Strange crash during qemu/anita/atf run

[Paul Goyette <paul%whooppee.com@localhost>]

My qemu-based build-and-test system just encountered a locking problem 
in test "rump/rumpkern/t_sp" (test case stress-killer).

Reader / writer lock error: rw_vector_enter: locking against myself

lock address : 0xffff80000ab71b90
current cpu  :                  0
current lwp  : 0xffff80000b9c1020
owner/count  : 0xffff80000b9c1020 flags    : 0x0000000000000004

panic: lock error
cpu0: Begin traceback...
printf_nolog() at netbsd:printf_nolog
lockdebug_abort() at netbsd:lockdebug_abort+0x3a
rw_vector_enter() at netbsd:rw_vector_enter+0x32b
uvm_fault_internal() at netbsd:uvm_fault_internal+0xca
trap() at netbsd:trap+0x4d5
uvm_fault(0xffff80000ab71b88, 0x10000, 1) -> e
fatal page fault in supervisor mode
trap type 6 code 0 rip ffffffff80270647 cs 8 rflags 246 cr2 100b8 cpl 0 
rsp ffff80000b9e2be0
Skipping crash dump on recursive panic
panic: trap
Faulted in mid-traceback; aborting...rebooting...


This does not seem to be easily reproduced, and since it happened under 
automated anita/qemu I didn't get a chance to grab any additional debug 
info.

This happened once before, a couple days ago, and before that there was 
another lock-related panic:

lockme_DESTROYHELD: fatal protection fault in supervisor mode
trap type 4 code 0 rip ffffffff804cce27 cs 8 rflags 206 cr2 7f7ff6e0e450 
cpl 8 rsp ffff80000b929b50
panic: trap


Does anyone have any clues here?


-------------------------------------------------------------------------
| Paul Goyette     | PGP Key fingerprint:     | E-mail addresses:       |
| Customer Service | FA29 0E3B 35AF E8AE 6651 | paul at whooppee.com    |
| Network Engineer | 0786 F758 55DE 53BA 7731 | pgoyette at juniper.net |
| Kernel Developer |                          | pgoyette at netbsd.org  |
-------------------------------------------------------------------------