Re: [RFC] oom-kill: give the dying task a higher priority

[David Rientjes <rientjes@google.com>]

On Tue, 1 Jun 2010, Minchan Kim wrote:

> Secondly, as Kame pointed out, we have to raise whole thread's
> priority to kill victim process for reclaiming pages. But I think it
> has deadlock problem.

Agreed, this has the potential to actually increase the amount of time for 
an oom killed task to fully exit: the exit path takes mm->mmap_sem on exit 
and if that is held by another thread waiting for the oom killed task to 
exit (i.e. reclaim has failed and the oom killer becomes a no-op because 
it sees an already killed task) then there's a livelock.  That's always 
been a problem, but is compounded with increasing the priority of a task 
not holding mm->mmap_sem if the thread holding the writelock actually 
isn't looking for memory but simply doesn't get a chance to release 
because it fails to run.

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