Re: [PATCH] oom: remove PF_EXITING check completely

From: David Rientjes
Date: Wed Jun 02 2010 - 17:02:39 EST


On Wed, 2 Jun 2010, Oleg Nesterov wrote:

> > Today, I've thought to make some bandaid patches for this issue. but
> > yes, I've reached the same conclusion.
> >
> > If we think multithread and core dump situation, all fixes are just
> > bandaid. We can't remove deadlock chance completely.
> >
> > The deadlock is certenaly worst result, then, minor PF_EXITING optimization
> > doesn't have so much worth.
>
> Agreed! I was always wondering if it really helps in practice.
>

Nack, this certainly does help in practice, it prevents needlessly killing
additional tasks when one is exiting and may free memory. It's much
better to defer killing something temporarily if an eligible task (i.e.
one that has a high probability of memory allocations on current's nodes
or contributing to its memcg) is exiting.

We depend on this check specifically for our use of cpusets, so please
don't remove it.
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