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authorHugh Dickins <hugh@veritas.com>2007-01-29 16:24:08 -0500
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-01-30 11:33:32 -0500
commit701dfbc1cbdd42b814dd76a885c4b73f97011d08 (patch)
tree4a8e8185616e7cc9c115de564bd2c6d626662217
parent8339f0008c47cdd921c73f6d53d5588b5484f93c (diff)
[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.h10
-rw-r--r--mm/filemap_xip.c4
-rw-r--r--mm/mremap.c1
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;
69#define ZERO_PAGE(vaddr) \ 69#define ZERO_PAGE(vaddr) \
70 (virt_to_page((void *)(empty_zero_page + (((unsigned long)(vaddr)) & zero_page_mask)))) 70 (virt_to_page((void *)(empty_zero_page + (((unsigned long)(vaddr)) & zero_page_mask))))
71 71
72#define __HAVE_ARCH_MOVE_PTE
73#define move_pte(pte, prot, old_addr, new_addr) \
74({ \
75 pte_t newpte = (pte); \
76 if (pte_present(pte) && pfn_valid(pte_pfn(pte)) && \
77 pte_page(pte) == ZERO_PAGE(old_addr)) \
78 newpte = mk_pte(ZERO_PAGE(new_addr), (prot)); \
79 newpte; \
80})
81
82extern void paging_init(void); 72extern void paging_init(void);
83 73
84/* 74/*
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,
183 address = vma->vm_start + 183 address = vma->vm_start +
184 ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); 184 ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
185 BUG_ON(address < vma->vm_start || address >= vma->vm_end); 185 BUG_ON(address < vma->vm_start || address >= vma->vm_end);
186 page = ZERO_PAGE(address); 186 page = ZERO_PAGE(0);
187 pte = page_check_address(page, mm, address, &ptl); 187 pte = page_check_address(page, mm, address, &ptl);
188 if (pte) { 188 if (pte) {
189 /* Nuke the page table entry. */ 189 /* Nuke the page table entry. */
@@ -246,7 +246,7 @@ xip_file_nopage(struct vm_area_struct * area,
246 __xip_unmap(mapping, pgoff); 246 __xip_unmap(mapping, pgoff);
247 } else { 247 } else {
248 /* not shared and writable, use ZERO_PAGE() */ 248 /* not shared and writable, use ZERO_PAGE() */
249 page = ZERO_PAGE(address); 249 page = ZERO_PAGE(0);
250 } 250 }
251 251
252out: 252out:
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,
105 if (pte_none(*old_pte)) 105 if (pte_none(*old_pte))
106 continue; 106 continue;
107 pte = ptep_clear_flush(vma, old_addr, old_pte); 107 pte = ptep_clear_flush(vma, old_addr, old_pte);
108 /* ZERO_PAGE can be dependant on virtual addr */
109 pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr); 108 pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
110 set_pte_at(mm, new_addr, new_pte, pte); 109 set_pte_at(mm, new_addr, new_pte, pte);
111 } 110 }