[PATCH V3] mm/hugetlb: try preferred node first when alloc gigantic page from cma

[Li Xinhai <lixinhai.lxh@gmail.com>]

Since commit cf11e85fc08cc6a4 ("mm: hugetlb: optionally allocate gigantic
hugepages using cma"), the gigantic page would be allocated from node
which is not the preferred node, although there are pages available from
that node. The reason is that the nid parameter has been ignored in
alloc_gigantic_page().

Besides, the __GFP_THISNODE also need be checked if user required to
alloc only from the preferred node.

After this patch, the preferred node is tried first before other allowed
nodes, and don't try to allocate from other nodes if __GFP_THISNODE is
specified. If user don't specify the preferred node, the current node
will be used as preferred node, which makes sure consistent behavior of
allocating gigantic and non-gigantic hugetlb page.

Fixes: cf11e85fc08cc6a4 ("mm: hugetlb: optionally allocate gigantic hugepages using cma")
Cc: Roman Gushchin <guro@fb.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com>
---
v2->V3
Consider current node as preferred node if nid is NUMA_NO_NODE, thanks
Mike.

v1->v2:
With review by Mike and Michal, need to check __GFP_THISNODE to avoid
allocate from other nodes.

 mm/hugetlb.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a301c2d672bf..5957dc80ebb1 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1250,21 +1250,32 @@ static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
 		int nid, nodemask_t *nodemask)
 {
 	unsigned long nr_pages = 1UL << huge_page_order(h);
+	if (nid == NUMA_NO_NODE)
+		nid = numa_mem_id();
 
 #ifdef CONFIG_CMA
 	{
 		struct page *page;
 		int node;
 
-		for_each_node_mask(node, *nodemask) {
-			if (!hugetlb_cma[node])
-				continue;
-
-			page = cma_alloc(hugetlb_cma[node], nr_pages,
-					 huge_page_order(h), true);
+		if (hugetlb_cma[nid]) {
+			page = cma_alloc(hugetlb_cma[nid], nr_pages,
+					huge_page_order(h), true);
 			if (page)
 				return page;
 		}
+
+		if (!(gfp_mask & __GFP_THISNODE)) {
+			for_each_node_mask(node, *nodemask) {
+				if (node == nid || !hugetlb_cma[node])
+					continue;
+
+				page = cma_alloc(hugetlb_cma[node], nr_pages,
+						huge_page_order(h), true);
+				if (page)
+					return page;
+			}
+		}
 	}
 #endif
 
-- 
2.18.4