From nobody Mon Feb 9 03:48:06 2026 Received: from out-174.mta1.migadu.com (out-174.mta1.migadu.com [95.215.58.174]) (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 C077936EA83 for ; Thu, 5 Feb 2026 09:02:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.174 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770282177; cv=none; b=lGI9QUmzWK6rEC7wZbHSKNTBnnp0faYP+TBFdLGd7g/9J3ba/h557SGuso/hTeR2FXvTz7qmI7wWizpaO+C4rKBIFiqUBV97dB7qhnlBQt9D9xpVQbntClCLUwZbyo38GcObbDi7eHwFhrs/iNOQoqe0t/BTl2T1EyUJ5qq5u98= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770282177; c=relaxed/simple; bh=sdbiiDWlwPwTxO+iS9bBtnS7KEtIQMdNhIjZr+nfeq0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=M7TS6PwvSUA0ENDR7QkdUdMGYaHTVW5UCUfPVnBa4AnnAGUtFXiRL8v4OHfkOmNDZjjRurGMNMEMDAKGD4ifwTxh1FMa2evY9xLI2JBJP+u61SNDLzQ/SAhYtxSrThAS7z8F2PABhhfDTXje/tBlB9B+7z15CYJor/GVNexgkag= 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=N1OtdHXU; arc=none smtp.client-ip=95.215.58.174 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="N1OtdHXU" 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=1770282175; 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=QAOP1V+p8DjZyPt8ukquYlqE0yR6eZreaGxjmoz7+YE=; b=N1OtdHXUihchpXMDHhkMzio44iCHxAJ/sdu5PAUUE4RMn3vsydl6nFRilXucTN4RWSP5wV 5hr1bW/nlblRcvODBSzsYaD9LZof+CH9WmtVPFwBlhQil8sxsyyDyU7+8ymQOqEF0Wpim9 VVLGOTTpest5FZFx6sSvie04tLkSvHM= 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, yosry.ahmed@linux.dev, 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, bhe@redhat.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: [PATCH v4 13/31] mm: migrate: prevent memory cgroup release in folio_migrate_mapping() Date: Thu, 5 Feb 2026 17:01:32 +0800 Message-ID: <4230a3381da7605324eef432c19e24eb6dd3c0fe.1770279888.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. To ensure safety, it will only be appropriate to hold the rcu read lock or acquire a reference to the memory cgroup returned by folio_memcg(), thereby preventing it from being released. In __folio_migrate_mapping(), the rcu read lock is employed to safeguard against the release of the memory cgroup in folio_migrate_mapping(). 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 Acked-by: Johannes Weiner Acked-by: Shakeel Butt --- mm/migrate.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/migrate.c b/mm/migrate.c index 1bf2cf8c44dd4..45ba49af2136c 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -672,6 +672,7 @@ static int __folio_migrate_mapping(struct address_space= *mapping, struct lruvec *old_lruvec, *new_lruvec; struct mem_cgroup *memcg; =20 + rcu_read_lock(); memcg =3D folio_memcg(folio); old_lruvec =3D mem_cgroup_lruvec(memcg, oldzone->zone_pgdat); new_lruvec =3D mem_cgroup_lruvec(memcg, newzone->zone_pgdat); @@ -699,6 +700,7 @@ static int __folio_migrate_mapping(struct address_space= *mapping, mod_lruvec_state(new_lruvec, NR_FILE_DIRTY, nr); __mod_zone_page_state(newzone, NR_ZONE_WRITE_PENDING, nr); } + rcu_read_unlock(); } local_irq_enable(); =20 --=20 2.20.1