diff options
author | Hugh Dickins <hugh@veritas.com> | 2005-10-29 18:16:27 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-10-29 21:40:40 -0700 |
commit | 705e87c0c3c38424f7f30556c85bc20e808d2f59 (patch) | |
tree | 7a237e6266f4801385e1226cc497b47e3a2458bd /mm/msync.c | |
parent | 8f4e2101fd7df9031a754eedb82e2060b51f8c45 (diff) | |
download | kernel_samsung_smdk4412-705e87c0c3c38424f7f30556c85bc20e808d2f59.zip kernel_samsung_smdk4412-705e87c0c3c38424f7f30556c85bc20e808d2f59.tar.gz kernel_samsung_smdk4412-705e87c0c3c38424f7f30556c85bc20e808d2f59.tar.bz2 |
[PATCH] mm: pte_offset_map_lock loops
Convert those common loops using page_table_lock on the outside and
pte_offset_map within to use just pte_offset_map_lock within instead.
These all hold mmap_sem (some exclusively, some not), so at no level can a
page table be whipped away from beneath them. But whereas pte_alloc loops
tested with the "atomic" pmd_present, these loops are testing with pmd_none,
which on i386 PAE tests both lower and upper halves.
That's now unsafe, so add a cast into pmd_none to test only the vital lower
half: we lose a little sensitivity to a corrupt middle directory, but not
enough to worry about. It appears that i386 and UML were the only
architectures vulnerable in this way, and pgd and pud no problem.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/msync.c')
-rw-r--r-- | mm/msync.c | 21 |
1 files changed, 6 insertions, 15 deletions
@@ -17,28 +17,22 @@ #include <asm/pgtable.h> #include <asm/tlbflush.h> -/* - * Called with mm->page_table_lock held to protect against other - * threads/the swapper from ripping pte's out from under us. - */ - static void msync_pte_range(struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, unsigned long end) { - struct mm_struct *mm = vma->vm_mm; pte_t *pte; + spinlock_t *ptl; int progress = 0; again: - pte = pte_offset_map(pmd, addr); + pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); do { unsigned long pfn; struct page *page; if (progress >= 64) { progress = 0; - if (need_resched() || - need_lockbreak(&mm->page_table_lock)) + if (need_resched() || need_lockbreak(ptl)) break; } progress++; @@ -58,8 +52,8 @@ again: set_page_dirty(page); progress += 3; } while (pte++, addr += PAGE_SIZE, addr != end); - pte_unmap(pte - 1); - cond_resched_lock(&mm->page_table_lock); + pte_unmap_unlock(pte - 1, ptl); + cond_resched(); if (addr != end) goto again; } @@ -97,7 +91,6 @@ static inline void msync_pud_range(struct vm_area_struct *vma, pgd_t *pgd, static void msync_page_range(struct vm_area_struct *vma, unsigned long addr, unsigned long end) { - struct mm_struct *mm = vma->vm_mm; pgd_t *pgd; unsigned long next; @@ -110,16 +103,14 @@ static void msync_page_range(struct vm_area_struct *vma, return; BUG_ON(addr >= end); - pgd = pgd_offset(mm, addr); + pgd = pgd_offset(vma->vm_mm, addr); flush_cache_range(vma, addr, end); - spin_lock(&mm->page_table_lock); do { next = pgd_addr_end(addr, end); if (pgd_none_or_clear_bad(pgd)) continue; msync_pud_range(vma, pgd, addr, next); } while (pgd++, addr = next, addr != end); - spin_unlock(&mm->page_table_lock); } /* |