Re: 4.8.8 kernel trigger OOM killer repeatedly when I have lots of RAM that should be free

[Vlastimil Babka]

On 11/22/2016 10:46 PM, Simon Kirby wrote:
> On Tue, Nov 22, 2016 at 05:14:02PM +0100, Vlastimil Babka wrote:
>
> > On 11/22/2016 05:06 PM, Marc MERLIN wrote:
> > > On Mon, Nov 21, 2016 at 01:56:39PM -0800, Marc MERLIN wrote:
> > > > On Mon, Nov 21, 2016 at 10:50:20PM +0100, Vlastimil Babka wrote:
> > > > > > 4.9rc5 however seems to be doing better, and is still running after 18
> > > > > > hours. However, I got a few page allocation failures as per below, but the
> > > > > > system seems to recover.
> > > > > > Vlastimil, do you want me to continue the copy on 4.9 (may take 3-5 days)
> > > > > > or is that good enough, and i should go back to 4.8.8 with that patch applied?
> > > > > > https://marc.info/?l=linux-mm&m=147423605024993
> > > > >
> > > > > Hi, I think it's enough for 4.9 for now and I would appreciate trying
> > > > > 4.8 with that patch, yeah.
> > > >
> > > > So the good news is that it's been running for almost 5H and so far so good.
> > >
> > > And the better news is that the copy is still going strong, 4.4TB and
> > > going. So 4.8.8 is fixed with that one single patch as far as I'm
> > > concerned.
> > >
> > > So thanks for that, looks good to me to merge.
> >
> > Thanks a lot for the testing. So what do we do now about 4.8? (4.7 is
> > already EOL AFAICS).
> >
> > - send the patch [1] as 4.8-only stable. Greg won't like that, I expect.
> >   - alternatively a simpler (againm 4.8-only) patch that just outright
> > prevents OOM for 0 < order < costly, as Michal already suggested.
> > - backport 10+ compaction patches to 4.8 stable
> > - something else?
> >
> > Michal? Linus?
> >
> > [1] https://marc.info/?l=linux-mm&m=147423605024993
>
> Sorry for my molasses rate of feedback. I found a workaround, setting
> vm/watermark_scale_factor to 500, and threw that in sysctl. This was on
> the MythTV box that OOMs everything after about a day on 4.8 otherwise.
>
> I've been running [1] for 9 days on it (4.8.4 + [1]) without issue, but
> just realized I forgot to remove the watermark_scale_factor workaround.
> I've restored that now, so I'll see if it becomes unhappy by tomorrow.

Thanks for the testing. Could you now try Michal's stable candidate [1] 
from this thread please?

[1] http://marc.info/?l=linux-mm&m=147988285831283&w=2

> I also threw up a few other things you had asked for (vmstat, zoneinfo
> before and after the first OOM on 4.8.4): http://0x.ca/sim/ref/4.8.4/
> (that was before booting into a rebuild with [1] applied)
>
> Simon-