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 A54D7E91297 for ; Thu, 5 Feb 2026 09:03:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1A84B6B00AA; Thu, 5 Feb 2026 04:03:17 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 169596B00AB; Thu, 5 Feb 2026 04:03:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0C0746B00AC; Thu, 5 Feb 2026 04:03:17 -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 EE8E76B00AA for ; Thu, 5 Feb 2026 04:03:16 -0500 (EST) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id B96CB14044F for ; Thu, 5 Feb 2026 09:03:16 +0000 (UTC) X-FDA: 84409813992.04.E61E7CC Received: from out-179.mta1.migadu.com (out-179.mta1.migadu.com [95.215.58.179]) by imf30.hostedemail.com (Postfix) with ESMTP id 0FF0980013 for ; Thu, 5 Feb 2026 09:03:14 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=QBVYfQQe; spf=pass (imf30.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.179 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=1770282195; 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=VkC4ZVvRMLdyP21ROmg0kuk5/4rFdLy2Jo+Fn1857AM=; b=74pdBTrW02xniPXjfN96MVKwzwTcx48FXdBaXzPtQjVDsIFwzExTiZHoxfsHOBi8NQpJyY jcM0ReTOaNLTLKnC6ZIrc/Wd655tuK4dvxQciUy84XD+kEIYlxatyCWvm5BXfIhn+GlcTJ o4qnoidfQMJILBWJ1lCcTmFLjqyrLIY= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=QBVYfQQe; spf=pass (imf30.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.179 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=1770282195; a=rsa-sha256; cv=none; b=h74MCaLddeRsrbk/k52YGyxFhaOh/mgt1EJq7+5TuTm4mdRgzDW3yobvbFeLWuwyQlkFcT LfrUjp3J/1zxm9FCN7oPeYKZprawXPLNXCSkNZAAe5Sl4cTvSYX5BwuJ2aMXIj9PGbCi1S eVPatHw8R6xv+16Zo0RgMbAwoYeClM8= 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=1770282192; 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=VkC4ZVvRMLdyP21ROmg0kuk5/4rFdLy2Jo+Fn1857AM=; b=QBVYfQQemftff+h3MW5wPhwO0xVI9V05+Q13myFP3gl3u7X/2oP6J4G2p66a1GmwqzG/nA 3jtMRqZ0Nh60kZSfMtG75/Y9rQBAHrZwrrMLQXZLUJGvW3aNftz/lULQepF9Q3ftu4W5pp AlQ9yCRwZ77ZFQgyMK+rzSb8FF3KWDg= 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 15/31] mm: memcontrol: prevent memory cgroup release in mem_cgroup_swap_full() Date: Thu, 5 Feb 2026 17:01:34 +0800 Message-ID: <366517642ed7dd6948621de101fa592450ee2c3d.1770279888.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: 0FF0980013 X-Rspamd-Server: rspam07 X-Stat-Signature: d85xs57rq71dodt6fyxpc96we9bar3zt X-HE-Tag: 1770282194-737002 X-HE-Meta: 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 78vfnI0e uE1nvl3+1UkBQpTO7aZ4l9Oinbn8VsOhOvHXMgERrQLPlphep8r2YmMOfhI8a5GSGXZjXB1KdPlK84OEYthGoYyYDPMkAaMTMu8LSAYmAOM5EbOpn4mtWx+7FRaUWmPS4dRMFpRF7q/HuOOkbXxslWiJXe9wUTriQBrY05kOoTKnPvYsl+Rj+b1umjTJH+m0Jg2BWv/RsDUQP1OEjTEmppJEs7e8Grxdmc+FL/NCUDylw6NDzyZBPKNF5kXDbBOBe3Nr0aDJ93M262xm2DgfB+hDU3M0y42m8sBxRc4wklcRvYopwQl9bJ4BgfA== 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 5508a4aced0cc..641c2fa077ccf 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