fsnotify: fix sb_connectors leak

Fix a leak in s_fsnotify_connectors counter in case of a race between
concurrent add of new fsnotify mark to an object.

The task that lost the race fails to drop the counter before freeing
the unused connector.

Following umount() hangs in fsnotify_sb_delete()/wait_var_event(),
because s_fsnotify_connectors never drops to zero.

Fixes: ec44610fe2 ("fsnotify: count all objects with attached connectors")
Reported-by: Murphy Zhou <jencce.kernel@gmail.com>
Link: https://lore.kernel.org/linux-fsdevel/20210907063338.ycaw6wvhzrfsfdlp@xzhoux.usersys.redhat.com/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Amir Goldstein 2021-09-09 14:56:34 +03:00 committed by Linus Torvalds
parent bf9f243f23
commit 4396a73115

View File

@ -531,6 +531,7 @@ static int fsnotify_attach_connector_to_object(fsnotify_connp_t *connp,
/* Someone else created list structure for us */
if (inode)
fsnotify_put_inode_ref(inode);
fsnotify_put_sb_connectors(conn);
kmem_cache_free(fsnotify_mark_connector_cachep, conn);
}