Re: [Xen-devel] arm: xl vcpu-pin leads to oom-killer slashing processes

[Julien Grall <julien.grall@xxxxxxx>]

On 05/12/2018 12:40, Andrii Anisov wrote:
> On 05.12.18 14:15, Julien Grall wrote:
> > > Yes, it thinks so. But it is not linked to domain .
> > What do you mean?
> It should be read as "But it is not linked to domain memory size".
So if you increase the memory of the dom0 you will still see the error?

> > A memory corruption by Xen is extremely unlikely. 
> I believe in that.
I need at least some sort of proof that Xen might corrupt the kernel. I don't 
believe we manage to just corrupt the kernel memory subsystem with good enough 
value reliably. So maybe we should start looking at more plausible cause.
> > So it looks like to me this is a related to your domain (kernel or userspace), 
> > possibly because memory has not been freed correctly.
> It might be. But happens only with and right after vcpu pinning.
It does not mean this is because of Xen. It might just be because of Xen drivers 
that does not free memory.
> > Below a list of questions to answer:
> >      - Can you give the steps to reproduce it from boot?
> The step is single and trivial, just try to pin vcpus from Dom0.
I tried and can't reproduce it. But I am using 4.20-rc4 and not 4.14.35. If you 
think the bug was introduced in recent Xen, then the first step is to downgrade 
Xen. If it does not happen on the downgraded version, then you can bisect it.
> >      - How much memory left do you have before calling xl vcpu-pin?
> Meminfo says
>      root@salvator-x:~# cat /proc/meminfo
>      MemTotal:        2995828 kB
>      MemFree:         2810360 kB
>      MemAvailable:    2758420 kB
How about after vCPU pining? Do you see the memory free going down?

> Top says:
>      Mem: 185592K used, 2810236K free, 21020K shrd, 0K buff, 53000K cached
>      CPU:   0% usr   8% sys   0% nic  91% idle   0% io   0% irq   0% sirq
>
> >      - When exactly do you pin the vCPUs? (i.e how long after boot)
> Right after login.
So that's reliably happening? Are you sure there are nothing else on the system 
using memory? For instance you seem to have nfs in place.
> >      - What are the other programs running? How much memory are they using?
> Weston, systemd daemons, Xen daemons, other Yocto daemons. Actually, nothing 
> special.
I would try to remove unnecessary programs. So you can narrow down the issues.

Cheers,

--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel