+ mm-list_lruc-revert-mm-list_lru-optimize-memcg_reparent_list_lru_node.patch added to -mm tree

+ mm-list_lruc-revert-mm-list_lru-optimize-memcg_reparent_list_lru_node.patch added to -mm tree

[Andrew Morton]

The patch titled
     Subject: mm/list_lru.c: revert "mm/list_lru: optimize memcg_reparent_list_lru_node()"
has been added to the -mm tree.  Its filename is
     mm-list_lruc-revert-mm-list_lru-optimize-memcg_reparent_list_lru_node.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-list_lruc-revert-mm-list_lru-optimize-memcg_reparent_list_lru_node.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-list_lruc-revert-mm-list_lru-optimize-memcg_reparent_list_lru_node.patch

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------------------------------------------------------
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()")
Cc: Waiman Long <longman@redhat.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeelb@google.com>
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.
 	 */
_

Patches currently in -mm which might be from akpm@linux-foundation.org are

mm-list_lruc-revert-mm-list_lru-optimize-memcg_reparent_list_lru_node.patch
mm.patch
mm-shmem-make-shmem_init-return-void-fix.patch
ksm-count-ksm-merging-pages-for-each-process-fix.patch
mm-memory_hotplug-refactor-hotadd_init_pgdat-and-try_online_node-checkpatch-fixes.patch
proc-fix-dentry-inode-overinstantiating-under-proc-pid-net-checkpatch-fixes.patch
fs-proc-kcorec-remove-check-of-list-iterator-against-head-past-the-loop-body-fix.patch
add-fat-messages-to-printk-index-checkpatch-fixes.patch
linux-next-rejects.patch
linux-next-git-rejects.patch
mm-oom_killc-fix-vm_oom_kill_table-ifdeffery.patch
b.patch