[PATCH v11 23/26] mm: add speculative page fault vmstats

[Laurent Dufour]

Add speculative_pgfault vmstat counter to count successful speculative page
fault handling.

Also fixing a minor typo in include/linux/vm_event_item.h.

Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxxxxxxx>
---
 include/linux/vm_event_item.h | 3 +++
 mm/memory.c                   | 3 +++
 mm/vmstat.c                   | 5 ++++-
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index 5c7f010676a7..a240acc09684 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -111,6 +111,9 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
 		SWAP_RA,
 		SWAP_RA_HIT,
 #endif
+#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
+		SPECULATIVE_PGFAULT,
+#endif
 		NR_VM_EVENT_ITEMS
 };
 
diff --git a/mm/memory.c b/mm/memory.c
index 30433bde32f2..48e1cf0a54ef 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4509,6 +4509,9 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
 
 	put_vma(vma);
 
+	if (ret != VM_FAULT_RETRY)
+		count_vm_event(SPECULATIVE_PGFAULT);
+
 	/*
 	 * The task may have entered a memcg OOM situation but
 	 * if the allocation error was handled gracefully (no
diff --git a/mm/vmstat.c b/mm/vmstat.c
index a2b9518980ce..3af74498a969 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1289,7 +1289,10 @@ const char * const vmstat_text[] = {
 	"swap_ra",
 	"swap_ra_hit",
 #endif
-#endif /* CONFIG_VM_EVENTS_COUNTERS */
+#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
+	"speculative_pgfault",
+#endif
+#endif /* CONFIG_VM_EVENT_COUNTERS */
 };
 #endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA */
 
-- 
2.7.4