hugetlb: balance freeing of huge pages across nodes

Free huges pages from nodes in round robin fashion in an attempt to keep
[persistent a.k.a static] hugepages balanced across nodes

New function free_pool_huge_page() is modeled on and performs roughly the
inverse of alloc_fresh_huge_page().  Replaces dequeue_huge_page() which
now has no callers, so this patch removes it.

Helper function hstate_next_node_to_free() uses new hstate member
next_to_free_nid to distribute "frees" across all nodes with huge pages.

Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 5cbc620bdfe0..16cdb75a543a 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -185,7 +185,8 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 #define HSTATE_NAME_LEN 32
 /* Defines one hugetlb page size */
 struct hstate {
-        int hugetlb_next_nid;
+        int next_nid_to_alloc;
+        int next_nid_to_free;
         unsigned int order;
         unsigned long mask;
         unsigned long max_huge_pages;