On Fri 25-05-18 12:43:00, Andrew Morton wrote:
On Fri, 25 May 2018 15:08:53 +0200 Vlastimil Babka vbabka@suse.cz wrote:
we might consider this for 4.17 although I don't know if there's anything currently broken. Stable backports should be more important, but will have to be reviewed carefully, as the code went through many changes. BTW I think that also the ac->preferred_zoneref reset is currently useless if we don't also reset ac->nodemask from a mempolicy to NULL first (which we probably should for the OOM victims etc?), but I would leave that for a separate patch.
Confused. If nothing is currently broken then why is a backport needed? Presumably because we expect breakage in the future? Can you expand on this?
__GFP_THISNODE is documented to _use_ the given node. Allocating from a different one is a bug. Maybe the current code can cope with that or at least doesn't blow up in an obvious way but the bug is still there.
I am still not sure what to do about the zonelist reset. It still seems like an echo from the past but using numa_node_id for __GFP_THISNODE is a clear bug because our task could have been migrated to a cpu on a different than requested node.
Acked-by: Michal Hocko mhocko@suse.com