Re: [patch 1/4] mm, oom: ensure sysrq+f always passes valid zonelist

From: Michal Hocko
Date: Wed Nov 14 2012 - 08:31:06 EST


On Wed 14-11-12 03:03:02, David Rientjes wrote:
> On Wed, 14 Nov 2012, Michal Hocko wrote:
>
> > > With hotpluggable and memoryless nodes, it's possible that node 0 will
> > > not be online, so use the first online node's zonelist rather than
> > > hardcoding node 0 to pass a zonelist with all zones to the oom killer.
> >
> > Makes sense although I haven't seen a machine with no 0 node yet.
>
> We routinely do testing with them, actually, just by physically removing
> all memory described by the SRAT that maps to node 0. You could do the
> same thing by making all pxms that map to node 0 to be hotpluggable in
> your memory affinity structure. I've been bit by it one too many times so
> I always keep in mind that no single node id is guaranteed to be online
> (although at least one node is always online); hence, first_online_node is
> the solution.

I thought that a boot cpu would be bound to a node0 or something similar.
Thanks for the clarification!

> > According to 13808910 this is indeed possible.
> >
> > > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > > Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
> >
> > Reviewed-by: Michal Hocko <mhocko@xxxxxxx>
> >
>
> Thanks!

--
Michal Hocko
SUSE Labs
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