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 91CECD29FF0 for ; Wed, 14 Jan 2026 11:34:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 008FE6B00AA; Wed, 14 Jan 2026 06:34:33 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EFECE6B00AB; Wed, 14 Jan 2026 06:34:32 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E2B8B6B00AC; Wed, 14 Jan 2026 06:34:32 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id D17E36B00AA for ; Wed, 14 Jan 2026 06:34:32 -0500 (EST) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 8525E16046E for ; Wed, 14 Jan 2026 11:34:32 +0000 (UTC) X-FDA: 84330361584.09.342AAAD Received: from out-172.mta0.migadu.com (out-172.mta0.migadu.com [91.218.175.172]) by imf06.hostedemail.com (Postfix) with ESMTP id 8BDCA180009 for ; Wed, 14 Jan 2026 11:34:29 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Y7jeyurN; spf=pass (imf06.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.172 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=1768390471; 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=em4Iy6O35b1A8UR+0FO08xHRW0BrOK64xODkveylgXo=; b=CTJMy55khLvQDQ2O7YRe9xP5+QLX4Er1wPOlPlCSG0l6pCvHExINPkyalILBwEXJnQgg2O TAWvTVIdRg/p3jm2n7wOwOqE98QnumK7SeKq6XY5cxyt8Z1e2bFtkK7kqN6QfPMKwhppy6 cmB4XqU050cbLtgYZDGdwXuZJB6KEl0= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Y7jeyurN; spf=pass (imf06.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.172 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=1768390471; a=rsa-sha256; cv=none; b=4oWphkpm4GA9GoAGr9Vs7eRJ5NDisGq3WYzuzazVpE0vFDg4YOXA5Nh0usontS9Xtgo/J5 LerJW/ph56ObQAVGgyUG2LtDvmNYUxQ5PB0ouTBuuvFOqAzYrkcvvsRrVloMlRcwVRjVL5 /lReyYrXsZtHLxNR1leAmJorVrh4Xlg= 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=1768390464; 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=em4Iy6O35b1A8UR+0FO08xHRW0BrOK64xODkveylgXo=; b=Y7jeyurNAc4uvEAfTJbTgqIYsRk+83DVSW416xY5r0eDb6iv3XH27yMYQ2bGbyNYhYd72+ PYMpbf/+shaKQ4FIyWr49L4PdVygdOGf/27V1nmPR89IlgW132TbT8c2ORTn1N6AVBlUfc xP0YLXfIhN8VvEXDrmrtOeYrYTwrmV0= 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 15/30] mm: memcontrol: prevent memory cgroup release in mem_cgroup_swap_full() Date: Wed, 14 Jan 2026 19:32:42 +0800 Message-ID: <3e739f195644611749093c8dd2c8dd2cea1d2485.1768389889.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: 8BDCA180009 X-Stat-Signature: fynntbqyxc6zmij4cczneceuem4qp3kf X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1768390469-150136 X-HE-Meta: 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 NJ5wrwdM UIiC4CWFbBPv1EE5elGemGkoUujvSck1AvhLf9Z4KtU3Zw4GWbeYd0jSniuN9ajqLwrvav949KmqxEZLktUg+zUyc3Pf5SxNZUdzIDhufaDA4LvTB6y080oH9+G/n+i8rPtFD0NsPgG4KF+AfuQIOOr9rZAovx2tY9ILF9JljVVOXGRP6/mVA3zrdq1+ya+TyxK+aTB+6bzszhc1UECzHl4u07PijWdQSPg0XHEd7EhNBKoM9dDLDn9wi2fRRMczX7gq8xAyDsrPd3LzmQUWpsUvx8lxcD3m2eUAn5lvcbbmsPDGjLsNpG5PBDN4CdMdhR/jv 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 mem_cgroup_swap_full(). 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/memcontrol.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index b5d4139ea1aaa..548e67dbf2386 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5283,27 +5283,29 @@ long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) bool mem_cgroup_swap_full(struct folio *folio) { struct mem_cgroup *memcg; + bool ret = false; VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); if (vm_swap_full()) return true; - if (do_memsw_account()) - return false; + if (do_memsw_account() || !folio_memcg_charged(folio)) + return ret; + rcu_read_lock(); memcg = folio_memcg(folio); - if (!memcg) - return false; - for (; !mem_cgroup_is_root(memcg); memcg = parent_mem_cgroup(memcg)) { unsigned long usage = page_counter_read(&memcg->swap); if (usage * 2 >= READ_ONCE(memcg->swap.high) || - usage * 2 >= READ_ONCE(memcg->swap.max)) - return true; + usage * 2 >= READ_ONCE(memcg->swap.max)) { + ret = true; + break; + } } + rcu_read_unlock(); - return false; + return ret; } static int __init setup_swap_account(char *s) -- 2.20.1