RE: [PATCH 2/4] iommufd: Avoid locking internal accesses during unmap

[Tian, Kevin]

> From: Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx>
> Sent: Sunday, July 26, 2026 3:44 PM
> 
> iommufd_access_notify_unmap() skips internal accesses because they do
> not have an external unmap callback to invoke.
> 
> However, the current test calls iommufd_lock_obj() before checking
> whether the access is internal. If iommufd_lock_obj() succeeds, the loop
> then sees the internal access and continues, bypassing the matching
> iommufd_put_object() used by the normal unmap path. This leaks the
> object reference taken by iommufd_lock_obj().
> 
> Check for internal accesses first so skipped entries are never locked.
> 
> Fixes: 27b77ea5feaa ("iommufd/access: Bypass access->ops->unmap for
> internal use")
> Cc: stable@xxxxxxxxxxxxxxx
> Assisted-by: Qoder:Qwen-3.8-MAX-Preview
> Signed-off-by: Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx>

Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>