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 E0717EFD204 for ; Wed, 25 Feb 2026 07:51:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4CA866B00A3; Wed, 25 Feb 2026 02:51:00 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 46B196B00A4; Wed, 25 Feb 2026 02:51:00 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3AAD76B00A5; Wed, 25 Feb 2026 02:51:00 -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 2735C6B00A3 for ; Wed, 25 Feb 2026 02:51:00 -0500 (EST) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id DFE4D16046A for ; Wed, 25 Feb 2026 07:50:59 +0000 (UTC) X-FDA: 84482207838.03.4637933 Received: from out-180.mta0.migadu.com (out-180.mta0.migadu.com [91.218.175.180]) by imf27.hostedemail.com (Postfix) with ESMTP id 26AB14000B for ; Wed, 25 Feb 2026 07:50:57 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=kSEBfFCo; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf27.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.180 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1772005858; a=rsa-sha256; cv=none; b=BNNvKiF7N5jdMCdoeTJIuoaLysztLKVd1fVLGeTKumn9HKygmuPTOHT/IfEwUbtzBTpj5X tkwKKcScUB1Ef6v28LpJSE2U09AdB0HGDlydIynb/RnjLlSynitSmurA8plCiRDEu/+Dvv fHTVf6DTktp+FZEaA7N1ejNoeyt6L7o= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=kSEBfFCo; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf27.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.180 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1772005858; 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=KC9muunDdo7KZdUVJjB4BFdSDYI642do47nscVtU+7t3t/ygGPKth8Z6NwKpW7TMVWQX4V AA2AGdcp2BUIKT5bEcEVCiRuKkw+rJ/SRyqIeFTUKASbgyDjbXBdLaN8Ux9EAkS21jy7Aj SjqMnwik8O320g3zdEzH9IyMHwBFZG4= 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=1772005856; 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=kSEBfFCoTY6CSo+CQsjXZoqRgLSgNwJWY78h9wNrmHKn6b/6//0bFsi9oatIQPlm7vnmuw WwZHqyJ2P+yL9L2FU4sopSApUmXQa5/JAYLF+u1OP9VMyfvoyy1MFfFq3fDOdFft5D3F5j 8d2j7c0gJTd7CDPUvCebJDj4XiKh1Gs= 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 v5 09/32] buffer: prevent memory cgroup release in folio_alloc_buffers() Date: Wed, 25 Feb 2026 15:48:42 +0800 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 26AB14000B X-Stat-Signature: 7pyj7gie6a5nhq4i383ksuhogfe88xrh X-HE-Tag: 1772005857-98792 X-HE-Meta: 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 jF7jLwXU udktgHeBncXbe/bujtF4OYE9VNQBEZCBkYPYvt4khs/2UFbo0BZtYyGiR2KkcFKKvxcHyGJUsoB4Yvq1hNolUlZYyOKg7IuwJeAHK0PSY9BDDWlH+YwcjeCKsHUtfWs43msAa8Y6o1dXnP4yc979jDdYvEDQOP4AIyCMIatNizL/fHo40931iiO7u+dlDhv/pHJTNHILG7fisVqGRcreArW/+az9cm8m+Lr2mGPZqKbjo9vlMvZk6M9W5BOxIOejSS+lKcBKjuMx6S1nKUFwBIoDnYAmVHFniqdMlgZ7ghBtZzLSxxYkWvgPkWOOLvHh2qa2G 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