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 B4E93D64085 for ; Wed, 17 Dec 2025 07:31:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 206656B00A1; Wed, 17 Dec 2025 02:31:06 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1C6EE6B00A3; Wed, 17 Dec 2025 02:31:06 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0F0586B00A4; Wed, 17 Dec 2025 02:31:06 -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 F04836B00A1 for ; Wed, 17 Dec 2025 02:31:05 -0500 (EST) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id BF7CA136CAF for ; Wed, 17 Dec 2025 07:31:05 +0000 (UTC) X-FDA: 84228141690.22.6EBCEE4 Received: from out-174.mta0.migadu.com (out-174.mta0.migadu.com [91.218.175.174]) by imf23.hostedemail.com (Postfix) with ESMTP id 0D4AE14000E for ; Wed, 17 Dec 2025 07:31:03 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Vm1diLNu; spf=pass (imf23.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.174 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=1765956664; a=rsa-sha256; cv=none; b=PbqLg75hfAkBc525hyFOZ48bbAWBjQr76gRpNPbrHurgFuGX7A5bpdCxd6IckSjcE2IXuJ B6wEU5BErxQAffZwo3osiDtEPL7/QY/jC6hsiTyGkw26rzzPjBGOrhEpHN76fWB52FWkcB UEdYvEbbwtMiAZJlRQHKEcp11w+Wxus= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Vm1diLNu; spf=pass (imf23.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.174 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=1765956664; 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=WKohFIfUqUoJgtR0v3jBFvc4zN9jyjHuINauLbc6uS8=; b=gu8PT8rOn/qyfF/OXxT0DNNc7vLCSfCJ6zt0NLbVSFqxzRd9YrHgqIsrUM2OsuUJnF9dRJ qlM//s0qKER5kddXn0B2WR0VpdAkNu3jg7+qzLY6pNLPlKSZB89Rd/upfieVqglu1s4uJz zK97F6d2jMvTPwKZf0SeReUkEdVJpik= 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=1765956659; 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=WKohFIfUqUoJgtR0v3jBFvc4zN9jyjHuINauLbc6uS8=; b=Vm1diLNu7R5n3RF3dF3GkU5FENNVYHqQ/FI+Kuws9mzfZAlFuI50n5b4rAfXOETi4aKA4D w353FHFeu0RHicJH2cE8lKXmT6xoKaStiAgtLBTHiJ1oNcNpWYzzxEUCjkQt0o7QBP1yko IJGaIa+hPaBFrWjsA4Ls4pWDa3l2niM= 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 11/28] mm: memcontrol: prevent memory cgroup release in count_memcg_folio_events() Date: Wed, 17 Dec 2025 15:27:35 +0800 Message-ID: <5f8032bc300b7c12e61446ba4f3d28fba5a7d9d5.1765956025.git.zhengqi.arch@bytedance.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Queue-Id: 0D4AE14000E X-Rspamd-Server: rspam04 X-Stat-Signature: nnycpzxbfry15gcyd6mfiri3877xm1uf X-HE-Tag: 1765956663-476316 X-HE-Meta: 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 j8rX9DM/ U6LBVB7N4P6YzTdyi/y57xJYu4NmaYnz9qHSng/7+s2iVaQAmOlkLm2tomeWxjlbQTjeMc76Z+wYUcUJiBagN8MxZ1cSm4kKUCfDobnLpg3Z0jKuR8FGAoHS/+l04nPo8FLenXZ2ZAK0tLGhxR4901PLpFTS5DdfBhBmLHIGNM/gqCdS8dM9GBXzEw4XzTKJfAzR7KN/15C7ieNKrnm5rvmrFonvKfYd293UPKMSuQ6/O7gc+Dk+Jcsh4pVKsItn60TbLGpkVhGe0XU9YgT2h5Xuxi7KKAN/NMcB1 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 --- 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 bc526e0d37e0b..69c4bcfb3c3cd 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -974,10 +974,15 @@ 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