Commit f58498b7 authored by David Hildenbrand's avatar David Hildenbrand Committed by Andrew Morton
Browse files

mm/page_alloc: don't use __GFP_HARDWALL when migrating pages via alloc_contig*() 

Patch series "mm: don't use __GFP_HARDWALL when migrating remote pages".

__GFP_HARDWALL means that we will be respecting the cpuset of the caller
when allocating a page.  However, when we are migrating remote allocations
(pages allocated from other context), the cpuset of the current context is
irrelevant.

For memory offlining + alloc_contig_*(), this is rather obvious.  There
might be other such page migration users, let's start with the obvious
ones.


This patch (of 2):

We'll migrate pages allocated by other contexts; respecting the cpuset of
the alloc_contig*() caller when allocating a migration target does not
make sense.

Drop the __GFP_HARDWALL.

Note that in an ideal world, migration code could figure out the cpuset
of the original context and take that into consideration.

Link: https://lkml.kernel.org/r/20241205090508.2095225-1-david@redhat.com
Link: https://lkml.kernel.org/r/20241205090508.2095225-2-david@redhat.com


Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Suggested-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reviewed-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reviewed-by: default avatarOscar Salvador <osalvador@suse.de>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent fa5d6179

mm/page_alloc.c

+3 −3
Original line number Diff line number Diff line
@@ -6412,11 +6412,11 @@ static int __alloc_contig_verify_gfp_mask(gfp_t gfp_mask, gfp_t *gfp_cc_mask) 
	 * page range. Migratable pages are movable, __GFP_MOVABLE is implied

	 * for them.

	 *

	 * Traditionally we always had __GFP_HARDWALL|__GFP_RETRY_MAYFAIL set,

	 * keep doing that to not degrade callers.

	 * Traditionally we always had __GFP_RETRY_MAYFAIL set, keep doing that

	 * to not degrade callers.

	 */

	*gfp_cc_mask = (gfp_mask & (reclaim_mask | cc_action_mask)) |

			__GFP_HARDWALL | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL;

			__GFP_MOVABLE | __GFP_RETRY_MAYFAIL;

	return 0;

}