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

[Michal Hocko <mhocko@kernel.org>]

On Tue 22-11-16 17:38:01, Greg KH 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?
> 
> Just wait for 4.8-stable to go end-of-life in a few weeks after 4.9 is
> released?  :)

OK, so can we push this through to 4.8 before EOL and make sure there
won't be any additional pre-mature high order OOM reports? The patch
should be simple enough and safe for the stable tree. There is no
upstream commit because 4.9 is fixed in a different way which would be
way too intrusive for the stable backport.
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