From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794426993; b=TRXDGd84ZtrjQzfltf1c3HCuZZT+HWRvXwerkCNzMIKhK5SFuHFaefMwUlJ5UvZ1S3pj l4nlZDl5Xht+M28kNvJYk+RdOs0xRxqDC5VHhlepYEG2yA4G2l2q/KYHjN3EIbixPG7+L VL34HnE6MU7lYRcgpr52KZ7gAc/buE2LIA8iNTGHdGXFDbvfh2TPcQ0UvY4wvFbP75sNn b4uAxlF56IMDDZGNTtg2HUtxIxHZeSxHhHnAlK4sVPwsSklC7JuhVUZEnGpfl7Q14rlrb tm4A4XgKyVJXdfiqc83SLy6EYKSKTmuZqNR1r8fIpN5xfeK++Co2SLkSxj/Hzt73IHA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794426993; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=yjWrPc+ppfsKBYDCt8Z9w/1rLGeHPWTkfaCA8ci4MQ0=; b=0nB28u8G6USXjG3fjEbyE8oVeJkcLn76S8IdTf+pfgz3TPVTp1ewfTNhBDMQERGYRPAx LWq+0O06/8+tPf+IcVn6pjRUPZfHrReCEc7Z78rs92hI+zq3DiB4TB+5oRoyFksLRp3sH R9Gjv155V8nzRhSAGuOSE6lq+iOZKYcP5ld8BeTn4rYLYiFkdBiAsS5w0c/zqz3zHk/ZA Mbcbqm2rIJ1Ho+A3Mqnid4sqqsW1UuSMGi6awW8BEtmjd8LAv1iF4bFs+HFbanGCW539B ESNKXJX1PgYSCStACLUR1cQgQFhGOhww6v6FfClBJv6Bz61T9WqxT5CmXmUNSvTi/YQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=gb9Tvmnz; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 62F87606A326 for ; Wed, 11 Nov 2026 19:56:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=gb9Tvmnz Received: by smtp.kernel.org (Postfix) with ESMTPSA id 59A691F00A07; Wed, 11 Nov 2026 19:56:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794426993; bh=yjWrPc+ppfsKBYDCt8Z9w/1rLGeHPWTkfaCA8ci4MQ0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=gb9Tvmnzprz4iRLtdlm2oKB1Hm7aN+C3JTf5xQPOHvI4KTtv8NQMLsiMUbnr+BeA+ xctKIQEZ27PE2+xka19PqKxja3FeWwhel6IkBewVo4TxujROSJ9CS5X1zH2V5JwlYY w2mTDNEOe5t6T+hdAW4wnPjRksZRngQOC/Pvs+/vZhgn78tj6BClj44Na8EqPbnGGO DuPmxKc4cuv6cxarea8WLbMU/gZdgdDv00rcWuLxpJ2xay0nOIar4kITGvRNZE6Nuv 17NJR6gFCi91p1cYRsucQN7LmAaUwUQEphOLE+GmafylzKf8cIh0tsTZTyj8hnjw10 nY8hKvEijfuZQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Rik van Riel , Michal Hocko , Shakeel Butt , Andrew Morton , Johannes Weiner , Muchun Song , Roman Gushchin , Sasha Levin Subject: [PATCH 6.6.y] mm/memcontrol: fix stuck FLUSHING_CACHED_CHARGE bit on isolated cpus Date: Wed, 11 Nov 2026 14:56:31 -0500 Message-ID: <20261111195600.4028594-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107053203-failed-6.6-d2f28a1a652e@kernel.org> References: <20261107053203-failed-6.6-d2f28a1a652e@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Rik van Riel [ Upstream commit d2f28a1a652e0a43f6f63de9b4e4d8d5f2716803 ] When drain_all_stock() sets FLUSHING_CACHED_CHARGE before checking isolation, schedule_drain_work() can drop the work in a separate RCU critical section, and housekeeping_update()'s synchronize_rcu() can race that second check, leaving the flag set. drain_local_stock() only clears the bit for work that ran, so the flag remains set and the stock is never drained again. Have schedule_drain_work() return whether the work was queued, and clear FLUSHING_CACHED_CHARGE in drain_all_stock() when the remote CPU is isolated, so future drains can retry. Link: https://lore.kernel.org/20260828135036.7d44361f@fangorn Fixes: 6a792697a53a ("memcg: do not drain charge pcp caches on remote isolated cpus") Suggested-by: Michal Hocko Suggested-by: Shakeel Butt Signed-off-by: Rik van Riel Signed-off-by: Andrew Morton Acked-by: Shakeel Butt Acked-by: Michal Hocko Cc: Johannes Weiner Cc: Muchun Song Cc: Roman Gushchin Cc: [ sashal: adapted schedule_drain_work() return handling to a direct flag clear in the existing single-stock isolation branch ] Signed-off-by: Sasha Levin --- mm/memcontrol.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 852fa93efe1be..d31ceaeb13b05 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2396,6 +2396,8 @@ static void drain_all_stock(struct mem_cgroup *root_memcg) drain_local_stock(&stock->work); else if (!cpu_is_isolated(cpu)) schedule_work_on(cpu, &stock->work); + else + clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); } } migrate_enable(); -- 2.53.0