Re: [PATCH] mm: fix oom work when memory is under pressure

[Michal Hocko <mhocko@suse.cz>]

On Tue 13-09-16 21:13:21, zhong jiang wrote:
> On 2016/9/13 1:44, Michal Hocko wrote:
[...]
> > If you want to solve this problem properly then you would have to give
> > tasks which are looping in the page allocator access to some portion of
> > memory reserves. This is quite tricky to do right, though.
>
> To use some portion of memory reserves is almost no effect in a so
> starvation scenario.  I think the hungtask still will occur. it can
> not solve the problem primarily.

Granting an access to memory reserves is of course no full solution but
it raises chances for a forward progress. Other solutions would have to
guarantee that the memory reclaimed on behalf of the requester will be
given to the requester. Not an easy task

> > Retry counters with the fail path have been proposed in the past and not
> > accepted.
>
> The above patch have been tested by runing the trinity.  The question
> is fixed.  Is there any reasonable reason oppose to the patch ? or it
> will bring in any side-effect.

Sure there is. Low order allocations have been traditionally non failing
and changing that behavior is a major obstacle because it opens up a
door to many bugs. I've tried to do something similar in the past and
there was a strong resistance against it. Believe me been there done
that...

-- 
Michal Hocko
SUSE Labs

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