vma = vma;
1723 if (unmap_mapping_range_vma(vma, vma->vm_start,
1724 vma->vm_end, details) < 0)
1730 * unmap_mapping_range - unmap the portion of all mmaps
1731 * in the specified address_space corresponding to the specified
1732 * page range in the underlying file.
1733 * @mapping: the address space containing mmaps to be unmapped.
1734 * @holebegin: byte in first page to unmap, relative to the start of
1735 * the underlying file. This will be rounded down to a PAGE_SIZE
1736 * boundary. Note that this is different from vmtruncate(), which
1737 * must keep the partial page. In contrast, we must get rid of
1739 * @holelen: size of prospective hole in bytes. This will be rounded
1740 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
1742 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
1743 * but 0 when invalidating pagecache, don't throw away private data.
1745 void unmap_mapping_range(struct address_space *mapping,
1746 loff_t const holebegin, loff_t const holelen, int even_cows)
1748 struct zap_details details;
1749 pgoff_t hba = holebegin >> PAGE_SHIFT;
1750 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1752 /* Check for overflow. */
1753 if (sizeof(holelen) > sizeof(hlen)) {
1755 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1756 if (holeend & ~(long long)ULONG_MAX)
1757 hlen = ULONG_MAX - hba + 1;
1760 details.check_mapping = even_cows? NULL: mapping;
1761 details.nonlinear_vma = NULL;
1762 details.first_index = hba;
1763 details.last_index = hba + hlen - 1;
1764 if (details.last_index < details.first_index)
1765 details.last_index = ULONG_MAX;
1766 details.i_mmap_lock = &mapping->i_mmap_lock;
1768 spin_lock(&mapping->i_mmap_lock);
1770 /* serialize i_size write against truncate_count write */
1772 /* Protect against page faults, and endless unmapping loops */
1773 mapping->truncate_count++;
1775 * For archs where spin_lock has inclusive semantics like ia64
1776 * this smp_mb() will prevent to read pagetable contents
1777 * before the truncate_count increment is visible to
1781 if (unlikely(is_restart_addr(mapping->truncate_count))) {
1782 if (mapping->truncate_count == 0)
1783 reset_vma_truncate_counts(mapping);
1784 mapping->truncate_count++;
1786 details.truncate_count = mapping->truncate_count;
1788 if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
1789 unmap_mapping_range_tree(&mapping->i_mmap, &details);
1790 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
1791 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
1792 spin_unlock(&mapping->i_mmap_lock);
1794 EXPORT_SYMBOL(unmap_mapping_range);
1797 * Handle all mappings that got truncated by a "truncate()"
1800 * NOTE! We have to be ready to update the memory sharing
1801 * between the file and the memory map for a potential last
1802 * incomplete page. Ugly, but necessary.
1804 int vmtruncate(struct inode * inode, loff_t offset)
1806 struct address_space *mapping = inode->i_mapping;
1807 unsigned long limit;
1809 if (inode->i_size < offset)
1812 * truncation of in-use swapfiles is disallowed - it would cause
1813 * subsequent swapout to scribble on the now-freed blocks.
1815 if (IS_SWAPFILE(inode))
1817 i_size_write(inode, offset);
1818 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
1819 truncate_inode_pages(mapping, offset);
1823 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1824 if (limit != RLIM_INFINITY && offset > limit)
1826 if (offset > inode->i_sb->s_maxbytes)
1828 i_size_write(inode, offset);
1831 if (inode->i_op && inode->i_op->truncate)
1832 inode->i_op->truncate(inode);
1835 send_sig(SIGXFSZ, current, 0);
1841 EXPORT_SYMBOL(vmtruncate);
1843 int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
1845 struct address_space *mapping = inode->i_mapping;
1848 * If the underlying filesystem is not going to provide
1849 * a way to truncate a range of blocks (punch a hole) -
1850 * we should return failure right now.
1852 if (!inode->i_op || !inode->i_op->truncate_range)
1855 mutex_lock(&inode->i_mutex);
1856 down_write(&inode->i_alloc_sem);
1857 unmap_mapping_range(mapping, offset, (end - offset), 1);
1858 truncate_inode_pages_range(mapping, offset, end);
1859 inode->i_op->truncate_range(inode, offset, end);
1860 up_write(&inode->i_alloc_sem);
1861 mutex_unlock(&inode->i_mutex);
1865 EXPORT_UNUSED_SYMBOL(vmtruncate_range); /* June 2006 */
1868 * Primitive swap readahead code. We simply read an aligned block of
1869 * (1 << page_cluster) entries in the swap area. This method is chosen
1870 * because it doesn't cost us any seek time. We also make sure to queue
1871 * the 'original' request together with the readahead ones...
