2021-06-17 10:33:22

by Juergen Gross

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Subject: Re: Linux 5.13-rc6 regression to 5.12.x: kernel OOM and panic during kernel boot in low memory Xen VM's (256MB assigned memory).

On 17.06.21 11:26, Sander Eikelenboom wrote:
> L.S.,
>
> I just tried to upgrade and test the linux kernel going from the 5.12
> kernel series to 5.13-rc6 on my homeserver with Xen, but ran in some
> trouble.
>
> Some VM's boot fine (with more than 256MB memory assigned), but the
> smaller (memory wise) PVH ones crash during kernel boot due to OOM.
> Booting VM's with 5.12(.9) kernel still works fine, also when dom0 is
> running 5.13-rc6 (but it has more memory assigned, so that is not
> unexpected).
>
> The 5.13-rc6'ish kernel is a pull of today, tried both with and without

> last AKPM's patches, but that
> makes no difference.
>
> Below are stacktraces from a few of the crashing VM's.
>
> Attached is the kernel .config
>
> Any pointers ?

Did you compare memory usage with a bootable guest between kernel 5.12
and 5.13-rc6?

Any chance you could bisect?


Juergen


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2021-06-17 16:05:16

by Sander Eikelenboom

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Subject: Re: Linux 5.13-rc6 regression to 5.12.x: kernel OOM and panic during kernel boot in low memory Xen VM's (256MB assigned memory).

On 17/06/2021 12:30, Juergen Gross wrote:
> On 17.06.21 11:26, Sander Eikelenboom wrote:
>> L.S.,
>>
>> I just tried to upgrade and test the linux kernel going from the 5.12
>> kernel series to 5.13-rc6 on my homeserver with Xen, but ran in some
>> trouble.
>>
>> Some VM's boot fine (with more than 256MB memory assigned), but the
>> smaller (memory wise) PVH ones crash during kernel boot due to OOM.
>> Booting VM's with 5.12(.9) kernel still works fine, also when dom0 is
>> running 5.13-rc6 (but it has more memory assigned, so that is not
>> unexpected).
>>
>> The 5.13-rc6'ish kernel is a pull of today, tried both with and without
>
>> last AKPM's patches, but that
>> makes no difference.
>>
>> Below are stacktraces from a few of the crashing VM's.
>>
>> Attached is the kernel .config
>>
>> Any pointers ?
>
> Did you compare memory usage with a bootable guest between kernel 5.12
> and 5.13-rc6?
>
> Any chance you could bisect?
>
>
> Juergen
>

Yeah a bisection is already underway, still 10 steps to go ...

--
Sander