From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f70.google.com (mail-pl0-f70.google.com [209.85.160.70]) by kanga.kvack.org (Postfix) with ESMTP id BC4DD6B0005 for ; Thu, 8 Feb 2018 12:18:10 -0500 (EST) Received: by mail-pl0-f70.google.com with SMTP id b6so133552plx.3 for ; Thu, 08 Feb 2018 09:18:10 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id o33-v6sor131379plb.85.2018.02.08.09.18.09 for (Google Transport Security); Thu, 08 Feb 2018 09:18:09 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <22e5e2e1-fd64-1a75-a80c-332a34266717@virtuozzo.com> 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: Dmitry Vyukov Date: Thu, 8 Feb 2018 18:17:48 +0100 Message-ID: Subject: Re: INFO: task hung in sync_blockdev Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Andrey Ryabinin 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 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? Unfortunately, syzbot uses GCE VMs for testing, and there does not seem to be such feature on GCE... -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org