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| author | Hugh Dickins <hugh@veritas.com> | 2007-01-29 21:24:08 +0000 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-01-30 08:33:32 -0800 |
| commit | 701dfbc1cbdd42b814dd76a885c4b73f97011d08 (patch) | |
| tree | 4a8e8185616e7cc9c115de564bd2c6d626662217 | |
| parent | 8339f0008c47cdd921c73f6d53d5588b5484f93c (diff) | |
| download | lwn-701dfbc1cbdd42b814dd76a885c4b73f97011d08.tar.gz lwn-701dfbc1cbdd42b814dd76a885c4b73f97011d08.zip | |
[PATCH] mm: mremap correct rmap accounting
Nick Piggin points out that page accounting on MIPS multiple ZERO_PAGEs
is not maintained by its move_pte, and could lead to freeing a ZERO_PAGE.
Instead of complicating that move_pte, just forget the minor optimization
when mremapping, and change the one thing which needed it for correctness
- filemap_xip use ZERO_PAGE(0) throughout instead of according to address.
[ "There is no block device driver one could use for XIP on mips
platforms" - Carsten Otte ]
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Andrew Morton <akpm@osdl.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | include/asm-mips/pgtable.h | 10 | ||||
| -rw-r--r-- | mm/filemap_xip.c | 4 | ||||
| -rw-r--r-- | mm/mremap.c | 1 |
3 files changed, 2 insertions, 13 deletions
diff --git a/include/asm-mips/pgtable.h b/include/asm-mips/pgtable.h index f2e1325fec6c..3fcfd7979de5 100644 --- a/include/asm-mips/pgtable.h +++ b/include/asm-mips/pgtable.h @@ -69,16 +69,6 @@ extern unsigned long zero_page_mask; #define ZERO_PAGE(vaddr) \ (virt_to_page((void *)(empty_zero_page + (((unsigned long)(vaddr)) & zero_page_mask)))) -#define __HAVE_ARCH_MOVE_PTE -#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; \ -}) - extern void paging_init(void); /* diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c index 45b3553865cf..9dd9fbb75139 100644 --- a/mm/filemap_xip.c +++ b/mm/filemap_xip.c @@ -183,7 +183,7 @@ __xip_unmap (struct address_space * mapping, address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); BUG_ON(address < vma->vm_start || address >= vma->vm_end); - page = ZERO_PAGE(address); + page = ZERO_PAGE(0); pte = page_check_address(page, mm, address, &ptl); if (pte) { /* Nuke the page table entry. */ @@ -246,7 +246,7 @@ xip_file_nopage(struct vm_area_struct * area, __xip_unmap(mapping, pgoff); } else { /* not shared and writable, use ZERO_PAGE() */ - page = ZERO_PAGE(address); + page = ZERO_PAGE(0); } out: diff --git a/mm/mremap.c b/mm/mremap.c index 9c769fa29f32..5d4bd4f95b8e 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -105,7 +105,6 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, if (pte_none(*old_pte)) continue; pte = ptep_clear_flush(vma, old_addr, old_pte); - /* ZERO_PAGE can be dependant on virtual addr */ pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr); set_pte_at(mm, new_addr, new_pte, pte); } |