Index: linux-2.6/mm/vmstat.c
===================================================================
--- linux-2.6.orig/mm/vmstat.c
+++ linux-2.6/mm/vmstat.c
@@ -28,6 +28,7 @@
 #include <linux/mm_inline.h>
 #include <linux/page_ext.h>
 #include <linux/page_owner.h>
+#include <linux/tick.h>
 
 #include "internal.h"
 
@@ -194,21 +195,50 @@ void fold_vm_numa_events(void)
 #endif
 
 #ifdef CONFIG_SMP
-static DEFINE_PER_CPU_ALIGNED(bool, vmstat_dirty);
+
+struct vmstat_dirty {
+	bool dirty;
+	bool cpuhotplug;
+};
+
+static DEFINE_PER_CPU_ALIGNED(struct vmstat_dirty, vmstat_dirty_pcpu);
+static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
+int sysctl_stat_interval __read_mostly = HZ;
 
 static inline void vmstat_mark_dirty(void)
 {
-	this_cpu_write(vmstat_dirty, true);
+	struct vmstat_dirty *vms = this_cpu_ptr(&vmstat_dirty_pcpu);
+
+#ifdef CONFIG_FLUSH_WORK_ON_RESUME_USER
+	int cpu = smp_processor_id();
+
+	if (tick_nohz_full_cpu(cpu) && !vms->dirty) {
+		struct delayed_work *dw;
+
+		dw = this_cpu_ptr(&vmstat_work);
+		if (!delayed_work_pending(dw) && !vms->cpuhotplug) {
+			unsigned long delay;
+
+			delay = round_jiffies_relative(sysctl_stat_interval);
+			queue_delayed_work_on(cpu, mm_percpu_wq, dw, delay);
+		}
+	}
+#endif
+	vms->dirty = true;
 }
 
 static inline void vmstat_clear_dirty(void)
 {
-	this_cpu_write(vmstat_dirty, false);
+	struct vmstat_dirty *vms = this_cpu_ptr(&vmstat_dirty_pcpu);
+
+	vms->dirty = false;
 }
 
 static inline bool is_vmstat_dirty(void)
 {
-	return this_cpu_read(vmstat_dirty);
+	struct vmstat_dirty *vms = this_cpu_ptr(&vmstat_dirty_pcpu);
+
+	return vms->dirty;
 }
 
 int calculate_pressure_threshold(struct zone *zone)
@@ -1886,9 +1916,6 @@ static const struct seq_operations vmsta
 #endif /* CONFIG_PROC_FS */
 
 #ifdef CONFIG_SMP
-static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
-int sysctl_stat_interval __read_mostly = HZ;
-
 #ifdef CONFIG_PROC_FS
 static void refresh_vm_stats(struct work_struct *work)
 {
@@ -1973,7 +2000,7 @@ static void vmstat_update(struct work_st
  * 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)
+void quiet_vmstat(bool user)
 {
 	if (system_state != SYSTEM_RUNNING)
 		return;
@@ -1981,13 +2008,18 @@ void quiet_vmstat(void)
 	if (!is_vmstat_dirty())
 		return;
 
+	refresh_cpu_vm_stats(false);
+
+#ifdef CONFIG_FLUSH_WORK_ON_RESUME_USER
+	if (!user)
+		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.
+	 * If the tick is stopped, cancel any delayed work to avoid
+	 * interruptions to this CPU in the future.
 	 */
-	refresh_cpu_vm_stats(false);
+	if (delayed_work_pending(this_cpu_ptr(&vmstat_work)))
+		cancel_delayed_work(this_cpu_ptr(&vmstat_work));
+#endif
 }
 
 /*
@@ -2008,8 +2040,15 @@ static void vmstat_shepherd(struct work_
 	/* Check processors whose vmstat worker threads have been disabled */
 	for_each_online_cpu(cpu) {
 		struct delayed_work *dw = &per_cpu(vmstat_work, cpu);
+		struct vmstat_dirty *vms = per_cpu_ptr(&vmstat_dirty_pcpu, cpu);
 
