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]) by smtp.lore.kernel.org (Postfix) with ESMTP id C9A77C433EF for ; Wed, 9 Mar 2022 22:06:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5E35A8D0002; Wed, 9 Mar 2022 17:06:32 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 56C058D0001; Wed, 9 Mar 2022 17:06:32 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 40C298D0002; Wed, 9 Mar 2022 17:06:32 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0190.hostedemail.com [216.40.44.190]) by kanga.kvack.org (Postfix) with ESMTP id 2CF108D0001 for ; Wed, 9 Mar 2022 17:06:32 -0500 (EST) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id C868E181CE284 for ; Wed, 9 Mar 2022 22:06:31 +0000 (UTC) X-FDA: 79226232582.26.413B8E3 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by imf28.hostedemail.com (Postfix) with ESMTP id 45158C0012 for ; Wed, 9 Mar 2022 22:06:31 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id BA856B823DD; Wed, 9 Mar 2022 22:06:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 196FFC340E8; Wed, 9 Mar 2022 22:06:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1646863588; bh=tCTg9iZ+l1L+YIDqIMzEn+ib+sAI8kfh/KLRU9a8GdY=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=DnDofeAkAHu7ywYFNpGq2nl3tLnncdXVE9rvFsKyBSNOIOJOafkOL8QwbSS0koDnB EQNB30prTqIQk3+HpHzIGRuDWGKWvLTwoQxbJSjYnMpd7r+DUF6ObJafeblDamGT+/ WS9QaikU/SW99qMzNydh5dTfD6RU571d84XqAqYY= Date: Wed, 9 Mar 2022 14:06:27 -0800 From: Andrew Morton To: Minchan Kim Cc: linux-mm , LKML , Chris Goldsworthy , Marcelo Tosatti , John Dias Subject: Re: [PATCH] mm: fs: fix lru_cache_disabled race in bh_lru Message-Id: <20220309140627.eeaa069daa921dbef64f8970@linux-foundation.org> In-Reply-To: <20220308180709.2017638-1-minchan@kernel.org> References: <20220308180709.2017638-1-minchan@kernel.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 45158C0012 X-Stat-Signature: 1tuqfr9bdd8giu3gab9ac3k4q53ufgi3 Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=DnDofeAk; dmarc=none; spf=pass (imf28.hostedemail.com: domain of akpm@linux-foundation.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-HE-Tag: 1646863591-152082 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: On Tue, 8 Mar 2022 10:07:09 -0800 Minchan Kim wrote: > Check lru_cache_disabled under bh_lru_lock. Otherwise, it could > introduce race below and it fails to migrate pages containing > buffer_head. > > CPU 0 CPU 1 > > bh_lru_install > lru_cache_disable > lru_cache_disabled = false > atomic_inc(&lru_disable_count); > invalidate_bh_lrus_cpu of CPU 0 > bh_lru_lock > __invalidate_bh_lrus > bh_lru_unlock > bh_lru_lock > install the bh > bh_lru_unlock What are the user-visible runtime effects of this bug? Is a cc:stable needed? Should there be a reported-by? Thanks.