Commit aa9bca05 authored by Weijie Yang's avatar Weijie Yang Committed by Linus Torvalds

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: default avatarWeijie Yang <weijie.yang@samsung.com>
Reviewed-by: default avatarBob Liu <bob.liu@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Reviewed-by: default avatarMinchan Kim <minchan@kernel.org>
Cc: <stable@vger.kernel.org>
From: Weijie Yang <weijie.yang@samsung.com>
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: default avatarWeijie Yang <weijie.yang@samsung.com>
Reviewed-by: default avatarBob Liu <bob.liu@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: <stable@vger.kernel.org>
Acked-by: default avatarSeth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e9cdd6e7
...@@ -804,6 +804,10 @@ static void zswap_frontswap_invalidate_area(unsigned type) ...@@ -804,6 +804,10 @@ static void zswap_frontswap_invalidate_area(unsigned type)
} }
tree->rbroot = RB_ROOT; tree->rbroot = RB_ROOT;
spin_unlock(&tree->lock); spin_unlock(&tree->lock);
zbud_destroy_pool(tree->pool);
kfree(tree);
zswap_trees[type] = NULL;
} }
static struct zbud_ops zswap_zbud_ops = { static struct zbud_ops zswap_zbud_ops = {
......
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