-		if (!delayed_work_pending(dw) && per_cpu(vmstat_dirty, cpu))
+#ifdef CONFIG_FLUSH_WORK_ON_RESUME_USER
+		/* NOHZ full CPUs manage their own vmstat flushing */
+		if (tick_nohz_full_cpu(cpu))
+			continue;
+#endif
+
+		if (!delayed_work_pending(dw) && vms->dirty)
 			queue_delayed_work_on(cpu, mm_percpu_wq, dw, 0);
 
 		cond_resched();
@@ -2044,6 +2083,25 @@ static void __init init_cpu_node_state(v
 
 static int vmstat_cpu_online(unsigned int cpu)
 {
+#ifdef CONFIG_FLUSH_WORK_ON_RESUME_USER
+	struct vmstat_dirty *vms = per_cpu_ptr(&vmstat_dirty_pcpu, cpu);
+
+	if (tick_nohz_full_cpu(cpu)) {
+		struct delayed_work *dw;
+
+		vms->cpuhotplug = false;
+		vms->dirty = true;
+
+		dw = this_cpu_ptr(&vmstat_work);
+		if (!delayed_work_pending(dw)) {
+			unsigned long delay;
+
+			delay = round_jiffies_relative(sysctl_stat_interval);
+			queue_delayed_work_on(cpu, mm_percpu_wq, dw, delay);
+		}
+	}
+#endif
+
 	refresh_zone_stat_thresholds();
 
 	if (!node_state(cpu_to_node(cpu), N_CPU)) {
@@ -2053,8 +2111,15 @@ static int vmstat_cpu_online(unsigned in
 	return 0;
 }
 
+/*
+ * ONLINE: The callbacks are invoked on the hotplugged CPU from the per CPU
+ * hotplug thread with interrupts and preemption enabled.
+ */
 static int vmstat_cpu_down_prep(unsigned int cpu)
 {
+	struct vmstat_dirty *vms = per_cpu_ptr(&vmstat_dirty_pcpu, cpu);
+
+	vms->cpuhotplug = true;
 	cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
 	return 0;
 }
Index: linux-2.6/include/linux/vmstat.h
===================================================================
--- linux-2.6.orig/include/linux/vmstat.h
+++ linux-2.6/include/linux/vmstat.h
@@ -290,7 +290,7 @@ extern void dec_zone_state(struct zone *
 extern void __dec_zone_state(struct zone *, enum zone_stat_item);
 extern void __dec_node_state(struct pglist_data *, enum node_stat_item);
 
-void quiet_vmstat(void);
+void quiet_vmstat(bool user);
 void cpu_vm_stats_fold(int cpu);
 void refresh_zone_stat_thresholds(void);
 
@@ -403,7 +403,7 @@ static inline void __dec_node_page_state
 
 static inline void refresh_zone_stat_thresholds(void) { }
 static inline void cpu_vm_stats_fold(int cpu) { }
-static inline void quiet_vmstat(void) { }
+static inline void quiet_vmstat(bool user) { }
 
 static inline void drain_zonestat(struct zone *zone,
 			struct per_cpu_zonestat *pzstats) { }
Index: linux-2.6/kernel/time/tick-sched.c
===================================================================
--- linux-2.6.orig/kernel/time/tick-sched.c
+++ linux-2.6/kernel/time/tick-sched.c
@@ -911,7 +911,7 @@ static void tick_nohz_stop_tick(struct t
 	 */
 	if (!ts->tick_stopped) {
 		calc_load_nohz_start();
-		quiet_vmstat();
+		quiet_vmstat(false);
 
 		ts->last_tick = hrtimer_get_expires(&ts->sched_timer);
 		ts->tick_stopped = 1;
Index: linux-2.6/mm/Kconfig
===================================================================
--- linux-2.6.orig/mm/Kconfig
+++ linux-2.6/mm/Kconfig
@@ -1124,6 +1124,19 @@ config PTE_MARKER_UFFD_WP
 	  purposes.  It is required to enable userfaultfd write protection on
 	  file-backed memory types like shmem and hugetlbfs.
 
+config FLUSH_WORK_ON_RESUME_USER
+	bool "Flush per-CPU vmstats on user return (for nohz full CPUs)"
+	depends on NO_HZ_FULL
+	default y
+
+	help
+	  By default, nohz full CPUs flush per-CPU vm statistics on return
+	  to userspace (to avoid additional interferences when executing
+	  userspace code). This has a small but measurable impact on
+	  system call performance. You can disable this to improve system call
+	  performance, at the expense of potential interferences to userspace
+	  execution.
+
 # multi-gen LRU {
 config LRU_GEN
 	bool "Multi-Gen LRU"
