| Message ID | 20250415121503.376811-1-osalvador@suse.de (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm, hugetlb: Avoid passing a null nodemask when there is mbind policy | expand |
On 4/15/25 14:15, Oscar Salvador wrote: > 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. It will also try the fallbacks using numa distance and not incrementing nid. > Signed-off-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> > --- > mm/hugetlb.c | 22 ++++++---------------- > 1 file changed, 6 insertions(+), 16 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index ccc4f08f8481..5e1cba0f835f 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -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; > - folio = alloc_surplus_hugetlb_folio(h, htlb_alloc_mask(h), > - node, NULL); > - if (folio) > - break; > - } > - } > + /* > + * 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), > + NUMA_NO_NODE, &alloc_nodemask); > if (!folio) { > alloc_ok = false; > break;
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index ccc4f08f8481..5e1cba0f835f 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -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; - folio = alloc_surplus_hugetlb_folio(h, htlb_alloc_mask(h), - node, NULL); - if (folio) - break; - } - } + /* + * 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), + NUMA_NO_NODE, &alloc_nodemask); if (!folio) { alloc_ok = false; break;
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. Signed-off-by: Oscar Salvador <osalvador@suse.de> --- mm/hugetlb.c | 22 ++++++---------------- 1 file changed, 6 insertions(+), 16 deletions(-)