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)
37 #include <linux/mman.h>
38 #include <linux/swap.h>
39 #include <linux/smp_lock.h>
41 #include <asm/uaccess.h>
42 #include <asm/pgtable.h>
44 unsigned long max_mapnr
= 0;
45 unsigned long num_physpages
= 0;
46 void * high_memory
= NULL
;
49 * We special-case the C-O-W ZERO_PAGE, because it's such
50 * a common occurrence (no need to read the page to know
51 * that it's zero - better for the cache and memory subsystem).
53 static inline void copy_cow_page(unsigned long from
, unsigned long to
)
55 if (from
== ZERO_PAGE
) {
62 mem_map_t
* mem_map
= NULL
;
65 * oom() prints a message (so that the user knows why the process died),
66 * and gives the process an untrappable SIGKILL.
68 void oom(struct task_struct
* task
)
70 printk("\nOut of memory for %s.\n", task
->comm
);
71 force_sig(SIGKILL
, task
);
75 * Note: this doesn't free the actual pages themselves. That
76 * has been handled earlier when unmapping all the memory regions.
78 static inline void free_one_pmd(pmd_t
* dir
)
85 printk("free_one_pmd: bad directory entry %08lx\n", pmd_val(*dir
));
89 pte
= pte_offset(dir
, 0);
94 static inline void free_one_pgd(pgd_t
* dir
)
102 printk("free_one_pgd: bad directory entry %08lx\n", pgd_val(*dir
));
106 pmd
= pmd_offset(dir
, 0);
108 for (j
= 0; j
< PTRS_PER_PMD
; j
++)
113 /* Low and high watermarks for page table cache.
114 The system should try to have pgt_water[0] <= cache elements <= pgt_water[1]
116 int pgt_cache_water
[2] = { 25, 50 };
118 /* Returns the number of pages freed */
119 int check_pgt_cache(void)
121 return do_check_pgt_cache(pgt_cache_water
[0], pgt_cache_water
[1]);
126 * This function clears all user-level page tables of a process - this
127 * is needed by execve(), so that old pages aren't in the way.
129 void clear_page_tables(struct mm_struct
*mm
, unsigned long first
, int nr
)
131 pgd_t
* page_dir
= mm
->pgd
;
133 if (page_dir
&& page_dir
!= swapper_pg_dir
) {
136 free_one_pgd(page_dir
);
140 /* keep the page table cache within bounds */
146 * This function just free's the page directory - the
147 * pages tables themselves have been freed earlier by
148 * clear_page_tables().
150 void free_page_tables(struct mm_struct
* mm
)
152 pgd_t
* page_dir
= mm
->pgd
;
155 if (page_dir
== swapper_pg_dir
)
163 "free_page_tables: Trying to free kernel pgd\n");
167 int new_page_tables(struct task_struct
* tsk
)
171 if (!(new_pg
= pgd_alloc()))
173 SET_PAGE_DIR(tsk
, new_pg
);
174 tsk
->mm
->pgd
= new_pg
;
178 #define PTE_TABLE_MASK ((PTRS_PER_PTE-1) * sizeof(pte_t))
179 #define PMD_TABLE_MASK ((PTRS_PER_PMD-1) * sizeof(pmd_t))
182 * copy one vm_area from one task to the other. Assumes the page tables
183 * already present in the new task to be cleared in the whole range
184 * covered by this vma.
