Re: [PATCH] mm,oom: use per signal_struct flag rather than clear TIF_MEMDIE

[Oleg Nesterov <oleg@redhat.com>]

On 06/30, Michal Hocko wrote:
>
> On Wed 29-06-16 22:14:09, Oleg Nesterov wrote:
> > On 06/28, Michal Hocko wrote:
> > >
> > >
> > > Could you point me to where it depends on that? I mean if we are past
> > > exit_mm then we have unmapped the address space most probably but why
> > > should we care about that in the scheduler? There shouldn't be any
> > > further access to the address space by that point. I can see that
> > > context_switch() checks task->mm but it should just work when it sees it
> > > non NULL, right?
> >
> > But who will do the final mmdrop() then? I am not saying this is impossible
> > to change, say we do this in finish_task_switch(TASK_DEAD) or even in
> > free_task(), but we do not want this?
>
> I thought it could be done somewhere in release_task after we unhash
> the process

No, we can't do this. Note that release_task() can be called right after
exit_notify() by its parent ot by the exiting thread itself. It can still
run after that and it needs ->active_mm.

Oleg.

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