X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=blobdiff_plain;f=mm%2Fbacking-dev.c;h=845e58b35507f413457a36526b84b1de5e409876;hp=2b49dd2bb6f54aeec9d987416d8f0a1188b7fdc4;hb=4cecd7e369e1b252db1d64451462221b362eed1c;hpb=0a749094a5e2bdcbef355b0c2eb3658fa6d7903c

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 2b49dd2bb6f5..845e58b35507 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -847,8 +847,9 @@ 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
@@ -868,7 +869,19 @@ long wait_iff_congested(struct zone *zone, int sync, long timeout)
 	 */
 	if (atomic_read(&nr_bdi_congested[sync]) == 0 ||
 			!zone_is_reclaim_congested(zone)) {
-		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);