qemu 2.7.0 segfaults in qemu_co_queue_run_restart()

I've been experiencing frequent segfaults lately with qemu 2.7.0 running Ubuntu 16.04 guests. The crash usually happens in qemu_co_queue_run_restart(). I haven't seen this so far with any other guests or distros.

Here is one back trace I obtained from one of the crashing VMs.

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(gdb) bt
#0  qemu_co_queue_run_restart (co=0x7fba8ff05aa0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:59
#1  0x000055c1656f39a9 in qemu_coroutine_enter (co=0x7fba8ff05aa0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119
#2  0x000055c1656f3e74 in qemu_co_queue_run_restart (co=0x7fba8dd20430) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60
#3  0x000055c1656f39a9 in qemu_coroutine_enter (co=0x7fba8dd20430) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119
#4  0x000055c1656f3e74 in qemu_co_queue_run_restart (co=0x7fba8dd14ea0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60
#5  0x000055c1656f39a9 in qemu_coroutine_enter (co=0x7fba8dd14ea0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119
#6  0x000055c1656f3e74 in qemu_co_queue_run_restart (co=0x7fba80c11dc0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60
#7  0x000055c1656f39a9 in qemu_coroutine_enter (co=0x7fba80c11dc0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119
#8  0x000055c1656f3e74 in qemu_co_queue_run_restart (co=0x7fba8dd0bd70) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60
#9  0x000055c1656f39a9 in qemu_coroutine_enter (co=0x7fba8dd0bd70) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119
#10 0x000055c1656f3fa0 in qemu_co_enter_next (queue=queue@entry=0x55c1669e75e0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:106
#11 0x000055c165692060 in timer_cb (blk=0x55c1669e7590, is_write=<optimized out>) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/block/throttle-groups.c:400
#12 0x000055c16564f615 in timerlist_run_timers (timer_list=0x55c166a53e80) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/qemu-timer.c:528
#13 0x000055c16564f679 in timerlistgroup_run_timers (tlg=tlg@entry=0x55c167c81cf8) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/qemu-timer.c:564
#14 0x000055c16564ff47 in aio_dispatch (ctx=ctx@entry=0x55c167c81bb0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/aio-posix.c:357
#15 0x000055c1656500e8 in aio_poll (ctx=0x55c167c81bb0, blocking=<optimized out>) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/aio-posix.c:479
#16 0x000055c1654b1c79 in iothread_run (opaque=0x55c167c81960) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/iothread.c:46
#17 0x00007fbc4b64f0a4 in allocate_stack (stack=<synthetic pointer>, pdp=<synthetic pointer>, attr=0x0) at allocatestack.c:416
#18 __pthread_create_2_1 (newthread=<error reading variable: Cannot access memory at address 0xffffffffffffff48>, attr=<error reading variable: Cannot access memory at address 0xffffffffffffff40>, 
    start_routine=<error reading variable: Cannot access memory at address 0xffffffffffffff58>, arg=<error reading variable: Cannot access memory at address 0xffffffffffffff50>) at pthread_create.c:539
Backtrace stopped: Cannot access memory at address 0x8
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The code that crashes is this
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void qemu_co_queue_run_restart(Coroutine *co)
{
    Coroutine *next;

    trace_qemu_co_queue_run_restart(co);
    while ((next = QSIMPLEQ_FIRST(&co->co_queue_wakeup))) {             
        QSIMPLEQ_REMOVE_HEAD(&co->co_queue_wakeup, co_queue_next);       <--- Crash occurs here this time
        qemu_coroutine_enter(next);
    }
}
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Expanding the macro QSIMPLEQ_REMOVE_HEAD gives us
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#define QSIMPLEQ_REMOVE_HEAD(head, field) do {                          \
    if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL)\
        (head)->sqh_last = &(head)->sqh_first;                          \
} while (/*CONSTCOND*/0)
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which corrsponds to
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if (((&co->co_queue_wakeup)->sqh_first = (&co->co_queue_wakeup)->sqh_first->co_queue_next.sqe_next) == NULL)\
        (&co->co_queue_wakeup)->sqh_last = &(&co->co_queue_wakeup)->sqh_first;
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Debugging the list we see
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(gdb) print *(&co->co_queue_wakeup->sqh_first) 
$6 = (struct Coroutine *) 0x1000
(gdb) print *(&co->co_queue_wakeup->sqh_first->co_queue_next) 
Cannot access memory at address 0x1030
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So the data in co->co_queue_wakeup->sqh_first is corrupted and represents an invalid address. Any idea why is that?