diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 7d0d0a3..5df4bcf 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -192,6 +192,10 @@ enum  hrtimer_base_type {
  * @nr_retries:		Total number of hrtimer interrupt retries
  * @nr_hangs:		Total number of hrtimer interrupt hangs
  * @max_hang_time:	Maximum time spent in hrtimer_interrupt
+ * @softirq_expiry_lock: Lock which is taken while softirq based hrtimer are
+ *			 expired
+ * @timer_waiters:	A hrtimer_cancel() invocation waits for the timer
+ *			callback to finish.
  * @expires_next:	absolute time of the next event, is required for remote
  *			hrtimer enqueue; it is the total first expiry time (hard
  *			and soft hrtimer are taken into account)
@@ -219,6 +223,10 @@ struct hrtimer_cpu_base {
 	unsigned short			nr_hangs;
 	unsigned int			max_hang_time;
 #endif
+#ifdef CONFIG_PREEMPT_RT
+	spinlock_t			softirq_expiry_lock;
+	atomic_t			timer_waiters;
+#endif
 	ktime_t				expires_next;
 	struct hrtimer			*next_timer;
 	ktime_t				softirq_expires_next;
@@ -350,6 +358,14 @@ extern void hrtimers_resume(void);
 
 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
 
+#ifdef CONFIG_PREEMPT_RT
+void hrtimer_cancel_wait_running(const struct hrtimer *timer);
+#else
+static inline void hrtimer_cancel_wait_running(struct hrtimer *timer)
+{
+	cpu_relax();
+}
+#endif
 
 /* Exported timer functions: */
 
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index c101f88..4991227 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1162,6 +1162,82 @@ int hrtimer_try_to_cancel(struct hrtimer *timer)
 }
 EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
 
+#ifdef CONFIG_PREEMPT_RT
+static void hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base)
+{
+	spin_lock_init(&base->softirq_expiry_lock);
+}
+
+static void hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base)
+{
+	spin_lock(&base->softirq_expiry_lock);
+}
+
+static void hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base)
+{
+	spin_unlock(&base->softirq_expiry_lock);
+}
+
+/*
+ * The counterpart to hrtimer_cancel_wait_running().
+ *
+ * If there is a waiter for cpu_base->expiry_lock, then it was waiting for
+ * the timer callback to finish. Drop expiry_lock and reaquire it. That
+ * allows the waiter to acquire the lock and make progress.
+ */
+static void hrtimer_sync_wait_running(struct hrtimer_cpu_base *cpu_base,
+				      unsigned long flags)
+{
+	if (atomic_read(&cpu_base->timer_waiters)) {
+		raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
+		spin_unlock(&cpu_base->softirq_expiry_lock);
+		spin_lock(&cpu_base->softirq_expiry_lock);
+		raw_spin_lock_irq(&cpu_base->lock);
+	}
+}
+
+/*
+ * This function is called on PREEMPT_RT kernels when the fast path
+ * deletion of a timer failed because the timer callback function was
+ * running.
+ *
+ * This prevents priority inversion, if the softirq thread on a remote CPU
+ * got preempted, and it prevents a life lock when the task which tries to
+ * delete a timer preempted the softirq thread running the timer callback
+ * function.
+ */
+void hrtimer_cancel_wait_running(const struct hrtimer *timer)
+{
+	struct hrtimer_clock_base *base = timer->base;
+
+	if (!timer->is_soft || !base || !base->cpu_base) {
+		cpu_relax();
+		return;
+	}
+
+	/*
+	 * Mark the base as contended and grab the expiry lock, which is
+	 * held by the softirq across the timer callback. Drop the lock
+	 * immediately so the softirq can expire the next timer. In theory
+	 * the timer could already be running again, but that's more than
+	 * unlikely and just causes another wait loop.
+	 */
+	atomic_inc(&base->cpu_base->timer_waiters);
+	spin_lock_bh(&base->cpu_base->softirq_expiry_lock);
+	atomic_dec(&base->cpu_base->timer_waiters);
+	spin_unlock_bh(&base->cpu_base->softirq_expiry_lock);
+}
+#else
+static inline void
+hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base) { }
+static inline void
+hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base) { }
+static inline void
+hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base) { }
+static inline void hrtimer_sync_wait_running(struct hrtimer_cpu_base *base,
+					     unsigned long flags) { }
+#endif
+
 /**
  * hrtimer_cancel - cancel a timer and wait for the handler to finish.
  * @timer:	the timer to be cancelled
@@ -1172,13 +1248,15 @@ EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
  */
 int hrtimer_cancel(struct hrtimer *timer)
 {
-	for (;;) {
-		int ret = hrtimer_try_to_cancel(timer);
+	int ret;
 
-		if (ret >= 0)
-			return ret;
-		cpu_relax();
-	}
+	do {
+		ret = hrtimer_try_to_cancel(timer);
+
+		if (ret < 0)
+			hrtimer_cancel_wait_running(timer);
+	} while (ret < 0);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(hrtimer_cancel);
 
@@ -1475,6 +1553,8 @@ static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,
 				break;
 
 			__run_hrtimer(cpu_base, base, timer, &basenow, flags);
+			if (active_mask == HRTIMER_ACTIVE_SOFT)
+				hrtimer_sync_wait_running(cpu_base, flags);
 		}
 	}
 }
@@ -1485,6 +1565,7 @@ static __latent_entropy void hrtimer_run_softirq(struct softirq_action *h)
 	unsigned long flags;
 	ktime_t now;
 
+	hrtimer_cpu_base_lock_expiry(cpu_base);
 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
 
 	now = hrtimer_update_base(cpu_base);
@@ -1494,6 +1575,7 @@ static __latent_entropy void hrtimer_run_softirq(struct softirq_action *h)
 	hrtimer_update_softirq_timer(cpu_base, true);
 
 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
+	hrtimer_cpu_base_unlock_expiry(cpu_base);
 }
 
 #ifdef CONFIG_HIGH_RES_TIMERS
@@ -1897,6 +1979,7 @@ int hrtimers_prepare_cpu(unsigned int cpu)
 	cpu_base->softirq_next_timer = NULL;
 	cpu_base->expires_next = KTIME_MAX;
 	cpu_base->softirq_expires_next = KTIME_MAX;
+	hrtimer_cpu_base_init_expiry_lock(cpu_base);
 	return 0;
 }