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 BF993D64085 for ; Wed, 17 Dec 2025 07:30:39 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 30FDC6B009E; Wed, 17 Dec 2025 02:30:39 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2F0E26B009F; Wed, 17 Dec 2025 02:30:39 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 224156B00A0; Wed, 17 Dec 2025 02:30:39 -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 0FFAF6B009E for ; Wed, 17 Dec 2025 02:30:39 -0500 (EST) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id CBBA15B893 for ; Wed, 17 Dec 2025 07:30:38 +0000 (UTC) X-FDA: 84228140556.30.1852DC4 Received: from out-184.mta0.migadu.com (out-184.mta0.migadu.com [91.218.175.184]) by imf15.hostedemail.com (Postfix) with ESMTP id 12CBEA000C for ; Wed, 17 Dec 2025 07:30:36 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=BKBDmMTT; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf15.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.184 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1765956637; a=rsa-sha256; cv=none; b=n3lZCjjaI0feyIz46FfQdkuF5Oa8qE71FmajC0rFLH3vHya3/cw6yrrLOey+bYEzv7HR/D VA1Jm0W0zjo2CEsy4gkMMqSXoN6ezGDh914JlI5VhXzsnoA4IF8n1tLNeApWVsdEvzYrB5 YUtH1E2QVuZzjKmu6qHy3LVGMBHR3x0= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=BKBDmMTT; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf15.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.184 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=1765956637; 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=TRju/G2AicNAtYXExappHAHtEmzxl9wl3ybhh14XiuA=; b=ZVPR32eyK8h1tmvuIuPSZznPi3JoDnPicMIDF0RxSBBit9lL1a4+9LFy/XoItqtOxgHnea QTqO0YbCJrPBUMda/5zQZVJapvGjRuETwi85b7grb1Sft7QBUUTEzovwi6A42w42addV52 8622vBZBsYtnp5aErNFzc0OYu9sddvs= 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=1765956630; 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=TRju/G2AicNAtYXExappHAHtEmzxl9wl3ybhh14XiuA=; b=BKBDmMTTYzW8+KMzw0Cb3xu5yMNfhSfyczOl2Mv78ulFxvyEK/rvQ2MT6DdrmHYG8sBJ4f 0ubQx0rUizrQc/VOotOqMHlErCaCFTLP7UWSLt0s/+GV3xQMxDZwaPZ74xKb/hK4pj6g8l moKY4bPgdI/MUiDypKfWktPBmaozvTU= 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, 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 v2 09/28] buffer: prevent memory cgroup release in folio_alloc_buffers() Date: Wed, 17 Dec 2025 15:27:33 +0800 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 12CBEA000C X-Rspamd-Server: rspam03 X-Stat-Signature: 6h7s8umn6ocshkb6t5ih6pb43zbagb1q X-Rspam-User: X-HE-Tag: 1765956636-37669 X-HE-Meta: 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 U86icHlG nPc5NhLDnI0MsxU4ncIgf4bFU2AI76/cDvMGF64EwIQAEenf2Ow1WEM+Vb7XLwnnxnfnMVzpZugrX3Less8P7OF+pUa9Jkmzm2An7po1FEbWeVRJ8T3am73zVrKG9MRcWMhdoQypQdC/F6EWmGTjDX9VBa0Uaw1404n2i/OefCAdx5ORwpgQ6jMio2/RV92jsg3wyY5daWPkWV53Rqc3ka8MVtSKxDszc5iSF8a+qoVDs+S1iYgF4GbUi18IPDmfaj5ww X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 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 --- fs/buffer.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/buffer.c b/fs/buffer.c index fd53b806ab7eb..4552d9cab0dbd 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -925,8 +925,7 @@ 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; @@ -947,6 +946,7 @@ 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