From nobody Fri Dec 19 17:39:36 2025 Received: from out-183.mta0.migadu.com (out-183.mta0.migadu.com [91.218.175.183]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7542833D4EB; Wed, 17 Dec 2025 07:32:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.183 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765956773; cv=none; b=CUqu+i8QYxNQLSQizMgCnL8c1OdDMUg3fYqd4mxxb6p8gWHdHUVs+PCQgZe8ljjtKkQ+CoiW9H5pzl1Ad5zOXlVMGvJTWabPvDNECYhC1OXrhtkuqEtjbk6ldhwoINjCmNLA3hZKCZ6tjFvSLFP6zc2v7yHWNX+evmrDnMv0r0A= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765956773; c=relaxed/simple; bh=ansN195gKGsOuB8x9C0oB4o91QVBkG5P7dmvk9I+fIg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iVRcyLPUK5xEXXHfk0qOPtGw6YW6eEpK4887TamTtqjD1JbIeyrPQjPlH+lAGuBv0Htv0zrrTFzyV1OEzhldZBE2chPG8Q3VpNXP2/2uKjFnn0HiHu+oK7K0H5YevwodOgBMk5wwOdVG7U/2u6EtP4c0bAS8v2iTM/JE7H28xRA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=utjimqar; arc=none smtp.client-ip=91.218.175.183 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="utjimqar" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1765956765; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=r7R2YsecSy/bMyWfSR2fXTDFkSfi8ZmuktkAOmJUkaM=; b=utjimqarpJXzPTVvhid+eE3cwOsJ/hVXX6Fz447+S0Nrj5Mhr4vYtYMabOisntRkuyl9gg MQYGXnv6tjh2xy/Ve9Lmnbfr5XyjYeZXIoIuOKmxsE5zZxZmcG1tdfavDUQWt8ksYgQ4hQ Asqcc8Q9449fvBZaJ9EYLaptzYLE8rs= From: Qi Zheng To: hannes@cmpxchg.org, hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, david@kernel.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, harry.yoo@oracle.com, imran.f.khan@oracle.com, kamalesh.babulal@oracle.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, chenridong@huaweicloud.com, mkoutny@suse.com, akpm@linux-foundation.org, hamzamahfooz@linux.microsoft.com, apais@linux.microsoft.com, lance.yang@linux.dev Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: [PATCH v2 19/28] mm: workingset: prevent lruvec release in workingset_refault() Date: Wed, 17 Dec 2025 15:27:43 +0800 Message-ID: <1b6ad26b5199b8134de37506b669ad4e3c0b6356.1765956026.git.zhengqi.arch@bytedance.com> In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" From: Muchun Song In the near future, a folio will no longer pin its corresponding memory cgroup. So an lruvec returned by folio_lruvec() could be released without the rcu read lock or a reference to its memory cgroup. In the current patch, the rcu read lock is employed to safeguard against the release of the lruvec in workingset_refault(). This serves as a preparatory measure for the reparenting of the LRU pages. Signed-off-by: Muchun Song Signed-off-by: Qi Zheng Reviewed-by: Harry Yoo --- mm/workingset.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/workingset.c b/mm/workingset.c index 445fc634196d8..427ca1a5625e8 100644 --- a/mm/workingset.c +++ b/mm/workingset.c @@ -560,11 +560,12 @@ void workingset_refault(struct folio *folio, void *sh= adow) * locked to guarantee folio_memcg() stability throughout. */ nr =3D folio_nr_pages(folio); + rcu_read_lock(); lruvec =3D folio_lruvec(folio); mod_lruvec_state(lruvec, WORKINGSET_REFAULT_BASE + file, nr); =20 if (!workingset_test_recent(shadow, file, &workingset, true)) - return; + goto out; =20 folio_set_active(folio); workingset_age_nonresident(lruvec, nr); @@ -580,6 +581,8 @@ void workingset_refault(struct folio *folio, void *shad= ow) lru_note_cost_refault(folio); mod_lruvec_state(lruvec, WORKINGSET_RESTORE_BASE + file, nr); } +out: + rcu_read_unlock(); } =20 /** --=20 2.20.1