hugetlb: abstract numa round robin selection

Need this as a separate function for a future patch.

No behaviour change.

Acked-by: Adam Litke <agl@us.ibm.com>
Acked-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 22 insertions, 15 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index bb49ce5d0067..5e620e25cf08 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -565,6 +565,27 @@ static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
         return page;
 }
 
+/*
+ * Use a helper variable to find the next node and then
+ * copy it back to hugetlb_next_nid afterwards:
+ * otherwise there's a window in which a racer might
+ * pass invalid nid MAX_NUMNODES to alloc_pages_node.
+ * But we don't need to use a spin_lock here: it really
+ * doesn't matter if occasionally a racer chooses the
+ * same nid as we do.  Move nid forward in the mask even
+ * if we just successfully allocated a hugepage so that
+ * the next caller gets hugepages on the next node.
+ */
+static int hstate_next_node(struct hstate *h)
+{
+        int next_nid;
+        next_nid = next_node(h->hugetlb_next_nid, node_online_map);
+        if (next_nid == MAX_NUMNODES)
+                next_nid = first_node(node_online_map);
+        h->hugetlb_next_nid = next_nid;
+        return next_nid;
+}
+
 static int alloc_fresh_huge_page(struct hstate *h)
 {
         struct page *page;
@@ -578,21 +599,7 @@ static int alloc_fresh_huge_page(struct hstate *h)
                 page = alloc_fresh_huge_page_node(h, h->hugetlb_next_nid);
                 if (page)
                         ret = 1;
-                /*
-                 * Use a helper variable to find the next node and then
-                 * copy it back to hugetlb_next_nid afterwards:
-                 * otherwise there's a window in which a racer might
-                 * pass invalid nid MAX_NUMNODES to alloc_pages_node.
-                 * But we don't need to use a spin_lock here: it really
-                 * doesn't matter if occasionally a racer chooses the
-                 * same nid as we do.  Move nid forward in the mask even
-                 * if we just successfully allocated a hugepage so that
-                 * the next caller gets hugepages on the next node.
-                 */
-                next_nid = next_node(h->hugetlb_next_nid, node_online_map);
-                if (next_nid == MAX_NUMNODES)
-                        next_nid = first_node(node_online_map);
-                h->hugetlb_next_nid = next_nid;
+                next_nid = hstate_next_node(h);
         } while (!page && h->hugetlb_next_nid != start_nid);
 
         if (ret)