@@ -75,17 +75,16 @@ static int test_signaling(void *arg, bool shared)
 		goto err_free;
 	}
 
-	if (shared) {
-		r = dma_resv_reserve_shared(&resv, 1);
-		if (r) {
-			pr_err("Resv shared slot allocation failed\n");
-			goto err_unlock;
-		}
+	r = dma_resv_reserve_shared(&resv, 1);
+	if (r) {
+		pr_err("Resv shared slot allocation failed\n");
+		goto err_unlock;
+	}
 
+	if (shared)
 		dma_resv_add_shared_fence(&resv, f);
-	} else {
+	else
 		dma_resv_add_excl_fence(&resv, f);
-	}
 
 	if (dma_resv_test_signaled(&resv, shared)) {
 		pr_err("Resv unexpectedly signaled\n");

@@ -134,17 +133,16 @@ static int test_for_each(void *arg, bool shared)
 		goto err_free;
 	}
 
-	if (shared) {
-		r = dma_resv_reserve_shared(&resv, 1);
-		if (r) {
-			pr_err("Resv shared slot allocation failed\n");
-			goto err_unlock;
-		}
+	r = dma_resv_reserve_shared(&resv, 1);
+	if (r) {
+		pr_err("Resv shared slot allocation failed\n");
+		goto err_unlock;
+	}
 
+	if (shared)
 		dma_resv_add_shared_fence(&resv, f);
-	} else {
+	else
 		dma_resv_add_excl_fence(&resv, f);
-	}
 
 	r = -ENOENT;
 	dma_resv_for_each_fence(&cursor, &resv, shared, fence) {

@@ -206,18 +204,17 @@ static int test_for_each_unlocked(void *arg, bool shared)
 		goto err_free;
 	}
 
-	if (shared) {
-		r = dma_resv_reserve_shared(&resv, 1);
-		if (r) {
-			pr_err("Resv shared slot allocation failed\n");
-			dma_resv_unlock(&resv);
-			goto err_free;
-		}
+	r = dma_resv_reserve_shared(&resv, 1);
+	if (r) {
+		pr_err("Resv shared slot allocation failed\n");
+		dma_resv_unlock(&resv);
+		goto err_free;
+	}
 
+	if (shared)
 		dma_resv_add_shared_fence(&resv, f);
-	} else {
+	else
 		dma_resv_add_excl_fence(&resv, f);
-	}
 	dma_resv_unlock(&resv);
 
 	r = -ENOENT;

@@ -290,18 +287,17 @@ static int test_get_fences(void *arg, bool shared)
 		goto err_resv;
 	}
 
-	if (shared) {
-		r = dma_resv_reserve_shared(&resv, 1);
-		if (r) {
-			pr_err("Resv shared slot allocation failed\n");
-			dma_resv_unlock(&resv);
-			goto err_resv;
-		}
+	r = dma_resv_reserve_shared(&resv, 1);
+	if (r) {
+		pr_err("Resv shared slot allocation failed\n");
+		dma_resv_unlock(&resv);
+		goto err_resv;
+	}
 
+	if (shared)
 		dma_resv_add_shared_fence(&resv, f);
-	} else {
+	else
 		dma_resv_add_excl_fence(&resv, f);
-	}
 	dma_resv_unlock(&resv);
 
 	r = dma_resv_get_fences(&resv, shared, &i, &fences);

@@ -1367,6 +1367,14 @@ void amdgpu_bo_fence(struct amdgpu_bo *bo, struct dma_fence *fence,
 		     bool shared)
 {
 	struct dma_resv *resv = bo->tbo.base.resv;
+	int r;
+
+	r = dma_resv_reserve_shared(resv, 1);
+	if (r) {
+		/* As last resort on OOM we block for the fence */
+		dma_fence_wait(fence, false);
+		return;
+	}
 
 	if (shared)
 		dma_resv_add_shared_fence(resv, fence);

