path: root/mm/ksm.c
diff options
authorAndrea Arcangeli <aarcange@redhat.com>2010-09-09 16:37:52 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-09-09 18:57:24 -0700
commit4969c1192d15afa3389e7ae3302096ff684ba655 (patch)
treeabe560c8f293191be65488c49f4db3f3a626e63c /mm/ksm.c
parentdrivers/mmc/host/imxmmc.c: adjust confusing if indentation (diff)
mm: fix swapin race condition
The pte_same check is reliable only if the swap entry remains pinned (by the page lock on swapcache). We've also to ensure the swapcache isn't removed before we take the lock as try_to_free_swap won't care about the page pin. One of the possible impacts of this patch is that a KSM-shared page can point to the anon_vma of another process, which could exit before the page is freed. This can leave a page with a pointer to a recycled anon_vma object, or worse, a pointer to something that is no longer an anon_vma. [riel@redhat.com: changelog help] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Hugh Dickins <hughd@google.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
1 files changed, 0 insertions, 3 deletions
diff --git a/mm/ksm.c b/mm/ksm.c
index e2ae00458320..b1873cf03ed9 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1504,8 +1504,6 @@ struct page *ksm_does_need_to_copy(struct page *page,
struct page *new_page;
- unlock_page(page); /* any racers will COW it, not modify it */
new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
if (new_page) {
copy_user_highpage(new_page, page, address, vma);
@@ -1521,7 +1519,6 @@ struct page *ksm_does_need_to_copy(struct page *page,
- page_cache_release(page);
return new_page;