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 248D5F30951 for ; Thu, 5 Mar 2026 11:55:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 905EC6B00A2; Thu, 5 Mar 2026 06:55:32 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8F7436B00A3; Thu, 5 Mar 2026 06:55:32 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7F0266B00A4; Thu, 5 Mar 2026 06:55:32 -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 6E5F96B00A2 for ; Thu, 5 Mar 2026 06:55:32 -0500 (EST) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 0293113BD9F for ; Thu, 5 Mar 2026 11:55:31 +0000 (UTC) X-FDA: 84511854504.18.C2A663C Received: from out-171.mta0.migadu.com (out-171.mta0.migadu.com [91.218.175.171]) by imf15.hostedemail.com (Postfix) with ESMTP id 45F81A0011 for ; Thu, 5 Mar 2026 11:55:30 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=bFsZqb75; spf=pass (imf15.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.171 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=1772711730; 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=98HTAgCgFMLsilH4QRkwk8a4UTEYNMYQTWZIQBuXIPY=; b=gDNKMwNyZ78KdetEbeOe4h4CjNMhiLFBTuKN/rZSNbrHghTcE6IALaaQQ2LDh/aGuKnB7n UZ2PGjlsF4eHF302vqlBmVbo/Lho29kPL/jmxbvBqv5dwL+cw78nGUrpeltXaVqFeQkZNM zBPFitE0/BPFlT6bCeMc6mLFeKHPWhY= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1772711730; a=rsa-sha256; cv=none; b=xpKjTIEcvfaQsw7vlZ/PLCotBLmf/AiLaX2SI022Ka/9W8wCBK2f1b7rsRR4vFAA6h77fj e7mi3WSecgCZ+KNU6TDL9W6rXf0F5bSRS0ek9esFqhhdNRNEVYtH2yCwgJHQeGW9XMjPr4 qoSZuzyI6qKzKE8FsgjF1RJKbOzzrBE= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=bFsZqb75; spf=pass (imf15.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.171 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev 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=1772711728; 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=98HTAgCgFMLsilH4QRkwk8a4UTEYNMYQTWZIQBuXIPY=; b=bFsZqb758HrKaEvWXtIxtvKoTg6QfwJ7pEZJpokSqrrOoLJ8VF9nif4svxs8qpkAxB4Y4Y rdw3fUGGmKpmai/wHzf85O2uTtFcrJ4xtujv6IcY2aosqGEHG2UO+xXiTuPGBskTdgfNuW 7c8/5gvkCqxiALRH8OnLSByUeqCnatU= 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 08/33] mm: memcontrol: prevent memory cgroup release in get_mem_cgroup_from_folio() Date: Thu, 5 Mar 2026 19:52:26 +0800 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 45F81A0011 X-Stat-Signature: ug86o4z113dwed41cfbd6y4arda54wi6 X-Rspam-User: X-HE-Tag: 1772711730-142409 X-HE-Meta: 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 APka4T02 uHYWozloMgdB0cLSfOi59f/hS3DSVCmn+jpbuvAiQghV4AC8SbFvKkr24P5KzWLgeu5geFhKorBxNMNb0LYaf63BZNpWkw4bGxjox47MtN2l7i1WLJFyVkf9cRrdK5VJPu3i3PDuCRxpBZ0zig8h5Rog0fXUn4xy+JCipJsb3yCsQwXiwkgBh5k2j6aYfXQ8hOfND0jzfiqzMVZykfLlZ/Lrbaj+EiSuPUkxm14IQKbYGQVf3ZwRew5HkkS17StEmwTx0 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 Acked-by: Shakeel Butt --- mm/memcontrol.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a60b692fb75a9..4820919c0d219 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -997,14 +997,18 @@ 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; + do { + memcg = folio_memcg(folio); + } while (unlikely(!css_tryget(&memcg->css))); rcu_read_unlock(); return memcg; } -- 2.20.1