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 9F5FDF30950 for ; Thu, 5 Mar 2026 11:57:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 197DF6B00BA; Thu, 5 Mar 2026 06:57:52 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 16BCD6B00BB; Thu, 5 Mar 2026 06:57:52 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 08BDE6B00BC; Thu, 5 Mar 2026 06:57:52 -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 EC80A6B00BA for ; Thu, 5 Mar 2026 06:57:51 -0500 (EST) Received: from smtpin26.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id B69AD16076D for ; Thu, 5 Mar 2026 11:57:51 +0000 (UTC) X-FDA: 84511860342.26.D743439 Received: from out-174.mta0.migadu.com (out-174.mta0.migadu.com [91.218.175.174]) by imf25.hostedemail.com (Postfix) with ESMTP id 02F9AA0011 for ; Thu, 5 Mar 2026 11:57:49 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=oWqeSw21; spf=pass (imf25.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.174 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=1772711870; 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=ejX7l1jJ+3zZrpw/s0MgoEX0ZgSj4YJxaA4fQLy6+XQr6Ji1YZnfmSeoB32ocKMPyX2Lgh Vzl0UNHHSI/RyIvSW7K2aiXaiMx4FFtOw95ssVZKVCGP5pgT/6v157ZfFFsXbjtKFp8pKd iaI/frtGLgh7RQABU+ZfhHeum2hIqhM= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1772711870; a=rsa-sha256; cv=none; b=YpZlnYg3c4GSQrYteU69Ck0vulsqUZwB+WWlM/LUGHpa3vXSbXnV2SegM9S48GvI9sBt5G B3s5026yqKqK6VzEBK7FTKSLzSVDS1IPep4olN9bQJTJRYoaNDPpQ7c2EGwLRScrrItjNx 4osRSMPQLvg+EJirGfC/4+zNZ7AFJ2w= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=oWqeSw21; spf=pass (imf25.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.174 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=1772711868; 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=oWqeSw21EVIisf+Wj+u9dXY6H5MlWHP/u/aRWPVeg4N/9LvC8U7YDcY9wxveLdQ3v0BfUa E8sqMktWT4x/T8OfAXV48BSFpMOvHwZPJVZm55nALNnWmslbD3f9FJ4zhCQyiZ4svU0plW AxWzHDpEn9gcI+cA28kiHMl7w8XkEAU= 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 21/33] mm: swap: prevent lruvec release in lru_gen_clear_refs() Date: Thu, 5 Mar 2026 19:52:39 +0800 Message-ID: <986cd26227191a48a7c34a2a15812d361f4ebd53.1772711148.git.zhengqi.arch@bytedance.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Stat-Signature: us8jpt4n8imcyyzg996p56bdkm85hrej X-Rspamd-Queue-Id: 02F9AA0011 X-Rspamd-Server: rspam03 X-HE-Tag: 1772711869-781450 X-HE-Meta: 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 jLTmsG2n Lmsj0a+RkuQNvT23Q5ydOCDuUJJO5RzWdeNMQqhYmHfc+QvJEaN+Vs/m2coEpBudVj9sK7kf8fzHPPoPcrt80kMJvofEt8xHDurQkoxJvWeZ3Uk0LQf7Lu1ooU0LdGndNt5jfuFcySXKJQH9lq6YX5Yi4jNLz/Ctjc1we85BuUIKJDB0SYbQh6KyP31oyrNTwCsEB4st77a4zd2i4x9p9voyVsZLGbBnfa9LeVYAINthfk9ILbdE4mkNVYMwT+Q8UTLCp4Q1Ezx1BSsI/z74MiwUQs0GGNWU32KKupKEJFs8Pz29UgbsakG2s6TtPRWY+zvP9 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