X-Git-Url: http://git.monstr.eu/?a=blobdiff_plain;f=mm%2Fvmstat.c;h=8ce2620344b2f8b4e673c8f48e92945b874ef36d;hb=c2f4954c2d3fc4f77b46c67585e17a58df4ba8e4;hp=a7ed56ac4c0b4a3c88aa1d1c49a6249cf29be9a8;hpb=4a3bb4200a5958d76cc26ebe4db4257efa56812b;p=linux-2.6-microblaze.git

diff --git a/mm/vmstat.c b/mm/vmstat.c
index a7ed56ac4c0b..8ce2620344b2 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -204,7 +204,7 @@ int calculate_normal_threshold(struct zone *zone)
 	 *
 	 * Some sample thresholds:
 	 *
-	 * Threshold	Processors	(fls)	Zonesize	fls(mem+1)
+	 * Threshold	Processors	(fls)	Zonesize	fls(mem)+1
 	 * ------------------------------------------------------------------
 	 * 8		1		1	0.9-1 GB	4
 	 * 16		2		2	0.9-1 GB	4
@@ -319,6 +319,16 @@ void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 	long x;
 	long t;
 
+	/*
+	 * Accurate vmstat updates require a RMW. On !PREEMPT_RT kernels,
+	 * atomicity is provided by IRQs being disabled -- either explicitly
+	 * or via local_lock_irq. On PREEMPT_RT, local_lock_irq only disables
+	 * CPU migrations and preemption potentially corrupts a counter so
+	 * disable preemption.
+	 */
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_disable();
+
 	x = delta + __this_cpu_read(*p);
 
 	t = __this_cpu_read(pcp->stat_threshold);
@@ -328,6 +338,9 @@ void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 		x = 0;
 	}
 	__this_cpu_write(*p, x);
+
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_enable();
 }
 EXPORT_SYMBOL(__mod_zone_page_state);
 
@@ -350,6 +363,10 @@ void __mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
 		delta >>= PAGE_SHIFT;
 	}
 
+	/* See __mod_node_page_state */
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_disable();
+
 	x = delta + __this_cpu_read(*p);
 
 	t = __this_cpu_read(pcp->stat_threshold);
@@ -359,6 +376,9 @@ void __mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
 		x = 0;
 	}
 	__this_cpu_write(*p, x);
+
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_enable();
 }
 EXPORT_SYMBOL(__mod_node_page_state);
 
@@ -391,6 +411,10 @@ void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
 	s8 __percpu *p = pcp->vm_stat_diff + item;
 	s8 v, t;
 
+	/* See __mod_node_page_state */
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_disable();
+
 	v = __this_cpu_inc_return(*p);
 	t = __this_cpu_read(pcp->stat_threshold);
 	if (unlikely(v > t)) {
@@ -399,6 +423,9 @@ void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
 		zone_page_state_add(v + overstep, zone, item);
 		__this_cpu_write(*p, -overstep);
 	}
+
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_enable();
 }
 
 void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
@@ -409,6 +436,10 @@ void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 
 	VM_WARN_ON_ONCE(vmstat_item_in_bytes(item));
 
+	/* See __mod_node_page_state */
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_disable();
+
 	v = __this_cpu_inc_return(*p);
 	t = __this_cpu_read(pcp->stat_threshold);
 	if (unlikely(v > t)) {
@@ -417,6 +448,9 @@ void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 		node_page_state_add(v + overstep, pgdat, item);
 		__this_cpu_write(*p, -overstep);
 	}
+
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_enable();
 }
 
 void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
@@ -437,6 +471,10 @@ void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
 	s8 __percpu *p = pcp->vm_stat_diff + item;
 	s8 v, t;
 
+	/* See __mod_node_page_state */
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_disable();
+
 	v = __this_cpu_dec_return(*p);
 	t = __this_cpu_read(pcp->stat_threshold);
 	if (unlikely(v < - t)) {
@@ -445,6 +483,9 @@ void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
 		zone_page_state_add(v - overstep, zone, item);
 		__this_cpu_write(*p, overstep);
 	}
+
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_enable();
 }
 
 void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
@@ -455,6 +496,10 @@ void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 
 	VM_WARN_ON_ONCE(vmstat_item_in_bytes(item));
 
+	/* See __mod_node_page_state */
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_disable();
+
 	v = __this_cpu_dec_return(*p);
 	t = __this_cpu_read(pcp->stat_threshold);
 	if (unlikely(v < - t)) {
@@ -463,6 +508,9 @@ void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 		node_page_state_add(v - overstep, pgdat, item);
 		__this_cpu_write(*p, overstep);
 	}
+
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_enable();
 }
 
 void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
@@ -1217,6 +1265,8 @@ const char * const vmstat_text[] = {
 	"pgreuse",
 	"pgsteal_kswapd",
 	"pgsteal_direct",
+	"pgdemote_kswapd",
+	"pgdemote_direct",
 	"pgscan_kswapd",
 	"pgscan_direct",
 	"pgscan_direct_throttle",
@@ -1452,7 +1502,7 @@ static void pagetypeinfo_showfree_print(struct seq_file *m,
 }
 
 /* Print out the free pages at each order for each migatetype */
-static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
+static void pagetypeinfo_showfree(struct seq_file *m, void *arg)
 {
 	int order;
 	pg_data_t *pgdat = (pg_data_t *)arg;
@@ -1464,8 +1514,6 @@ static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
 	seq_putc(m, '\n');
 
 	walk_zones_in_node(m, pgdat, true, false, pagetypeinfo_showfree_print);
-
-	return 0;
 }
 
 static void pagetypeinfo_showblockcount_print(struct seq_file *m,
@@ -1501,7 +1549,7 @@ static void pagetypeinfo_showblockcount_print(struct seq_file *m,
 }
 
 /* Print out the number of pageblocks for each migratetype */
-static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
+static void pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
 {
 	int mtype;
 	pg_data_t *pgdat = (pg_data_t *)arg;
@@ -1512,8 +1560,6 @@ static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
 	seq_putc(m, '\n');
 	walk_zones_in_node(m, pgdat, true, false,
 		pagetypeinfo_showblockcount_print);
-
-	return 0;
 }
 
 /*
@@ -1873,11 +1919,6 @@ static void vmstat_update(struct work_struct *w)
 	}
 }
 
-/*
- * Switch off vmstat processing and then fold all the remaining differentials
- * until the diffs stay at zero. The function is used by NOHZ and can only be
- * invoked when tick processing is not active.
- */
 /*
  * Check if the diffs for a certain cpu indicate that
  * an update is needed.
@@ -1894,17 +1935,15 @@ static bool need_update(int cpu)
 		/*
 		 * The fast way of checking if there are any vmstat diffs.
 		 */
-		if (memchr_inv(pzstats->vm_stat_diff, 0, NR_VM_ZONE_STAT_ITEMS *
-			       sizeof(pzstats->vm_stat_diff[0])))
+		if (memchr_inv(pzstats->vm_stat_diff, 0, sizeof(pzstats->vm_stat_diff)))
 			return true;
 
 		if (last_pgdat == zone->zone_pgdat)
 			continue;
 		last_pgdat = zone->zone_pgdat;
 		n = per_cpu_ptr(zone->zone_pgdat->per_cpu_nodestats, cpu);
-		if (memchr_inv(n->vm_node_stat_diff, 0, NR_VM_NODE_STAT_ITEMS *
-			       sizeof(n->vm_node_stat_diff[0])))
-		    return true;
+		if (memchr_inv(n->vm_node_stat_diff, 0, sizeof(n->vm_node_stat_diff)))
+			return true;
 	}
 	return false;
 }