186 * 08Jan98 Merged into one routine from several inline routines to reduce
187 * variable count and make things faster. -jj
189 int copy_page_range(struct mm_struct
*dst
, struct mm_struct
*src
,
190 struct vm_area_struct
*vma
)
192 pgd_t
* src_pgd
, * dst_pgd
;
193 unsigned long address
= vma
->vm_start
;
194 unsigned long end
= vma
->vm_end
;
195 unsigned long cow
= (vma
->vm_flags
& (VM_SHARED
| VM_MAYWRITE
)) == VM_MAYWRITE
;
197 src_pgd
= pgd_offset(src
, address
)-1;
198 dst_pgd
= pgd_offset(dst
, address
)-1;
201 pmd_t
* src_pmd
, * dst_pmd
;
203 src_pgd
++; dst_pgd
++;
207 if (pgd_none(*src_pgd
))
208 goto skip_copy_pmd_range
;
209 if (pgd_bad(*src_pgd
)) {
210 printk("copy_pmd_range: bad pgd (%08lx)\n",
213 skip_copy_pmd_range
: address
= (address
+ PGDIR_SIZE
) & PGDIR_MASK
;
218 if (pgd_none(*dst_pgd
)) {
219 if (!pmd_alloc(dst_pgd
, 0))
223 src_pmd
= pmd_offset(src_pgd
, address
);
224 dst_pmd
= pmd_offset(dst_pgd
, address
);
227 pte_t
* src_pte
, * dst_pte
;
231 if (pmd_none(*src_pmd
))
232 goto skip_copy_pte_range
;
233 if (pmd_bad(*src_pmd
)) {
234 printk("copy_pte_range: bad pmd (%08lx)\n", pmd_val(*src_pmd
));
236 skip_copy_pte_range
: address
= (address
+ PMD_SIZE
) & PMD_MASK
;
239 goto cont_copy_pmd_range
;
241 if (pmd_none(*dst_pmd
)) {
242 if (!pte_alloc(dst_pmd
, 0))
246 src_pte
= pte_offset(src_pmd
, address
);
247 dst_pte
= pte_offset(dst_pmd
, address
);
250 pte_t pte
= *src_pte
;
251 unsigned long page_nr
;
256 goto cont_copy_pte_range
;
257 if (!pte_present(pte
)) {
258 swap_duplicate(pte_val(pte
));
259 set_pte(dst_pte
, pte
);
260 goto cont_copy_pte_range
;
262 page_nr
= MAP_NR(pte_page(pte
));
263 if (page_nr
>= max_mapnr
||
264 PageReserved(mem_map
+page_nr
)) {
265 set_pte(dst_pte
, pte
);
266 goto cont_copy_pte_range
;
268 /* If it's a COW mapping, write protect it both in the parent and the child */
270 pte
= pte_wrprotect(pte
);
271 set_pte(src_pte
, pte
);
273 /* If it's a shared mapping, mark it clean in the child */
274 if (vma
->vm_flags
& VM_SHARED
)
275 pte
= pte_mkclean(pte
);
276 set_pte(dst_pte
, pte_mkold(pte
));
277 atomic_inc(&mem_map
[page_nr
].count
);
279 cont_copy_pte_range
: address
+= PAGE_SIZE
;
284 } while ((unsigned long)src_pte
& PTE_TABLE_MASK
);
286 cont_copy_pmd_range
: src_pmd
++;
288 } while ((unsigned long)src_pmd
& PMD_TABLE_MASK
);
298 * Return indicates whether a page was freed so caller can adjust rss
300 static inline int free_pte(pte_t page
)
302 if (pte_present(page
)) {
303 unsigned long addr
= pte_page(page
);
304 if (MAP_NR(addr
) >= max_mapnr
|| PageReserved(mem_map
+MAP_NR(addr
)))
307 * free_page() used to be able to clear swap cache
308 * entries. We may now have to do it manually.
310 free_page_and_swap_cache(addr
);
313 swap_free(pte_val(page
));
317 static inline void forget_pte(pte_t page
)
319 if (!pte_none(page
)) {
320 printk("forget_pte: old mapping existed!\n");
325 static inline int zap_pte_range(pmd_t
* pmd
, unsigned long address
, unsigned long size
)
333 printk("zap_pte_range: bad pmd (%08lx)\n", pmd_val(*pmd
));
337 pte
= pte_offset(pmd
, address
);
338 address
&= ~PMD_MASK
;
339 if (address
+ size
> PMD_SIZE
)
340 size
= PMD_SIZE
- address
;
353 freed
+= free_pte(page
);
358 static inline int zap_pmd_range(pgd_t
* dir
, unsigned long address
, unsigned long size
)
367 printk("zap_pmd_range: bad pgd (%08lx)\n", pgd_val(*dir
));
371 pmd
= pmd_offset(dir
, address
);
372 address
&= ~PGDIR_MASK
;
373 end
= address
+ size
;
374 if (end
> PGDIR_SIZE
)
378 freed
+= zap_pte_range(pmd
, address
, end
- address
);
379 address
= (address
+ PMD_SIZE
) & PMD_MASK
;
381 } while (address
< end
);
386 * remove user pages in a given range.
