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 <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Greg Thelen <[email protected]>
Cc: Glauber Costa <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Tejun Heo <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h
index 53c1d6b78270..ee9486ac0621 100644
--- a/include/linux/list_lru.h
+++ b/include/linux/list_lru.h
@@ -31,6 +31,9 @@ struct list_lru_node {
 
 struct list_lru {
 	struct list_lru_node	*node;
+#ifdef CONFIG_MEMCG_KMEM
+	struct list_head	list;
+#endif
 };
 
 void list_lru_destroy(struct list_lru *lru);