vmstat: Workaround for issue where dirty page count goes negative

popcornmix · popcornmix · commit 96911e1c38ab · 2014-07-29T23:10:06.000+01:00
See: #617 http://www.spinics.net/lists/linux-mm/msg72236.html
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
@@ -235,7 +235,11 @@ static inline void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
 static inline void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
 {
 	atomic_long_dec(&zone->vm_stat[item]);
+	if (item == NR_FILE_DIRTY && unlikely(atomic_long_read(&zone->vm_stat[item]) < 0))
+		atomic_long_set(&zone->vm_stat[item], 0);
 	atomic_long_dec(&vm_stat[item]);
+	if (item == NR_FILE_DIRTY && unlikely(atomic_long_read(&vm_stat[item]) < 0))
+		atomic_long_set(&vm_stat[item], 0);
 }
 
 static inline void __inc_zone_page_state(struct page *page,

Original file line number	Diff line number	Diff line change
`@@ -235,7 +235,11 @@ static inline void __inc_zone_state(struct zone *zone, enum zone_stat_item item)`
`235`	`235`	`static inline void __dec_zone_state(struct zone *zone, enum zone_stat_item item)`
`236`	`236`	`{`
`237`	`237`	`atomic_long_dec(&zone->vm_stat[item]);`
	`238`	`+ if (item == NR_FILE_DIRTY && unlikely(atomic_long_read(&zone->vm_stat[item]) < 0))`
	`239`	`+ atomic_long_set(&zone->vm_stat[item], 0);`
`238`	`240`	`atomic_long_dec(&vm_stat[item]);`
	`241`	`+ if (item == NR_FILE_DIRTY && unlikely(atomic_long_read(&vm_stat[item]) < 0))`
	`242`	`+ atomic_long_set(&vm_stat[item], 0);`
`239`	`243`	`}`
`240`	`244`
`241`	`245`	`static inline void __inc_zone_page_state(struct page *page,`