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From: Andrew Morton <akpm@linux-foundation.org>
To: songmuchun@bytedance.com,shakeelb@google.com,roman.gushchin@linux.dev,mhocko@suse.com,longman@redhat.com,hannes@cmpxchg.org,akpm@linux-foundation.org,patches@lists.linux.dev,linux-mm@kvack.org,mm-commits@vger.kernel.org,torvalds@linux-foundation.org,akpm@linux-foundation.org
Subject: [patch 8/9] mm/list_lru.c: revert "mm/list_lru: optimize memcg_reparent_list_lru_node()"
Date: Fri, 08 Apr 2022 13:09:13 -0700	[thread overview]
Message-ID: <20220408200914.7C6C3C385A3@smtp.kernel.org> (raw)
In-Reply-To: <20220408130819.a89195e527ce58dfbe0700b9@linux-foundation.org>

From: Andrew Morton <akpm@linux-foundation.org>
Subject: mm/list_lru.c: revert "mm/list_lru: optimize memcg_reparent_list_lru_node()"

405cc51fc1049c73 ("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: 405cc51fc1049c73 ("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>
---

 mm/list_lru.c |    6 ------
 1 file changed, 6 deletions(-)

--- a/mm/list_lru.c~mm-list_lruc-revert-mm-list_lru-optimize-memcg_reparent_list_lru_node
+++ a/mm/list_lru.c
@@ -395,12 +395,6 @@ static void memcg_reparent_list_lru_node
 	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,
 	 * we have to use IRQ-safe primitives here to avoid deadlock.
 	 */
_

WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: songmuchun@bytedance.com, shakeelb@google.com,
	roman.gushchin@linux.dev, mhocko@suse.com, longman@redhat.com,
	hannes@cmpxchg.org, akpm@linux-foundation.org,
	patches@lists.linux.dev, linux-mm@kvack.org,
	mm-commits@vger.kernel.org, torvalds@linux-foundation.org,
	akpm@linux-foundation.org
Subject: [patch 8/9] mm/list_lru.c: revert "mm/list_lru: optimize memcg_reparent_list_lru_node()"
Date: Fri, 08 Apr 2022 13:09:13 -0700	[thread overview]
Message-ID: <20220408200914.7C6C3C385A3@smtp.kernel.org> (raw)
In-Reply-To: <20220408130819.a89195e527ce58dfbe0700b9@linux-foundation.org>

From: Andrew Morton <akpm@linux-foundation.org>
Subject: mm/list_lru.c: revert "mm/list_lru: optimize memcg_reparent_list_lru_node()"

405cc51fc1049c73 ("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: 405cc51fc1049c73 ("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>
---

 mm/list_lru.c |    6 ------
 1 file changed, 6 deletions(-)

--- a/mm/list_lru.c~mm-list_lruc-revert-mm-list_lru-optimize-memcg_reparent_list_lru_node
+++ a/mm/list_lru.c
@@ -395,12 +395,6 @@ static void memcg_reparent_list_lru_node
 	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,
 	 * we have to use IRQ-safe primitives here to avoid deadlock.
 	 */
_

  parent reply	other threads:[~2022-04-08 20:09 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-08 20:08 incoming Andrew Morton
2022-04-08 20:08 ` [patch 1/9] mm: migrate: use thp_order instead of HPAGE_PMD_ORDER for new page allocation Andrew Morton
2022-04-08 20:08   ` Andrew Morton
2022-04-08 20:10   ` Matthew Wilcox
2022-04-08 20:08 ` [patch 2/9] highmem: fix checks in __kmap_local_sched_{in,out} Andrew Morton
2022-04-08 20:08   ` Andrew Morton
2022-04-08 20:08 ` [patch 3/9] lz4: fix LZ4_decompress_safe_partial read out of bound Andrew Morton
2022-04-08 20:08   ` Andrew Morton
2022-04-08 20:09 ` [patch 4/9] mm/sparsemem: fix 'mem_section' will never be NULL gcc 12 warning Andrew Morton
2022-04-08 20:09   ` Andrew Morton
2022-04-11  9:00   ` Oscar Salvador
2022-04-08 20:09 ` [patch 5/9] mmmremap.c: avoid pointless invalidate_range_start/end on mremap(old_size=0) Andrew Morton
2022-04-08 20:09   ` Andrew Morton
2022-04-08 20:09 ` [patch 6/9] mm/mempolicy: fix mpol_new leak in shared_policy_replace Andrew Morton
2022-04-08 20:09   ` Andrew Morton
2022-04-08 20:09 ` [patch 7/9] mailmap: update Vasily Averin's email address Andrew Morton
2022-04-08 20:09   ` Andrew Morton
2022-04-08 20:09 ` Andrew Morton [this message]
2022-04-08 20:09   ` [patch 8/9] mm/list_lru.c: revert "mm/list_lru: optimize memcg_reparent_list_lru_node()" Andrew Morton
2022-04-08 20:09 ` [patch 9/9] MAINTAINERS: add Tom as clang reviewer Andrew Morton
2022-04-08 20:09   ` Andrew Morton

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