1 files changed, 24 insertions, 6 deletions

diff --git a/mm/pdflush.c b/mm/pdflush.c
index 118905e3d78..235ac440c44 100644
--- a/mm/pdflush.c
+++ b/mm/pdflush.c
@@ -98,7 +98,6 @@ static int __pdflush(struct pdflush_work *my_work)
         INIT_LIST_HEAD(&my_work->list);
 
         spin_lock_irq(&pdflush_lock);
-        nr_pdflush_threads++;
         for ( ; ; ) {
                 struct pdflush_work *pdf;
 
@@ -126,20 +125,26 @@ static int __pdflush(struct pdflush_work *my_work)
 
                 (*my_work->fn)(my_work->arg0);
 
+                spin_lock_irq(&pdflush_lock);
+
                 /*
                  * Thread creation: For how long have there been zero
                  * available threads?
+                 *
+                 * To throttle creation, we reset last_empty_jifs.
                  */
                 if (time_after(jiffies, last_empty_jifs + 1 * HZ)) {
-                        /* unlocked list_empty() test is OK here */
                         if (list_empty(&pdflush_list)) {
-                                /* unlocked test is OK here */
-                                if (nr_pdflush_threads < MAX_PDFLUSH_THREADS)
+                                if (nr_pdflush_threads < MAX_PDFLUSH_THREADS) {
+                                        last_empty_jifs = jiffies;
+                                        nr_pdflush_threads++;
+                                        spin_unlock_irq(&pdflush_lock);
                                         start_one_pdflush_thread();
+                                        spin_lock_irq(&pdflush_lock);
+                                }
                         }
                 }
 
-                spin_lock_irq(&pdflush_lock);
                 my_work->fn = NULL;
 
                 /*
@@ -236,13 +241,26 @@ int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0)
 
 static void start_one_pdflush_thread(void)
 {
-        kthread_run(pdflush, NULL, "pdflush");
+        struct task_struct *k;
+
+        k = kthread_run(pdflush, NULL, "pdflush");
+        if (unlikely(IS_ERR(k))) {
+                spin_lock_irq(&pdflush_lock);
+                nr_pdflush_threads--;
+                spin_unlock_irq(&pdflush_lock);
+        }
 }
 
 static int __init pdflush_init(void)
 {
         int i;
 
+        /*
+         * Pre-set nr_pdflush_threads...  If we fail to create,
+         * the count will be decremented.
+         */
+        nr_pdflush_threads = MIN_PDFLUSH_THREADS;
+
         for (i = 0; i < MIN_PDFLUSH_THREADS; i++)
                 start_one_pdflush_thread();
         return 0;