Commit 00ccf40a authored by Oscar Salvador's avatar Oscar Salvador Committed by Andrew Morton
Browse files

mm, hugetlb: avoid passing a null nodemask when there is mbind policy 

Before trying to allocate a page, gather_surplus_pages() sets up a
nodemask for the nodes we can allocate from, but instead of passing the
nodemask down the road to the page allocator, it iterates over the nodes
within that nodemask right there, meaning that the page allocator will
receive a preferred_nid and a null nodemask.

This is a problem when using a memory policy, because it might be that the
page allocator ends up using a node as a fallback which is not represented
in the policy.

Avoid that by passing the nodemask directly to the page allocator, so it
can filter out fallback nodes that are not part of the nodemask.

Link: https://lkml.kernel.org/r/20250415121503.376811-1-osalvador@suse.de


Signed-off-by: default avatarOscar Salvador <osalvador@suse.de>
Reviewed-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent f736953e

mm/hugetlb.c

+6 −16
Original line number Diff line number Diff line
@@ -2419,7 +2419,6 @@ static int gather_surplus_pages(struct hstate *h, long delta) 
	long i;

	long needed, allocated;

	bool alloc_ok = true;

	int node;

	nodemask_t *mbind_nodemask, alloc_nodemask;



	mbind_nodemask = policy_mbind_nodemask(htlb_alloc_mask(h));
@@ -2443,21 +2442,12 @@ static int gather_surplus_pages(struct hstate *h, long delta) 
	for (i = 0; i < needed; i++) {

		folio = NULL;



		/* Prioritize current node */

		if (node_isset(numa_mem_id(), alloc_nodemask))

			folio = alloc_surplus_hugetlb_folio(h, htlb_alloc_mask(h),

					numa_mem_id(), NULL);



		if (!folio) {

			for_each_node_mask(node, alloc_nodemask) {

				if (node == numa_mem_id())

					continue;

		/*

		 * It is okay to use NUMA_NO_NODE because we use numa_mem_id()

		 * down the road to pick the current node if that is the case.

		 */

		folio = alloc_surplus_hugetlb_folio(h, htlb_alloc_mask(h),

						node, NULL);

				if (folio)

					break;

			}

		}

						    NUMA_NO_NODE, &alloc_nodemask);

		if (!folio) {

			alloc_ok = false;

			break;