arm64: unify idmap removal

[cascardo/linux.git] / mm / vmstat.c

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 64bd0aa..084c672 100644 (file)
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1396,10 +1396,15 @@ static void vmstat_update(struct work_struct *w)
                 * Counters were updated so we expect more updates
                 * to occur in the future. Keep on running the
                 * update worker thread.
+                * If we were marked on cpu_stat_off clear the flag
+                * so that vmstat_shepherd doesn't schedule us again.
                 */
-               queue_delayed_work_on(smp_processor_id(), vmstat_wq,
-                       this_cpu_ptr(&vmstat_work),
-                       round_jiffies_relative(sysctl_stat_interval));
+               if (!cpumask_test_and_clear_cpu(smp_processor_id(),
+                                               cpu_stat_off)) {
+                       queue_delayed_work_on(smp_processor_id(), vmstat_wq,
+                               this_cpu_ptr(&vmstat_work),
+                               round_jiffies_relative(sysctl_stat_interval));
+               }
        } else {
                /*
                 * We did not update any counters so the app may be in
@@ -1408,17 +1413,7 @@ static void vmstat_update(struct work_struct *w)
                 * Defer the checking for differentials to the
                 * shepherd thread on a different processor.
                 */
-               int r;
-               /*
-                * Shepherd work thread does not race since it never
-                * changes the bit if its zero but the cpu
-                * online / off line code may race if
-                * worker threads are still allowed during
-                * shutdown / startup.
-                */
-               r = cpumask_test_and_set_cpu(smp_processor_id(),
-                       cpu_stat_off);
-               VM_BUG_ON(r);
+               cpumask_set_cpu(smp_processor_id(), cpu_stat_off);
        }
 }
 
@@ -1427,18 +1422,6 @@ static void vmstat_update(struct work_struct *w)
  * until the diffs stay at zero. The function is used by NOHZ and can only be
  * invoked when tick processing is not active.
  */
-void quiet_vmstat(void)
-{
-       if (system_state != SYSTEM_RUNNING)
-               return;
-
-       do {
-               if (!cpumask_test_and_set_cpu(smp_processor_id(), cpu_stat_off))
-                       cancel_delayed_work(this_cpu_ptr(&vmstat_work));
-
-       } while (refresh_cpu_vm_stats(false));
-}
-
 /*
  * Check if the diffs for a certain cpu indicate that
  * an update is needed.
@@ -1462,6 +1445,30 @@ static bool need_update(int cpu)
        return false;
 }
 
+void quiet_vmstat(void)
+{
+       if (system_state != SYSTEM_RUNNING)
+               return;
+
+       /*
+        * If we are already in hands of the shepherd then there
+        * is nothing for us to do here.
+        */
+       if (cpumask_test_and_set_cpu(smp_processor_id(), cpu_stat_off))
+               return;
+
+       if (!need_update(smp_processor_id()))
+               return;
+
+       /*
+        * Just refresh counters and do not care about the pending delayed
+        * vmstat_update. It doesn't fire that often to matter and canceling
+        * it would be too expensive from this path.
+        * vmstat_shepherd will take care about that for us.
+        */
+       refresh_cpu_vm_stats(false);
+}
+
 
 /*
  * Shepherd worker thread that checks the
@@ -1479,18 +1486,25 @@ static void vmstat_shepherd(struct work_struct *w)
 
        get_online_cpus();
        /* Check processors whose vmstat worker threads have been disabled */
-       for_each_cpu(cpu, cpu_stat_off)
-               if (need_update(cpu) &&
-                       cpumask_test_and_clear_cpu(cpu, cpu_stat_off))
-
-                       queue_delayed_work_on(cpu, vmstat_wq,
-                               &per_cpu(vmstat_work, cpu), 0);
+       for_each_cpu(cpu, cpu_stat_off) {
+               struct delayed_work *dw = &per_cpu(vmstat_work, cpu);
 
+               if (need_update(cpu)) {
+                       if (cpumask_test_and_clear_cpu(cpu, cpu_stat_off))
+                               queue_delayed_work_on(cpu, vmstat_wq, dw, 0);
+               } else {
+                       /*
+                        * Cancel the work if quiet_vmstat has put this
+                        * cpu on cpu_stat_off because the work item might
+                        * be still scheduled
+                        */
+                       cancel_delayed_work(dw);
+               }
+       }
        put_online_cpus();
 
        schedule_delayed_work(&shepherd,
                round_jiffies_relative(sysctl_stat_interval));
-
 }
 
 static void __init start_shepherd_timer(void)
@@ -1498,7 +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))