Re: [PATCH] oom_kill: oom_score_adj broken for processes with small memory usage

[Michal Hocko]

On Thu 01-07-21 07:54:30, minyard@xxxxxxx wrote:
> From: Corey Minyard <cminyard@xxxxxxxxxx>
> 
> If you have a process with less than 1000 totalpages, the calculation:
> 
>   adj = (long)p->signal->oom_score_adj;
>   ...
>   adj *= totalpages / 1000;
> 
> will always result in adj being zero no matter what oom_score_adj is,
> which could result in the wrong process being picked for killing.
> 
> Fix by adding 1000 to totalpages before dividing.

Yes, this is a known limitation of the oom_score_adj and its scale.
Is this a practical problem to be solved though? I mean 0-1000 pages is
not really that much different from imprecision at a larger scale where
tasks are effectively considered equal.

I have to say I do not really like the proposed workaround. It doesn't
really solve the problem yet it adds another special case.
-- 
Michal Hocko
SUSE Labs