From: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Subject: mm: vmscan: protect shrinker idr replace with CONFIG_MEMCG
Since commit 0a432dcbeb32edc ("mm: shrinker: make shrinker not depend on
memcg kmem"), shrinkers' idr is protected by CONFIG_MEMCG instead of
CONFIG_MEMCG_KMEM, so it makes no sense to protect shrinker idr replace
with CONFIG_MEMCG_KMEM.
And in the CONFIG_MEMCG && CONFIG_SLOB case, shrinker_idr contains only
shrinker, and it is deferred_split_shrinker. But it is never actually
called, since idr_replace() is never compiled due to the wrong #ifdef.
The deferred_split_shrinker all the time is staying in half-registered
state, and it's never called for subordinate mem cgroups.
Link: http://lkml.kernel.org/r/1575486978-45249-1-git-send-email-yang.shi@xxxxxxxxxxxxxxxxx
Fixes: 0a432dcbeb32 ("mm: shrinker: make shrinker not depend on memcg kmem")
Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Reviewed-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Roman Gushchin <guro@xxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [5.4+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/vmscan.c~mm-vmscan-protect-shrinker-idr-replace-with-config_memcg
+++ a/mm/vmscan.c
@@ -387,7 +387,7 @@ void register_shrinker_prepared(struct s
{
down_write(&shrinker_rwsem);
list_add_tail(&shrinker->list, &shrinker_list);
-#ifdef CONFIG_MEMCG_KMEM
+#ifdef CONFIG_MEMCG
if (shrinker->flags & SHRINKER_MEMCG_AWARE)
idr_replace(&shrinker_idr, shrinker, shrinker->id);
#endif
_
