Re: [Qemu-devel] qemu crash in coroutine bdrv_co_do_rw

[Stefan Hajnoczi]

On Thu, Feb 26, 2015 at 10:29:57AM +0100, Christian Borntraeger wrote:
> is this some know issue? Under heavy load with lots of dataplane devices I 
> sometimes get a segfault in the bdrc_co_do_rw routine:
> 
> #0  bdrv_co_do_rw (opaque=0x0) at /home/cborntra/REPOS/qemu/block.c:4791
> 4791      if (!acb->is_write) {
> (gdb) bt
> #0  bdrv_co_do_rw (opaque=0x0) at /home/cborntra/REPOS/qemu/block.c:4791
> #1  0x00000000801aeb78 in coroutine_trampoline (i0=<optimized out>, 
> i1=-725099072) at /home/cborntra/REPOS/qemu/coroutine-ucontext.c:80
> #2  0x000003fffbe1cca2 in __makecontext_ret () from /lib64/libc.so.6
> Backtrace stopped: previous frame identical to this frame (corrupt stack?)
> (gdb) up
> #1  0x00000000801aeb78 in coroutine_trampoline (i0=<optimized out>, 
> i1=-725099072) at /home/cborntra/REPOS/qemu/coroutine-ucontext.c:80
> 80            co->entry(co->entry_arg);
> (gdb) print *co
> $1 = {entry = 0x801a3c28 <bdrv_co_do_rw>, entry_arg = 0x0, caller = 
> 0x3ffe2fff788, pool_next = {sle_next = 0x3ffd2287990}, co_queue_wakeup = 
> {tqh_first = 0x0, 
>     tqh_last = 0x3ffd4c7dde0}, co_queue_next = {tqe_next = 0x0, tqe_prev = 
> 0x0}}
> 
> As you can see enty_arg is 0, causing the problem. Do you have any quick idea 
> before I start debugging?

No, I haven't seen this bug before.  Are you running qemu.git/master?

Have you tried disabling the coroutine pool (freelist)?

Stefan

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