---

yaml
---
r: 343309
b: refs/heads/master
c: d8a8e1f
h: refs/heads/master
i:
  343307: f2993d2
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 97ae17497e996ff09bf97b6db3b33f7fd4029092
+refs/heads/master: d8a8e1f0da3d29d7268b3300c96a059d63901b76

trunk/Documentation/vm/transhuge.txt

@@ -197,6 +197,14 @@ thp_split is incremented every time a huge page is split into base
 	pages. This can happen for a variety of reasons but a common
 	reason is that a huge page is old and is being reclaimed.
 
+thp_zero_page_alloc is incremented every time a huge zero page is
+	successfully allocated. It includes allocations which where
+	dropped due race with other allocation. Note, it doesn't count
+	every map of the huge zero page, only its allocation.
+
+thp_zero_page_alloc_failed is incremented if kernel fails to allocate
+	huge zero page and falls back to using small pages.
+
 As the system ages, allocating huge pages may be expensive as the
 system uses memory compaction to copy data around memory to free a
 huge page for use. There are some counters in /proc/vmstat to help

trunk/include/linux/vm_event_item.h

@@ -58,6 +58,8 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
 		THP_COLLAPSE_ALLOC,
 		THP_COLLAPSE_ALLOC_FAILED,
 		THP_SPLIT,
+		THP_ZERO_PAGE_ALLOC,
+		THP_ZERO_PAGE_ALLOC_FAILED,
 #endif
 		NR_VM_EVENT_ITEMS
 };

trunk/mm/huge_memory.c

@@ -184,8 +184,11 @@ static unsigned long get_huge_zero_page(void)
 
 	zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
 			HPAGE_PMD_ORDER);
-	if (!zero_page)
+	if (!zero_page) {
+		count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
 		return 0;
+	}
+	count_vm_event(THP_ZERO_PAGE_ALLOC);
 	preempt_disable();
 	if (cmpxchg(&huge_zero_pfn, 0, page_to_pfn(zero_page))) {
 		preempt_enable();

trunk/mm/vmstat.c

@@ -801,6 +801,8 @@ const char * const vmstat_text[] = {
 	"thp_collapse_alloc",
 	"thp_collapse_alloc_failed",
 	"thp_split",
+	"thp_zero_page_alloc",
+	"thp_zero_page_alloc_failed",
 #endif
 
 #endif /* CONFIG_VM_EVENTS_COUNTERS */