From nobody Tue Feb 10 02:43:32 2026 Received: from out-180.mta0.migadu.com (out-180.mta0.migadu.com [91.218.175.180]) (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 C6F17395D9C for ; Wed, 14 Jan 2026 11:34:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.180 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768390450; cv=none; b=URXfLT1xkbbLUZg0/O7poB8wqOVhPv7JQ3AUMeDxjUO3uHfYg+V25DiS7/nEMIC6JKK8o42Fod3ec4kw4INuYRvSQMIunBhTHC4m1TL9C01ezRMo7VAlGquxzed7WYsi6WjagjzobERz4hcmDNRr7nIMc21bEdDilzsfT3Q3P9A= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768390450; c=relaxed/simple; bh=fii8P6n9zfdAnG0LmjBLziDV1WKRvVaIXpeZMkRmqmQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=K33xm9b/NoCfxpnsPtFnTjArqaq7MYzTzkf2afmbgm5mef1S0cS6krA5Ie4SJ/uoZtttOavIdXU2Wvw0GMkYdivwxQ3NIcoyvRBKvq5O57O5Zq8/r/V1EpD4hOPFAc+agIygC37DnnKtInf2Jf4w5XSmn7LTfvR4jlG/CzD9j1E= 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=YoU4Iky8; arc=none smtp.client-ip=91.218.175.180 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="YoU4Iky8" 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=1768390446; 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=642wzt5sbJwBZzq4cokZbiQed5LcU+/gP3D7+Nkqfps=; b=YoU4Iky8HLVffHiXRoGwvgVGzlVPeumBdrWGgRX3FHJHeSUAOcRyplIqVBvX9ZV4PECp/m wVNVWs204n5weRpItm0WRWIOH/sVQ0v44YN9b6egvXft4ZURKshYA+NNhwh95UbPIEutz7 4pgDms5mDpXAR/EA0KbeGFqdVrblkV4= 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 Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: [PATCH v3 13/30] mm: migrate: prevent memory cgroup release in folio_migrate_mapping() Date: Wed, 14 Jan 2026 19:32:40 +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. 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 4688b9e38cd2f..1aec3f5509538 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -671,6 +671,7 @@ 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); @@ -698,6 +699,7 @@ 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