[PATCH] devpts: plug the memory leak in kill_sb

[Ilija Hadzic <ihadzic@research.bell-labs.com>]

When devpts is unmounted, there may be a no-longer-used
IDR tree hanging off the superblock we are about to kill.
This needs to be cleaned up before destroying the SB.

The leak is usually not a big deal because unmounting
devpts is typically done when shutting down the whole
machine. However, shutting down an LXC container instead
of a physical machine exposes the problem (the garbage is
detectable with kmemleak).

Signed-off-by: Ilija Hadzic <ihadzic@research.bell-labs.com>
Cc: stable@vger.kernel.org
---
 fs/devpts/inode.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index 073d30b..a726b9f 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -498,6 +498,7 @@ static void devpts_kill_sb(struct super_block *sb)
 {
 	struct pts_fs_info *fsi = DEVPTS_SB(sb);
 
+	ida_destroy(&fsi->allocated_ptys);
 	kfree(fsi);
 	kill_litter_super(sb);
 }
-- 
1.8.2.1