From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751859AbeBIPbk (ORCPT ); Fri, 9 Feb 2018 10:31:40 -0500 Received: from mail-eopbgr00101.outbound.protection.outlook.com ([40.107.0.101]:58432 "EHLO EUR02-AM5-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751145AbeBIPbh (ORCPT ); Fri, 9 Feb 2018 10:31:37 -0500 Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=aryabinin@virtuozzo.com; Subject: Re: INFO: task hung in sync_blockdev To: Dmitry Vyukov Cc: Jan Kara , Andi Kleen , syzbot , Andrew Morton , jlayton@redhat.com, LKML , Linux-MM , Mel Gorman , Ingo Molnar , rgoldwyn@suse.com, syzkaller-bugs@googlegroups.com, linux-fsdevel@vger.kernel.org References: <001a11447070ac6fcb0564a08cb1@google.com> <20180207155229.GC10945@tassilo.jf.intel.com> <20180208092839.ebe5rk6mtvkk5da4@quack2.suse.cz> <20180208140833.lpr4yjn7g3v3cdy3@quack2.suse.cz> <20180208161821.f7x3gopytdtzgf65@quack2.suse.cz> <22e5e2e1-fd64-1a75-a80c-332a34266717@virtuozzo.com> From: Andrey Ryabinin Message-ID: Date: Fri, 9 Feb 2018 18:31:51 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [195.214.232.6] X-ClientProxiedBy: HE1PR08CA0048.eurprd08.prod.outlook.com (2603:10a6:7:2a::19) To VI1PR08MB2830.eurprd08.prod.outlook.com (2603:10a6:802:19::27) X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 2211207d-c4f0-4826-9a99-08d56fd22fb5 X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(5600026)(4604075)(4534165)(7168020)(4627221)(201703031133081)(201702281549075)(2017052603307)(7153060)(7193020);SRVR:VI1PR08MB2830; X-Microsoft-Exchange-Diagnostics: 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X-Microsoft-Exchange-Diagnostics: 1;VI1PR08MB2830;20:loLprnGksPnuE/8cuML180xc7IUQY4oEYIAEXnO22tcm++yixP7dd73slBhx0pf6DRUVWpDBnyWNpfBaDAH2Z2Z9sPWqbxiNu8lRen32chmgmLEoXWoNSOr95DRHe8xSnSq9+GrQCz18gETBT9xzvJ74h/Bny3qvIy/+Z1Yso88= X-OriginatorOrg: virtuozzo.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Feb 2018 15:31:26.7039 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 2211207d-c4f0-4826-9a99-08d56fd22fb5 X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 0bc7f26d-0264-416e-a6fc-8352af79c58f X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR08MB2830 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/08/2018 08:17 PM, Dmitry Vyukov wrote: > On Thu, Feb 8, 2018 at 5:23 PM, Andrey Ryabinin wrote: >> >> >> On 02/08/2018 07:18 PM, Jan Kara wrote: >> >>>> By "full kernel crashdump" you mean kdump thing, or something else? >>> >>> Yes, the kdump thing (for KVM guest you can grab the memory dump also from >>> the host in a simplier way and it should be usable with the crash utility >>> AFAIK). >>> >> >> In QEMU monitor 'dump-guest-memory' command: >> >> (qemu) help dump-guest-memory >> dump-guest-memory [-p] [-d] [-z|-l|-s] filename [begin length] -- dump guest memory into file 'filename'. >> -p: do paging to get guest's memory mapping. >> -d: return immediately (do not wait for completion). >> -z: dump in kdump-compressed format, with zlib compression. >> -l: dump in kdump-compressed format, with lzo compression. >> -s: dump in kdump-compressed format, with snappy compression. >> begin: the starting physical address. >> length: the memory size, in bytes > > > Nice! > Do you know straight away if it's scriptable/automatable? Or do I just > send some magic sequence of bytes representing ^A+C, > dump-guest-memory, \n to stdin pipe? > I wouldn't do it via stdin. You can setup monitor on any chardev you like and send command there when you know that guest paniced. Look for -mon and -chardev qemu options. > Unfortunately, syzbot uses GCE VMs for testing, and there does not > seem to be such feature on GCE... > Well, you still have kdump.