X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=mm%2Fbacking-dev.c;h=a988d4ef39da00732848fdbc9111ecde62716a68;hb=edd7917229fdc03d09f45758ea674913af20a19d;hp=8ed2ffd963c53b910f91e1b60b04c56385a3129f;hpb=172473407962df19d0344fcdba90b02d16fe98d0;p=firefly-linux-kernel-4.4.55.git

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 8ed2ffd963c5..a988d4ef39da 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -757,15 +757,20 @@ static int cgwb_bdi_init(struct backing_dev_info *bdi)
 	if (!bdi->wb_congested)
 		return -ENOMEM;
 
+	atomic_set(&bdi->wb_congested->refcnt, 1);
+
 	err = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL);
 	if (err) {
-		kfree(bdi->wb_congested);
+		wb_congested_put(bdi->wb_congested);
 		return err;
 	}
 	return 0;
 }
 
-static void cgwb_bdi_destroy(struct backing_dev_info *bdi) { }
+static void cgwb_bdi_destroy(struct backing_dev_info *bdi)
+{
+	wb_congested_put(bdi->wb_congested);
+}
 
 #endif	/* CONFIG_CGROUP_WRITEBACK */
 
@@ -825,6 +830,20 @@ int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
 }
 EXPORT_SYMBOL(bdi_register_dev);
 
+int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner)
+{
+	int rc;
+
+	rc = bdi_register(bdi, NULL, "%u:%u", MAJOR(owner->devt),
+			MINOR(owner->devt));
+	if (rc)
+		return rc;
+	bdi->owner = owner;
+	get_device(owner);
+	return 0;
+}
+EXPORT_SYMBOL(bdi_register_owner);
+
 /*
  * Remove bdi from bdi_list, and ensure that it is no longer visible
  */
@@ -849,6 +868,11 @@ void bdi_unregister(struct backing_dev_info *bdi)
 		device_unregister(bdi->dev);
 		bdi->dev = NULL;
 	}
+
+	if (bdi->owner) {
+		put_device(bdi->owner);
+		bdi->owner = NULL;
+	}
 }
 
 void bdi_exit(struct backing_dev_info *bdi)
@@ -957,8 +981,9 @@ EXPORT_SYMBOL(congestion_wait);
  * jiffies for either a BDI to exit congestion of the given @sync queue
  * or a write to complete.
  *
- * In the absence of zone congestion, cond_resched() is called to yield
- * the processor if necessary but otherwise does not sleep.
+ * In the absence of zone congestion, a short sleep or a cond_resched is
+ * performed to yield the processor and to allow other subsystems to make
+ * a forward progress.
  *
  * The return value is 0 if the sleep is for the full timeout. Otherwise,
  * it is the number of jiffies that were still remaining when the function
@@ -978,7 +1003,19 @@ long wait_iff_congested(struct zone *zone, int sync, long timeout)
 	 */
 	if (atomic_read(&nr_wb_congested[sync]) == 0 ||
 	    !test_bit(ZONE_CONGESTED, &zone->flags)) {
-		cond_resched();
+
+		/*
+		 * Memory allocation/reclaim might be called from a WQ
+		 * context and the current implementation of the WQ
+		 * concurrency control doesn't recognize that a particular
+		 * WQ is congested if the worker thread is looping without
+		 * ever sleeping. Therefore we have to do a short sleep
+		 * here rather than calling cond_resched().
+		 */
+		if (current->flags & PF_WQ_WORKER)
+			schedule_timeout_uninterruptible(1);
+		else
+			cond_resched();
 
 		/* In case we scheduled, work out time remaining */
 		ret = timeout - (jiffies - start);