388 void zap_page_range(struct mm_struct
*mm
, unsigned long address
, unsigned long size
)
391 unsigned long end
= address
+ size
;
394 dir
= pgd_offset(mm
, address
);
395 while (address
< end
) {
396 freed
+= zap_pmd_range(dir
, address
, end
- address
);
397 address
= (address
+ PGDIR_SIZE
) & PGDIR_MASK
;
401 * Update rss for the mm_struct (not necessarily current->mm)
410 static inline void zeromap_pte_range(pte_t
* pte
, unsigned long address
, unsigned long size
, pte_t zero_pte
)
414 address
&= ~PMD_MASK
;
415 end
= address
+ size
;
419 pte_t oldpage
= *pte
;
420 set_pte(pte
, zero_pte
);
422 address
+= PAGE_SIZE
;
424 } while (address
< end
);
427 static inline int zeromap_pmd_range(pmd_t
* pmd
, unsigned long address
, unsigned long size
, pte_t zero_pte
)
431 address
&= ~PGDIR_MASK
;
432 end
= address
+ size
;
433 if (end
> PGDIR_SIZE
)
436 pte_t
* pte
= pte_alloc(pmd
, address
);
439 zeromap_pte_range(pte
, address
, end
- address
, zero_pte
);
440 address
= (address
+ PMD_SIZE
) & PMD_MASK
;
442 } while (address
< end
);
446 int zeromap_page_range(unsigned long address
, unsigned long size
, pgprot_t prot
)
450 unsigned long beg
= address
;
451 unsigned long end
= address
+ size
;
454 zero_pte
= pte_wrprotect(mk_pte(ZERO_PAGE
, prot
));
455 dir
= pgd_offset(current
->mm
, address
);
456 flush_cache_range(current
->mm
, beg
, end
);
457 while (address
< end
) {
458 pmd_t
*pmd
= pmd_alloc(dir
, address
);
462 error
= zeromap_pmd_range(pmd
, address
, end
- address
, zero_pte
);
465 address
= (address
+ PGDIR_SIZE
) & PGDIR_MASK
;
468 flush_tlb_range(current
->mm
, beg
, end
);
473 * maps a range of physical memory into the requested pages. the old
474 * mappings are removed. any references to nonexistent pages results
475 * in null mappings (currently treated as "copy-on-access")
477 static inline void remap_pte_range(pte_t
* pte
, unsigned long address
, unsigned long size
,
478 unsigned long phys_addr
, pgprot_t prot
)
482 address
&= ~PMD_MASK
;
483 end
= address
+ size
;
488 pte_t oldpage
= *pte
;
491 mapnr
= MAP_NR(__va(phys_addr
));
492 if (mapnr
>= max_mapnr
|| PageReserved(mem_map
+mapnr
))
493 set_pte(pte
, mk_pte_phys(phys_addr
, prot
));
495 address
+= PAGE_SIZE
;
496 phys_addr
+= PAGE_SIZE
;
498 } while (address
< end
);
501 static inline int remap_pmd_range(pmd_t
* pmd
, unsigned long address
, unsigned long size
,
502 unsigned long phys_addr
, pgprot_t prot
)
506 address
&= ~PGDIR_MASK
;
507 end
= address
+ size
;
508 if (end
> PGDIR_SIZE
)
510 phys_addr
-= address
;
512 pte_t
* pte
= pte_alloc(pmd
, address
);
515 remap_pte_range(pte
, address
, end
- address
, address
+ phys_addr
, prot
);
516 address
= (address
+ PMD_SIZE
) & PMD_MASK
;
518 } while (address
< end
);
522 int remap_page_range(unsigned long from
, unsigned long phys_addr
, unsigned long size
, pgprot_t prot
)
526 unsigned long beg
= from
;
527 unsigned long end
= from
+ size
;
530 dir
= pgd_offset(current
->mm
, from
);
531 flush_cache_range(current
->mm
, beg
, end
);
533 pmd_t
*pmd
= pmd_alloc(dir
, from
);
537 error
= remap_pmd_range(pmd
, from
, end
- from
, phys_addr
+ from
, prot
);
540 from
= (from
+ PGDIR_SIZE
) & PGDIR_MASK
;
543 flush_tlb_range(current
->mm
, beg
, end
);
548 * sanity-check function..
