From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ivanoab7.miniserver.com ([37.128.132.42] helo=www.kot-begemot.co.uk) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iL8eV-0007Ny-HZ for linux-um@lists.infradead.org; Thu, 17 Oct 2019 16:29:29 +0000 Subject: Re: uml segfault during I/O From: Anton Ivanov References: <1ccf27d8-6b6a-7d08-acef-93077f07511b@cambridgegreys.com> <5dc5e0694d2fcf2f8bb083e3861fd1b39c768b8c.camel@researchut.com> Message-ID: <4892b3ca-6b26-0b96-d21f-ac8b31fb2270@cambridgegreys.com> Date: Thu, 17 Oct 2019 17:29:21 +0100 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-um" Errors-To: linux-um-bounces+geert=linux-m68k.org@lists.infradead.org To: rrs@researchut.com, linux-um@lists.infradead.org On 17/10/2019 16:03, Anton Ivanov wrote: > > > On 17/10/2019 14:33, Anton Ivanov wrote: >> >> >> On 17/10/2019 14:30, Ritesh Raj Sarraf wrote: >>> On Thu, 2019-10-17 at 14:02 +0100, Anton Ivanov wrote: >>>> Looking into that. I have not run into anything like that, but I have >>>> not used any of the legacy networking for 5 odd years now. >>>> >>> >>> Do you think this is related to networking ? I ask because there was no >>> network activity going on. >> >> no, it's disk somewhere. I managed to reproduce it with 5.2 stock on >> Debian 5.2 host. >> >>> >>> apt is just an example. The packages were all already downloaded and >>> there was no network activity. Rather, there was block I/O. >> >> I am looking into that. >> >>> >>> One thing I noticed, which may or may not be useful to this report. I >>> was booting the uml guest and immediately logging into it and running >>> the block I/O. And the segfault would occur. >>> >>> If I, instead, booted the uml vm and let it remain idle for a minute or >>> so and then did the I/O, it worked fine. So I am not sure if there is >>> any lazy initialization happening in the background which gets >>> corrupted during immediate hot boot I/O. >> >> Interesting... >> >>> >>> On the other hand, if you think there can be any number of commands to >>> run locally that could generate more information, please assist me so. >> >> As I said - I managed to reproduce it, I am looking at it. In first >> instance I am trying with a couple of version up/down to see if this >> is 5.2 specific. > > I cannot even get it to start on 5.4-rc1, 5.3 shows the same symptoms. This is something outside the UBD driver as such. There were no notable changes to it since we ported it to block-mq and added DISCARD which was quite a while back. I am going to check the other usual suspects such as IRQs, but that is something I test quite extensively when working on the networking side. So I suspect that this is something outside UML which is showing only in UML for some reason. A. > >> >>> >>> Thanks, >>> Ritesh >>> >>> >>> _______________________________________________ >>> linux-um mailing list >>> linux-um@lists.infradead.org >>> http://lists.infradead.org/mailman/listinfo/linux-um >>> >> > -- Anton R. Ivanov Cambridgegreys Limited. Registered in England. Company Number 10273661 https://www.cambridgegreys.com/ _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um