From e13f634f50d5f3bf0f49c7e915cc31019b58297b Mon Sep 17 00:00:00 2001
From: Jiayuan Chen <jiayuan.chen@shopee.com>
Date: Thu, 2 Jul 2026 20:02:28 +0800
Subject: [PATCH] memcg: bail out memory.max when memcg is dying

memory.max has the same high-latency reclaim loop as memory.high, and may
additionally invoke the OOM killer on a cgroup that is already going away,
further delaying its removal.

Mitigate this by bailing out of the loop once memcg_is_dying().

Link: https://lore.kernel.org/20260702120235.376752-3-jiayuan.chen@linux.dev
Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com>
Reported-by: Zhou Yingfu <yingfu.zhou@shopee.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jiayuan Chen <jiayuan.chen@linux.dev>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/memcontrol.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8ca42e79686c..22f55aeb94f3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4854,6 +4854,10 @@ static ssize_t memory_max_write(struct kernfs_open_file *of,
 		if (signal_pending(current))
 			break;
 
+		/* cgroup_rmdir() waits for us with cgroup_mutex held. */
+		if (memcg_is_dying(memcg))
+			break;
+
 		if (!drained) {
 			drain_all_stock(memcg);
 			drained = true;