550 static void put_page(pte_t
* page_table
, pte_t pte
)
552 if (!pte_none(*page_table
)) {
553 free_page_and_swap_cache(pte_page(pte
));
556 /* no need for flush_tlb */
557 set_pte(page_table
, pte
);
561 * This routine is used to map in a page into an address space: needed by
562 * execve() for the initial stack and environment pages.
564 unsigned long put_dirty_page(struct task_struct
* tsk
, unsigned long page
, unsigned long address
)
570 if (MAP_NR(page
) >= max_mapnr
)
571 printk("put_dirty_page: trying to put page %08lx at %08lx\n",page
,address
);
572 if (atomic_read(&mem_map
[MAP_NR(page
)].count
) != 1)
573 printk("mem_map disagrees with %08lx at %08lx\n",page
,address
);
574 pgd
= pgd_offset(tsk
->mm
,address
);
575 pmd
= pmd_alloc(pgd
, address
);
581 pte
= pte_alloc(pmd
, address
);
587 if (!pte_none(*pte
)) {
588 printk("put_dirty_page: pte %08lx already exists\n",
593 flush_page_to_ram(page
);
594 set_pte(pte
, pte_mkwrite(pte_mkdirty(mk_pte(page
, PAGE_COPY
))));
595 /* no need for flush_tlb */
600 * This routine handles present pages, when users try to write
601 * to a shared page. It is done by copying the page to a new address
602 * and decrementing the shared-page counter for the old page.
604 * Goto-purists beware: the only reason for goto's here is that it results
605 * in better assembly code.. The "default" path will see no jumps at all.
607 * Note that this routine assumes that the protection checks have been
608 * done by the caller (the low-level page fault routine in most cases).
609 * Thus we can safely just mark it writable once we've done any necessary
612 * We also mark the page dirty at this point even though the page will
613 * change only once the write actually happens. This avoids a few races,
614 * and potentially makes it more efficient.
616 static int do_wp_page(struct task_struct
* tsk
, struct vm_area_struct
* vma
,
617 unsigned long address
, pte_t
*page_table
)
620 unsigned long old_page
, new_page
;
621 struct page
* page_map
;
624 new_page
= __get_free_page(GFP_USER
);
625 /* Did someone else copy this page for us while we slept? */
626 if (pte_val(*page_table
) != pte_val(pte
))
628 if (!pte_present(pte
))
632 old_page
= pte_page(pte
);
633 if (MAP_NR(old_page
) >= max_mapnr
)
636 page_map
= mem_map
+ MAP_NR(old_page
);
639 * We can avoid the copy if:
640 * - we're the only user (count == 1)
641 * - the only other user is the swap cache,
642 * and the only swap cache user is itself,
643 * in which case we can remove the page
644 * from the swap cache.
646 switch (atomic_read(&page_map
->count
)) {
648 if (!PageSwapCache(page_map
))
650 if (swap_count(page_map
->offset
) != 1)
652 delete_from_swap_cache(page_map
);
655 /* We can release the kernel lock now.. */
658 flush_cache_page(vma
, address
);
659 set_pte(page_table
, pte_mkdirty(pte_mkwrite(pte
)));
660 flush_tlb_page(vma
, address
);
671 if (PageReserved(mem_map
+ MAP_NR(old_page
)))
673 copy_cow_page(old_page
,new_page
);
674 flush_page_to_ram(old_page
);
675 flush_page_to_ram(new_page
);
676 flush_cache_page(vma
, address
);
677 set_pte(page_table
, pte_mkwrite(pte_mkdirty(mk_pte(new_page
, vma
->vm_page_prot
))));
679 flush_tlb_page(vma
, address
);
683 printk("do_wp_page: bogus page at address %08lx (%08lx)\n",address
,old_page
);
684 send_sig(SIGKILL
, tsk
, 1);
691 * This function zeroes out partial mmap'ed pages at truncation time..
