On Sun 21-08-16 23:19:50, Arkadiusz Miskiewicz wrote:

On Friday 19 of August 2016, Vlastimil Babka wrote:

quoted

On 08/18/2016 08:49 PM, Arkadiusz Miskiewicz wrote:

quoted

On Wednesday 17 of August 2016, Michal Hocko wrote:

quoted

On Wed 17-08-16 10:34:54, Arkadiusz MiA?kiewicz wrote:
[...]

quoted

With "[PATCH] mm, oom: report compaction/migration stats for higher
order requests" patch:
https://ixion.pld-linux.org/~arekm/p2/ext4/log-20160817.txt

Didn't count much - all counters are 0
compaction_stall:0 compaction_fail:0 compact_migrate_scanned:0
compact_free_scanned:0 compact_isolated:0 pgmigrate_success:0
pgmigrate_fail:0

Dohh, COMPACTION counters are events and those are different than other
counters we have. They only have per-cpu representation and so we would
have to do
+       for_each_online_cpu(cpu) {
+               struct vm_event_state *this = &per_cpu(vm_event_states,
cpu); +               ret += this->event[item];
+       }

which is really nasty because, strictly speaking, we would have to do
{get,put}_online_cpus around that loop and that uses locking and we do
not want to possibly block in this path just because something is in the
middle of the hotplug. So let's scratch that patch for now and sorry I
haven't realized that earlier.

quoted

two processes were killed by OOM (rm and cp), the rest of rm/cp didn't
finish

and I'm interrupting it to try that next patch:

quoted

Could you try to test with
patch from
http://lkml.kernel.org/r/20160816031222.GC16913@js1304-P5Q-DELUXE
please? Ideally on top of linux-next. You can add both the compaction
counters patch in the oom report and high order atomic reserves patch
on top.

Uhm, was going to use it on top of 4.7.[01] first.

OK

So with 
http://lkml.kernel.org/r/20160816031222.GC16913@js1304-P5Q-DELUXE OOM no
longer happens (all 10x rm/cp processes finished).

Is it on top of 4.7 then? 

Yes, it was on top of 4.7.0.

quoted

That's a bit different from the other reporter
who needed both linux-next and this patch to avoid OOM.
In any case the proper solution should restrict this disabled heuristic
to highest compaction priority, which needs the patches from linux-next
anyway.

So can you please also try linux-next with the patch from
http://marc.info/?l=linux-mm&m=147158805719821 ?

https://ixion.pld-linux.org/~arekm/p2/ext4/log-20160819.txt
https://ixion.pld-linux.org/~arekm/p2/ext4/log-trace_pipe-20160819.txt.gz

rm/cp -al x10 succeeded without any OOM

so the question is - which solution is "the one" for stable/4.7.x ?

I will send an email later today with other people reporting pre-mature
OOMs later today and will make sure you are on the CC list as well.

Thanks for the testing!
-- 
Michal Hocko
SUSE Labs

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