Re: [PATCH] oom: Make coredump interruptible

From: Oleg Nesterov
Date: Sun Jun 13 2010 - 11:56:11 EST

On 06/13, KOSAKI Motohiro wrote:
> > On 06/04, Oleg Nesterov wrote:
> > >
> > Perhaps something like below makes sense for now.
> Probably, this works. at least I don't find any problems.
> But umm... Do you mean we can't implement per-process oom flags?

Sorry, can't understand what you mean.

> example,
> 1) back to implement signal->oom_victim
> because We are using SIGKILL for OOM and struct signal
> naturally represent signal target.

Yes, but if this process participates in the coredump, we should find
the right thread, or mark mm or mm->core_state.

In fact, I was never sure that oom-kill should kill the single process.
Perhaps it should kill all tasks using the same ->mm instead. But this
is another story.

> 2) mm->nr_oom_killed_task
> just avoid simple flag. instead counting number of tasks of
> oom-killed.

again, can't understand.

> I think both avoid your explained problem. Am I missing something?

I guess that I am missing something ;) Please clarify?

> But, again, I have no objection to your patch. because I really hope to
> fix coredump vs oom issue.

Yes, I think this is important. And if we keep the PF_EXITING check in
select_bad_process(), it should be fixed so that at least the coredump
can't fool it. And the "p != current" is obviously not right too.

I'll try to do something next week, the patches should be simple.


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