mm,vmacache: count number of system-wide flushes

These flushes deal with sequence number overflows, such as for long lived
threads.  These are rare, but interesting from a debugging PoV.  As such,
display the number of flushes when vmacache debugging is enabled.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 3 insertions, 0 deletions

diff --git a/mm/vmacache.c b/mm/vmacache.c
index 9f25af825dec..b6e3662fe339 100644
--- a/mm/vmacache.c
+++ b/mm/vmacache.c
@@ -17,6 +17,8 @@ void vmacache_flush_all(struct mm_struct *mm)
 {
         struct task_struct *g, *p;
 
+        count_vm_vmacache_event(VMACACHE_FULL_FLUSHES);
+
         /*
          * Single threaded tasks need not iterate the entire
          * list of process. We can avoid the flushing as well
diff --git a/mm/vmstat.c b/mm/vmstat.c
index b090e9e3d626..1284f89fca08 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -900,6 +900,7 @@ const char * const vmstat_text[] = {
 #ifdef CONFIG_DEBUG_VM_VMACACHE
         "vmacache_find_calls",
         "vmacache_find_hits",
+        "vmacache_full_flushes",
 #endif
 #endif /* CONFIG_VM_EVENTS_COUNTERS */
 };