3 files changed, 16 insertions, 0 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index f9a45ebcc7b1..6a488ad2dce5 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -908,6 +908,7 @@ NORET_TYPE void do_exit(long code)
         profile_task_exit(tsk);
 
         WARN_ON(atomic_read(&tsk->fs_excl));
+        WARN_ON(blk_needs_flush_plug(tsk));
 
         if (unlikely(in_interrupt()))
                 panic("Aiee, killing interrupt handler!");
diff --git a/kernel/fork.c b/kernel/fork.c
index 25e429152ddc..027c80e5162f 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1204,6 +1204,9 @@ static struct task_struct *copy_process(unsigned long clone_flags,
          * Clear TID on mm_release()?
          */
         p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
+#ifdef CONFIG_BLOCK
+        p->plug = NULL;
+#endif
 #ifdef CONFIG_FUTEX
         p->robust_list = NULL;
 #ifdef CONFIG_COMPAT
diff --git a/kernel/sched.c b/kernel/sched.c
index 18d38e4ec7ba..ca098bf4cc65 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3978,6 +3978,16 @@ need_resched_nonpreemptible:
                 switch_count = &prev->nvcsw;
         }
 
+        /*
+         * If we are going to sleep and we have plugged IO queued, make
+         * sure to submit it to avoid deadlocks.
+         */
+        if (prev->state != TASK_RUNNING && blk_needs_flush_plug(prev)) {
+                raw_spin_unlock(&rq->lock);
+                blk_flush_plug(prev);
+                raw_spin_lock(&rq->lock);
+        }
+
         pre_schedule(rq, prev);
 
         if (unlikely(!rq->nr_running))
@@ -5333,6 +5343,7 @@ void __sched io_schedule(void)
 
         delayacct_blkio_start();
         atomic_inc(&rq->nr_iowait);
+        blk_flush_plug(current);
         current->in_iowait = 1;
         schedule();
         current->in_iowait = 0;
@@ -5348,6 +5359,7 @@ long __sched io_schedule_timeout(long timeout)
 
         delayacct_blkio_start();
         atomic_inc(&rq->nr_iowait);
+        blk_flush_plug(current);
         current->in_iowait = 1;
         ret = schedule_timeout(timeout);
         current->in_iowait = 0;