693 static void partial_clear(struct vm_area_struct
*vma
, unsigned long address
)
697 pte_t
*page_table
, pte
;
699 page_dir
= pgd_offset(vma
->vm_mm
, address
);
700 if (pgd_none(*page_dir
))
702 if (pgd_bad(*page_dir
)) {
703 printk("bad page table directory entry %p:[%lx]\n", page_dir
, pgd_val(*page_dir
));
707 page_middle
= pmd_offset(page_dir
, address
);
708 if (pmd_none(*page_middle
))
710 if (pmd_bad(*page_middle
)) {
711 printk("bad page table directory entry %p:[%lx]\n", page_dir
, pgd_val(*page_dir
));
712 pmd_clear(page_middle
);
715 page_table
= pte_offset(page_middle
, address
);
717 if (!pte_present(pte
))
719 flush_cache_page(vma
, address
);
720 address
&= ~PAGE_MASK
;
721 address
+= pte_page(pte
);
722 if (MAP_NR(address
) >= max_mapnr
)
724 memset((void *) address
, 0, PAGE_SIZE
- (address
& ~PAGE_MASK
));
725 flush_page_to_ram(pte_page(pte
));
729 * Handle all mappings that got truncated by a "truncate()"
732 * NOTE! We have to be ready to update the memory sharing
733 * between the file and the memory map for a potential last
734 * incomplete page. Ugly, but necessary.
736 void vmtruncate(struct inode
* inode
, unsigned long offset
)
738 struct vm_area_struct
* mpnt
;
740 truncate_inode_pages(inode
, offset
);
743 mpnt
= inode
->i_mmap
;
745 struct mm_struct
*mm
= mpnt
->vm_mm
;
746 unsigned long start
= mpnt
->vm_start
;
747 unsigned long end
= mpnt
->vm_end
;
748 unsigned long len
= end
- start
;
751 /* mapping wholly truncated? */
752 if (mpnt
->vm_offset
>= offset
) {
753 flush_cache_range(mm
, start
, end
);
754 zap_page_range(mm
, start
, len
);
755 flush_tlb_range(mm
, start
, end
);
758 /* mapping wholly unaffected? */
759 diff
= offset
- mpnt
->vm_offset
;
762 /* Ok, partially affected.. */
764 len
= (len
- diff
) & PAGE_MASK
;
765 if (start
& ~PAGE_MASK
) {
766 partial_clear(mpnt
, start
);
767 start
= (start
+ ~PAGE_MASK
) & PAGE_MASK
;
769 flush_cache_range(mm
, start
, end
);
770 zap_page_range(mm
, start
, len
);
771 flush_tlb_range(mm
, start
, end
);
772 } while ((mpnt
= mpnt
->vm_next_share
) != NULL
);
777 * This is called with the kernel lock held, we need
778 * to return without it.
780 static int do_swap_page(struct task_struct
* tsk
,
781 struct vm_area_struct
* vma
, unsigned long address
,
782 pte_t
* page_table
, pte_t entry
, int write_access
)
784 if (!vma
->vm_ops
|| !vma
->vm_ops
->swapin
) {
785 swap_in(tsk
, vma
, page_table
, pte_val(entry
), write_access
);
786 flush_page_to_ram(pte_page(*page_table
));
788 pte_t page
= vma
->vm_ops
->swapin(vma
, address
- vma
->vm_start
+ vma
->vm_offset
, pte_val(entry
));
789 if (pte_val(*page_table
) != pte_val(entry
)) {
790 free_page(pte_page(page
));
792 if (atomic_read(&mem_map
[MAP_NR(pte_page(page
))].count
) > 1 &&
793 !(vma
->vm_flags
& VM_SHARED
))
794 page
= pte_wrprotect(page
);
797 flush_page_to_ram(pte_page(page
));
798 set_pte(page_table
, page
);
806 * This only needs the MM semaphore
808 static int do_anonymous_page(struct task_struct
* tsk
, struct vm_area_struct
* vma
, pte_t
*page_table
, int write_access
)
810 pte_t entry
= pte_wrprotect(mk_pte(ZERO_PAGE
, vma
->vm_page_prot
));
812 unsigned long page
= __get_free_page(GFP_USER
);
816 entry
= pte_mkwrite(pte_mkdirty(mk_pte(page
, vma
->vm_page_prot
)));
819 flush_page_to_ram(page
);
821 put_page(page_table
, entry
);
826 * do_no_page() tries to create a new page mapping. It aggressively
827 * tries to share with existing pages, but makes a separate copy if
828 * the "write_access" parameter is true in order to avoid the next
831 * As this is called only for pages that do not currently exist, we
832 * do not need to flush old virtual caches or the TLB.
