[Intel-gfx] [PATCH 01/23] drm/i915: Drop vm.ref for duplicate vma on construction

[Tvrtko Ursulin]

On 02/07/2020 09:32, Chris Wilson wrote:
> As we allow for parallel threads to create vma instances in parallel,
> and we only filter out the duplicates upon reacquiring the spinlock for
> the rbtree, we have to free the loser of the constructors' race. When
> freeing, we should also drop any resource references acquired for the
> redundant vma.
> 
> Fixes: 2850748ef876 ("drm/i915: Pull i915_vma_pin under the vm->mutex")
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> Cc: <stable at vger.kernel.org> # v5.5+
> ---
>   drivers/gpu/drm/i915/i915_vma.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
> index 1f63c4a1f055..7fe1f317cd2b 100644
> --- a/drivers/gpu/drm/i915/i915_vma.c
> +++ b/drivers/gpu/drm/i915/i915_vma.c
> @@ -198,6 +198,7 @@ vma_create(struct drm_i915_gem_object *obj,
>   		cmp = i915_vma_compare(pos, vm, view);
>   		if (cmp == 0) {
>   			spin_unlock(&obj->vma.lock);
> +			i915_vm_put(vm);
>   			i915_vma_free(vma);
>   			return pos;
>   		}
> 

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Regards,

Tvrtko