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 C7905D64085 for ; Wed, 17 Dec 2025 07:30:27 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 380F26B0099; Wed, 17 Dec 2025 02:30:27 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 3625A6B009B; Wed, 17 Dec 2025 02:30:27 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 26BD76B009D; Wed, 17 Dec 2025 02:30:27 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 160826B0099 for ; Wed, 17 Dec 2025 02:30:27 -0500 (EST) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id C1C4A5B890 for ; Wed, 17 Dec 2025 07:30:26 +0000 (UTC) X-FDA: 84228140052.16.298E248 Received: from out-184.mta0.migadu.com (out-184.mta0.migadu.com [91.218.175.184]) by imf16.hostedemail.com (Postfix) with ESMTP id 0B835180008 for ; Wed, 17 Dec 2025 07:30:24 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="ht/pt0s4"; spf=pass (imf16.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.184 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=1765956625; 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=WJaSY8/LO9jJ6S19J29RE7irvv8d++fvHvljBrkMe5g=; b=JqeiL9Db8f4/EJG27LOsfiU+z+L/jvt9YoCV/fOoq5lRHMxy3QI8Ud04rRgTwNCerxnxxA QWccnnrg/suFJ7F3Ww9NfCWhnwYP6RY20k5uPuufpp6NlM7ByhlF4JlxRpvqmuf/lojaaE I/4Sn39DjLUYYgRP3vL1C1xa32ktEOI= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="ht/pt0s4"; spf=pass (imf16.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.184 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=1765956625; a=rsa-sha256; cv=none; b=1iltkAjTVRBaP0h346mdD1qKpbJOGF4wxB9jE57mXu3f8F/OgJhCMTX6NtLkQ/spy9jT6g kNraPCe8y3uKpRBk+zVi5rFuPBqz4R1Ekk8GkAVhq3h+30mqMEYKRki6a+pJGMP9/ZWKXa iVIsUbGR2weuyFmtthzBz+56jliBe7s= 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=1765956616; 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=WJaSY8/LO9jJ6S19J29RE7irvv8d++fvHvljBrkMe5g=; b=ht/pt0s4g+3r53ot1RQ62n1/WqHwohZA9oU7UDB4uUGCVJQQfb73NonfcosdEPDPprev9u kp/QvCPPE1NpyYcUK+QXcQhfINyowuqc1uV/DUY3uHn9/sZ24vHwfj08oOrtlHG1H5nQDq esXNLr5XLmnrkUJOnln+Nwks5ycdKwc= 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 08/28] mm: memcontrol: prevent memory cgroup release in get_mem_cgroup_from_folio() Date: Wed, 17 Dec 2025 15:27:32 +0800 Message-ID: <29e5c116de15e55be082a544e3f24d8ddb6b3476.1765956025.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: rspam02 X-Stat-Signature: ekekjmrkt1m5z97w6r8goxiwr9c77czt X-Rspam-User: X-Rspamd-Queue-Id: 0B835180008 X-HE-Tag: 1765956624-686337 X-HE-Meta: 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 EBothoBh 6UEfLxSZjDrLAozK6mf5/CgdNn23/x9pkyCRcqcLKPaiyZh32a76CIiu3FtUw7QAvG+qW3Uiwn6aMro075cDOymaIf3MU7rMVXkFJnLsaqoCD+TQX1FbyOLr4h6daM2wJGV+Lb66RaQ1xopouv/JGEkEarjofzNmJVWNxmHWuFhOOSRMSi5+Gvw5zb761ycLE6fZsD3/pnsgJBTEHfyj8bmLUXws0wylzT+00kB4XXmT/59cfvmkmZQjH7mOI7UEQ4b0X 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 get_mem_cgroup_from_folio(). 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 | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 21b5aad34cae7..431b3154c70c5 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -973,14 +973,19 @@ struct mem_cgroup *get_mem_cgroup_from_current(void) */ struct mem_cgroup *get_mem_cgroup_from_folio(struct folio *folio) { - struct mem_cgroup *memcg = folio_memcg(folio); + struct mem_cgroup *memcg; if (mem_cgroup_disabled()) return NULL; + if (!folio_memcg_charged(folio)) + return root_mem_cgroup; + rcu_read_lock(); - if (!memcg || WARN_ON_ONCE(!css_tryget(&memcg->css))) - memcg = root_mem_cgroup; +retry: + memcg = folio_memcg(folio); + if (unlikely(!css_tryget(&memcg->css))) + goto retry; rcu_read_unlock(); return memcg; } -- 2.20.1