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>> + if (dmabuf->ops->match_mapping) { >> + ret = dmabuf->ops->match_mapping(&match_args); >> + } >> + >> attach->dmabuf = dmabuf; >> attach->importer_ops = importer_ops; >> attach->importer_priv = importer_priv; > > I may misunderstand the intended contract. match_mapping() runs while the > attachment is still zeroed and without dmabuf->resv held. > > Patch 11's amdgpu callback needs importer_ops and importer_priv, so its XGMI > match cannot work here. Patch 12's VFIO callback asserts dmabuf->resv and > reads priv->vdev, which cleanup changes under that lock. > > Should the core initialize the attachment and hold dmabuf->resv for > match_mapping(), or should callbacks avoid attachment and lock-protected > state? Right. This completely misplaced. The matching can't be done at attachment time, but rather needs to be done before creating a mapping while holding the resv lock so that the matching decision can't change. Regards, Christian. > > Thanks, > Karl