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 B0E16E91297 for ; Thu, 5 Feb 2026 09:04:11 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1E5906B00B9; Thu, 5 Feb 2026 04:04:11 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1D03C6B00BB; Thu, 5 Feb 2026 04:04:11 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0CFE76B00BC; Thu, 5 Feb 2026 04:04:11 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id EE28A6B00B9 for ; Thu, 5 Feb 2026 04:04:10 -0500 (EST) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id BE106140450 for ; Thu, 5 Feb 2026 09:04:10 +0000 (UTC) X-FDA: 84409816260.22.778003E Received: from out-181.mta1.migadu.com (out-181.mta1.migadu.com [95.215.58.181]) by imf03.hostedemail.com (Postfix) with ESMTP id 120B12000E for ; Thu, 5 Feb 2026 09:04:08 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=WAJrOF27; spf=pass (imf03.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.181 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=1770282249; 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=t9Y+n3DRy5ziu0jwNvh/aL8GYBQdqH0RekOvcRC+IC0c6I5baCKtv7US7TaDxGj1avxzE7 8u6ACkcHoKG4BtOuqu6Qu6+xu1noziW5xdySFHjdHOgYWh8P5QCsv+qCA9jSQT7amZmznB moIudMMXUkKGKZ8lM6a6qSz88inl2UA= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=WAJrOF27; spf=pass (imf03.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.181 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=1770282249; a=rsa-sha256; cv=none; b=ji6g+jgqzjgxjf0zLRmXVC+2kb8c4SkmR10YtaAWJeX62sQOrAkLtOjqUKS89fY6jtOJUQ OZl3RHngkt71e8Vl0tTqiR0wGScuTiVupJM7bQnLofT+qrXS7R4WWtNAAwtqRRfM0xrsT5 CO5yhUFBcJ2qtuple+yfEl0bMypMYxI= 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=1770282247; 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=WAJrOF27HCB5BG4W4Di4FgtDhc8i110kCSU2tRmeUnuO1z1k7WPQt/L4RHD1/2BsrxR3mX zyHHe1wcSNkf2b+itnL1IIRsE6hcaMU1L/Pna41B8IAASe182aVKqM4oSd5dzRHEQq9IjY 3sKzG7UJhuWg/yfG+NB0L90DJYIBxx0= 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 Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: [PATCH v4 21/31] mm: swap: prevent lruvec release in lru_gen_clear_refs() Date: Thu, 5 Feb 2026 17:01:40 +0800 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 120B12000E X-Stat-Signature: tt68ctrobryymowsa39hoowpgygmz4wn X-Rspam-User: X-HE-Tag: 1770282248-908636 X-HE-Meta: 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 FykJkFuw M5qhEBYe1aC1xZskFHNd791KsW69F8ELVzHlDaiYRGKUaIMClobVUoZAIoy1g1JAg+nA8Gz15D9WC6qgk8hz0SYDZk9uijaZO06LVsre+GEOnkqJb+4RyzO4JpBRnqxd5Yyo0v9EwEKMHd9xHu7I/mOnW/QZuwEyhB4TsBAgw0l5ZLSsduj1bMLct2XtRAuL6oJIm7wTRWzVs7uv+Tzra6RmDU06kJef/vPZACFCrd5TEzjoZm+legRnwJGwJK+8Ag2MkjqOAct/AHGN68HzO1qmdHpkhshjWh+lHkG5ejD5QvMeYUObDwa1Rhw== 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