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 88FEDD64085 for ; Wed, 17 Dec 2025 07:33:19 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EB93A6B009B; Wed, 17 Dec 2025 02:33:18 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E62D56B00A0; Wed, 17 Dec 2025 02:33:18 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D96FB6B00B1; Wed, 17 Dec 2025 02:33:18 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id C60C16B009B for ; Wed, 17 Dec 2025 02:33:18 -0500 (EST) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 852A95B862 for ; Wed, 17 Dec 2025 07:33:18 +0000 (UTC) X-FDA: 84228147276.16.05B3614 Received: from out-171.mta0.migadu.com (out-171.mta0.migadu.com [91.218.175.171]) by imf03.hostedemail.com (Postfix) with ESMTP id C507B20012 for ; Wed, 17 Dec 2025 07:33:16 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=tfCThczT; spf=pass (imf03.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=1765956797; 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=TEKzYkGMehRKc5BRVPJO6+VCdZxZFdG/Vbt/yGKMiiM=; b=27xiZXM4Rf42Z1qZmNKXTTZQnsCmplTSL8F/11a+edG63IXTDahI2kYK32xCur0B11C814 2lKpvqi+EsvJDyQ4d1GZFUzlrh2e9t5aFs+91fdOcOsnhgy5h7ZV3wVLUxzgqNfi+M+i6m ZYTAHXMsaLam26MwLIaoCOqgasMA98E= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=tfCThczT; spf=pass (imf03.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-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1765956797; a=rsa-sha256; cv=none; b=slexV+V10YI6vkFKyo+7Kzj3596ia4YAkdZo1yWb+Pcb1x4E7HFkEnnUh4gS7H/TgjSGR2 kDHBTHF4UN8r3Z5IDRVyoU1Xhv2+x+vVgQx34zvo9QUvQU3YTlrHOBQQiR2BOh4U1ezZq7 ISjwQyHKSFDB9YrLq7w1OFENh2BSLd8= 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=1765956790; 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=TEKzYkGMehRKc5BRVPJO6+VCdZxZFdG/Vbt/yGKMiiM=; b=tfCThczTZ5dXkREXxScD5XtwTpBC3Z49+zvUce5Q/nbsjgKPLwV4v8wGIQWkwug47qe12I N6JYxxROFlYv9wp09tles8iGrq3+oTnJifX3x5SldxBXk8H1lwOEOLDqkg8XlgU+LhZJAA 4q/eNpVSgu5kYQ9ENtmtE7Ar3sRAt84= 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 21/28] mm: swap: prevent lruvec release in lru_gen_clear_refs() Date: Wed, 17 Dec 2025 15:27:45 +0800 Message-ID: <42682f81686e31019504a6e025fa08d2c9dea718.1765956026.git.zhengqi.arch@bytedance.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Stat-Signature: tdk6q6no1n9ud781ct1p3zsj8oyyjshd X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: C507B20012 X-HE-Tag: 1765956796-316232 X-HE-Meta: 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 MXpTeft7 NFxTJSdqZsFaeH7WD5yXKYA7rowyhk/eZl5I7Sw/I1hf+ILYnsLTslFzbGp5ZhxWTkVdprTtyNThxKdu46NBnH5SUOlx8Fk0dXISzyorOQFam623jrBD+6JkRyMR72V1u9gA6jrBZB2F9KUOzqNLYVZ/2tZQohwlDVSfUU9XlOk6DF8pbDgyxpgUFcIvYhGjCrHfuUfL/PCQB84fkDs738Eg3x1Vya9sX3lwOB/rnBsO2GYa4W9ZK1i6TA9KX5ft1//NH 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 --- mm/swap.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/mm/swap.c b/mm/swap.c index ec0c654e128dc..0606795f3ccf3 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