From nobody Thu Apr 2 00:15:03 2026 Received: from out-172.mta0.migadu.com (out-172.mta0.migadu.com [91.218.175.172]) (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 DF5643947BC for ; Thu, 5 Mar 2026 11:56:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772711784; cv=none; b=gnT7cS1z5e5k/YtEDXOQEpp5MzEc3qSaYWyWCdkZOJCwRCdJvbXs3cjTWYczQIyJC4XeZt+ZDtvVpkeEE+Aow1sqEJ8/PbrpOjuIKZsExupJf4HDbmjGh1T2qV9OC8NeGVEL2LVJrvm6PSKWCgtmHQuCV5TCvcEGSR4ab0i7Gbw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772711784; c=relaxed/simple; bh=jnH4Rpx9d7OsmMtOIIwLWbBWcTx9HUujpy4PZ4gm5HQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aePpJENhvMmyuCPXZcGIvbvZc/ha39lPDixqcPJWCbXDiZPyjeIYRfNyElFnF28k33C6S4xeJKlGChry0H+zMRHlHUJFPKeorfj1cQYrqrMKWJ+QrEkEf6k1T5coa1WCRYNAh1L66mmmDlg0olMWG4renv/PaDdsb5N/kSOnnXA= 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=FxYOARU5; arc=none smtp.client-ip=91.218.175.172 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="FxYOARU5" 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=1772711780; 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=8hyqbb8F2NRNHHFp77Ms/+jViunOCmw3TEFzht4PTD4=; b=FxYOARU5x0g+Zna+Ay1ysDbQ1ntMsGhY8lLL89aloYuqaM4oNBrujP2pa/q0wx6LwQTaci fEFYT5Sp4lq00AepmhrB0Hut0n4GXtU8qSaP1MKimCke1uJOslo9LqbnfjQJFz5e6dfAeb K7bYbN5wfpK5v5eB3OUoXcoLkaNQKDE= 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, usamaarif642@gmail.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: [PATCH v6 13/33] mm: migrate: prevent memory cgroup release in folio_migrate_mapping() Date: Thu, 5 Mar 2026 19:52:31 +0800 Message-ID: <0f156c2f1188f256855617953f8305f43e066065.1772711148.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 6cc654858da65..27e6103037c29 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