From nobody Fri Dec 19 20:54:54 2025 Received: from out-181.mta0.migadu.com (out-181.mta0.migadu.com [91.218.175.181]) (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 688F533E376 for ; Wed, 17 Dec 2025 07:33:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.181 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765956786; cv=none; b=GUoPysBpcsJ80gj7VdeINHNV8HpYcVqdBXq6f/33cHnHlNFysOT8Nd10MyaPTxbxFdt9mWdb7Ni8C3n7Y3w5bt/p+bJh4HS/dkzh39d6SOvsp4Asmt/WORg9vXBDYXHPUDMoqQefbrGyhluyjNK6frOpYwDiz2QW6llu++FKyM8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765956786; c=relaxed/simple; bh=V2QjUp/J2A3sgD5j0GufhNzAkOwa8ipgKv/DGTi1o4s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sOc8CSZHqsKS4gbAk0V23b7xRGJ6T6U9Fgx7n8OTp5Dgg7OeqSgYLkJq3Hw0bjFZOeNPydFS0Cp2y2rfxV1rOmo+MODMC6OzspshcLh1InRng7oT9GDt/43Xh+kkxMmW52Ami3fqAql53fNMhZiKoYnln1imsdr554QqwYfN4dk= 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=qss7+xs4; arc=none smtp.client-ip=91.218.175.181 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="qss7+xs4" 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=1765956778; 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=3hCVtkwWInjeWp1lZK86oR9Lr8eWsGStrPfk/NkSL0k=; b=qss7+xs4+fcC/k4TRH856pLkCsZ3zf6NmhCCKBEDP94wPzgJX5Se5bzxYs1nQvCcPAFf1H IUyFBywc0v7UZh6JX+MCryCQnvJm9NcBRnkhxr55rLWMPZBrpBYI7A4pbR3nSLhuCbDRTI 7cQwLAFU/zWeAVJrioGetOwSuqdGWIE= 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 , Nhat Pham , Chengming Zhou , Qi Zheng Subject: [PATCH v2 20/28] mm: zswap: prevent lruvec release in zswap_folio_swapin() Date: Wed, 17 Dec 2025 15:27:44 +0800 Message-ID: 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 zswap_folio_swapin(). This serves as a preparatory measure for the reparenting of the LRU pages. Signed-off-by: Muchun Song Acked-by: Nhat Pham Reviewed-by: Chengming Zhou Signed-off-by: Qi Zheng Reviewed-by: Harry Yoo Acked-by: Johannes Weiner --- mm/zswap.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/zswap.c b/mm/zswap.c index b468046a90754..738d914e53549 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -664,8 +664,10 @@ void zswap_folio_swapin(struct folio *folio) struct lruvec *lruvec; =20 if (folio) { + rcu_read_lock(); lruvec =3D folio_lruvec(folio); atomic_long_inc(&lruvec->zswap_lruvec_state.nr_disk_swapins); + rcu_read_unlock(); } } =20 --=20 2.20.1