diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index f8604a09c10191a5359df14735ef3f73dd6b0b58..1723a1f5b20edb24f6ee87ca5ee37bcbcc0e91f7 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -683,14 +683,14 @@ static void i915_ring_seqno_info(struct seq_file *m,
 	seq_printf(m, "Current sequence (%s): %x\n",
 		   engine->name, intel_engine_get_seqno(engine));
 
-	spin_lock(&b->lock);
+	spin_lock_irq(&b->lock);
 	for (rb = rb_first(&b->waiters); rb; rb = rb_next(rb)) {
 		struct intel_wait *w = container_of(rb, typeof(*w), node);
 
 		seq_printf(m, "Waiting (%s): %s [%d] on %x\n",
 			   engine->name, w->tsk->comm, w->tsk->pid, w->seqno);
 	}
-	spin_unlock(&b->lock);
+	spin_unlock_irq(&b->lock);
 }
 
 static int i915_gem_seqno_info(struct seq_file *m, void *data)
@@ -1355,14 +1355,14 @@ static int i915_hangcheck_info(struct seq_file *m, void *unused)
 			   yesno(intel_engine_has_waiter(engine)),
 			   yesno(test_bit(engine->id,
 					  &dev_priv->gpu_error.missed_irq_rings)));
-		spin_lock(&b->lock);
+		spin_lock_irq(&b->lock);
 		for (rb = rb_first(&b->waiters); rb; rb = rb_next(rb)) {
 			struct intel_wait *w = container_of(rb, typeof(*w), node);
 
 			seq_printf(m, "\t%s [%d] waiting for %x\n",
 				   w->tsk->comm, w->tsk->pid, w->seqno);
 		}
-		spin_unlock(&b->lock);
+		spin_unlock_irq(&b->lock);
 
 		seq_printf(m, "\tACTHD = 0x%08llx [current 0x%08llx]\n",
 			   (long long)engine->hangcheck.acthd,
@@ -3265,14 +3265,14 @@ static int i915_engine_info(struct seq_file *m, void *unused)
 				   I915_READ(RING_PP_DIR_DCLV(engine)));
 		}
 
-		spin_lock(&b->lock);
+		spin_lock_irq(&b->lock);
 		for (rb = rb_first(&b->waiters); rb; rb = rb_next(rb)) {
 			struct intel_wait *w = container_of(rb, typeof(*w), node);
 
 			seq_printf(m, "\t%s [%d] waiting for %x\n",
 				   w->tsk->comm, w->tsk->pid, w->seqno);
 		}
-		spin_unlock(&b->lock);
+		spin_unlock_irq(&b->lock);
 
 		seq_puts(m, "\n");
 	}
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index ef3698120d92ef6e68387a40d96f614aae8e5a34..7ba40487e345167b6c65ff7bf73b35b9aeb570da 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -1043,7 +1043,7 @@ static void error_record_engine_waiters(struct intel_engine_cs *engine,
 	if (RB_EMPTY_ROOT(&b->waiters))
 		return;
 
-	if (!spin_trylock(&b->lock)) {
+	if (!spin_trylock_irq(&b->lock)) {
 		ee->waiters = ERR_PTR(-EDEADLK);
 		return;
 	}
@@ -1051,7 +1051,7 @@ static void error_record_engine_waiters(struct intel_engine_cs *engine,
 	count = 0;
 	for (rb = rb_first(&b->waiters); rb != NULL; rb = rb_next(rb))
 		count++;
-	spin_unlock(&b->lock);
+	spin_unlock_irq(&b->lock);
 
 	waiter = NULL;
 	if (count)
@@ -1061,7 +1061,7 @@ static void error_record_engine_waiters(struct intel_engine_cs *engine,
 	if (!waiter)
 		return;
 
-	if (!spin_trylock(&b->lock)) {
+	if (!spin_trylock_irq(&b->lock)) {
 		kfree(waiter);
 		ee->waiters = ERR_PTR(-EDEADLK);
 		return;
@@ -1079,7 +1079,7 @@ static void error_record_engine_waiters(struct intel_engine_cs *engine,
 		if (++ee->num_waiters == count)
 			break;
 	}
-	spin_unlock(&b->lock);
+	spin_unlock_irq(&b->lock);
 }
 
 static void error_record_engine_registers(struct drm_i915_error_state *error,
diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
index 0d5def0d2dfe0465e3a32f4727ff7aad0dbb70b9..c410d3d6465f2b5c51d1e2007c333c3c18e9ce84 100644
--- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
@@ -83,16 +83,18 @@ static void irq_enable(struct intel_engine_cs *engine)
 	 */
 	engine->breadcrumbs.irq_posted = true;
 
