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 4C5C2D29FEC for ; Wed, 14 Jan 2026 11:34:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B9CF06B0089; Wed, 14 Jan 2026 06:34:00 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B5D596B00A1; Wed, 14 Jan 2026 06:34:00 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A18DE6B00A3; Wed, 14 Jan 2026 06:34:00 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 937AF6B0089 for ; Wed, 14 Jan 2026 06:34:00 -0500 (EST) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 4126859001 for ; Wed, 14 Jan 2026 11:34:00 +0000 (UTC) X-FDA: 84330360240.23.780ADF9 Received: from out-181.mta0.migadu.com (out-181.mta0.migadu.com [91.218.175.181]) by imf24.hostedemail.com (Postfix) with ESMTP id A0D1A180007 for ; Wed, 14 Jan 2026 11:33:58 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=HmrG1zrR; spf=pass (imf24.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.181 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=1768390438; 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=s82tZFT3iNsr3WMx/4d8Ml9gjp1Ep9qgTy0gWjRVe+I=; b=uOpWcfGGgNyMlKDTLG5wyQoyxzKsCoK2UsI9vQyfb/r+uW+sQq7646MytPFvu3g8xs7co0 1lLqQ6HcVYKQ7blWpDpos8w7Yv1kYgkn0UHDbFmX0w6akdWWGA1gdOOMk3slMw/rMFxSt7 ElSMVAysVd9p3jqbitaNdaUlfoniNcU= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=HmrG1zrR; spf=pass (imf24.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.181 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=1768390438; a=rsa-sha256; cv=none; b=Oe6avez1ro4uLqxKyfdiMBt25GZDhSzdwn0Pxfgr103a9ZO37RkUYDvx7A7RZ/wMv+wzO5 7jB7vsST5cPSQbJEGbR30V3hujn1M/Srwgf4Sx8eZysw2zNu+3ixd5IgHFyeKJg0UazjYQ u5PMb530GJASYdV9yq2X+dMRemh09/c= 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=1768390436; 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=s82tZFT3iNsr3WMx/4d8Ml9gjp1Ep9qgTy0gWjRVe+I=; b=HmrG1zrRF9bILjq52W5M0fEv/Kh1W49u+KPtADu7tHudamR6wf/d+m8tGOauHvXjCtLxt0 SAGGpGRko4EltwHQF42dxC+zQLNuRLzEivYmePLOfQl/bjCpK8oakNCbMzF1SdgNcXjczG ggkH48Uzs8Fts/TIPgaIlQNj1AaZhJo= 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 Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: [PATCH v3 12/30] mm: page_io: prevent memory cgroup release in page_io module Date: Wed, 14 Jan 2026 19:32:39 +0800 Message-ID: <0242e03552f49b54cecef97d90ad1b61e7904703.1768389889.git.zhengqi.arch@bytedance.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: A0D1A180007 X-Stat-Signature: 18k4werz73mnxwos4kqwy5zty1d8mgae X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1768390438-886721 X-HE-Meta: U2FsdGVkX1/VJumxSz4Y7KlREU8YRahRShw31z1ZLtZGYqVF8fFIiaMFwSd3wAqc429+CVRrG4TKUA2lQRyft3S69DTjGvvo6JQzrgrBm4LSsXWCBqqTVEFaA7W7xEUMlyYj/tChFohx1shItwU/8q8fhhzBu7uZSpkgOOTRTwPaOF/nuEpeWnw/1fHNA4bdLeJTHaPVVoVg/xzTVEYAz1GJhenqgXyvYpLy75ZTtOwD3S2W6Fud+rk+nVo4t/A/LhSGA+6+rPcIguBvfFXxKY93D06SmTDXh/mgBLndVS6LLOcdp3IkFi7y9MYuQxAwu9t7G79nm/qAMLSYBCleX/NuVWzlEP6lyMidcdIUOaYRDeNWzAq3izZYILsFpCfr39VQ5FFj/GKpwRWSb8l0ll6FSLp2FiUsVhtUC4boEQ8uGp49Y4uuch/OfgaoG85VWQvrri++4MR0qnWKx5N45FftKb0oewHNVaG2zWaqITaosutCI/IGcympW40+aaPjUQuM6UotRoTCaanaGUdAGKTfhbxEexpyChK08do4Ik30Z72/Go10K0gGXEfk2l0h0E78oQh8s+avuiR+UuTJ/WG1+DJ8CPTd/NK5KRJAyqMmOhSFXxtXsYXdDa11kjsH2dzf2Rhw6EkLOaU9pEjW1kKmwsGezs+101Bc8ff/yOjl8doAw0rAMHoywrKjVbDZckRn9W6gpQ1ngNoiQ3Y5LpRYszRsRlulAU9vK525WJVZ7KMB/aBi2wrKPo1VkfvoFiwRRyDav811FEo6VNSUbml0To0pi2/nOUekJLlsHKbfIkr4zanfxYbv1Sv4nahmFUivnRxEXXjEqrag8G3VhjYXbVWKEdqpTbQmGmtOmo1O4DO6OJbIugJExjkWbPhWKLWvIYBKTHxiuWz1rKtt/keto21MB5oQ 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 rcu read lock is employed to safeguard against the release of the memory cgroup in swap_writeout() and bio_associate_blkg_from_page(). 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/page_io.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/mm/page_io.c b/mm/page_io.c index a2c034660c805..63b262f4c5a9b 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -276,10 +276,14 @@ int swap_writeout(struct folio *folio, struct swap_iocb **swap_plug) count_mthp_stat(folio_order(folio), MTHP_STAT_ZSWPOUT); goto out_unlock; } + + rcu_read_lock(); if (!mem_cgroup_zswap_writeback_enabled(folio_memcg(folio))) { + rcu_read_unlock(); folio_mark_dirty(folio); return AOP_WRITEPAGE_ACTIVATE; } + rcu_read_unlock(); __swap_writepage(folio, swap_plug); return 0; @@ -307,11 +311,11 @@ static void bio_associate_blkg_from_page(struct bio *bio, struct folio *folio) struct cgroup_subsys_state *css; struct mem_cgroup *memcg; - memcg = folio_memcg(folio); - if (!memcg) + if (!folio_memcg_charged(folio)) return; rcu_read_lock(); + memcg = folio_memcg(folio); css = cgroup_e_css(memcg->css.cgroup, &io_cgrp_subsys); bio_associate_blkg_from_css(bio, css); rcu_read_unlock(); -- 2.20.1