diff options
| author | Nick Piggin <nickpiggin@yahoo.com.au> | 2005-09-27 21:45:18 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-09-28 07:46:40 -0700 |
| commit | 8b1f3124618b54cf125dea3a074b9cf469117723 (patch) | |
| tree | 19ef8a7fe9cc5b1c46dc973ea151edab4aba2b8a | |
| parent | 95001ee9256df846e374f116c92ca8e0beec1527 (diff) | |
[PATCH] mm: move_pte to remap ZERO_PAGE
Move the ZERO_PAGE remapping complexity to the move_pte macro in
asm-generic, have it conditionally depend on
__HAVE_ARCH_MULTIPLE_ZERO_PAGE, which gets defined for MIPS.
For architectures without __HAVE_ARCH_MULTIPLE_ZERO_PAGE, move_pte becomes
a noop.
From: Hugh Dickins <hugh@veritas.com>
Fix nasty little bug we've missed in Nick's mremap move ZERO_PAGE patch.
The "pte" at that point may be a swap entry or a pte_file entry: we must
check pte_present before perhaps corrupting such an entry.
Patch below against 2.6.14-rc2-mm1, but the same bug is in 2.6.14-rc2's
mm/mremap.c, and more dangerous there since it's affecting all arches: I
think the safest course is to send Nick's patch and Yoichi's build fix and
this fix (build tested) on to Linus - so only MIPS can be affected.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | include/asm-generic/pgtable.h | 13 | ||||
| -rw-r--r-- | include/asm-mips/pgtable.h | 2 | ||||
| -rw-r--r-- | mm/mremap.c | 6 |
3 files changed, 18 insertions, 3 deletions
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index f86c1e54946..ff28c8b31f5 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -158,6 +158,19 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres #define lazy_mmu_prot_update(pte) do { } while (0) #endif +#ifndef __HAVE_ARCH_MULTIPLE_ZERO_PAGE +#define move_pte(pte, prot, old_addr, new_addr) (pte) +#else +#define move_pte(pte, prot, old_addr, new_addr) \ +({ \ + pte_t newpte = (pte); \ + if (pte_present(pte) && pfn_valid(pte_pfn(pte)) && \ + pte_page(pte) == ZERO_PAGE(old_addr)) \ + newpte = mk_pte(ZERO_PAGE(new_addr), (prot)); \ + newpte; \ +}) +#endif + /* * When walking page tables, get the address of the next boundary, * or the end address of the range if that comes earlier. Although no diff --git a/include/asm-mips/pgtable.h b/include/asm-mips/pgtable.h index cbd1672c94c..eaf5d9b3a0e 100644 --- a/include/asm-mips/pgtable.h +++ b/include/asm-mips/pgtable.h @@ -68,6 +68,8 @@ extern unsigned long zero_page_mask; #define ZERO_PAGE(vaddr) \ (virt_to_page(empty_zero_page + (((unsigned long)(vaddr)) & zero_page_mask))) +#define __HAVE_ARCH_MULTIPLE_ZERO_PAGE + extern void paging_init(void); /* diff --git a/mm/mremap.c b/mm/mremap.c index a32fed454bd..f343fc73a8b 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -141,10 +141,10 @@ move_one_page(struct vm_area_struct *vma, unsigned long old_addr, if (dst) { pte_t pte; pte = ptep_clear_flush(vma, old_addr, src); + /* ZERO_PAGE can be dependant on virtual addr */ - if (pfn_valid(pte_pfn(pte)) && - pte_page(pte) == ZERO_PAGE(old_addr)) - pte = pte_wrprotect(mk_pte(ZERO_PAGE(new_addr), new_vma->vm_page_prot)); + pte = move_pte(pte, new_vma->vm_page_prot, + old_addr, new_addr); set_pte_at(mm, new_addr, dst, pte); } else error = -ENOMEM; |