linux uml segfault

Anton Ivanov anton.ivanov at kot-begemot.co.uk
Wed Feb 24 06:44:39 EST 2021



On 23/02/2021 17:26, Ritesh Raj Sarraf wrote:
> Added the debian bug report in CC.
> 
> On Tue, 2021-02-23 at 17:19 +0000, Anton Ivanov wrote:
>>> The current Debian user-mode-linux package in unstable is based on
>>> the 5.10.5 stable source which includes the mentioned patch, but is
>>> still causing an error for some users.
>>
>> After updating the tree to 5.10.5 and applying all Debian patches
>> from the package, I cannot reproduce the bug.
>>
>> I am running it on 5.10, 5.2 and 4.19 hosts with the same parameters
>> without issues. Hosts are all up to date Debian 10.8 and so is the
>> UML userspace.
>>
> 
> Did you mean 5.10, 5.2 and 4.19 (UML) guests ?
> 
> We've seen this happen on Debian Testing and Unstable Host (of which
> the former would soon be the next stable i.e. Debian Bullseye).
> 
> In our tests, when running the same linux uml binary (5.10) on a Debian
> Stable Host, it is working fine.

I cannot reproduce it on a physical Bullseye host using the Debian user-mode-linux package compiled from source.

Environment - Bullseye minimal install and build deps. 6 cores/12 threads Ryzen

I cannot reproduce it using the upstream source and the patches from the user-mode-linux package

Environment - same as above.

I cannot reproduce it using the upstream source + patches and compiling on Buster using the following:

1. Bullseye physical host, minimal install, same hardware

2. Bullseye VM, minimal install, running with 4 vCPUs on the same host

3. Bullseye LXC container running on a Debian Buster host, minimal install, same hardware

In all cases it boots cleanly and there are no segfaults.

So, frankly, no idea what is causing it to crash - I have run most combinations of 5.10 on a 5.10, all work fine here.

-- 
Anton R. Ivanov
https://www.kot-begemot.co.uk/



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