@@ -179,11 +179,9 @@ static int submit_fence_sync(struct etnaviv_gem_submit *submit)
 		struct etnaviv_gem_submit_bo *bo = &submit->bos[i];
 		struct dma_resv *robj = bo->obj->base.resv;
 
-		if (!(bo->flags & ETNA_SUBMIT_BO_WRITE)) {
-			ret = dma_resv_reserve_shared(robj, 1);
-			if (ret)
-				return ret;
-		}
+		ret = dma_resv_reserve_shared(robj, 1);
+		if (ret)
+			return ret;
 
 		if (submit->flags & ETNA_SUBMIT_NO_IMPLICIT)
 			continue;

@@ -100,7 +100,8 @@ bool i915_gem_clflush_object(struct drm_i915_gem_object *obj,
 	trace_i915_gem_object_clflush(obj);
 
 	clflush = NULL;
-	if (!(flags & I915_CLFLUSH_SYNC))
+	if (!(flags & I915_CLFLUSH_SYNC) &&
+	    dma_resv_reserve_shared(obj->base.resv, 1) == 0)
 		clflush = clflush_work_create(obj);
 	if (clflush) {
 		i915_sw_fence_await_reservation(&clflush->base.chain,

@@ -989,11 +989,9 @@ static int eb_validate_vmas(struct i915_execbuffer *eb)
 			}
 		}
 
-		if (!(ev->flags & EXEC_OBJECT_WRITE)) {
-			err = dma_resv_reserve_shared(vma->resv, 1);
-			if (err)
-				return err;
-		}
+		err = dma_resv_reserve_shared(vma->resv, 1);
+		if (err)
+			return err;
 
 		GEM_BUG_ON(drm_mm_node_allocated(&vma->node) &&
 			   eb_vma_misplaced(&eb->exec[i], vma, ev->flags));

@@ -179,7 +179,10 @@ static int igt_lmem_pages_migrate(void *arg)
 					  i915_gem_object_is_lmem(obj),
 					  0xdeadbeaf, &rq);
 		if (rq) {
-			dma_resv_add_excl_fence(obj->base.resv, &rq->fence);
+			err = dma_resv_reserve_shared(obj->base.resv, 1);
+			if (!err)
+				dma_resv_add_excl_fence(obj->base.resv,
+							&rq->fence);
 			i915_request_put(rq);
 		}
 		if (err)

@@ -1255,6 +1255,12 @@ int _i915_vma_move_to_active(struct i915_vma *vma,
 			intel_frontbuffer_put(front);
 		}
 
+		if (!(flags & __EXEC_OBJECT_NO_RESERVE)) {
+			err = dma_resv_reserve_shared(vma->resv, 1);
+			if (unlikely(err))
+				return err;
+		}
+
 		if (fence) {
 			dma_resv_add_excl_fence(vma->resv, fence);
 			obj->write_domain = I915_GEM_DOMAIN_RENDER;

@@ -894,6 +894,13 @@ static int igt_lmem_write_cpu(void *arg)
 	}
 
 	i915_gem_object_lock(obj, NULL);
+
+	err = dma_resv_reserve_shared(obj->base.resv, 1);
+	if (err) {
+		i915_gem_object_unlock(obj);
+		goto out_put;
+	}
+
 	/* Put the pages into a known state -- from the gpu for added fun */
 	intel_engine_pm_get(engine);
 	err = intel_context_migrate_clear(engine->gt->migrate.context, NULL,

@@ -255,13 +255,11 @@ int lima_gem_get_info(struct drm_file *file, u32 handle, u32 *va, u64 *offset)
 static int lima_gem_sync_bo(struct lima_sched_task *task, struct lima_bo *bo,
 			    bool write, bool explicit)
 {
-	int err = 0;
+	int err;
 
-	if (!write) {
-		err = dma_resv_reserve_shared(lima_bo_resv(bo), 1);
-		if (err)
-			return err;
-	}
+	err = dma_resv_reserve_shared(lima_bo_resv(bo), 1);
+	if (err)
+		return err;
 
