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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B5A9AC43217 for ; Fri, 11 Feb 2022 14:37:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350947AbiBKOhV (ORCPT ); Fri, 11 Feb 2022 09:37:21 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:39348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242516AbiBKOhU (ORCPT ); Fri, 11 Feb 2022 09:37:20 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 347CC188; Fri, 11 Feb 2022 06:37:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=xDS2cI/G7I7Pz1FO/b0GGCLA/neDA3CUGtTdIi3Kxmw=; b=DiwyC2U1oICQI8XH4WIMg6OoP1 da2zROQJylJHR/am2VUi7ytvDHVJrPRl4sNIbRymv3jjuN55pqSKvmP3kqaGmCnr/1wOP5Vq2tlmq 6tRpYF8Xekva5k0MKJRwl6L4nDPgOG3VIzFlIq0ExyRpChMgkKHFVgshddkUjWGNxDByZMsX9xZBn V2viILZgRTn1yFTHZPFymlzptBy68x8h0PeGfQcKxODbBo83AYxG5Cr0oxdkYLaMz9QCtVWzsNQ5V KU8wCsZHrkHfW3+rCRJ96XL5PuFqPhKNVNjSi8dxC42ECSAVzPXyrXx8lxmupOj/bvr7sRMP4ihEq aHCs6y1A==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nIX2t-00AThU-BS; Fri, 11 Feb 2022 14:37:11 +0000 Date: Fri, 11 Feb 2022 14:37:11 +0000 From: Matthew Wilcox To: Lee Jones Cc: "Darrick J. Wong" , linux-kernel@vger.kernel.org, Stable , Christoph Hellwig , Dave Chinner , Goldwyn Rodrigues , "Darrick J . Wong" , Bob Peterson , Damien Le Moal , Theodore Ts'o , Andreas Gruenbacher , Ritesh Harjani , Johannes Thumshirn , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, cluster-devel@redhat.com, syzbot+0ed9f769264276638893@syzkaller.appspotmail.com Subject: Re: [PATCH 1/1] Revert "iomap: fall back to buffered writes for invalidation failures" Message-ID: References: <20220209085243.3136536-1-lee.jones@linaro.org> <20220210045911.GF8338@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Thu, Feb 10, 2022 at 10:15:52AM +0000, Lee Jones wrote: > On Wed, 09 Feb 2022, Darrick J. Wong wrote: > > > On Wed, Feb 09, 2022 at 08:52:43AM +0000, Lee Jones wrote: > > > This reverts commit 60263d5889e6dc5987dc51b801be4955ff2e4aa7. > > > > > > Reverting since this commit opens a potential avenue for abuse. > > > > What kind of abuse? Did you conclude there's an avenue solely because > > some combination of userspace rigging produced a BUG warning? Or is > > this a real problem that someone found? > > Genuine question: Is the ability for userspace to crash the kernel > not enough to cause concern? I would have thought that we'd want to > prevent this. The kernel doesn't crash. It's a BUG(). That means it kills the task which caused the BUG(). If you've specified that the kernel should crash on seeing a BUG(), well, you made that decision, and you get to live with the consequences. > The link provided doesn't contain any further analysis. Only the > reproducer and kernel configuration used, which are both too large to > enter into a Git commit. But not too large to put in an email. Which you should have sent to begin with, not a stupid reversion commit. > > OH WAIT, you're running this on the Android 5.10 kernel, aren't you? > > The BUG report came from page_buffers failing to find any buffer heads > > attached to the page. > > https://android.googlesource.com/kernel/common/+/refs/heads/android12-5.10-2022-02/fs/ext4/inode.c#2647 > > Yes, the H/W I have to prototype these on is a phone and the report > that came in was specifically built against the aforementioned > kernel. > > > Yeah, don't care. > > "There is nothing to worry about, as it's intended behaviour"? No. You've come in like a fucking meteorite full of arrogance and ignorance. Nobody's reacting well to you right now. Start again, write a good bug report in a new thread.