`cb_mutex` has been removed since this commit(https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/include/linux/netlink.h?h=v6.11&id=5fbf57a937f418fe204f9dbb7735e91984f4ee6a) in 6.11. For compatibility reasons, `cb_mutex` should not be used in 6.11 and later versions. Signed-off-by: brokestar233 <3765589194@qq.com>