drm/i915: Drop vm.ref for duplicate vma on construction

As we allow for parallel threads to create the same vma instance
concurrently, 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: 2850748ef8 ("drm/i915: Pull i915_vma_pin under the vm->mutex")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: <stable@vger.kernel.org> # v5.5+
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200702083225.20044-1-chris@chris-wilson.co.uk
(cherry picked from commit 2377427cdd)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
This commit is contained in:
Chris Wilson 2020-07-02 09:32:03 +01:00 committed by Rodrigo Vivi
parent 9eb0463cfe
commit 42723673a1

View file

@ -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;
}