From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 819EEF30951 for ; Thu, 5 Mar 2026 11:55:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EF6996B00A3; Thu, 5 Mar 2026 06:55:42 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EE7806B00A5; Thu, 5 Mar 2026 06:55:42 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DE42F6B00A6; Thu, 5 Mar 2026 06:55:42 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id CB96E6B00A3 for ; Thu, 5 Mar 2026 06:55:42 -0500 (EST) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 8360B1CE1A for ; Thu, 5 Mar 2026 11:55:42 +0000 (UTC) X-FDA: 84511854924.06.988B82C Received: from out-170.mta0.migadu.com (out-170.mta0.migadu.com [91.218.175.170]) by imf15.hostedemail.com (Postfix) with ESMTP id C55DEA0011 for ; Thu, 5 Mar 2026 11:55:40 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=VoyQbhDY; spf=pass (imf15.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.170 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1772711740; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=/198v9MPJs+KJCrWZ0LWBhkz6feBqnUHTx73TsS3q/w=; b=TMpr8+KEmszMEwhRqgsayUgslrENslCTXQD2TzUo8nqI9GqpH/IGx9atHFI9tUdRJ5c4v8 IEu9yVlffvfqU40ttf8cUIORJnWxRTolaHh46HJ87WQENLMDVCB3RBPc8CXjg0gfd+MCcp VLyZZmdRR753ezh6ca9PSst0LrNA7II= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=VoyQbhDY; spf=pass (imf15.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.170 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1772711741; a=rsa-sha256; cv=none; b=WG6YtSXSTy7aUOLi0VhbYhEBBz0XAt6ur7mZGuAwPR4fLEpU5uixtYQ+nvRVSvH9Qj7J0y i6qZMlDrHTn2dNDUbQZGNqxVgmTpx4QboNo1sLARoQf2wr7Qt9YoE0WRtXtarPs0csyLKe U/CyNn+dx2974jJste95eNejbTYEoVU= 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=1772711739; 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=/198v9MPJs+KJCrWZ0LWBhkz6feBqnUHTx73TsS3q/w=; b=VoyQbhDY1PB+RM6iyqZa3x0Jh2dPgk7SFfWgibufrQHOlTEslOuFJAu9GjifThbapQVtua GxytC/w0MWXOIowX12iVAw+ZNgiQLCSKsK/Hzk8l0BRxSt7qQuQ4Vtv/zD4rGjWM/S56PU xD1eYLKZAhEzrdgXKBHIOReFT3GAaA8= 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 09/33] buffer: prevent memory cgroup release in folio_alloc_buffers() Date: Thu, 5 Mar 2026 19:52:27 +0800 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: C55DEA0011 X-Rspamd-Server: rspam07 X-Stat-Signature: aujd3j6zrhjhgy7ebh9od95b58gf6mn3 X-Rspam-User: X-HE-Tag: 1772711740-873195 X-HE-Meta: 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 iA6Uq5Nq Eap6u31xyL34+QutmcNAwclMtgH0Ne7XiN0UpdwMhIoCKnZM7pFcHHhQBcYY/hjB30e9B9RXohZBGEGcZREQWFyTHT/ldXlrPljn0Ofvu0XQ84EI3jkFbKwF/wc7FWhVJndmymVG8za92VbDjnZALwjo7rLR/ON2oPACz0s3HNkwSbTjYMoG1Q3cJqDHKcD+TFZM+fr31EujWfeB4Z/DMczv+OH+9li6Edl42SUd5t69HR8fTAyVDz0IXAtkN+n3+aMGpI0O4hb+JBE9b4i0ntLMPeecFOZYmzvb3cIsfgJ1rdJocU/yiPQFx5+Kffp2ga0Dm Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 the current patch, the function get_mem_cgroup_from_folio() is employed to safeguard against the release of the memory cgroup. 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 --- fs/buffer.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/buffer.c b/fs/buffer.c index 22b43642ba574..343c97eab9e57 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -922,8 +922,7 @@ struct buffer_head *folio_alloc_buffers(struct folio *folio, unsigned long size, long offset; struct mem_cgroup *memcg, *old_memcg; - /* The folio lock pins the memcg */ - memcg = folio_memcg(folio); + memcg = get_mem_cgroup_from_folio(folio); old_memcg = set_active_memcg(memcg); head = NULL; @@ -944,6 +943,7 @@ struct buffer_head *folio_alloc_buffers(struct folio *folio, unsigned long size, } out: set_active_memcg(old_memcg); + mem_cgroup_put(memcg); return head; /* * In case anything failed, we just free everything we got. -- 2.20.1