 	/* explicit sync use user passed dep fence */
 	if (explicit)

@@ -320,16 +320,14 @@ static int submit_fence_sync(struct msm_gem_submit *submit, bool no_implicit)
 		struct drm_gem_object *obj = &submit->bos[i].obj->base;
 		bool write = submit->bos[i].flags & MSM_SUBMIT_BO_WRITE;
 
-		if (!write) {
-			/* NOTE: _reserve_shared() must happen before
-			 * _add_shared_fence(), which makes this a slightly
-			 * strange place to call it.  OTOH this is a
-			 * convenient can-fail point to hook it in.
-			 */
-			ret = dma_resv_reserve_shared(obj->resv, 1);
-			if (ret)
-				return ret;
-		}
+		/* NOTE: _reserve_shared() must happen before
+		 * _add_shared_fence(), which makes this a slightly
+		 * strange place to call it.  OTOH this is a
+		 * convenient can-fail point to hook it in.
+		 */
+		ret = dma_resv_reserve_shared(obj->resv, 1);
+		if (ret)
+			return ret;
 
 		/* exclusive fences must be ordered */
 		if (no_implicit && !write)

@@ -349,12 +349,9 @@ nouveau_fence_sync(struct nouveau_bo *nvbo, struct nouveau_channel *chan,
 	struct nouveau_fence *f;
 	int ret;
 
-	if (!exclusive) {
-		ret = dma_resv_reserve_shared(resv, 1);
-
-		if (ret)
-			return ret;
-	}
+	ret = dma_resv_reserve_shared(resv, 1);
+	if (ret)
+		return ret;
 
 	dma_resv_for_each_fence(&cursor, resv, exclusive, fence) {
 		struct nouveau_channel *prev = NULL;

@@ -247,6 +247,10 @@ static int panfrost_acquire_object_fences(struct drm_gem_object **bos,
 	int i, ret;
 
 	for (i = 0; i < bo_count; i++) {
+		ret = dma_resv_reserve_shared(bos[i]->resv, 1);
+		if (ret)
+			return ret;
+
 		/* panfrost always uses write mode in its current uapi */
 		ret = drm_sched_job_add_implicit_dependencies(job, bos[i],
 							      true);

@@ -221,9 +221,6 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
 
 	fbo->base = *bo;
 
-	ttm_bo_get(bo);
-	fbo->bo = bo;
-
 	/**
 	 * Fix up members that we shouldn't copy directly:
 	 * TODO: Explicit member copy would probably be better here.

@@ -246,6 +243,15 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
 	ret = dma_resv_trylock(&fbo->base.base._resv);
 	WARN_ON(!ret);
 
+	ret = dma_resv_reserve_shared(&fbo->base.base._resv, 1);
+	if (ret) {
+		kfree(fbo);
+		return ret;
+	}
+
+	ttm_bo_get(bo);
+	fbo->bo = bo;
+
 	ttm_bo_move_to_lru_tail_unlocked(&fbo->base);
 
 	*new_obj = &fbo->base;

@@ -90,6 +90,7 @@ int ttm_eu_reserve_buffers(struct ww_acquire_ctx *ticket,
 
 	list_for_each_entry(entry, list, head) {
 		struct ttm_buffer_object *bo = entry->bo;
+		unsigned int num_fences;
 
 		ret = ttm_bo_reserve(bo, intr, (ticket == NULL), ticket);
 		if (ret == -EALREADY && dups) {

@@ -100,12 +101,10 @@ int ttm_eu_reserve_buffers(struct ww_acquire_ctx *ticket,
 			continue;
 		}
 
+		num_fences = min(entry->num_shared, 1u);
 		if (!ret) {
-			if (!entry->num_shared)
-				continue;
-
 			ret = dma_resv_reserve_shared(bo->base.resv,
-								entry->num_shared);
+						      num_fences);
 			if (!ret)
 				continue;
 		}

