From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965031AbbLOLFv (ORCPT ); Tue, 15 Dec 2015 06:05:51 -0500 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:34562 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964803AbbLOLFt (ORCPT ); Tue, 15 Dec 2015 06:05:49 -0500 To: Jens Axboe , Ming Lei Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Rob Herring , Eric Auger , "linux-arm-kernel@lists.infradead.org" From: Andre Przywara Subject: block layer bug with 4.4-rc3+ X-Enigmail-Draft-Status: N1110 Organization: ARM Ltd. Message-ID: <566FF3ED.1000503@arm.com> Date: Tue, 15 Dec 2015 11:05:17 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, I've been experiencing issues with at least 4.4-rc3 (including current HEAD) on a Calxeda Midway (4*ARM Cortex-A15 (32-bit), 8GB RAM, SATA spinning disk or SSD). After some disk I/O load (kernel compile with -j6) I see the kernel screaming: [ 103.736982] ata1.00: exception Emask 0x0 SAct 0x3ffff0 SErr 0x0 action 0x6 frozen [ 103.744476] ata1.00: failed command: WRITE FPDMA QUEUED [ 103.749707] ata1.00: cmd 61/00:20:48:6b:41/08:00:0a:00:00/40 tag 4 ncq 1048576 out [ 103.749707] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout) [ 103.764659] ata1.00: status: { DRDY } [ 103.768321] ata1.00: failed command: WRITE FPDMA QUEUED [ 103.773547] ata1.00: cmd 61/98:28:48:73:41/42:00:0a:00:00/40 tag 5 ncq 8728576 out [ 103.773547] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout) < repeated with increasing tag numbers> This repeats for a while, but then seems to recover later, though I haven't checked if there are more issues and rebooted instead to avoid filesystem damage. While I agree that this looks like a disk error on the first glance, I never saw this before 4.4-rc2, had the very same error on different nodes (with another spinning disk and even an SSD) and I can make it vanish by reverting the commit I identified after bisection: commit 578270bfbd2803dc7b0b03fbc2ac119efbc73195 Author: Ming Lei Date: Tue Nov 24 10:35:29 2015 +0800 block: fix segment split ... I understand that this fix seems sane, but actually reverting it fixes the issue for me: 4.4-rc5 crashed within some minutes with the above log, 4.4-rc5 with 578270bfbd reverted survived 19 hours of continuous kernel compiles without issues. Looking at the git history of that file I see quite some recent changes there, but it's beyond my understanding of the code to spot the real culprit. Can anyone point me to a change in blk-merge.c I could try to revert to identify the real root cause? I can run tests quickly, though a real positive case would need some hours of runtime to be sure it's fine. Many thanks! Cheers, Andre.