rmap: anon_vma_prepare() can leak anon_vma_chain
authorOleg Nesterov <oleg@redhat.com>
Fri, 23 Apr 2010 17:18:01 +0000 (13:18 -0400)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sat, 24 Apr 2010 18:31:25 +0000 (11:31 -0700)
commit31f2b0ebc01fd332cb0997f7ce9f9cde29af9e20
treefc9d4cb410052afcc56bb8442a2dbcb8950464a8
parent93b4a44f3ad69520d605aace3f3486b8eb754b96
rmap: anon_vma_prepare() can leak anon_vma_chain

If find_mergeable_anon_vma() succeeds but another thread installs
->anon_vma before we take ptl, then allocated == NULL but avc should be
freed.  Change the code to check avc != NULL to detect this case.

Also, a couple of whitespace changes to make the critical section more
visible.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Pete Zaitcev <zaitcev@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/rmap.c