In order to ensure that all invalidations are completed before the operation returns to userspace (i.e. before the munmap() syscall returns) we need to wait upon the outstanding operations. We are allowed to block inside the invalidate_range_start callback, and as struct_mutex is the inner lock with mmap_sem we can wait upon the struct_mutex without provoking lockdep into warning about a deadlock. However, we don't actually want to wait upon outstanding rendering whilst holding the struct_mutex if we can help it otherwise we also block other processes from submitting work to the GPU. So first we do a wait without the lock and then when we reacquire the lock, we double check that everything is ready for removing the invalidated pages. Finally to wait upon the outstanding unpinning tasks, we create a private workqueue as a means to conveniently wait upon all at once. The drawback is that this workqueue is per-mm, so any threads concurrently invalidating objects will wait upon each other. The advantage of using the workqueue is that we can wait in parallel for completion of rendering and unpinning of several objects (of particular importance if the process terminates with a whole mm full of objects). v2: Apply a cup of tea to the changelog. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94699 Testcase: igt/gem_userptr_blits/sync-unmap-cycles Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> Cc: Michał Winiarski <michal.winiarski@xxxxxxxxx> --- drivers/gpu/drm/i915/i915_gem_userptr.c | 48 ++++++++++++++++++++++++++++++++- 1 file changed, 47 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c index 291a9393493d..92b39186b05a 100644 --- a/drivers/gpu/drm/i915/i915_gem_userptr.c +++ b/drivers/gpu/drm/i915/i915_gem_userptr.c @@ -49,6 +49,7 @@ struct i915_mmu_notifier { struct hlist_node node; struct mmu_notifier mn; struct rb_root objects; + struct workqueue_struct *wq; }; struct i915_mmu_object { @@ -60,6 +61,40 @@ struct i915_mmu_object { bool attached; }; +static void wait_rendering(struct drm_i915_gem_object *obj) +{ + struct drm_device *dev = obj->base.dev; + struct drm_i915_gem_request *requests[I915_NUM_ENGINES]; + unsigned reset_counter; + int i, n; + + if (!obj->active) + return; + + n = 0; + for (i = 0; i < I915_NUM_ENGINES; i++) { + struct drm_i915_gem_request *req; + + req = obj->last_read_req[i]; + if (req == NULL) + continue; + + requests[n++] = i915_gem_request_reference(req); + } + + reset_counter = atomic_read(&to_i915(dev)->gpu_error.reset_counter); + mutex_unlock(&dev->struct_mutex); + + for (i = 0; i < n; i++) + __i915_wait_request(requests[i], reset_counter, false, + NULL, NULL); + + mutex_lock(&dev->struct_mutex); + + for (i = 0; i < n; i++) + i915_gem_request_unreference(requests[i]); +} + static void cancel_userptr(struct work_struct *work) { struct i915_mmu_object *mo = container_of(work, typeof(*mo), work); @@ -75,6 +110,8 @@ static void cancel_userptr(struct work_struct *work) struct i915_vma *vma, *tmp; bool was_interruptible; + wait_rendering(obj); + was_interruptible = dev_priv->mm.interruptible; dev_priv->mm.interruptible = false; @@ -140,7 +177,7 @@ static void i915_gem_userptr_mn_invalidate_range_start(struct mmu_notifier *_mn, */ mo = container_of(it, struct i915_mmu_object, it); if (kref_get_unless_zero(&mo->obj->base.refcount)) - schedule_work(&mo->work); + queue_work(mn->wq, &mo->work); list_add(&mo->link, &cancelled); it = interval_tree_iter_next(it, start, end); @@ -148,6 +185,8 @@ static void i915_gem_userptr_mn_invalidate_range_start(struct mmu_notifier *_mn, list_for_each_entry(mo, &cancelled, link) del_object(mo); spin_unlock(&mn->lock); + + flush_workqueue(mn->wq); } static const struct mmu_notifier_ops i915_gem_userptr_notifier = { @@ -167,10 +206,16 @@ i915_mmu_notifier_create(struct mm_struct *mm) spin_lock_init(&mn->lock); mn->mn.ops = &i915_gem_userptr_notifier; mn->objects = RB_ROOT; + mn->wq = alloc_workqueue("i915-userptr-release", WQ_UNBOUND, 0); + if (mn->wq == NULL) { + kfree(mn); + return ERR_PTR(-ENOMEM); + } /* Protected by mmap_sem (write-lock) */ ret = __mmu_notifier_register(&mn->mn, mm); if (ret) { + destroy_workqueue(mn->wq); kfree(mn); return ERR_PTR(ret); } @@ -256,6 +301,7 @@ i915_mmu_notifier_free(struct i915_mmu_notifier *mn, return; mmu_notifier_unregister(&mn->mn, mm); + destroy_workqueue(mn->wq); kfree(mn); } -- 2.8.0.rc3 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
