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authorHugh Dickins <hugh@veritas.com>2005-10-29 18:16:27 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-10-29 21:40:40 -0700
commit705e87c0c3c38424f7f30556c85bc20e808d2f59 (patch)
tree7a237e6266f4801385e1226cc497b47e3a2458bd /mm/msync.c
parent8f4e2101fd7df9031a754eedb82e2060b51f8c45 (diff)
downloadlinux-sh-705e87c0c3c38424f7f30556c85bc20e808d2f59.tar.gz
[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.c21
1 files changed, 6 insertions, 15 deletions
diff --git a/mm/msync.c b/mm/msync.c
index 860395486060..0e040e9c39d8 100644
--- a/mm/msync.c
+++ b/mm/msync.c
@@ -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);
}
/*