Summary

backlight_drvinit() calls lockuninit(&backlight_lock) (line 147) -- teardown routine (kern_lock.c:1324 De-initialize a lock) -- instead of lockinit(&backlight_lock wmesg timo flags) which sets lk_wmesg. Lock declared static struct lock (BSS-zeroed lk_wmesg stays NULL). lockmgr uses lk_wmesg as tsleep message on contention (kern_lock.c:179 251 382 440 699). If lock contended tsleep(...NULL...) invoked. Currently only guards alloc_unr/free_unr/make_dev/destroy_dev in infrequent register/destroy so not observed. No unprivileged trigger register/destroy kernel/root-initiated. Risk malformed lock state under future heavier use or lock debugging assertions. lockinit documented prerequisite kern_lock.c:1296.