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 83024EFD204 for ; Wed, 25 Feb 2026 07:55:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E43866B00B9; Wed, 25 Feb 2026 02:55:01 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E00646B00BB; Wed, 25 Feb 2026 02:55:01 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D441C6B00BC; Wed, 25 Feb 2026 02:55:01 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id C0A7D6B00B9 for ; Wed, 25 Feb 2026 02:55:01 -0500 (EST) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 83AFBB8EE7 for ; Wed, 25 Feb 2026 07:55:01 +0000 (UTC) X-FDA: 84482218002.18.96C5FB9 Received: from out-188.mta0.migadu.com (out-188.mta0.migadu.com [91.218.175.188]) by imf22.hostedemail.com (Postfix) with ESMTP id D2D13C0007 for ; Wed, 25 Feb 2026 07:54:59 +0000 (UTC) Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=tle46y7d; spf=pass (imf22.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.188 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=1772006100; a=rsa-sha256; cv=none; b=Ct3Jagbj81ZJzysyUR6wCj2lHSTMajYd7KdZL4debYcChOtyaJOmWhsfBF+EJqQoG6vpAx uNJlBeGkME+SOvKODfLxettIpde9nIQCulxj+S9mBVb8kCHfTZl9IUZ69zKgBSjyv4mB6U jNUsNjXcF695Cl6ThPVghM5ZlytfXMI= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=tle46y7d; spf=pass (imf22.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.188 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=1772006100; 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=9FlmauyfzMJ30WpiQCMliVOAMipux2gAWQ7/AZwbz08=; b=Ul2dfePWma7Sq10Z1ajwYK0utWcdQ+pSXRsrgy/tIV3qOZjeNwrbaB8O4SzV2hIsFwVOWk MsxSYuTMSqyNG6JOBZuZq2JNbc3S9FEDyVffYKY7vTtry3gTd5DQRs2yC2AsGTlXB8Okpe ufViARD6LI9pj61Nai9Y2fRF3qHUdG0= 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=1772006098; 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=9FlmauyfzMJ30WpiQCMliVOAMipux2gAWQ7/AZwbz08=; b=tle46y7d9kpYoWp6mN0mjfokD8fL+rIjd2+QtkwlVOIykASwxMaLLCVFA8y7YQFZgxCmax 2dDyGcyd0b7Yif8LBIthUvv2UVBO1nf/20x50SR2qOAcZY52F43E35EmlD0lQrkgUa2DjF t852LCK+qY1BZyxlVhY8cYjbSnH6SvE= 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 21/32] mm: swap: prevent lruvec release in lru_gen_clear_refs() Date: Wed, 25 Feb 2026 15:53:04 +0800 Message-ID: <986cd26227191a48a7c34a2a15812d361f4ebd53.1772005110.git.zhengqi.arch@bytedance.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: D2D13C0007 X-Stat-Signature: nztx5iddpr4i5ya1iyomahwhnxkys4nu X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1772006099-952428 X-HE-Meta: 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 PEiGiT/s zVVx+OdAXxPXuxhSt110lYGvtrq3R9hq/QocXfK/7Y1wjk+KBw4R6y6YQ4xxs5ZMSCKgnZEeGHB5qIj4lsIwOG9OdF2reG3so9iwawt24MFqgh0SKZb8GNtOpN7upoEbFli/haya/s9bup/cWqZOW57VOTFoQ0yp7lDYCWmxwafiyOEmIN+jEzIAtM2dmqVcIO++xlNDdmks8oOzU4ZvT8Qx9kAWbybOUtZ1Dqd+gSmvTh6s6VDXgCMqbIDX53lvXVYaofbJq4lytUgwz7XplPCEQOC4mAB+n284RNwf2qvvBdXTvzIrdbW/BSRmWxCcx4Bn2 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. So an lruvec returned by folio_lruvec() could be released without the rcu read lock or a reference to its memory cgroup. In the current patch, the rcu read lock is employed to safeguard against the release of the lruvec in lru_gen_clear_refs(). 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/swap.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/mm/swap.c b/mm/swap.c index 245ba159e01d7..cb1148a92d8ec 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -412,18 +412,20 @@ static void lru_gen_inc_refs(struct folio *folio) static bool lru_gen_clear_refs(struct folio *folio) { - struct lru_gen_folio *lrugen; int gen = folio_lru_gen(folio); int type = folio_is_file_lru(folio); + unsigned long seq; if (gen < 0) return true; set_mask_bits(&folio->flags.f, LRU_REFS_FLAGS | BIT(PG_workingset), 0); - lrugen = &folio_lruvec(folio)->lrugen; + rcu_read_lock(); + seq = READ_ONCE(folio_lruvec(folio)->lrugen.min_seq[type]); + rcu_read_unlock(); /* whether can do without shuffling under the LRU lock */ - return gen == lru_gen_from_seq(READ_ONCE(lrugen->min_seq[type])); + return gen == lru_gen_from_seq(seq); } #else /* !CONFIG_LRU_GEN */ -- 2.20.1