1873 * This has been extended to use the NUMA policies from the mm triggering
1876 * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
1878 void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma)
1881 struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL;
1884 struct page *new_page;
1885 unsigned long offset;
1888 * Get the number of handles we should do readahead io to.
1890 num = valid_swaphandles(entry, &offset);
1891 for (i = 0; i < num; offset++, i++) {
1892 /* Ok, do the async read-ahead now */
1893 new_page = read_swap_cache_async(swp_entry(swp_type(entry),
1894 offset), vma, addr);
1897 page_cache_release(new_page);
1900 * Find the next applicable VMA for the NUMA policy.
1906 if (addr >= vma->vm_end) {
1908 next_vma = vma ? vma->vm_next : NULL;
1910 if (vma && addr < vma->vm_start)
1913 if (next_vma && addr >= next_vma->vm_start) {
1915 next_vma = vma->vm_next;
1920 lru_add_drain(); /* Push any new pages onto the LRU now */
1924 * We enter with non-exclusive mmap_sem (to exclude vma changes,
1925 * but allow concurrent faults), and pte mapped but not yet locked.
1926 * We return with mmap_sem still held, but pte unmapped and unlocked.
1928 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
1929 unsigned long address, pte_t *page_table, pmd_t *pmd,
1930 int write_access, pte_t orig_pte)
1936 int ret = VM_FAULT_MINOR;
1938 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
1941 entry = pte_to_swp_entry(orig_pte);
1942 if (is_migration_entry(entry)) {
1943 migration_entry_wait(mm, pmd, address);
1946 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
1947 page = lookup_swap_cache(entry);
1949 swapin_readahead(entry, address, vma);
1950 page = read_swap_cache_async(entry, vma, address);
1953 * Back out if somebody else faulted in this pte
1954 * while we released the pte lock.
1956 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1957 if (likely(pte_same(*page_table, orig_pte)))
1959 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
1963 /* Had to read the page from swap area: Major fault */
1964 ret = VM_FAULT_MAJOR;
1965 count_vm_event(PGMAJFAULT);
1969 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
1970 mark_page_accessed(page);
1974 * Back out if somebody else already faulted in this pte.
1976 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1977 if (unlikely(!pte_same(*page_table, orig_pte)))
1980 if (unlikely(!PageUptodate(page))) {
1981 ret = VM_FAULT_SIGBUS;
1985 /* The page isn't present yet, go ahead with the fault. */
1987 inc_mm_counter(mm, anon_rss);
1988 pte = mk_pte(page, vma->vm_page_prot);
1989 if (write_access && can_share_swap_page(page)) {
1990 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
1994 flush_icache_page(vma, page);
1995 set_pte_at(mm, address, page_table, pte);
1996 page_add_anon_rmap(page, vma, address);
2000 remove_exclusive_swap_page(page);
2004 if (do_wp_page(mm, vma, address,
2005 page_table, pmd, ptl, pte) == VM_FAULT_OOM)
2010 /* No need to invalidate - it was non-present before */
2011 update_mmu_cache(vma, address, pte);
2012 lazy_mmu_prot_update(pte);
2014 pte_unmap_unlock(page_table, ptl);
2018 pte_unmap_unlock(page_table, ptl);
2020 page_cache_release(page);
2025 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2026 * but allow concurrent faults), and pte mapped but not yet locked.
2027 * We return with mmap_sem still held, but pte unmapped and unlocked.
