From aa9bca05a467c61dcea4142b2877d5392de5bdce Mon Sep 17 00:00:00 2001 From: Weijie Yang Date: Wed, 16 Oct 2013 13:46:54 -0700 Subject: [PATCH] mm/zswap: bugfix: memory leak when re-swapon zswap_tree is not freed when swapoff, and it got re-kmalloced in swapon, so a memory leak occurs. Free the memory of zswap_tree in zswap_frontswap_invalidate_area(). Signed-off-by: Weijie Yang Reviewed-by: Bob Liu Cc: Minchan Kim Reviewed-by: Minchan Kim Cc: From: Weijie Yang Subject: 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. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Weijie Yang Reviewed-by: Bob Liu Cc: Minchan Kim Cc: Acked-by: Seth Jennings Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/zswap.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/zswap.c b/mm/zswap.c index 841e35f1db22..d93510c6aa2d 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -804,6 +804,10 @@ static void zswap_frontswap_invalidate_area(unsigned type) } tree->rbroot = RB_ROOT; spin_unlock(&tree->lock); + + zbud_destroy_pool(tree->pool); + kfree(tree); + zswap_trees[type] = NULL; } static struct zbud_ops zswap_zbud_ops = {