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 CBB6AE91297 for ; Thu, 5 Feb 2026 09:02:50 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3E3DD6B00A7; Thu, 5 Feb 2026 04:02:50 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 391976B00A8; Thu, 5 Feb 2026 04:02:50 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 29B056B00A9; Thu, 5 Feb 2026 04:02:50 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 0F9C46B00A7 for ; Thu, 5 Feb 2026 04:02:50 -0500 (EST) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id B59C958A26 for ; Thu, 5 Feb 2026 09:02:49 +0000 (UTC) X-FDA: 84409812858.21.A6BAB02 Received: from out-188.mta1.migadu.com (out-188.mta1.migadu.com [95.215.58.188]) by imf01.hostedemail.com (Postfix) with ESMTP id F167340006 for ; Thu, 5 Feb 2026 09:02:47 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=erBLz1He; spf=pass (imf01.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.188 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=1770282168; 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=IOi+V9LyT/1CZGTIV2A2h8dDIR737cICRGaWqsLu0er6HIMXifHhneF1d3rqqIniAGPHg+ 8uzDDvRkUIrzKYOXH6zpm0TvSjzk/ID4ZczWhcyIuZX33B/hL0Gxa1MGN+6YaspfL/zv/Q QrGmEa0SU2joVKg9DXBFF4zD2dCZAKo= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=erBLz1He; spf=pass (imf01.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.188 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=1770282168; a=rsa-sha256; cv=none; b=M1q1Ce0Vq9eZiE7WV29FpPFZdtajN1IiNOxZzPeLO2Y2KsAThRylZ9Nbus9MyrV25uDfFs BSK00q6+1V8VlPGnfcX6+4pwRIDIt0VU5dm1iGsWCuMQGkqqD2Lnoc3/L5AcIM0+rh4wa7 o8LGqmWGzm2UKXRrTqvH3DUr5eDu8G0= 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=1770282166; 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=erBLz1HeMegVFPPeha110SLblcBQhIgpCtxuFzHpIUTarxrMbF2odGtdfOwJ7O3DtbThau so8xMWG1irDvelZ5WFNSdLACWsOf/8Xsm6H1P34+UBbWJANSbel3BxkbmFEJhoQCMAB/kR EZAHSX9B9Vo5PMYVabTHIS/NUzaQiNk= 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 12/31] mm: page_io: prevent memory cgroup release in page_io module Date: Thu, 5 Feb 2026 17:01:31 +0800 Message-ID: <28e046370ee364658799704b40d06d3cae8dbfeb.1770279888.git.zhengqi.arch@bytedance.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: F167340006 X-Stat-Signature: 55s3zkaffb6gjj9eoiai8x6585qcofi6 X-Rspam-User: X-HE-Tag: 1770282167-239594 X-HE-Meta: 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 TiuIz/Yu vS5vuIhdXjI5lqjKJZ4QX1xzwHTn9cOCJZZpDBBIQD2BgyoaaWvad8WCT3ZfM7nTbbn1XFoK2McNqVOQSQgjaXwpenbumFEXFhuA666gJtfZdPc1ppaPEBdB97jTB1eej9gUtLYGEfdqMCPqklFCMi7zi81bVd4kPxqBdeae7IDyDi+7jIfAe8HOhT7bT+zgF1KpmdbnNYI4cfeh2e7IcDRJp+a55MdxY4KfX6J0xJL8J/jLkDOQmJpRHBQhZUY+9dfPpf+33PL2y6CsTMPzB1NP0nOgawJyvECZ0cjed6M//fDHKf/tgTCLL0g== 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