On Fri 25-05-18 12:43:00, Andrew Morton wrote: > On Fri, 25 May 2018 15:08:53 +0200 Vlastimil Babka <vbabka@xxxxxxx> 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@xxxxxxxx> -- Michal Hocko SUSE Labs