@@ -120,9 +119,9 @@ int ttm_eu_reserve_buffers(struct ww_acquire_ctx *ticket,
 			ret = ttm_bo_reserve_slowpath(bo, intr, ticket);
 		}
 
-		if (!ret && entry->num_shared)
+		if (!ret)
 			ret = dma_resv_reserve_shared(bo->base.resv,
-								entry->num_shared);
+						      num_fences);
 
 		if (unlikely(ret != 0)) {
 			if (ticket) {

@@ -259,16 +259,21 @@ v3d_lock_bo_reservations(struct v3d_job *job,
 		return ret;
 
 	for (i = 0; i < job->bo_count; i++) {
+		ret = dma_resv_reserve_shared(job->bo[i]->resv, 1);
+		if (ret)
+			goto fail;
+
 		ret = drm_sched_job_add_implicit_dependencies(&job->base,
 							      job->bo[i], true);
-		if (ret) {
-			drm_gem_unlock_reservations(job->bo, job->bo_count,
-						    acquire_ctx);
-			return ret;
-		}
+		if (ret)
+			goto fail;
 	}
 
 	return 0;
+
+fail:
+	drm_gem_unlock_reservations(job->bo, job->bo_count, acquire_ctx);
+	return ret;
 }
 
 /**

@@ -157,12 +157,14 @@ int vgem_fence_attach_ioctl(struct drm_device *dev,
 	}
 
 	/* Expose the fence via the dma-buf */
-	ret = 0;
 	dma_resv_lock(resv, NULL);
-	if (arg->flags & VGEM_FENCE_WRITE)
-		dma_resv_add_excl_fence(resv, fence);
-	else if ((ret = dma_resv_reserve_shared(resv, 1)) == 0)
-		dma_resv_add_shared_fence(resv, fence);
+	ret = dma_resv_reserve_shared(resv, 1);
+	if (!ret) {
+		if (arg->flags & VGEM_FENCE_WRITE)
+			dma_resv_add_excl_fence(resv, fence);
+		else
+			dma_resv_add_shared_fence(resv, fence);
+	}
 	dma_resv_unlock(resv);
 
 	/* Record the fence in our idr for later signaling */

@@ -214,6 +214,7 @@ void virtio_gpu_array_add_obj(struct virtio_gpu_object_array *objs,
 
 int virtio_gpu_array_lock_resv(struct virtio_gpu_object_array *objs)
 {
+	unsigned int i;
 	int ret;
 
 	if (objs->nents == 1) {

@@ -222,6 +223,14 @@ int virtio_gpu_array_lock_resv(struct virtio_gpu_object_array *objs)
 		ret = drm_gem_lock_reservations(objs->objs, objs->nents,
 						&objs->ticket);
 	}
+	if (ret)
+		return ret;
+
+	for (i = 0; i < objs->nents; ++i) {
+		ret = dma_resv_reserve_shared(objs->objs[i]->resv, 1);
+		if (ret)
+			return ret;
+	}
 	return ret;
 }
 

@@ -1053,16 +1053,22 @@ void vmw_bo_fence_single(struct ttm_buffer_object *bo,
 			 struct vmw_fence_obj *fence)
 {
 	struct ttm_device *bdev = bo->bdev;
-
 	struct vmw_private *dev_priv =
 		container_of(bdev, struct vmw_private, bdev);
+	int ret;
 
-	if (fence == NULL) {
+	if (fence == NULL)
 		vmw_execbuf_fence_commands(NULL, dev_priv, &fence, NULL);
+	else
+		dma_fence_get(&fence->base);
+
+	ret = dma_resv_reserve_shared(bo->base.resv, 1);
+	if (!ret)
 		dma_resv_add_excl_fence(bo->base.resv, &fence->base);
-		dma_fence_put(&fence->base);
-	} else
-		dma_resv_add_excl_fence(bo->base.resv, &fence->base);
+	else
+		/* Last resort fallback when we are OOM */
+		dma_fence_wait(&fence->base, false);
+	dma_fence_put(&fence->base);
 }