From 8b1f3124618b54cf125dea3a074b9cf469117723 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Tue, 27 Sep 2005 21:45:18 -0700 Subject: [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 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 Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-generic/pgtable.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'include/asm-generic') 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 -- cgit v1.2.3-70-g09d2