2029 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
2030 unsigned long address, pte_t *page_table, pmd_t *pmd,
2038 /* Allocate our own private page. */
2039 pte_unmap(page_table);
2041 if (unlikely(anon_vma_prepare(vma)))
2043 page = alloc_zeroed_user_highpage(vma, address);
2047 entry = mk_pte(page, vma->vm_page_prot);
2048 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2050 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2051 if (!pte_none(*page_table))
2053 inc_mm_counter(mm, anon_rss);
2054 lru_cache_add_active(page);
2055 page_add_new_anon_rmap(page, vma, address);
2057 /* Map the ZERO_PAGE - vm_page_prot is readonly */
2058 page = ZERO_PAGE(address);
2059 page_cache_get(page);
2060 entry = mk_pte(page, vma->vm_page_prot);
2062 ptl = pte_lockptr(mm, pmd);
2064 if (!pte_none(*page_table))
2066 inc_mm_counter(mm, file_rss);
2067 page_add_file_rmap(page);
2070 set_pte_at(mm, address, page_table, entry);
2072 /* No need to invalidate - it was non-present before */
2073 update_mmu_cache(vma, address, entry);
2074 lazy_mmu_prot_update(entry);
2076 pte_unmap_unlock(page_table, ptl);
2077 return VM_FAULT_MINOR;
2079 page_cache_release(page);
2082 return VM_FAULT_OOM;
2086 * do_no_page() tries to create a new page mapping. It aggressively
2087 * tries to share with existing pages, but makes a separate copy if
2088 * the "write_access" parameter is true in order to avoid the next
2091 * As this is called only for pages that do not currently exist, we
2092 * do not need to flush old virtual caches or the TLB.
2094 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2095 * but allow concurrent faults), and pte mapped but not yet locked.
2096 * We return with mmap_sem still held, but pte unmapped and unlocked.
2098 static int do_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
2099 unsigned long address, pte_t *page_table, pmd_t *pmd,
2103 struct page *new_page;
2104 struct address_space *mapping = NULL;
2106 unsigned int sequence = 0;
2107 int ret = VM_FAULT_MINOR;
2109 struct page *dirty_page = NULL;
2111 pte_unmap(page_table);
2112 BUG_ON(vma->vm_flags & VM_PFNMAP);
2115 mapping = vma->vm_file->f_mapping;
2116 sequence = mapping->truncate_count;
2117 smp_rmb(); /* serializes i_size against truncate_count */
2120 new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
2122 * No smp_rmb is needed here as long as there's a full
2123 * spin_lock/unlock sequence inside the ->nopage callback
2124 * (for the pagecache lookup) that acts as an implicit
2125 * smp_mb() and prevents the i_size read to happen
2126 * after the next truncate_count read.
2129 /* no page was available -- either SIGBUS or OOM */
2130 if (new_page == NOPAGE_SIGBUS)
2131 return VM_FAULT_SIGBUS;
2132 if (new_page == NOPAGE_OOM)
2133 return VM_FAULT_OOM;
2136 * Should we do an early C-O-W break?
2139 if (!(vma->vm_flags & VM_SHARED)) {
2142 if (unlikely(anon_vma_prepare(vma)))
2144 page = alloc_page_vma(GFP_HIGHUSER, vma, address);
2147 copy_user_highpage(page, new_page, address);
2148 page_cache_release(new_page);
2153 /* if the page will be shareable, see if the backing
2154 * address space wants to know that the page is about
2155 * to become writable */
2156 if (vma->vm_ops->page_mkwrite &&
2157 vma->vm_ops->page_mkwrite(vma, new_page) < 0
2159 page_cache_release(new_page);
2160 return VM_FAULT_SIGBUS;
2165 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2167 * For a file-backed vma, someone could have truncated or otherwise
2168 * invalidated this page. If unmap_mapping_range got called,
2169 * retry getting the page.
2171 if (mapping && unlikely(sequence != mapping->truncate_count)) {
2172 pte_unmap_unlock(page_table, ptl);
2173 page_cache_release(new_page);
2175 sequence = mapping->truncate_count;
2181 * This silly early PAGE_DIRTY setting removes a race
2182 * due to the bad i386 page protection. But it's valid
2183 * for other architectures too.
2185 * Note that if write_access is true, we either now have
2186 * an exclusive copy of the page, or this is a shared mapping,
2187 * so we can make it writable and dirty to avoid having to
2188 * handle that later.
