refcount_read
WARN_ON(refcount_read(&wl->refcount));
if (refcount_read(&wl->refcount))
if (refcount_read(&wl->refcount))
if (WARN_RATELIMIT(!refcount_read(&wl->refcount),
GEM_BUG_ON(refcount_read(&vma_res->hold_count) != 1);