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 67658C433EF for ; Wed, 9 Mar 2022 22:40:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id AEDFA8D0002; Wed, 9 Mar 2022 17:40:45 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A9D6E8D0001; Wed, 9 Mar 2022 17:40:45 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 93EA98D0002; Wed, 9 Mar 2022 17:40:45 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 84CD98D0001 for ; Wed, 9 Mar 2022 17:40:45 -0500 (EST) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 42D11181CCB09 for ; Wed, 9 Mar 2022 22:40:45 +0000 (UTC) X-FDA: 79226318850.26.D7BA8E1 Received: from mail-pg1-f179.google.com (mail-pg1-f179.google.com [209.85.215.179]) by imf10.hostedemail.com (Postfix) with ESMTP id C1326C0012 for ; Wed, 9 Mar 2022 22:40:44 +0000 (UTC) Received: by mail-pg1-f179.google.com with SMTP id o23so3122705pgk.13 for ; Wed, 09 Mar 2022 14:40:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=pvPyQOUK1Gw9CokGjQgnCkQhkHHplgDsrtGMviZ3X7A=; b=BaBvApgiq6eKkKHjV5y9VNHSX8YDVNOkXj5MayW95Bs0iCadLeVSVrBWCSdznB/PA4 0gKQ2wbaRy7xLMnNrIapT0t2YDCwEkZbX6Z2RsTW+Vxjk9bX0Nl42o76dLzzL3OdIF+b 8qXFqJI1VXyVwT/F93OTri8tbdhSHqlQOdcASY9uXy8RcNqd6XwZwMCNRWhyh2QG/Nea 9XCa2PeR7oijZX6OcHOj3mt6MMzGw0+QbQea2MlyfD7hGKunuDfDz2l+8uzuyyeBH6fr TBk2OQETxmRVJeM0n+PhbCEGu8kAyfbQXYuQNAAZ2ouSFjKQ+gE076+73neyZ7eCz52M wcCg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=pvPyQOUK1Gw9CokGjQgnCkQhkHHplgDsrtGMviZ3X7A=; b=eP9rbVVFPMDmZdd3E/7SiXKIDO6l8mUNKTUzjZD4xj7PBERRh/NiIkIJXKG8/D9QLK urdsfcGnAGHNKb0Z0XM1lLx7WYqdBoS9PRLbKg1FCWJKcYNTqoWpmMydrqCqkHKs4ftb khRa5b+lGHbQxuS8maJehZzrB8c6hWmFI5aHyxqv/ZjgQ9edAmcPxieDRAf2M7wEqAjD RJx32DHRB82kpVUk7+hXA9ide14A/3RZtsJhpl2dfuNTGarS5bN6kE90pJLjjSwrxvMy J82GDD0hZDVWnVdRBXIrKCecwMGRTeDz1EdJM9FdnOkGOFRLwuJRHuLx3ewFUGCgcvv4 0VrQ== X-Gm-Message-State: AOAM530qpXMPFlySsakFpedLjCi3JwtOENDBitObxP94LcmvCt+zm7oj xwC+rrup6Ec1rbMoacqPAVE= X-Google-Smtp-Source: ABdhPJw3G9FAPbU5cZQShJnDrdis4xALn9ruAKxBY0EJXFu4TjXvyQ0wqkxKipN1LGB2EDM5nIH+dg== X-Received: by 2002:a65:61ad:0:b0:378:8f01:7674 with SMTP id i13-20020a6561ad000000b003788f017674mr1576104pgv.314.1646865643638; Wed, 09 Mar 2022 14:40:43 -0800 (PST) Received: from google.com ([2620:15c:211:201:aee3:831e:b1d0:905f]) by smtp.gmail.com with ESMTPSA id 2-20020a631342000000b0037487b6b018sm3166928pgt.0.2022.03.09.14.40.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Mar 2022 14:40:43 -0800 (PST) Date: Wed, 9 Mar 2022 14:40:41 -0800 From: Minchan Kim To: Andrew Morton 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: References: <20220308180709.2017638-1-minchan@kernel.org> <20220309140627.eeaa069daa921dbef64f8970@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220309140627.eeaa069daa921dbef64f8970@linux-foundation.org> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: C1326C0012 X-Rspam-User: Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=BaBvApgi; spf=pass (imf10.hostedemail.com: domain of minchan.kim@gmail.com designates 209.85.215.179 as permitted sender) smtp.mailfrom=minchan.kim@gmail.com; dmarc=fail reason="SPF not aligned (relaxed), DKIM not aligned (relaxed)" header.from=kernel.org (policy=none) X-Stat-Signature: ubmttgt5b95cyt5i5zi3nk4ohz1ttik3 X-HE-Tag: 1646865644-992308 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Mar 09, 2022 at 02:06:27PM -0800, Andrew Morton wrote: > 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? Once the race happens, CMA allocation fails, which is critical for the workload CMA allocation depends. > > Is a cc:stable needed? Ah, missed it. I think it would be rare to trigger the race considering how CMA allocation would be rare but once it happens, it makes the CMA allocation failure, which is critical for some. And the patch size is small enough so I think it's worth to add in the stable. > > Should there be a reported-by? I found it on my own while I reviewed Marcelo's other patchset so I don't think we need to add my reported-by. Andrew, please tell me if you want me resend it.