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 05DBBD64085 for ; Wed, 17 Dec 2025 07:32:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 68FF46B00A9; Wed, 17 Dec 2025 02:32:00 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 678266B00AB; Wed, 17 Dec 2025 02:32:00 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 591296B00AC; Wed, 17 Dec 2025 02:32:00 -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 46EA66B00A9 for ; Wed, 17 Dec 2025 02:32:00 -0500 (EST) Received: from smtpin05.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 12CBF136CC3 for ; Wed, 17 Dec 2025 07:32:00 +0000 (UTC) X-FDA: 84228144000.05.66CCE12 Received: from out-177.mta0.migadu.com (out-177.mta0.migadu.com [91.218.175.177]) by imf16.hostedemail.com (Postfix) with ESMTP id 61699180004 for ; Wed, 17 Dec 2025 07:31:58 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=soa+opLi; spf=pass (imf16.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.177 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=1765956718; 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=V4K7YSAAoMX3+MZNm3D3u3VukDVTNTfZTJaO+WTfHwU=; b=0fpNAe4JlfRGfAMiXrynfUrLa+JA0NXU0W0EuyCVXVGne3wnYmTBrXxod4QRElZzmL1cr1 ET/+p7OFtV83ctCDmvn8kiD+N7sQSDW9lxWDfDmja4WnfEZr3KQCppq0X5Nu9FmcEGmWCU rqH8YMxp7449HAuY9DUZnRTSApi2JtA= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=soa+opLi; spf=pass (imf16.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.177 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=1765956718; a=rsa-sha256; cv=none; b=joi4hOCXRmin9ujBLwE46N42Ax42WGdrEPCTPYaox9Lh3SGYF1FU+9QbjiWRo7DGz85Z1y 3uhsnqmKPSeadowldaqMeBvBKDUWzuAhuufvGu9IH3NW6SruekYQcDeOvvEJBhyZUKpFU9 r7MDi6hb7i5OSBG8ueDcCOP/78ybtks= 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=1765956711; 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=V4K7YSAAoMX3+MZNm3D3u3VukDVTNTfZTJaO+WTfHwU=; b=soa+opLiHzhlpOkib/c47niPkRmdgYD8ywE7qI/ViG3fYKxPr3bMPex+1o4kW9a9f4HlRa 2oFTuBu1qByHbwxK1c+5vo0S2/VfJbGBb7/DRCsw0TO+bIx2hsf0PZnxhl0CabMJ40pyLE U5+XoS3KoIKWlGB4LdX/NaW8KUaFXI0= 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 15/28] mm: memcontrol: prevent memory cgroup release in mem_cgroup_swap_full() Date: Wed, 17 Dec 2025 15:27:39 +0800 Message-ID: <4dd1fb48ef4367e0932dbe7265d876bd95880808.1765956025.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: 61699180004 X-Stat-Signature: m4nytnc5ng44ia63jiqmua8ixaxo3pxz X-Rspam-User: X-HE-Tag: 1765956718-656953 X-HE-Meta: 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 f2A4CsH5 i35a991P3W2CKYZ3P08xcdJpkrYfWOK8zqV1I6mm6onLsj7mi7E1gP1C/Z0DcJO1dBb/bVpVKqskPLNPGILP6jGIpkgjD5rVSQBVt8z9ghGnRiWTWhDAygOGposSY46CH6R66GHhRQDwqd9rKwNgUZOcjXlUBimKBsh41NbMl/HgCxjzyRIwirJUgOFlxGRphT+LCZhOG129JxZuaxVPvrIyaCb1FZyxBwVQGkc60s39dUr2IM6V61pOH37xCX+ms7X0s 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 --- mm/memcontrol.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 131f940c03fa0..f2c891c1f49d5 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5267,17 +5267,21 @@ bool mem_cgroup_swap_full(struct folio *folio) if (do_memsw_account()) return false; - memcg = folio_memcg(folio); - if (!memcg) + if (!folio_memcg_charged(folio)) return false; + rcu_read_lock(); + memcg = folio_memcg(folio); 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)) + usage * 2 >= READ_ONCE(memcg->swap.max)) { + rcu_read_unlock(); return true; + } } + rcu_read_unlock(); return false; } -- 2.20.1