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=-0.9 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID 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 3E489C28CF6 for ; Thu, 2 Aug 2018 02:23:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D0D93208A4 for ; Thu, 2 Aug 2018 02:23:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="hpDnHZ2w"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="hpDnHZ2w" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D0D93208A4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726141AbeHBEMA (ORCPT ); Thu, 2 Aug 2018 00:12:00 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:48180 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725921AbeHBEMA (ORCPT ); Thu, 2 Aug 2018 00:12:00 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id B6AA1602B7; Thu, 2 Aug 2018 02:23:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1533176591; bh=JN5I1dnxDyziBpQOLN5udr7oKu/3RV3FSL2Ye4jtXuM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=hpDnHZ2wGMjlv0aba6xpYMICvo+FLRjHjB+S6QnZUgrfPCAV5fthrYaENbMXWdRIg hgMknB/SmTj2KMFwjdJn5VPQiXheHh3axyJre3AM806ClKKbXLKSEB7AbXiJknCqsQ 1L1s5nkDJBu2+tFyEiPrQRmUzvjhM28SlfTKbbMg= Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id F3DEF6079C; Thu, 2 Aug 2018 02:23:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1533176591; bh=JN5I1dnxDyziBpQOLN5udr7oKu/3RV3FSL2Ye4jtXuM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=hpDnHZ2wGMjlv0aba6xpYMICvo+FLRjHjB+S6QnZUgrfPCAV5fthrYaENbMXWdRIg hgMknB/SmTj2KMFwjdJn5VPQiXheHh3axyJre3AM806ClKKbXLKSEB7AbXiJknCqsQ 1L1s5nkDJBu2+tFyEiPrQRmUzvjhM28SlfTKbbMg= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Wed, 01 Aug 2018 19:23:10 -0700 From: Sodagudi Prasad To: "Darrick J. Wong" Cc: "Theodore Y. Ts'o" , adilger.kernel@dilger.ca, wen.xu@gatech.edu, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Remounting filesystem read-only In-Reply-To: <20180728074704.GA4203@magnolia> References: <366cf3ac534bbadaaa61714a43006ac7@codeaurora.org> <20180727195213.GE13922@thunk.org> <20180728001823.GA28432@thunk.org> <20180728074704.GA4203@magnolia> Message-ID: <91cab9ba274131c4701fe4c1ce444d6b@codeaurora.org> X-Sender: psodagud@codeaurora.org User-Agent: Roundcube Webmail/1.2.5 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018-07-28 00:47, Darrick J. Wong wrote: > On Fri, Jul 27, 2018 at 08:18:23PM -0400, Theodore Y. Ts'o wrote: >> On Fri, Jul 27, 2018 at 01:34:31PM -0700, Sodagudi Prasad wrote: >> > > The error should be pretty clear: "Inode table for bg 0 marked as >> > > needing zeroing". That should never happen. >> > >> > Can you provide any debug patch to detect when this corruption is happening? >> > Source of this corruption and how this is partition getting corrupted? >> > Or which file system operation lead to this corruption? >> >> Do you have a reliable repro? If it's a one-off, it can be caused by >> *anything*. Crappy hardware, a bug in some proprietary, binary-only >> GPU driver dereferencing some wild pointer that corrupts kernel >> memory, etc. >> >> Asking for a debug patch is like asking for "can you create technology >> that can detect when a cockroach enter my house?" > > Well, ext4 *could* add metadata read and write verifiers to complain > loudly in dmesg about stuff that shouldn't be there, so at least we'd > know when we're writing cockroaches into the house... :) > > --D > Hi Ted, Below change fixed this issue. Thanks for your support. https://github.com/torvalds/linux/commit/5012284700775a4e6e3fbe7eac4c543c4874b559 "ext4: fix check to prevent initializing reserved inodes" -Thanks, Prasad >> So if you have a reliable repro, then we know what operations might be >> triggering the corruption, and then you work on creating a minimal >> repro, and only *then* when we have a restricted set of possibilities >> that might be the cause (for example, if removing a GPU call makes the >> problem go away, then the patch would need to be in the proprietary >> GPU driver....) >> >> > I am digging code a bit around this warning to understand more. >> >> The warning means that a flag in block group descriptor #0 is set >> that should never be set. How did the flag get set? There is any >> number of things that could cause that. >> >> You might want to look at the block group descriptor via dumpe2fs or >> debugfs, to see if it's just a single bit getting flipped, or if the >> entire block group descriptor is garbage. Note that under normal code >> paths, the flag *never* gets set by ext4 kernel code. The flag will >> get set on non-block group 0 block group descriptors by ext4, and the >> ext4 kernel code will only clear the flag. >> >> Of course, if there is a bug in some driver that dereferences a >> pointer widely, all bets are off. >> >> - Ted -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, Linux Foundation Collaborative Project