2190 /* Only go through if we didn't race with anybody else... */
2191 if (pte_none(*page_table)) {
2192 flush_icache_page(vma, new_page);
2193 entry = mk_pte(new_page, vma->vm_page_prot);
2195 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2196 set_pte_at(mm, address, page_table, entry);
2198 inc_mm_counter(mm, anon_rss);
2199 lru_cache_add_active(new_page);
2200 page_add_new_anon_rmap(new_page, vma, address);
2202 inc_mm_counter(mm, file_rss);
2203 page_add_file_rmap(new_page);
2205 dirty_page = new_page;
2206 get_page(dirty_page);
2210 /* One of our sibling threads was faster, back out. */
2211 page_cache_release(new_page);
2215 /* no need to invalidate: a not-present page shouldn't be cached */
2216 update_mmu_cache(vma, address, entry);
2217 lazy_mmu_prot_update(entry);
2219 pte_unmap_unlock(page_table, ptl);
2221 set_page_dirty(dirty_page);
2222 put_page(dirty_page);
2226 page_cache_release(new_page);
2227 return VM_FAULT_OOM;
2231 * Fault of a previously existing named mapping. Repopulate the pte
2232 * from the encoded file_pte if possible. This enables swappable
2235 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2236 * but allow concurrent faults), and pte mapped but not yet locked.
2237 * We return with mmap_sem still held, but pte unmapped and unlocked.
2239 static int do_file_page(struct mm_struct *mm, struct vm_area_struct *vma,
2240 unsigned long address, pte_t *page_table, pmd_t *pmd,
2241 int write_access, pte_t orig_pte)
2246 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2247 return VM_FAULT_MINOR;
2249 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
2251 * Page table corrupted: show pte and kill process.
2253 print_bad_pte(vma, orig_pte, address);
2254 return VM_FAULT_OOM;
2256 /* We can then assume vm->vm_ops && vma->vm_ops->populate */
2258 pgoff = pte_to_pgoff(orig_pte);
2259 err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE,
2260 vma->vm_page_prot, pgoff, 0);
2262 return VM_FAULT_OOM;
2264 return VM_FAULT_SIGBUS;
2265 return VM_FAULT_MAJOR;
2269 * These routines also need to handle stuff like marking pages dirty
2270 * and/or accessed for architectures that don't do it in hardware (most
2271 * RISC architectures). The early dirtying is also good on the i386.
2273 * There is also a hook called "update_mmu_cache()" that architectures
2274 * with external mmu caches can use to update those (ie the Sparc or
2275 * PowerPC hashed page tables that act as extended TLBs).
2277 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2278 * but allow concurrent faults), and pte mapped but not yet locked.
2279 * We return with mmap_sem still held, but pte unmapped and unlocked.
2281 static inline int handle_pte_fault(struct mm_struct *mm,
2282 struct vm_area_struct *vma, unsigned long address,
2283 pte_t *pte, pmd_t *pmd, int write_access)
2289 old_entry = entry = *pte;
2290 if (!pte_present(entry)) {
2291 if (pte_none(entry)) {
2292 if (!vma->vm_ops || !vma->vm_ops->nopage)
2293 return do_anonymous_page(mm, vma, address,
2294 pte, pmd, write_access);
2295 return do_no_page(mm, vma, address,
2296 pte, pmd, write_access);
2298 if (pte_file(entry))
2299 return do_file_page(mm, vma, address,
2300 pte, pmd, write_access, entry);
2301 return do_swap_page(mm, vma, address,
2302 pte, pmd, write_access, entry);
2305 ptl = pte_lockptr(mm, pmd);
2307 if (unlikely(!pte_same(*pte, entry)))
2310 if (!pte_write(entry))
2311 return do_wp_page(mm, vma, address,
2312 pte, pmd, ptl, entry);
2313 entry = pte_mkdirty(entry);
2315 entry = pte_mkyoung(entry);
2316 if (!pte_same(old_entry, entry)) {
2317 ptep_set_access_flags(vma, address, pte, entry, write_access);
2318 update_mmu_cache(vma, address, entry);
2319 lazy_mmu_prot_update(entry);
2322 * This is needed only for protection faults but the arch code
2323 * is not yet telling us if this is a protection fault or not.
