Re: [patch -mm 13/18] oom: avoid race for oom killed tasks detaching mm prior to exit

[David Rientjes <rientjes@google.com>]

On Tue, 1 Jun 2010, KOSAKI Motohiro wrote:

> > Tasks detach its ->mm prior to exiting so it's possible that in progress
> > oom kills or already exiting tasks may be missed during the oom killer's
> > tasklist scan.  When an eligible task is found with either TIF_MEMDIE or
> > PF_EXITING set, the oom killer is supposed to be a no-op to avoid
> > needlessly killing additional tasks.  This closes the race between a task
> > detaching its ->mm and being removed from the tasklist.
> > 
> > Out of memory conditions as the result of memory controllers will
> > automatically filter tasks that have detached their ->mm (since
> > task_in_mem_cgroup() will return 0).  This is acceptable, however, since
> > memcg constrained ooms aren't the result of a lack of memory resources but
> > rather a limit imposed by userspace that requires a task be killed
> > regardless.
> > 
> > [oleg@redhat.com: fix PF_EXITING check for !p->mm tasks]
> > Acked-by: Nick Piggin <npiggin@suse.de>
> > Signed-off-by: David Rientjes <rientjes@google.com>
> 
> need respin.
> 

No, it applies to mmotm-2010-05-21-16-05 as all of these patches do.  I 
know you've pushed Oleg's patches but they are also included here so no 
respin is necessary unless they are merged first (and I think that should 
only happen if Andrew considers them to be rc material).  I'll base my 
patchsets on the -mm tree.

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