On Sat 17-02-24 01:31:35, Donet Tom wrote:
[...]
> +static inline bool mpol_preferred_should_numa_migrate(int exec_node, int folio_node,
> + struct mempolicy *pol)
> +{
> + /* if the executing node is in the policy node mask, migrate */
> + if (node_isset(exec_node, pol->nodes))
> + return true;
> +
> + /* If the folio node is in policy node mask, don't migrate */
> + if (node_isset(folio_node, pol->nodes))
> + return false;
> + /*
> + * both the folio node and executing node are outside the policy nodemask,
> + * migrate as normal numa fault migration.
> + */
> + return true;
> +}
I have looked at this again and only now noticed that this doesn't
really work as one would expected.
case MPOL_PREFERRED_MANY:
/*
* use current page if in policy nodemask,
* else select nearest allowed node, if any.
* If no allowed nodes, use current [!misplaced].
*/
if (node_isset(curnid, pol->nodes))
goto out;
z = first_zones_zonelist(
node_zonelist(numa_node_id(), GFP_HIGHUSER),
gfp_zone(GFP_HIGHUSER),
&pol->nodes);
polnid = zone_to_nid(z->zone);
break;
Will collapse the whole MPOL_PREFERRED_MANY nodemask into the first
notde into that mask. Is that really what we want here? Shouldn't we use
the full nodemask as the migration target?
--
Michal Hocko
SUSE Labs
