[Qemu-block] intermittent failure in test-replication

[Peter Maydell]

Hi; I seem to be getting an intermittent failure in
tests/test-replication:

MALLOC_PERTURB_=${MALLOC_PERTURB_:-$(( ${RANDOM:-0} % 255 + 1))}
gtester -k --verbose -m=quick tests/test-replication
TEST: tests/test-replication... (pid=8465)
  /replication/primary/read:                                           OK
  /replication/primary/write:                                          OK
  /replication/primary/start:                                          OK
  /replication/primary/stop:                                           OK
  /replication/primary/do_checkpoint:                                  OK
  /replication/primary/get_error_all:                                  OK
  /replication/secondary/read:                                         OK
  /replication/secondary/write:                                        OK
  /replication/secondary/start:                                        OK
  /replication/secondary/stop:
qemu: qemu_mutex_unlock_impl: Operation not permitted
FAIL
GTester: last random seed: R02S46f564a1d3ba1513490a19cb15805626
(pid=8735)
  /replication/secondary/do_checkpoint:                                OK
  /replication/secondary/get_error_all:                                OK
FAIL: tests/test-replication

This was on an x86-64 Linux system. I think the error means "thread
tried to unlock a mutex it does not own"...

This is probably an "unly happens when system is under heavy load"
issue and/or a race condition.

thanks
-- PMM