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 5268BD29FF1 for ; Wed, 14 Jan 2026 11:35:21 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BB00F6B00B7; Wed, 14 Jan 2026 06:35:20 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B29346B00B9; Wed, 14 Jan 2026 06:35:20 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A48DE6B00BA; Wed, 14 Jan 2026 06:35:20 -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 9257D6B00B7 for ; Wed, 14 Jan 2026 06:35:20 -0500 (EST) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 6043D13B117 for ; Wed, 14 Jan 2026 11:35:20 +0000 (UTC) X-FDA: 84330363600.28.6797D73 Received: from out-182.mta0.migadu.com (out-182.mta0.migadu.com [91.218.175.182]) by imf25.hostedemail.com (Postfix) with ESMTP id 9DA4AA0003 for ; Wed, 14 Jan 2026 11:35:18 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=BCBEdXVl; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf25.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.182 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1768390518; a=rsa-sha256; cv=none; b=2lH+dcIyNs0GomVh5i4vJoMABcMwf9tYUnrdxkNXDKQOKbA1F7xt0OG8I+Wmp0tNBldnvJ YVaawxtm0Nugojna7QFSZxsd3MvpksJSaoboAzY/k5bsByyR16dZ8VcLbNcs03R4JMzVcu 3Z0pOGxCewECEJknRD4IcTJveIBKWAM= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=BCBEdXVl; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf25.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.182 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1768390518; 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=N7eS22aXVYqUZqNDZGtuDyTUi+iDu7aHgfUKGCiEHE93G3JH737C6KZ6iN3MKBGoEWu2sy kM1vU44m6RUEEXW+H73Gk7rOxpjW9G3d1ETDSFGP1Mhw7JvAYv6C/jHK83+Muk6XH6Ns6D Mu3jl5l7Zv/p4fvO0tpC10ZXjDZfXAE= 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=1768390516; 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=BCBEdXVlLqQkp46ysfV3oumStNfgTGk2xCFjGUXhfJr7hPbVLCfcUx0ooPvCE079FQEBjQ d5mYDx4hvC/B5S3BE7Mg7thsNh3e5eQYUgGmRZoJLaOS3ACuXv15yRP/EIq9etX+UZWwQN ilKNF2+Mnh/m0rfu7RNltXiX2KqJc8o= 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 Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: [PATCH v3 21/30] mm: swap: prevent lruvec release in lru_gen_clear_refs() Date: Wed, 14 Jan 2026 19:32:48 +0800 Message-ID: <80e4240d06e51ec90245accbe7bd038994a35dbd.1768389889.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: 9DA4AA0003 X-Rspamd-Server: rspam06 X-Stat-Signature: 8d4w8b7h3ab3e8ttzzpfr7tg41ixxpkh X-Rspam-User: X-HE-Tag: 1768390518-123187 X-HE-Meta: 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 1xkIDHYi xywZyvMOr6Af8LHVkRfzXOS7WuQ5/fP+sn9GffO1/tWpWAJ9HqLI8bN+F2AWX3n/MCEpzDAOZwnsum133eSFPnf6KjRTgWsM6WYtD1ERFrn2GYqBHBJoVt9opI0EhZZdAMZRnKynf6NRx96GGHdj9ml/7KPjb36bQ/SsJfDZX2Oyy6uPV6q4wCI+PklJGKP+ABTSJq60UiShLQt6TzsHmo0y9sbBzK/9Gx6b+BSyDldn38JUcAyK1gd4NAhssLW8bQ1Z41iziEsUiiuy2fxLY7YWiyPaPWS3V19X+morfGlZteJwhM3rGw9kGgteJqITy4Y7I 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. 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