From: Adam Litke <agl@us.ibm.com>

Allocating huge pages directly from the buddy allocator is not guaranteed to
succeed.  Success depends on several factors (such as the amount of physical
memory available and the level of fragmentation).  With the addition of
dynamic hugetlb pool resizing, allocations can occur much more frequently. 
For these reasons it is desirable to keep track of huge page allocation
successes and failures.

Add two new vmstat entries to track huge page allocations that succeed and
fail.  The presence of the two entries is contingent upon CONFIG_HUGETLB_PAGE
being enabled.

Signed-off-by: Adam Litke <agl@us.ibm.com>
Signed-off-by: Eric Munson <ebmunson@us.ibm.com>
Tested-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Andy Whitcroft <apw@shadowen.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/vmstat.h |    8 +++++++-
 mm/hugetlb.c           |    7 +++++++
 mm/vmstat.c            |    4 ++++
 3 files changed, 18 insertions(+), 1 deletion(-)

diff -puN include/linux/vmstat.h~hugetlb-vmstat-events-for-huge-page-allocations include/linux/vmstat.h
--- a/include/linux/vmstat.h~hugetlb-vmstat-events-for-huge-page-allocations
+++ a/include/linux/vmstat.h
@@ -25,6 +25,12 @@
 #define HIGHMEM_ZONE(xx)
 #endif
 
+#ifdef CONFIG_HUGETLB_PAGE
+#define HTLB_STATS	HTLB_BUDDY_PGALLOC, HTLB_BUDDY_PGALLOC_FAIL,
+#else
+#define HTLB_STATS
+#endif
+
 #define FOR_ALL_ZONES(xx) DMA_ZONE(xx) DMA32_ZONE(xx) xx##_NORMAL HIGHMEM_ZONE(xx) , xx##_MOVABLE
 
 enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
@@ -36,7 +42,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
 		FOR_ALL_ZONES(PGSCAN_KSWAPD),
 		FOR_ALL_ZONES(PGSCAN_DIRECT),
 		PGINODESTEAL, SLABS_SCANNED, KSWAPD_STEAL, KSWAPD_INODESTEAL,
-		PAGEOUTRUN, ALLOCSTALL, PGROTATED,
+		PAGEOUTRUN, ALLOCSTALL, PGROTATED, HTLB_STATS
 		NR_VM_EVENT_ITEMS
 };
 
diff -puN mm/hugetlb.c~hugetlb-vmstat-events-for-huge-page-allocations mm/hugetlb.c
--- a/mm/hugetlb.c~hugetlb-vmstat-events-for-huge-page-allocations
+++ a/mm/hugetlb.c
@@ -242,6 +242,11 @@ static int alloc_fresh_huge_page(void)
 		hugetlb_next_nid = next_nid;
 	} while (!page && hugetlb_next_nid != start_nid);
 
+	if (ret)
+		count_vm_event(HTLB_BUDDY_PGALLOC);
+	else
+		count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
+
 	return ret;
 }
 
@@ -302,9 +307,11 @@ static struct page *alloc_buddy_huge_pag
 		 */
 		nr_huge_pages_node[nid]++;
 		surplus_huge_pages_node[nid]++;
+		__count_vm_event(HTLB_BUDDY_PGALLOC);
 	} else {
 		nr_huge_pages--;
 		surplus_huge_pages--;
+		__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
 	}
 	spin_unlock(&hugetlb_lock);
 
diff -puN mm/vmstat.c~hugetlb-vmstat-events-for-huge-page-allocations mm/vmstat.c
--- a/mm/vmstat.c~hugetlb-vmstat-events-for-huge-page-allocations
+++ a/mm/vmstat.c
@@ -645,6 +645,10 @@ static const char * const vmstat_text[] 
 	"allocstall",
 
 	"pgrotated",
+#ifdef CONFIG_HUGETLB_PAGE
+	"htlb_buddy_alloc_success",
+	"htlb_buddy_alloc_fail",
+#endif
 #endif
 };
 
_