Merge branch 'from-linus' into upstream

3 files changed, 50 insertions, 53 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 72248d1b9e3..ab81fdd4572 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -2231,19 +2231,25 @@ static const struct cpuset *nearest_exclusive_ancestor(const struct cpuset *cs)
  * So only GFP_KERNEL allocations, if all nodes in the cpuset are
  * short of memory, might require taking the callback_mutex mutex.
  *
- * The first loop over the zonelist in mm/page_alloc.c:__alloc_pages()
- * calls here with __GFP_HARDWALL always set in gfp_mask, enforcing
- * hardwall cpusets - no allocation on a node outside the cpuset is
- * allowed (unless in interrupt, of course).
- *
- * The second loop doesn't even call here for GFP_ATOMIC requests
- * (if the __alloc_pages() local variable 'wait' is set).  That check
- * and the checks below have the combined affect in the second loop of
- * the __alloc_pages() routine that:
+ * The first call here from mm/page_alloc:get_page_from_freelist()
+ * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets, so
+ * no allocation on a node outside the cpuset is allowed (unless in
+ * interrupt, of course).
+ *
+ * The second pass through get_page_from_freelist() doesn't even call
+ * here for GFP_ATOMIC calls.  For those calls, the __alloc_pages()
+ * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
+ * in alloc_flags.  That logic and the checks below have the combined
+ * affect that:
  *	in_interrupt - any node ok (current task context irrelevant)
  *	GFP_ATOMIC   - any node ok
  *	GFP_KERNEL   - any node in enclosing mem_exclusive cpuset ok
  *	GFP_USER     - only nodes in current tasks mems allowed ok.
+ *
+ * Rule:
+ *    Don't call cpuset_zone_allowed() if you can't sleep, unless you
+ *    pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
+ *    the code that might scan up ancestor cpusets and sleep.
  **/
 
 int __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
@@ -2255,6 +2261,7 @@ int __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
 	if (in_interrupt())
 		return 1;
 	node = z->zone_pgdat->node_id;
+	might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
 	if (node_isset(node, current->mems_allowed))
 		return 1;
 	if (gfp_mask & __GFP_HARDWALL)	/* If hardwall request, stop here */
diff --git a/kernel/sched.c b/kernel/sched.c
index 4c64f85698a..c13f1bd2df7 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -665,55 +665,13 @@ static int effective_prio(task_t *p)
 }
 
 /*
- * We place interactive tasks back into the active array, if possible.
- *
- * To guarantee that this does not starve expired tasks we ignore the
- * interactivity of a task if the first expired task had to wait more
- * than a 'reasonable' amount of time. This deadline timeout is
- * load-dependent, as the frequency of array switched decreases with
- * increasing number of running tasks. We also ignore the interactivity
- * if a better static_prio task has expired, and switch periodically
- * regardless, to ensure that highly interactive tasks do not starve
- * the less fortunate for unreasonably long periods.
- */
-static inline int expired_starving(runqueue_t *rq)
-{
-	int limit;
-
-	/*
-	 * Arrays were recently switched, all is well
-	 */
-	if (!rq->expired_timestamp)
-		return 0;
-
-	limit = STARVATION_LIMIT * rq->nr_running;
-
-	/*
-	 * It's time to switch arrays
-	 */
-	if (jiffies - rq->expired_timestamp >= limit)
-		return 1;
-
-	/*
-	 * There's a better selection in the expired array
-	 */
-	if (rq->curr->static_prio > rq->best_expired_prio)
-		return 1;
-
-	/*
-	 * All is well
-	 */
-	return 0;
-}
-
-/*
  * __activate_task - move a task to the runqueue.
  */
 static void __activate_task(task_t *p, runqueue_t *rq)
 {
 	prio_array_t *target = rq->active;
 
-	if (unlikely(batch_task(p) || (expired_starving(rq) && !rt_task(p))))
+	if (batch_task(p))
 		target = rq->expired;
 	enqueue_task(p, target);
 	rq->nr_running++;
@@ -2532,6 +2490,22 @@ unsigned long long current_sched_time(const task_t *tsk)
 }
 
 /*
+ * We place interactive tasks back into the active array, if possible.
+ *
+ * To guarantee that this does not starve expired tasks we ignore the
+ * interactivity of a task if the first expired task had to wait more
+ * than a 'reasonable' amount of time. This deadline timeout is
+ * load-dependent, as the frequency of array switched decreases with
+ * increasing number of running tasks. We also ignore the interactivity
+ * if a better static_prio task has expired:
+ */
+#define EXPIRED_STARVING(rq) \
+	((STARVATION_LIMIT && ((rq)->expired_timestamp && \
+		(jiffies - (rq)->expired_timestamp >= \
+			STARVATION_LIMIT * ((rq)->nr_running) + 1))) || \
+			((rq)->curr->static_prio > (rq)->best_expired_prio))
+
+/*
  * Account user cpu time to a process.
  * @p: the process that the cpu time gets accounted to
  * @hardirq_offset: the offset to subtract from hardirq_count()
@@ -2666,7 +2640,7 @@ void scheduler_tick(void)
 
 		if (!rq->expired_timestamp)
 			rq->expired_timestamp = jiffies;
-		if (!TASK_INTERACTIVE(p) || expired_starving(rq)) {
+		if (!TASK_INTERACTIVE(p) || EXPIRED_STARVING(rq)) {
 			enqueue_task(p, rq->expired);
 			if (p->static_prio < rq->best_expired_prio)
 				rq->best_expired_prio = p->static_prio;
diff --git a/kernel/timer.c b/kernel/timer.c
index 67eaf0f5409..9e49deed468 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -541,6 +541,22 @@ found:
 	}
 	spin_unlock(&base->lock);
 
+	/*
+	 * It can happen that other CPUs service timer IRQs and increment
+	 * jiffies, but we have not yet got a local timer tick to process
+	 * the timer wheels.  In that case, the expiry time can be before
+	 * jiffies, but since the high-resolution timer here is relative to
+	 * jiffies, the default expression when high-resolution timers are
+	 * not active,
+	 *
+	 *   time_before(MAX_JIFFY_OFFSET + jiffies, expires)
+	 *
+	 * would falsely evaluate to true.  If that is the case, just
+	 * return jiffies so that we can immediately fire the local timer
+	 */
+	if (time_before(expires, jiffies))
+		return jiffies;
+
 	if (time_before(hr_expires, expires))
 		return hr_expires;