On 10/3/23 11:11, Thomas Hellström wrote: <snip>
+ +/** + * drm_gpuvm_bo_evict() - add / remove a &drm_gpuvm_bo to / from the &drm_gpuvms + * evicted list + * @vm_bo: the &drm_gpuvm_bo to add or remove + * @evict: indicates whether the object is evicted + * + * Adds a &drm_gpuvm_bo to or removes it from the &drm_gpuvms evicted list. + */ +void +drm_gpuvm_bo_evict(struct drm_gpuvm_bo *vm_bo, bool evict) +{ + struct drm_gem_object *obj = vm_bo->obj; + + dma_resv_assert_held(obj->resv); + + /* Always lock list transactions, even if DRM_GPUVM_RESV_PROTECTED is + * set. This is required to protect multiple concurrent calls to + * drm_gpuvm_bo_evict() with BOs with different dma_resv. + */This doesn't work. The RESV_PROTECTED case requires the evicted flag we discussed before. The list is either protected by the spinlock or the resv. Otherwise a list add could race with a list removal elsewhere.
I think it does unless I miss something, but it might be a bit subtle though. Concurrent drm_gpuvm_bo_evict() are protected by the spinlock. Additionally, when drm_gpuvm_bo_evict() is called we hold the dma-resv of the corresponding GEM object. In drm_gpuvm_validate() I assert that we hold *all* dma-resv, which implies that no one can call drm_gpuvm_bo_evict() on any of the VM's objects and no one can add a new one and directly call drm_gpuvm_bo_evict() on it either.
Thanks, Thomas
