Re: [PATCH 3/8] mm,oom: Use list of mm_struct used by OOM victims.

[Oleg Nesterov <oleg@redhat.com>]

On 07/05, Oleg Nesterov wrote:
>
> > I don't think so. Setting MMF_OOM_REAPED indicates that memory used by that
> > mm is already reclaimed by the OOM reaper or by __mmput().
>
> Sure, this is clear,
>
> > mm->mm_users == 0
> > alone does not mean memory used by that mm is already reclaimed.
>   ^^^^^
>
> Of course! I meant that oom_has_pending_mm() can check _both_ mm_users and
> MMF_OOM_REAPED and then we do not need to set MMF_OOM_REAPED in exit_mm() path.
>
> No?

OK, perhaps you meant that mm_users == 0 can't help because __mmput() can block
after that and thus we should not assume this memory is already reclaimed...

So yes this probably needs more thinking. perhaps we can check mm->vma == NULL.

>
> > Making exit_oom_mm() a no-op for CONFIG_MMU=y would be OK,
>
> Yes. Not only because this can simplify other changes. I do believe that the less
> "oom" hooks we have the better, even if this needs some complications in oom_kill.c.
>
> For example, this series removes the extra try_to_freeze_tasks() from freeze_processes()
> (which is in fact the "oom" hook) and personally I do like this fact.
>
> And. Of course I am not sure this is possible, but to me it would be very nice
> to kill oom_reaper_list altogether if CONFIG_MMU=n.
>
> Oleg.

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