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 08948EFD202 for ; Wed, 25 Feb 2026 07:50:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6A5686B0099; Wed, 25 Feb 2026 02:50:51 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 683706B009B; Wed, 25 Feb 2026 02:50:51 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 593A76B009D; Wed, 25 Feb 2026 02:50:51 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 47B416B0099 for ; Wed, 25 Feb 2026 02:50:51 -0500 (EST) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id F32CE1C54D for ; Wed, 25 Feb 2026 07:50:50 +0000 (UTC) X-FDA: 84482207460.28.AA076BE Received: from out-180.mta0.migadu.com (out-180.mta0.migadu.com [91.218.175.180]) by imf25.hostedemail.com (Postfix) with ESMTP id 4E0BDA000D for ; Wed, 25 Feb 2026 07:50:49 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=svJaI0II; spf=pass (imf25.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.180 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=1772005849; 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=zqKlQwIe/CEU5YhxXMP3izWR/dZSc156G/ZchYoa8VC3cGXJmEFtHAMcLSlJeBH5EZ9Knz 2cNw17HrRS+ile/lKqncBIw1bpRYLdSyAL7X61w2pXIwfT5jW8pgHW1co5wQ8bro7sd5Eq yP7VXrpFK6BO3NcSaOfqpKKtiOrQ5uc= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=svJaI0II; spf=pass (imf25.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.180 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=1772005849; a=rsa-sha256; cv=none; b=U7PQSTgoLVVJkzQlLQNJsXpqRNtlKa5wCf2Pq3WQavGpUbu2PuSH/v4iHZjpc7u0q2mnjl cjWyL/3soCFtAavb4gHFHkA90RkTIxyOau2Cj5VbkU5lT2UZ/3VFmAmrvuJVjnlbyOjvML fQlwK2KxC5+j1UtjzDaDTO5RB50pzU8= 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=1772005847; 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=svJaI0IIUjaH2GnFILnNu368taKYEaOfgu5AfunL14OCwFYiU2jryceYra4EP2QJbKUPwG 6EtNuXXn+eqRf9xRdrt7ciwHo93I9lyVn1GT1fiXoALEPU8zOuaWhG7e+3PgPzhcB1cQ8Q rijiTZlJhn/FEXvZa/6T+ZJWhOo9YAI= 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 v5 08/32] mm: memcontrol: prevent memory cgroup release in get_mem_cgroup_from_folio() Date: Wed, 25 Feb 2026 15:48:41 +0800 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Queue-Id: 4E0BDA000D X-Rspamd-Server: rspam02 X-Stat-Signature: ff7bu1mtdzkwaauc79ew4xsousd4bbg8 X-HE-Tag: 1772005849-216594 X-HE-Meta: U2FsdGVkX19/pbemwtRDcpVHoTgoms5CUmLeafaBAE7kpdlSb6HYdU2/hdejmD8DkCkR8UPZE3JricmOt/mSBtxQmB91TXwxlLqU2KIdaL/CSh1Bqt9eRHVFwKpkyhcwr2EfPhbdKun44vRavSbUagkejPBx1b0tOd5jWxKCmAuHfanqFpWhx9Hn6mctW2BKSfxmHvyA2f/gQwgJR00ElO1QgdnLHgYnv+LPwYSSKZ4WNSQ8BEBfmG0sHMP+tHv5f8vvJNf5gWzp+Vu6PbiSWJ1uYu8vvZibbQ3qglseTTzZyltSJP6Nm5PLE2oOfFTZn/2qM+UgOGkEyc/yu6+Xw1Vmz2eeoRfwQw5SmcSanYQ1dwr9mwLj0i6irGHNNo4eEqXgOH9OTG3sYOH/RmGhlhhSHB3GUhZOll35FLPTbOgS+eOnWPRgRBnlpnMU/N0bSA2uuCY4epNVA7xzCIplN0B5ymB1Xvsz93IWEEcr+fvt6YNLHd+IHn5zycorn0YN3swmsLpJAp4uv4C8plmQqJpIs1bofPTMW3LC7jTVgRlInhISiSkBkpYOMk5lzfx4S03kfVgz9Her8ADstGvk6/cGCacmBFEUN2F/0nwGjGTEBcO5SdWby8dAr4bbQ/gDse2rcXya1CQ+t87gKgVrPpr7BCXyIHJV/loVw0C4jqbhpjIueEdIg6U5acWj6SWb/7i8/wn8De6lLvtEb2+MuIpeUDeKHcYMSU6aJWuhVmhJAD527WAE0XQjWRgmNkepZYxzTAD+h4hCkcg34XF4t9iUZafAjmHjE6YyD2+UdT+HF8K4FyYNadvq69g7gxaJhghlcYoF/MNuZkTw7gls+rhcogU8Z9N0iILnmdCtrTqUdhh1/x19a6pxz7aCoNXpWwX42/IJ3xn2Ib0YADYdSZz5ALtCSOKJX//EIcFAEwnkdEMKhlX/i/Hq98BKlExzW6t17pkAxHpGLM2AsUa VocDO5TA k2eSY4fPk01E938tvWZR+m9cOMN3n1Ujzb9VXxnoasEUxyugKPdvkNlJO9fOU+KLLfxAcWiUNEOHNwT2jHWuob63LeeM5GqOTl9E9eTm6Tb82dVH8RWEnC3hOaTi0BYXxgNvd+GfLUw1twpwuZJLS+EvOGvibynDr+nM/Ye7eXfO8abbxcE3FcWdP5s77tY9wHpI/fvPV49sVw5PPME54rBTC49nc/0n5v8R33iP7hLb/HW2o08l4t8r+Mq5z2GisgKT7 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