834 * This is called with the MM semaphore and the kernel lock held.
835 * We need to release the kernel lock as soon as possible..
837 static int do_no_page(struct task_struct
* tsk
, struct vm_area_struct
* vma
,
838 unsigned long address
, int write_access
, pte_t
*page_table
)
843 if (!vma
->vm_ops
|| !vma
->vm_ops
->nopage
) {
845 return do_anonymous_page(tsk
, vma
, page_table
, write_access
);
849 * The third argument is "no_share", which tells the low-level code
850 * to copy, not share the page even if sharing is possible. It's
851 * essentially an early COW detection.
853 page
= vma
->vm_ops
->nopage(vma
, address
& PAGE_MASK
,
854 (vma
->vm_flags
& VM_SHARED
)?0:write_access
);
863 * This silly early PAGE_DIRTY setting removes a race
864 * due to the bad i386 page protection. But it's valid
865 * for other architectures too.
867 * Note that if write_access is true, we either now have
868 * an exclusive copy of the page, or this is a shared mapping,
869 * so we can make it writable and dirty to avoid having to
872 flush_page_to_ram(page
);
873 entry
= mk_pte(page
, vma
->vm_page_prot
);
875 entry
= pte_mkwrite(pte_mkdirty(entry
));
876 } else if (atomic_read(&mem_map
[MAP_NR(page
)].count
) > 1 &&
877 !(vma
->vm_flags
& VM_SHARED
))
878 entry
= pte_wrprotect(entry
);
879 put_page(page_table
, entry
);
880 /* no need to invalidate: a not-present page shouldn't be cached */
885 * These routines also need to handle stuff like marking pages dirty
886 * and/or accessed for architectures that don't do it in hardware (most
887 * RISC architectures). The early dirtying is also good on the i386.
889 * There is also a hook called "update_mmu_cache()" that architectures
890 * with external mmu caches can use to update those (ie the Sparc or
891 * PowerPC hashed page tables that act as extended TLBs).
893 static inline int handle_pte_fault(struct task_struct
*tsk
,
894 struct vm_area_struct
* vma
, unsigned long address
,
895 int write_access
, pte_t
* pte
)
902 if (!pte_present(entry
)) {
904 return do_no_page(tsk
, vma
, address
, write_access
, pte
);
905 return do_swap_page(tsk
, vma
, address
, pte
, entry
, write_access
);
908 entry
= pte_mkyoung(entry
);
910 flush_tlb_page(vma
, address
);
912 if (!pte_write(entry
))
913 return do_wp_page(tsk
, vma
, address
, pte
);
915 entry
= pte_mkdirty(entry
);
917 flush_tlb_page(vma
, address
);
924 * By the time we get here, we already hold the mm semaphore
926 int handle_mm_fault(struct task_struct
*tsk
, struct vm_area_struct
* vma
,
927 unsigned long address
, int write_access
)
932 pgd
= pgd_offset(vma
->vm_mm
, address
);
933 pmd
= pmd_alloc(pgd
, address
);
935 pte_t
* pte
= pte_alloc(pmd
, address
);
937 if (handle_pte_fault(tsk
, vma
, address
, write_access
, pte
)) {
938 update_mmu_cache(vma
, address
, *pte
);
947 * Simplistic page force-in..
949 void make_pages_present(unsigned long addr
, unsigned long end
)
952 struct vm_area_struct
* vma
;
954 vma
= find_vma(current
->mm
, addr
);
955 write
= (vma
->vm_flags
& VM_WRITE
) != 0;
957 handle_mm_fault(current
, vma
, addr
, write
);