aboutsummaryrefslogtreecommitdiffstats
path: root/mm/hugetlb.c
diff options
context:
space:
mode:
authorMel Gorman <mel@csn.ul.ie>2009-12-14 20:59:53 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-15 11:53:23 -0500
commit4eb2b1dcd598f8489130405c81c60c289896d92a (patch)
tree87bf0dec35f55688595447de65eb95952eb3dabc /mm/hugetlb.c
parent70da2340fbc68e91e701762f785479ab495a0869 (diff)
hugetlb: acquire the i_mmap_lock before walking the prio_tree to unmap a page
When the owner of a mapping fails COW because a child process is holding a reference, the children VMAs are walked and the page is unmapped. The i_mmap_lock is taken for the unmapping of the page but not the walking of the prio_tree. In theory, that tree could be changing if the lock is not held. This patch takes the i_mmap_lock properly for the duration of the prio_tree walk. [hugh.dickins@tiscali.co.uk: Spotted the problem in the first place] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/hugetlb.c')
-rw-r--r--mm/hugetlb.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 2ef66a2a148..6df8065039e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2237,6 +2237,12 @@ static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
2237 + (vma->vm_pgoff >> PAGE_SHIFT); 2237 + (vma->vm_pgoff >> PAGE_SHIFT);
2238 mapping = (struct address_space *)page_private(page); 2238 mapping = (struct address_space *)page_private(page);
2239 2239
2240 /*
2241 * Take the mapping lock for the duration of the table walk. As
2242 * this mapping should be shared between all the VMAs,
2243 * __unmap_hugepage_range() is called as the lock is already held
2244 */
2245 spin_lock(&mapping->i_mmap_lock);
2240 vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) { 2246 vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
2241 /* Do not unmap the current VMA */ 2247 /* Do not unmap the current VMA */
2242 if (iter_vma == vma) 2248 if (iter_vma == vma)
@@ -2250,10 +2256,11 @@ static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
2250 * from the time of fork. This would look like data corruption 2256 * from the time of fork. This would look like data corruption
2251 */ 2257 */
2252 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER)) 2258 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
2253 unmap_hugepage_range(iter_vma, 2259 __unmap_hugepage_range(iter_vma,
2254 address, address + huge_page_size(h), 2260 address, address + huge_page_size(h),
2255 page); 2261 page);
2256 } 2262 }
2263 spin_unlock(&mapping->i_mmap_lock);
2257 2264
2258 return 1; 2265 return 1;
2259} 2266}