-	spin_lock_irq(&engine->i915->irq_lock);
+	/* Caller disables interrupts */
+	spin_lock(&engine->i915->irq_lock);
 	engine->irq_enable(engine);
-	spin_unlock_irq(&engine->i915->irq_lock);
+	spin_unlock(&engine->i915->irq_lock);
 }
 
 static void irq_disable(struct intel_engine_cs *engine)
 {
-	spin_lock_irq(&engine->i915->irq_lock);
+	/* Caller disables interrupts */
+	spin_lock(&engine->i915->irq_lock);
 	engine->irq_disable(engine);
-	spin_unlock_irq(&engine->i915->irq_lock);
+	spin_unlock(&engine->i915->irq_lock);
 
 	engine->breadcrumbs.irq_posted = false;
 }
@@ -293,9 +295,9 @@ bool intel_engine_add_wait(struct intel_engine_cs *engine,
 	struct intel_breadcrumbs *b = &engine->breadcrumbs;
 	bool first;
 
-	spin_lock(&b->lock);
+	spin_lock_irq(&b->lock);
 	first = __intel_engine_add_wait(engine, wait);
-	spin_unlock(&b->lock);
+	spin_unlock_irq(&b->lock);
 
 	return first;
 }
@@ -326,7 +328,7 @@ void intel_engine_remove_wait(struct intel_engine_cs *engine,
 	if (RB_EMPTY_NODE(&wait->node))
 		return;
 
-	spin_lock(&b->lock);
+	spin_lock_irq(&b->lock);
 
 	if (RB_EMPTY_NODE(&wait->node))
 		goto out_unlock;
@@ -400,7 +402,7 @@ void intel_engine_remove_wait(struct intel_engine_cs *engine,
 	GEM_BUG_ON(rb_first(&b->waiters) !=
 		   (b->first_wait ? &b->first_wait->node : NULL));
 	GEM_BUG_ON(!rcu_access_pointer(b->irq_seqno_bh) ^ RB_EMPTY_ROOT(&b->waiters));
-	spin_unlock(&b->lock);
+	spin_unlock_irq(&b->lock);
 }
 
 static bool signal_complete(struct drm_i915_gem_request *request)
@@ -473,14 +475,14 @@ static int intel_breadcrumbs_signaler(void *arg)
 			 * we just completed - so double check we are still
 			 * the oldest before picking the next one.
 			 */
-			spin_lock(&b->lock);
+			spin_lock_irq(&b->lock);
 			if (request == b->first_signal) {
 				struct rb_node *rb =
 					rb_next(&request->signaling.node);
 				b->first_signal = rb ? to_signaler(rb) : NULL;
 			}
 			rb_erase(&request->signaling.node, &b->signals);
-			spin_unlock(&b->lock);
+			spin_unlock_irq(&b->lock);
 
 			i915_gem_request_put(request);
 		} else {
@@ -502,7 +504,14 @@ void intel_engine_enable_signaling(struct drm_i915_gem_request *request)
 	struct rb_node *parent, **p;
 	bool first, wakeup;
 
-	/* locked by dma_fence_enable_sw_signaling() */
+	/* Note that we may be called from an interrupt handler on another
+	 * device (e.g. nouveau signaling a fence completion causing us
+	 * to submit a request, and so enable signaling). As such,
+	 * we need to make sure that all other users of b->lock protect
+	 * against interrupts, i.e. use spin_lock_irqsave.
+	 */
+
+	/* locked by dma_fence_enable_sw_signaling() (irqsafe fence->lock) */
 	assert_spin_locked(&request->lock);
 	if (!request->global_seqno)
 		return;
@@ -594,7 +603,7 @@ void intel_engine_reset_breadcrumbs(struct intel_engine_cs *engine)
 	struct intel_breadcrumbs *b = &engine->breadcrumbs;
 
 	cancel_fake_irq(engine);
-	spin_lock(&b->lock);
+	spin_lock_irq(&b->lock);
 
 	__intel_breadcrumbs_disable_irq(b);
 	if (intel_engine_has_waiter(engine)) {
@@ -607,7 +616,7 @@ void intel_engine_reset_breadcrumbs(struct intel_engine_cs *engine)
 		irq_disable(engine);
 	}
 
-	spin_unlock(&b->lock);
+	spin_unlock_irq(&b->lock);
 }
 
 void intel_engine_fini_breadcrumbs(struct intel_engine_cs *engine)
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 891629caab6ca0a6b9ddcb9f1bcd67422445507b..d16c74ae8f54d78618a83271302650043a49d82d 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -207,7 +207,7 @@ struct intel_engine_cs {
 		struct task_struct __rcu *irq_seqno_bh; /* bh for interrupts */
 		bool irq_posted;
 
-		spinlock_t lock; /* protects the lists of requests */
+		spinlock_t lock; /* protects the lists of requests; irqsafe */
 		struct rb_root waiters; /* sorted by retirement, priority */
 		struct rb_root signals; /* sorted by retirement */
 		struct intel_wait *first_wait; /* oldest waiter by retirement */