[PATCH v12 27/31] 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@xxxxxxxxxxxxx>
---
 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 47a3441cf4c4..137666e91074 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -109,6 +109,9 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
 #ifdef CONFIG_SWAP
 		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 509851ad7c95..c65e8011d285 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4367,6 +4367,9 @@ vm_fault_t __handle_speculative_fault(struct mm_struct *mm,
 
 	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 a7d493366a65..93f54b31e150 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1288,7 +1288,10 @@ 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 */
 
-- 
2.21.0