[RFC PATCH 20/28] mm: introduce per-VMA lock statistics

[Suren Baghdasaryan <surenb@google.com>]

Add a new CONFIG_PER_VMA_LOCK_STATS config option to dump extra
statistics about handling page fault under VMA lock.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
 include/linux/vm_event_item.h | 6 ++++++
 include/linux/vmstat.h        | 6 ++++++
 mm/Kconfig.debug              | 8 ++++++++
 mm/vmstat.c                   | 6 ++++++
 4 files changed, 26 insertions(+)

diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index f3fc36cd2276..a325783ed05d 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -150,6 +150,12 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
 #ifdef CONFIG_X86
 		DIRECT_MAP_LEVEL2_SPLIT,
 		DIRECT_MAP_LEVEL3_SPLIT,
+#endif
+#ifdef CONFIG_PER_VMA_LOCK_STATS
+		VMA_LOCK_SUCCESS,
+		VMA_LOCK_ABORT,
+		VMA_LOCK_RETRY,
+		VMA_LOCK_MISS,
 #endif
 		NR_VM_EVENT_ITEMS
 };
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index bfe38869498d..0c2611899cfc 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -131,6 +131,12 @@ static inline void vm_events_fold_cpu(int cpu)
 #define count_vm_vmacache_event(x) do {} while (0)
 #endif
 
+#ifdef CONFIG_PER_VMA_LOCK_STATS
+#define count_vm_vma_lock_event(x) count_vm_event(x)
+#else
+#define count_vm_vma_lock_event(x) do {} while (0)
+#endif
+
 #define __count_zid_vm_events(item, zid, delta) \
 	__count_vm_events(item##_NORMAL - ZONE_NORMAL + zid, delta)
 
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index ce8dded36de9..075642763a03 100644
--- a/mm/Kconfig.debug
+++ b/mm/Kconfig.debug
@@ -207,3 +207,11 @@ config PTDUMP_DEBUGFS
 	  kernel.
 
 	  If in doubt, say N.
+
+
+config PER_VMA_LOCK_STATS
+	bool "Statistics for per-vma locks"
+	depends on PER_VMA_LOCK
+	help
+	  Statistics for per-vma locks.
+	  If in doubt, say N.
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 90af9a8572f5..3f3804c846a6 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1411,6 +1411,12 @@ const char * const vmstat_text[] = {
 	"direct_map_level2_splits",
 	"direct_map_level3_splits",
 #endif
+#ifdef CONFIG_PER_VMA_LOCK_STATS
+	"vma_lock_success",
+	"vma_lock_abort",
+	"vma_lock_retry",
+	"vma_lock_miss",
+#endif
 #endif /* CONFIG_VM_EVENT_COUNTERS || CONFIG_MEMCG */
 };
 #endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA || CONFIG_MEMCG */
-- 
2.37.2.672.g94769d06f0-goog