list_lru: organize all list_lrus to list
To make list_lru memcg aware, we need all list_lrus to be kept on a list
protected by a mutex, so that we could sleep while walking over the
list.
Therefore after this change list_lru_destroy may sleep. Fortunately,
there is only one user that calls it from an atomic context - it's
put_super - and we can easily fix it by calling list_lru_destroy before
put_super in destroy_locked_super - anyway we don't longer need lrus by
that time.
Another point that should be noted is that list_lru_destroy is allowed
to be called on an uninitialized zeroed-out object, in which case it is
a no-op. Before this patch this was guaranteed by kfree, but now we
need an explicit check there.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/super.c b/fs/super.c
index a2b735a..b027849 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -282,6 +282,14 @@
unregister_shrinker(&s->s_shrink);
fs->kill_sb(s);
+ /*
+ * Since list_lru_destroy() may sleep, we cannot call it from
+ * put_super(), where we hold the sb_lock. Therefore we destroy
+ * the lru lists right now.
+ */
+ list_lru_destroy(&s->s_dentry_lru);
+ list_lru_destroy(&s->s_inode_lru);
+
put_filesystem(fs);
put_super(s);
} else {
