According to fs/dlm/lock.c, the kernel may sleep under a spinlock, and the function call path is: dlm_master_lookup (acquire the spinlock) dlm_send_rcom_lookup_dump create_rcom dlm_lowcomms_get_buffer nodeid2con mutex_lock --> may sleep
This bug is found by my static analysis tool and my code review. Thanks, Jia-Ju Bai