On Wed, 16 Oct 2024 at 02:44, Nicolin Chen <nicolinc@xxxxxxxxxx> wrote: > > On Mon, Oct 14, 2024 at 07:01:40PM -0700, Nicolin Chen wrote: > > On Tue, Oct 15, 2024 at 09:15:01AM +0800, Zhangfei Gao wrote: > > > > > > > iommufd_device_bind > > > > > iommufd_device_attach > > > > > iommufd_vdevice_alloc_ioctl > > > > > > > > > > iommufd_device_detach > > > > > iommufd_device_unbind // refcount check fail > > > > > iommufd_vdevice_destroy ref-- > > > > > > > > Things should be symmetric. As you suspected, vdevice should be > > > > destroyed before iommufd_device_detach. > > > > > > I am trying based on your for_iommufd_viommu_p2-v3 branch, do you have > > > this issue? > > > In checking whether close fd before unbind? > > > > Oops, my bad. I will provide a fix. > > This should fix the problem: > > --------------------------------------------------------------------- > diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c > index 5fd3dd420290..13100cfea29d 100644 > --- a/drivers/iommu/iommufd/device.c > +++ b/drivers/iommu/iommufd/device.c > @@ -277,6 +277,11 @@ EXPORT_SYMBOL_NS_GPL(iommufd_ctx_has_group, IOMMUFD); > */ > void iommufd_device_unbind(struct iommufd_device *idev) > { > + mutex_lock(&idev->igroup->lock); > + /* idev->vdev object should be destroyed prior, yet just in case.. */ > + if (idev->vdev) > + iommufd_object_remove(idev->ictx, NULL, idev->vdev->obj.id, 0); > + mutex_unlock(&idev->igroup->lock); > iommufd_object_destroy_user(idev->ictx, &idev->obj); > } > EXPORT_SYMBOL_NS_GPL(iommufd_device_unbind, IOMMUFD); > --------------------------------------------------------------------- Not yet [ 574.162112] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000004 [ 574.261102] pc : iommufd_object_remove+0x7c/0x278 [ 574.265795] lr : iommufd_device_unbind+0x44/0x98 in check Thanks > > Thanks > Nicolin