vmstat: make vmstat_update deferrable

Commit 0eb77e988032 ("vmstat: make vmstat_updater deferrable again and
shut down on idle") made vmstat_shepherd deferrable.  vmstat_update
itself is still useing standard timer which might interrupt idle task.
This is possible because "mm, vmstat: make quiet_vmstat lighter" removed
cancel_delayed_work from the quiet_vmstat.

Change vmstat_work to use DEFERRABLE_WORK to prevent from pointless
wakeups from the idle context.

Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 1543f64..084c672 100644 (file)
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1512,7 +1512,7 @@ static void __init start_shepherd_timer(void)
        int cpu;
 
        for_each_possible_cpu(cpu)
-               INIT_DELAYED_WORK(per_cpu_ptr(&vmstat_work, cpu),
+               INIT_DEFERRABLE_WORK(per_cpu_ptr(&vmstat_work, cpu),
                        vmstat_update);
 
        if (!alloc_cpumask_var(&cpu_stat_off, GFP_KERNEL))