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 16A1BF30951 for ; Thu, 5 Mar 2026 11:56:48 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 807C06B00AF; Thu, 5 Mar 2026 06:56:47 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 7D8046B00B1; Thu, 5 Mar 2026 06:56:47 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6F5316B00B2; Thu, 5 Mar 2026 06:56:47 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 5E0706B00AF for ; Thu, 5 Mar 2026 06:56:47 -0500 (EST) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 2CEA05B7F4 for ; Thu, 5 Mar 2026 11:56:47 +0000 (UTC) X-FDA: 84511857654.24.446B67E Received: from out-186.mta0.migadu.com (out-186.mta0.migadu.com [91.218.175.186]) by imf16.hostedemail.com (Postfix) with ESMTP id 6B7D2180004 for ; Thu, 5 Mar 2026 11:56:45 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=rFyAWsFw; spf=pass (imf16.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.186 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=1772711805; 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=evy5ffpxH1pOU6KU8S5DoExZmuc8IAjbV0oiS0M36hM=; b=ZQ0XbmZI959WAXhw934TmG+wLXdgwxIuLypnkQOVO58R8FuO6aGi0pcJZ+lK41jkc8KMO7 iu9CN3i/7keqfl4KWk2Fr8ZHN63xvA4dK4SOdBwu9wGjGspINTD/D9fEK5Rl/IovQzQme2 Z7m4rUoZLbOlZLAcnxq8xPpshgXZEC4= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=rFyAWsFw; spf=pass (imf16.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.186 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=1772711805; a=rsa-sha256; cv=none; b=UBJLmoqythuR2+XcjNcPsGwpEOtKgbvMGvWaf0GpbOKfGoN+T1YoVtTFzM5tJfptJpvfA9 fGHZfTN6yXFrraZ7v2RaUxSOAyTik6LsX6Ts/AXrRi0RkThMdlYj8ddqKFg1vG3ycCfgL4 YEii0QgCfLlWftUtge9U6/fD9mRCs6U= 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=1772711803; 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=evy5ffpxH1pOU6KU8S5DoExZmuc8IAjbV0oiS0M36hM=; b=rFyAWsFwp6ftMmtwWBjFPZuuy+ovo7+R0luaziVgpgjr5WTaq8+zWKMGUQzhQlZfUTq3Ek gEz5fQWKGv5h+FfKYvTOMlmL4usXczqwQMgmQxXj1wwI9eoEvsMGqEZREUbRjLpCLamjX1 zhtW0Qi/5QgfqLC47w3RZu4F4drXcPI= 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, usamaarif642@gmail.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: [PATCH v6 15/33] mm: memcontrol: prevent memory cgroup release in mem_cgroup_swap_full() Date: Thu, 5 Mar 2026 19:52:33 +0800 Message-ID: <21d1abab7342615745ea4c18a88237335ab44d13.1772711148.git.zhengqi.arch@bytedance.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Stat-Signature: fro7usx64fpmn47trz9qefzdo914h4pq X-Rspamd-Server: rspam09 X-Rspam-User: X-Rspamd-Queue-Id: 6B7D2180004 X-HE-Tag: 1772711805-758576 X-HE-Meta: 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 Ahy3GuTX kecW6UsonaisWhRfxJXSZLWSXob+j7dxRPRxbEocwm6Beo3bb9qkLNZ7VSSBLu5eqn062qdiitn383emCB1NwHI4Jomm2YaFxudGSP064Kp5ZDL3/xlhEXY2DurBrfb5JXlEM/GcTaSLXyuQ61e6EELciQzFEXWY7i4Jz6kGFadvPQ2TafinYReTek3Gg1EvuiZAslHgIejBfnrvyB3vFqlI5P79jHByQ3m1rC3xKgHeBGOa0mso/XuZwI9gsTNPi2Xh3sBr7Ingv8A8q8oNtQLRHFshuTGxJeeOdCDTxNllMJYY0VVRaip+usOdXIKQWxeXf 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 a4bb8b8b2c457..063fdfdd58223 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5345,27 +5345,29 @@ 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