2 files changed, 16 insertions, 6 deletions

diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 09ed48833b54..a492385b2089 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -732,13 +732,13 @@ i915_request_alloc(struct intel_engine_cs *engine, struct i915_gem_context *ctx)
         rq = kmem_cache_alloc(i915->requests,
                               GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
         if (unlikely(!rq)) {
+                i915_retire_requests(i915);
+
                 /* Ratelimit ourselves to prevent oom from malicious clients */
-                ret = i915_gem_wait_for_idle(i915,
-                                             I915_WAIT_LOCKED |
-                                             I915_WAIT_INTERRUPTIBLE,
-                                             MAX_SCHEDULE_TIMEOUT);
-                if (ret)
-                        goto err_unreserve;
+                rq = i915_gem_active_raw(&ce->ring->timeline->last_request,
+                                         &i915->drm.struct_mutex);
+                if (rq)
+                        cond_synchronize_rcu(rq->rcustate);
 
                 /*
                  * We've forced the client to stall and catch up with whatever
@@ -758,6 +758,8 @@ i915_request_alloc(struct intel_engine_cs *engine, struct i915_gem_context *ctx)
                 }
         }
 
+        rq->rcustate = get_state_synchronize_rcu();
+
         INIT_LIST_HEAD(&rq->active_list);
         rq->i915 = i915;
         rq->engine = engine;
diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
index 9898301ab7ef..7fa94b024968 100644
--- a/drivers/gpu/drm/i915/i915_request.h
+++ b/drivers/gpu/drm/i915/i915_request.h
@@ -101,6 +101,14 @@ struct i915_request {
         struct intel_signal_node signaling;
 
         /*
+         * The rcu epoch of when this request was allocated. Used to judiciously
+         * apply backpressure on future allocations to ensure that under
+         * mempressure there is sufficient RCU ticks for us to reclaim our
+         * RCU protected slabs.
+         */
+        unsigned long rcustate;
+
+        /*
          * Fences for the various phases in the request's lifetime.
          *
          * The submit fence is used to await upon all of the request's