2324 * This still avoids useless tlb flushes for .text page faults
2328 flush_tlb_page(vma, address);
2331 pte_unmap_unlock(pte, ptl);
2332 return VM_FAULT_MINOR;
2336 * By the time we get here, we already hold the mm semaphore
2338 int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2339 unsigned long address, int write_access)
2346 __set_current_state(TASK_RUNNING);
2348 count_vm_event(PGFAULT);
2350 if (unlikely(is_vm_hugetlb_page(vma)))
2351 return hugetlb_fault(mm, vma, address, write_access);
2353 pgd = pgd_offset(mm, address);
2354 pud = pud_alloc(mm, pgd, address);
2356 return VM_FAULT_OOM;
2357 pmd = pmd_alloc(mm, pud, address);
2359 return VM_FAULT_OOM;
2360 pte = pte_alloc_map(mm, pmd, address);
2362 return VM_FAULT_OOM;
2364 return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
2367 EXPORT_SYMBOL_GPL(__handle_mm_fault);
2369 #ifndef __PAGETABLE_PUD_FOLDED
2371 * Allocate page upper directory.
2372 * We've already handled the fast-path in-line.
2374 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2376 pud_t *new = pud_alloc_one(mm, address);
2380 spin_lock(&mm->page_table_lock);
2381 if (pgd_present(*pgd)) /* Another has populated it */
2384 pgd_populate(mm, pgd, new);
2385 spin_unlock(&mm->page_table_lock);
2389 /* Workaround for gcc 2.96 */
2390 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2394 #endif /* __PAGETABLE_PUD_FOLDED */
2396 #ifndef __PAGETABLE_PMD_FOLDED
2398 * Allocate page middle directory.
2399 * We've already handled the fast-path in-line.
2401 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2403 pmd_t *new = pmd_alloc_one(mm, address);
2407 spin_lock(&mm->page_table_lock);
2408 #ifndef __ARCH_HAS_4LEVEL_HACK
2409 if (pud_present(*pud)) /* Another has populated it */
2412 pud_populate(mm, pud, new);
2414 if (pgd_present(*pud)) /* Another has populated it */
2417 pgd_populate(mm, pud, new);
2418 #endif /* __ARCH_HAS_4LEVEL_HACK */
2419 spin_unlock(&mm->page_table_lock);
2423 /* Workaround for gcc 2.96 */
2424 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2428 #endif /* __PAGETABLE_PMD_FOLDED */
2430 int make_pages_present(unsigned long addr, unsigned long end)
2432 int ret, len, write;
2433 struct vm_area_struct * vma;
2435 vma = find_vma(current->mm, addr);
2438 write = (vma->vm_flags & VM_WRITE) != 0;
2439 BUG_ON(addr >= end);
2440 BUG_ON(end > vma->vm_end);
2441 len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE;
2442 ret = get_user_pages(current, current->mm, addr,
2443 len, write, 0, NULL, NULL);
2446 return ret == len ? 0 : -1;
2450 * Map a vmalloc()-space virtual address to the physical page.
2452 struct page * vmalloc_to_page(void * vmalloc_addr)
2454 unsigned long addr = (unsigned long) vmalloc_addr;
2455 struct page *page = NULL;
2456 pgd_t *pgd = pgd_offset_k(addr);
2461 if (!pgd_none(*pgd)) {
2462 pud = pud_offset(pgd, addr);
2463 if (!pud_none(*pud)) {
2464 pmd = pmd_offset(pud, addr);
2465 if (!pmd_none(*pmd)) {
2466 ptep = pte_offset_map(pmd, addr);
2468 if (pte_present(pte))
2469 page = pte_page(pte);
2477 EXPORT_SYMBOL(vmalloc_to_page);
2480 * Map a vmalloc()-space virtual address to the physical page frame number.
2482 unsigned long vmalloc_to_pfn(void * vmalloc_addr)
2484 return page_to_pfn(vmalloc_to_page(vmalloc_addr));
2487 EXPORT_SYMBOL(vmalloc_to_pfn);
2489 #if !defined(__HAVE_ARCH_GATE_AREA)
2491 #if defined(AT_SYSINFO_EHDR)
2492 static struct vm_area_struct gate_vma;
2494 static int __init gate_vma_init(void)
2496 gate_vma.vm_mm = NULL;
2497 gate_vma.vm_start = FIXADDR_USER_START;
2498 gate_vma.vm_end = FIXADDR_USER_END;
2499 gate_vma.vm_page_prot = PAGE_READONLY;
2500 gate_vma.vm_flags = 0;
2503 __initcall(gate_vma_init);
2506 struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
2508 #ifdef AT_SYSINFO_EHDR
2515 int in_gate_area_no_task(unsigned long addr)
2517 #ifdef AT_SYSINFO_EHDR
2518 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
2524 #endif /* __HAVE_ARCH_GATE_AREA */