From: Weijie Yang Date: Tue, 12 Nov 2013 23:08:26 +0000 (-0800) Subject: mm/zswap: bugfix: memory leak when invalidate and reclaim occur concurrently X-Git-Tag: v3.13-rc1~106^2~187 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=67d13fe846c57a54d12578e7a4518f68c5c86ad7;p=pandora-kernel.git mm/zswap: bugfix: memory leak when invalidate and reclaim occur concurrently Consider the following scenario: thread 0: reclaim entry x (get refcount, but not call zswap_get_swap_cache_page) thread 1: call zswap_frontswap_invalidate_page to invalidate entry x. finished, entry x and its zbud is not freed as its refcount != 0 now, the swap_map[x] = 0 thread 0: now call zswap_get_swap_cache_page swapcache_prepare return -ENOENT because entry x is not used any more zswap_get_swap_cache_page return ZSWAP_SWAPCACHE_NOMEM zswap_writeback_entry do nothing except put refcount Now, the memory of zswap_entry x and its zpage leak. Modify: - check the refcount in fail path, free memory if it is not referenced. - use ZSWAP_SWAPCACHE_FAIL instead of ZSWAP_SWAPCACHE_NOMEM as the fail path can be not only caused by nomem but also by invalidate. Signed-off-by: Weijie Yang Reviewed-by: Bob Liu Reviewed-by: Minchan Kim Acked-by: Seth Jennings Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed