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 25AA4E91290 for ; Thu, 5 Feb 2026 09:02:22 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8B6066B0092; Thu, 5 Feb 2026 04:02:21 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 84B076B009B; Thu, 5 Feb 2026 04:02:21 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 786156B00A4; Thu, 5 Feb 2026 04:02:21 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 621A76B0092 for ; Thu, 5 Feb 2026 04:02:21 -0500 (EST) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 08E02C1C88 for ; Thu, 5 Feb 2026 09:02:21 +0000 (UTC) X-FDA: 84409811682.04.51152D9 Received: from out-170.mta1.migadu.com (out-170.mta1.migadu.com [95.215.58.170]) by imf21.hostedemail.com (Postfix) with ESMTP id 496A81C0004 for ; Thu, 5 Feb 2026 09:02:19 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Rub8sARC; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf21.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.170 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=1770282139; 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=z0u4X3qGXgYyNfrzLzU8BizQ+vhvSMeoi5s8ySDp/8o=; b=NIZIB8vQuWIt9sTNIDfVttovxIf7SIpAov3LQ29U/NJGHf4xLTeEqQhTU/N+jduFn9j0le 5tKraHxNwKlvJk76/sZFymPMPDrb+dJ0tVBR7uicIcLjSDcihr2YyURR6M00BKOdnewTga 6MHy1LPyvcar1jEgiv0m/COjDpyuIM4= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1770282139; a=rsa-sha256; cv=none; b=5e97SecxbTNoNKHJiO8Th+dUJsLElyN1128HzH3Sjo6zFCsPgtGi7scQGayskG9D+uT5JQ 6ILgdqsDgl3yAcC/l5iMbdwtF3VaWxEfXQp8Eul9cDF++UiyiBII3/SudQuRH0dw53MguF 0TkI+yy0StP7CLhTXquJgCga4+Z2AE8= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Rub8sARC; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf21.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.170 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev 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=1770282137; 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=z0u4X3qGXgYyNfrzLzU8BizQ+vhvSMeoi5s8ySDp/8o=; b=Rub8sARCWUqqz8QIAScGUeh64VvqACia5l5MPo9Zu8Clf00z7wJNF9NkdlvFCQxPeg1KjV 3OlN/oT7NUtlT0Nvv9dPHaB9RbwEpWbREDl3Vdn132CHhDA9TTY70o6MPC50P9xWmezg/p BpSvAxenj2HHM8+I+hvB473ZaCBAXCg= 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 Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: [PATCH v4 09/31] buffer: prevent memory cgroup release in folio_alloc_buffers() Date: Thu, 5 Feb 2026 17:01:28 +0800 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 496A81C0004 X-Stat-Signature: iou6z87khkisd3i683jbd8a1w53irbaw X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1770282139-636197 X-HE-Meta: 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 huQ/sxMN sPb0A5GBs+Hm0cymb5HL+ZEaN6PF15FJMQFIPhIBA7JJGE4M+16ytQBQ1CwhxINfOLgFvhKuwOM550FPiUV+Wt6Emw5FSuzXlPeZHn5XLHzVZaG30YklbLxdlBbe/q+bKlPH+SHimOEyo6DoZ93+PuXNC5lRqhqo+h572hEN3lXvEW88Xv3LIlBjFsXqWBVmH0DHY4Nk9HGnpaWVDsIX7k/G+Xwqr63dlBkhZwXsnLYMe+JAix01C5tJQ3QJy/ngAI4inesXSx1Hg9xl/zU7YvXl8BM7sVPckxED7x+2hVARfXdXkv3Ue2o6O/w== 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 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 b67791690ed33..d80b635cff162 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -926,8 +926,7 @@ 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; @@ -948,6 +947,7 @@ 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