+ memcg-oom-simplify-mem_cgroup_oom_synchronize.patch added to mm-unstable branch

+ memcg-oom-simplify-mem_cgroup_oom_synchronize.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: memcg, oom: simplify mem_cgroup_oom_synchronize
has been added to the -mm mm-unstable branch.  Its filename is
     memcg-oom-simplify-mem_cgroup_oom_synchronize.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/memcg-oom-simplify-mem_cgroup_oom_synchronize.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Haifeng Xu <haifeng.xu@shopee.com>
Subject: memcg, oom: simplify mem_cgroup_oom_synchronize
Date: Fri, 7 Apr 2023 09:06:44 +0000

Since commit 29ef680ae7c2 ("memcg, oom: move out_of_memory back to the
charge path"), only oom_kill_disable is set, oom killer will be delayed to
page fault path.  So the oom_kill_disable check is unnecessary.

In the charge patch, even if the oom_lock in memcg can't be acquired, the
oom handing can also be invoked.  In order to keep the behavior consistent
with it, remove the lock check.

Also the explicit wakeup for the lock holder is unneeded because the lock
contender won't be scheduled out.

Link: https://lkml.kernel.org/r/20230407090644.399108-1-haifeng.xu@shopee.com
Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com>
Suggested-by: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memcontrol.c |   22 ++++------------------
 1 file changed, 4 insertions(+), 18 deletions(-)

--- a/mm/memcontrol.c~memcg-oom-simplify-mem_cgroup_oom_synchronize
+++ a/mm/memcontrol.c
@@ -2027,26 +2027,12 @@ bool mem_cgroup_oom_synchronize(bool han
 	if (locked)
 		mem_cgroup_oom_notify(memcg);
 
-	if (locked && !READ_ONCE(memcg->oom_kill_disable)) {
-		mem_cgroup_unmark_under_oom(memcg);
-		finish_wait(&memcg_oom_waitq, &owait.wait);
-		mem_cgroup_out_of_memory(memcg, current->memcg_oom_gfp_mask,
-					 current->memcg_oom_order);
-	} else {
-		schedule();
-		mem_cgroup_unmark_under_oom(memcg);
-		finish_wait(&memcg_oom_waitq, &owait.wait);
-	}
+	schedule();
+	mem_cgroup_unmark_under_oom(memcg);
+	finish_wait(&memcg_oom_waitq, &owait.wait);
 
-	if (locked) {
+	if (locked)
 		mem_cgroup_oom_unlock(memcg);
-		/*
-		 * There is no guarantee that an OOM-lock contender
-		 * sees the wakeups triggered by the OOM kill
-		 * uncharges.  Wake any sleepers explicitly.
-		 */
-		memcg_oom_recover(memcg);
-	}
 cleanup:
 	current->memcg_in_oom = NULL;
 	css_put(&memcg->css);
_

Patches currently in -mm which might be from haifeng.xu@shopee.com are

cpuset-clean-up-cpuset_node_allowed.patch
memcg-oom-simplify-mem_cgroup_oom_synchronize.patch