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mm/list_lru.c: revert "mm/list_lru: optimize memcg_reparent_list_lru_node()" 

Commit 405cc51fc1 ("mm/list_lru: optimize memcg_reparent_list_lru_node()")
has subtle races which are proving ugly to fix.  Revert the original
optimization.  If quantitative testing indicates that we have a
significant problem here then other implementations can be looked at.

Fixes: 405cc51fc1 ("mm/list_lru: optimize memcg_reparent_list_lru_node()")
Acked-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrew Morton 2022-04-08 13:09:13 -07:00 committed by Linus Torvalds
parent 0347b2b95c
commit b33e104447
1 changed files with 0 additions and 6 deletions
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6
mm/list_lru.c
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@ -394,12 +394,6 @@ static void memcg_reparent_list_lru_node(struct list_lru *lru, int nid,
int dst_idx = dst_memcg->kmemcg_id; int dst_idx = dst_memcg->kmemcg_id;
struct list_lru_one *src, *dst; struct list_lru_one *src, *dst;
/*
* If there is no lru entry in this nlru, we can skip it immediately.
*/
if (!READ_ONCE(nlru->nr_items))
return;
/* /*
* Since list_lru_{add,del} may be called under an IRQ-safe lock, * Since list_lru_{add,del} may be called under an IRQ-safe lock,
* we have to use IRQ-safe primitives here to avoid deadlock. * we have to use IRQ-safe primitives here to avoid deadlock.