mon segv in msg following "do not register lossy client connections"

Hi, I've been seeing a mon segfault in current master which can be consistently tripped from a kernel CephFS mount attempt against a vstart cluster: Thread 14 "msgr-worker-2" received signal SIGSEGV, Segmentation fault. [Switching to Thread 0x7f42403bf700 (LWP 92639)] 0x00007f4247d2b960 in __lll_unlock_elision () from /lib64/libpthread.so.0 (gdb) bt #0 0x00007f4247d2b960 in __lll_unlock_elision () from /lib64/libpthread.so.0 #1 0x00007f424b1b4f4f in __gthread_mutex_unlock (__mutex=0x5613b7e0a2c8) at /usr/include/c++/7/x86_64-suse-linux/bits/gthr-default.h:778 #2 0x00007f424b1baa8a in std::mutex::unlock (this=0x5613b7e0a2c8) at /usr/include/c++/7/bits/std_mutex.h:121 #3 0x00007f424b5664d0 in ProtocolV1::open (this=0x5613b83a7800, reply=..., authorizer_reply=...) at /home/david/ceph/src/msg/async/ProtocolV1.cc:2481 #4 0x00007f424b561e4a in ProtocolV1::handle_connect_message_2 (this=0x5613b83a7800) at /home/david/ceph/src/msg/async/ProtocolV1.cc:2055 #5 0x00007f424b55fd1f in ProtocolV1::handle_connect_message_1 (this=0x5613b83a7800, buffer=0x5613b8289000 "\332*\244j\270\217\001/\b", r=0) at /home/david/ceph/src/msg/async/ProtocolV1.cc:1915 (rest in https://paste.opensuse.org/43958295 ) Git bisect points at the following commit as the culprit: c48a29b9edde3c6d3c msg/async: do not register lossy client connections I'll raise a ticket to track this, but just thought I'd ping the list to see whether others were hitting it... Cheers, David