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=-4.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 BC455C433E0 for ; Mon, 13 Jul 2020 12:12:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8FCE62072D for ; Mon, 13 Jul 2020 12:12:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="rBNMv/m7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729616AbgGMMMs (ORCPT ); Mon, 13 Jul 2020 08:12:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34882 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728714AbgGMMMs (ORCPT ); Mon, 13 Jul 2020 08:12:48 -0400 Received: from mail-qt1-x842.google.com (mail-qt1-x842.google.com [IPv6:2607:f8b0:4864:20::842]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 39266C061794 for ; Mon, 13 Jul 2020 05:12:48 -0700 (PDT) Received: by mail-qt1-x842.google.com with SMTP id g13so9666104qtv.8 for ; Mon, 13 Jul 2020 05:12:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=RpYSNQC2exuWKUTSRfbzznKwmjgAwfUEWqW8RzotbS4=; b=rBNMv/m7LaTM5arw6QzFTxkwPH7OghzX2+1T4d0DECfS6DFMcAv1644Lu5aG+V9mCd PMKwN8m//5IvkMkE7befYGE5dNlHQGJ1XgOmVUFV5n1VP1FlkC+JoX7DQVbBuwjIflg0 Xiha5OPk6LbG69HWASAzNTROcVKp7AAUVGBPk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=RpYSNQC2exuWKUTSRfbzznKwmjgAwfUEWqW8RzotbS4=; b=TRrkA8A4tvQCiAmr/xtIs6grMT3SpFYdyoVBw6VLzkTlEtkr2OsQeKcz+p9Dc2KIu4 htkEHqKf9psBxH1DtWCiCHwnpi578rRVn93ZwFb5Ri8YPJdG45RBqjQDDn4QtBUweG8H 0NB5+NBqcYwXrmJjdHsM4NcWFEj2nnvNA7qCMyTr+Fr6iLF2dP+hBUJBxyvOMTrJYDqz l5JOLRxj/WQ46kkDX3/nIKDHPOGVTRlOWofO2/X9IRGfDFUDCnzwtU3+Ie3uprw1C3Zu OH2K472oYmyC6ZsHm+6DjjejzirldB7Mf9eXbBKGTzLbviRsdeK5edKtaOIwpk0Qq2I8 GhkQ== X-Gm-Message-State: AOAM531AwjIbPL+oss8ieWmuOYeUl1/JzHybthIRX2rK6c3hgrOVd1AE 8DcSHjgLzNCT4DGadsfjBsgyyQ== X-Google-Smtp-Source: ABdhPJwx4Win/yPZB7k/hma4rHDpqXlvpi9H6cFu4C0fIA3YbzEIBjZE/+zuFQEGlEfG1eUL1EaC+w== X-Received: by 2002:ac8:1a12:: with SMTP id v18mr85096949qtj.347.1594642366926; Mon, 13 Jul 2020 05:12:46 -0700 (PDT) Received: from localhost ([2620:15c:6:12:cad3:ffff:feb3:bd59]) by smtp.gmail.com with ESMTPSA id b8sm19823302qtg.45.2020.07.13.05.12.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Jul 2020 05:12:46 -0700 (PDT) Date: Mon, 13 Jul 2020 08:12:45 -0400 From: Joel Fernandes To: Linus Torvalds Cc: Naresh Kamboju , linux- stable , open list , linux-mm , Arnd Bergmann , Andrew Morton , Roman Gushchin , Michal Hocko , lkft-triage@lists.linaro.org, Chris Down , Michel Lespinasse , Fan Yang , Brian Geffon , Anshuman Khandual , Will Deacon , Catalin Marinas , pugaowei@gmail.com, Jerome Glisse , Greg Kroah-Hartman , Mel Gorman , Hugh Dickins , Al Viro , Tejun Heo , Sasha Levin Subject: Re: WARNING: at mm/mremap.c:211 move_page_tables in i386 Message-ID: <20200713121245.GA3926869@google.com> References: <20200712215041.GA3644504@google.com> <20200713025354.GB3644504@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Sun, Jul 12, 2020 at 08:51:26PM -0700, Linus Torvalds wrote: > > > Maybe saying "doing the pmd copies for the initial stack isn't > > > important, so let's just note this as a special case and get rid of > > > the WARN_ON()" might be an alternative solution. > > > > Personally, I feel it is better to keep the warning just so in the future we > > can detect any bugs. > > I don't disagree, the warning didn't happen to find a bug now, but it > did fine a case we might be able to do better. > > So now that I feel we understand the issue, and it's not a horrible > problem, just a (very hard to trigger) warning, I don't think there's > any huge hurry. > > I think think I will - for now - change the WARN_ON() to > WARN_ON_ONCE() (so that it doesn't floow the logs if somebody triggers > this odd special case this malisiously), and add a note about how > this happens to the code for posterito. > > And if/when you figure out a better way to fix it, we can update the note. > > Ok? Yes, that sounds great to me. thanks, - Joel