3 files changed, 12 insertions, 5 deletions

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index ff8bac63213f..e6e0cb5437e6 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -109,6 +109,7 @@ void bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
                                 long nr_pages, int sb_locked);
 int bdi_writeback_task(struct bdi_writeback *wb);
 int bdi_has_dirty_io(struct backing_dev_info *bdi);
+void bdi_arm_supers_timer(void);
 
 extern spinlock_t bdi_lock;
 extern struct list_head bdi_list;
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 707d0dc6da0f..660a87a22511 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -48,7 +48,6 @@ static struct timer_list sync_supers_timer;
 
 static int bdi_sync_supers(void *);
 static void sync_supers_timer_fn(unsigned long);
-static void arm_supers_timer(void);
 
 static void bdi_add_default_flusher_task(struct backing_dev_info *bdi);
 
@@ -252,7 +251,7 @@ static int __init default_bdi_init(void)
 
         init_timer(&sync_supers_timer);
         setup_timer(&sync_supers_timer, sync_supers_timer_fn, 0);
-        arm_supers_timer();
+        bdi_arm_supers_timer();
 
         err = bdi_init(&default_backing_dev_info);
         if (!err)
@@ -374,10 +373,13 @@ static int bdi_sync_supers(void *unused)
         return 0;
 }
 
-static void arm_supers_timer(void)
+void bdi_arm_supers_timer(void)
 {
         unsigned long next;
 
+        if (!dirty_writeback_interval)
+                return;
+
         next = msecs_to_jiffies(dirty_writeback_interval * 10) + jiffies;
         mod_timer(&sync_supers_timer, round_jiffies_up(next));
 }
@@ -385,7 +387,7 @@ static void arm_supers_timer(void)
 static void sync_supers_timer_fn(unsigned long unused)
 {
         wake_up_process(sync_supers_tsk);
-        arm_supers_timer();
+        bdi_arm_supers_timer();
 }
 
 static int bdi_forker_task(void *ptr)
@@ -428,7 +430,10 @@ static int bdi_forker_task(void *ptr)
 
                         spin_unlock_bh(&bdi_lock);
                         wait = msecs_to_jiffies(dirty_writeback_interval * 10);
-                        schedule_timeout(wait);
+                        if (wait)
+                                schedule_timeout(wait);
+                        else
+                                schedule();
                         try_to_freeze();
                         continue;
                 }
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 53b2fcf2d283..0d7bbe859550 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -690,6 +690,7 @@ int dirty_writeback_centisecs_handler(ctl_table *table, int write,
         void __user *buffer, size_t *length, loff_t *ppos)
 {
         proc_dointvec(table, write, buffer, length, ppos);
+        bdi_arm_supers_timer();
         return 0;
 }