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 X-Spam-Level: X-Spam-Status: No, score=-14.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30B2FC64E7B for ; Mon, 30 Nov 2020 12:50:54 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9B8672084C for ; Mon, 30 Nov 2020 12:50:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="1kvwSylo" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9B8672084C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 962848D0002; Mon, 30 Nov 2020 07:50:52 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8EB5C8D0001; Mon, 30 Nov 2020 07:50:52 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7B1D78D0002; Mon, 30 Nov 2020 07:50:52 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0147.hostedemail.com [216.40.44.147]) by kanga.kvack.org (Postfix) with ESMTP id 620888D0001 for ; Mon, 30 Nov 2020 07:50:52 -0500 (EST) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 264438249980 for ; Mon, 30 Nov 2020 12:50:52 +0000 (UTC) X-FDA: 77541069144.09.sink46_0c00506273a2 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin09.hostedemail.com (Postfix) with ESMTP id 16D8F180AD820 for ; Mon, 30 Nov 2020 12:50:52 +0000 (UTC) X-HE-Tag: sink46_0c00506273a2 X-Filterd-Recvd-Size: 2917 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf21.hostedemail.com (Postfix) with ESMTP for ; Mon, 30 Nov 2020 12:50:51 +0000 (UTC) Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8961920691; Mon, 30 Nov 2020 12:50:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1606740650; bh=nfZbtD73DTePQNKxwwpOaKw4hDXsUnEjnQEC4OR5G60=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=1kvwSyloW3NYJEioeDsZchDROm/p5cjKC6OD8usi2aliaiJbyb3Hd2TZr5ldIiNbd jahX7zmBEXJF2ZkCuLNyz1l4O06gPk6+6fzvzvibeanc6NWTo8/hk4aAtUDc5xUZJK tZBa152K3FU1v2X158ga4j8T46oHfSDay0u0LpdU= Date: Mon, 30 Nov 2020 12:50:46 +0000 From: Will Deacon To: Peter Zijlstra Cc: Vlastimil Babka , Mohamed Alzayat , "Aneesh Kumar K.V" , linux-mm@kvack.org Subject: Re: Potential bug in soft-dirty bits (with test case) Message-ID: <20201130125045.GG24563@willie-the-truck> References: <2e60ad6d-7bdf-e19e-4ad9-6942f76088d3@suse.cz> <20201130120241.GP3040@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201130120241.GP3040@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) 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 Mon, Nov 30, 2020 at 01:02:41PM +0100, Peter Zijlstra wrote: > On Mon, Nov 30, 2020 at 12:51:59PM +0100, Vlastimil Babka wrote: > > On 11/30/20 11:37 AM, Mohamed Alzayat wrote: > > > > Thanks for confirming, Vlastimil! > > > > > > The first bad commit is: 0758cd8304942292e95a0f750c374533db378b32 > > > asm-generic/tlb: avoid potential double flush > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0758cd8304942292e95a0f750c374533db378b32 > > > > > > Reverting this commit solves the problem, but this might not be the > > > right way of fixing it. > > > > Thanks for bisecting! Let's CC people involved in that commit. All important > > should be in the quoted conversation above. > > There's a thread about it here: > > https://lkml.kernel.org/r/20201120143557.6715-1-will@kernel.org > > That softdirty code really shouldn't be using mmu_gather imo, but I'm > still not clear on what exactly is broken why there. I'll spin a v2 of that series soon, so I'll add folks here to cc. The fact that a test noticed the missing invalidation is a pretty good reason for us to add it back! Will