Merge tag 'v4.11-rc5' into patchwork

Linux 4.11-rc5

* tag 'v4.11-rc5': (1168 commits)
  Linux 4.11-rc5
  tty: pl011: fix earlycon work-around for QDF2400 erratum 44
  kasan: do not sanitize kexec purgatory
  drivers/rapidio/devices/tsi721.c: make module parameter variable name unique
  mm/hugetlb.c: don't call region_abort if region_chg fails
  kasan: report only the first error by default
  hugetlbfs: initialize shared policy as part of inode allocation
  mm: fix section name for .data..ro_after_init
  mm, hugetlb: use pte_present() instead of pmd_present() in follow_huge_pmd()
  mm: workingset: fix premature shadow node shrinking with cgroups
  mm: rmap: fix huge file mmap accounting in the memcg stats
  mm: move mm_percpu_wq initialization earlier
  mm: migrate: fix remove_migration_pte() for ksm pages
  nfs: flexfiles: fix kernel OOPS if MDS returns unsupported DS type
  NFSv4.1 fix infinite loop on IO BAD_STATEID error
  serial: 8250_EXAR: fix duplicate Kconfig text and add missing help text
  tty/serial: atmel: fix TX path in atmel_console_write()
  tty/serial: atmel: fix race condition (TX+DMA)
  serial: mxs-auart: Fix baudrate calculation
  irqchip/mips-gic: Fix Local compare interrupt
  ...

1 files changed, 8 insertions, 3 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 956383844116..3b31fc05a0f1 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3287,10 +3287,15 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
 	struct task_struct *p;
 
 	/*
-	 * Optimization: we know that if all tasks are in
-	 * the fair class we can call that function directly:
+	 * Optimization: we know that if all tasks are in the fair class we can
+	 * call that function directly, but only if the @prev task wasn't of a
+	 * higher scheduling class, because otherwise those loose the
+	 * opportunity to pull in more work from other CPUs.
 	 */
-	if (likely(rq->nr_running == rq->cfs.h_nr_running)) {
+	if (likely((prev->sched_class == &idle_sched_class ||
+		    prev->sched_class == &fair_sched_class) &&
+		   rq->nr_running == rq->cfs.h_nr_running)) {
+
 		p = fair_sched_class.pick_next_task(rq, prev, rf);
 		if (unlikely(p == RETRY_TASK))
 			goto again;