Re: Still OOM problems with 4.9er/4.10er kernels

[Michal Hocko]

On Tue 28-02-17 07:06:41, Gerhard Wiesinger wrote:
> On 27.02.2017 09:27, Michal Hocko wrote:
> >On Sun 26-02-17 09:40:42, Gerhard Wiesinger wrote:
> >>On 04.01.2017 10:11, Michal Hocko wrote:
> >>>>The VM stops working (e.g. not pingable) after around 8h (will be restarted
> >>>>automatically), happened serveral times.
> >>>>
> >>>>Had also further OOMs which I sent to Mincham.
> >>>Could you post them to the mailing list as well, please?
> >>Still OOMs on dnf update procedure with kernel 4.10: 4.10.0-1.fc26.x86_64 as
> >>well on 4.9.9-200.fc25.x86_64
> >>
> >>On 4.10er kernels:
> >[...]
> >>kernel: Node 0 DMA32 free:5012kB min:2264kB low:2828kB high:3392kB
> >>active_anon:143580kB inactive_anon:143300kB active_file:2576kB
> >>inactive_file:2560kB unevictable:0kB writepending:0kB present:376688kB
> >>managed:353968kB mlocked:0kB slab_reclaimable:13708kB
> >>slab_unreclaimable:18064kB kernel_stack:2352kB pagetables:12888kB bounce:0kB
> >>free_pcp:412kB local_pcp:88kB free_cma:0kB
> >[...]
> >
> >>On 4.9er kernels:
> >[...]
> >>kernel: Node 0 DMA32 free:3356kB min:2668kB low:3332kB high:3996kB
> >>active_anon:122148kB inactive_anon:112068kB active_file:81324kB
> >>inactive_file:101972kB unevictable:0kB writepending:4648kB present:507760kB
> >>managed:484384kB mlocked:0kB slab_reclaimable:17660kB
> >>slab_unreclaimable:21404kB kernel_stack:2432kB pagetables:10124kB bounce:0kB
> >>free_pcp:120kB local_pcp:0kB free_cma:0kB
> >In both cases the amount if free memory is above the min watermark, so
> >we shouldn't be hitting the oom. We might have somebody freeing memory
> >after the last attempt, though...
> >
> >[...]
> >>Should be very easy to reproduce with a low mem VM (e.g. 192MB) under KVM
> >>with ext4 and Fedora 25 and some memory load and updating the VM.
> >>
> >>Any further progress?
> >The linux-next (resp. mmotm tree) has new tracepoints which should help
> >to tell us more about what is going on here. Could you try to enable
> >oom/reclaim_retry_zone and vmscan/mm_vmscan_direct_reclaim_{begin,end}
> 
> Is this available in this version?
> 
> https://koji.fedoraproject.org/koji/buildinfo?buildID=862775
> 
> kernel-4.11.0-0.rc0.git5.1.fc26

no idea.

> 
> How to enable?

mount -t tracefs none /trace
echo 1 > /trace/events/oom/reclaim_retry_zone/enabled
echo 1 > /trace/events/vmscan/mm_vmscan_direct_reclaim_begin
echo 1 > /trace/events/vmscan/mm_vmscan_direct_reclaim_end
-- 
Michal Hocko
SUSE Labs