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 08A38D29FEC for ; Wed, 14 Jan 2026 11:33:53 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 739AB6B0099; Wed, 14 Jan 2026 06:33:52 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 6FA916B00A1; Wed, 14 Jan 2026 06:33:52 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 63A876B00A3; Wed, 14 Jan 2026 06:33:52 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 500126B0099 for ; Wed, 14 Jan 2026 06:33:52 -0500 (EST) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 20466B9A60 for ; Wed, 14 Jan 2026 11:33:52 +0000 (UTC) X-FDA: 84330359904.09.881E8AD Received: from out-184.mta0.migadu.com (out-184.mta0.migadu.com [91.218.175.184]) by imf21.hostedemail.com (Postfix) with ESMTP id 6D6FF1C0006 for ; Wed, 14 Jan 2026 11:33:50 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=OGrepS5E; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf21.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=1768390430; a=rsa-sha256; cv=none; b=ulVTn6D1WicqeB2C2mnM0d5yg3DKSXuiU4cYdBl86Eu2MYxb7QpFhuH8ctXdxV8DgF6lX6 MwBIFY801ASBulYRgTRirIKu5IzZD1N/J40Ibiks7P2AqTBhDOK9QwHzMbmzO69274g/X9 /SUV3e3eoacYSS61xT2tH2hX2J4BJBs= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=OGrepS5E; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf21.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=1768390430; 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=wCcB0UGPb0CSzzkeBaE2CAurOVf6PC++ahaCYPhogr8=; b=jAR9e2V6auKYysi5ADBHhmiLjpo71idaOHLdiqnlWZ34/4257A9wwBwh1oNGPM7IvYf6d7 7t6LcnIERem9zjBLX/rQxIA8JjryHeaWk/a67ccvrrTJ1wOuAC1rBeYPi0SJIVRNp79IYD hXPse7ZhsTtPlikHV97a9FKE+83Nxg0= 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=1768390428; 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=wCcB0UGPb0CSzzkeBaE2CAurOVf6PC++ahaCYPhogr8=; b=OGrepS5EADanSDbnfcHAHrI+1eYigZjnEBbgUYBgJdtCBcfId+muqORTBBvjhGmTBycGVz SB0/6P5mAPv56UDMtFN3er1Iz8WqARaPjEdd6X4Mir7G7xmNi3r/m67Mqb7d1FTfrKBXFG lKIcziY6h/BpCZGiRqLLKPO8jFCNZZE= 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 11/30] mm: memcontrol: prevent memory cgroup release in count_memcg_folio_events() Date: Wed, 14 Jan 2026 19:32:38 +0800 Message-ID: <1a9b3ffaa06c5e72a6853e3513aa6564164ed45a.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-Server: rspam12 X-Rspamd-Queue-Id: 6D6FF1C0006 X-Stat-Signature: 76trs8e5pqgnnd69udi9epthwuzxjutr X-Rspam-User: X-HE-Tag: 1768390430-412567 X-HE-Meta: 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 v6YDHvEL LlLi6lw3o8IwyM4GSvNsyGYyI9fanUhjrB1W5p00m/oSjad5rqgJuYyS8F9ScGj4iUtIgcQ9lLdoFSGfxuAZ+dEaC+xgFOhTYNEWH+q2luZ4hs7B9cJ4ZRoAeojKxE7BXdO5Qt3GOEag8T7n7ZQFiCwjozlXEvrJfvdSmC4Z1OCo9fEY15KP0zP94VTZt+E5rNn+Vyrgs+TApTvrWWmqcY6jz1nNBodZm1gdscZ1wY8OySvpSUp+ZKi63JzIwAPTCr0OOipDtPe4GrmMXbL7JXW44rWD3gb3Qzzcb5B9TC9BOkAPvyXO/T/ll/KipmuAlYKbIcDGATnNCiPgPvZGbJemtamSsXIuP93Qm 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 count_memcg_folio_events(). 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 --- include/linux/memcontrol.h | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 6b987f7089ca4..f1556759d0d3f 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -976,10 +976,15 @@ void count_memcg_events(struct mem_cgroup *memcg, enum vm_event_item idx, static inline void count_memcg_folio_events(struct folio *folio, enum vm_event_item idx, unsigned long nr) { - struct mem_cgroup *memcg = folio_memcg(folio); + struct mem_cgroup *memcg; - if (memcg) - count_memcg_events(memcg, idx, nr); + if (!folio_memcg_charged(folio)) + return; + + rcu_read_lock(); + memcg = folio_memcg(folio); + count_memcg_events(memcg, idx, nr); + rcu_read_unlock(); } static inline void count_memcg_events_mm(struct mm_struct *mm, -- 2.20.1