From: Weijie Yang <weijie.yang@xxxxxxxxxxx>
Subject: 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 <weijie.yang@xxxxxxxxxxx>
Reviewed-by: Bob Liu <bob.liu@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Reviewed-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
From: Weijie Yang <weijie.yang@xxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxxx: coding-style fixes]
Signed-off-by: Weijie Yang <weijie.yang@xxxxxxxxxxx>
Reviewed-by: Bob Liu <bob.liu@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Acked-by: Seth Jennings <sjenning@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/zswap.c | 4 ++++
1 file changed, 4 insertions(+)
diff -puN mm/zswap.c~mm-zswap-bugfix-memory-leak-when-re-swapon mm/zswap.c
--- a/mm/zswap.c~mm-zswap-bugfix-memory-leak-when-re-swapon
+++ a/mm/zswap.c
@@ -804,6 +804,10 @@ static void zswap_frontswap_invalidate_a
}
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 = {
_
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html