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authorChristoph Lameter <clameter@engr.sgi.com>2006-02-28 16:59:16 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-02-28 20:53:44 -0800
commite8788c0cce63e0cc8689a123d1ce0af1e28cd583 (patch)
tree9350d9fc11a5a6ca81d4ee063278999e4dfe869d /mm
parent6af6aab34a88050c8270ef75ddbdefef5c1dca00 (diff)
downloadlwn-e8788c0cce63e0cc8689a123d1ce0af1e28cd583.tar.gz
lwn-e8788c0cce63e0cc8689a123d1ce0af1e28cd583.zip
[PATCH] remove_from_swap: fix locking
remove_from_swap() currently attempts to use page_lock_anon_vma to obtain an anon_vma lock. That is not working since the page may have been remapped via swap ptes in order to move the page. However, do_migrate_pages() obtain the mmap_sem lock and therefore there is a guarantee that the anonymous vma will not vanish from under us. There is therefore no need to use page_lock_anon_vma. Signed-off-by: Christoph Lameter <clameter@sgi.com> Acked-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')
-rw-r--r--mm/rmap.c18
1 files changed, 13 insertions, 5 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index df2c41c2a9a2..d8ce5ff61454 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -212,25 +212,33 @@ out:
* through real pte's pointing to valid pages and then releasing
* the page from the swap cache.
*
- * Must hold page lock on page.
+ * Must hold page lock on page and mmap_sem of one vma that contains
+ * the page.
*/
void remove_from_swap(struct page *page)
{
struct anon_vma *anon_vma;
struct vm_area_struct *vma;
+ unsigned long mapping;
- if (!PageAnon(page) || !PageSwapCache(page))
+ if (!PageSwapCache(page))
return;
- anon_vma = page_lock_anon_vma(page);
- if (!anon_vma)
+ mapping = (unsigned long)page->mapping;
+
+ if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0)
return;
+ /*
+ * We hold the mmap_sem lock. So no need to call page_lock_anon_vma.
+ */
+ anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON);
+ spin_lock(&anon_vma->lock);
+
list_for_each_entry(vma, &anon_vma->head, anon_vma_node)
remove_vma_swap(vma, page);
spin_unlock(&anon_vma->lock);
-
delete_from_swap_cache(page);
}
EXPORT_SYMBOL(remove_from_swap);