Re: [Qemu-devel] coroutines: block: Co-routine re-entered recursively when migrating disk with iothreads

["Jason J. Herne" <jjherne@linux.vnet.ibm.com>]

On 05/25/2016 04:36 AM, Fam Zheng wrote:
> On Tue, 05/24 11:05, Jason J. Herne wrote:
>> Thread 13 (Thread 0x3ff989ff910 (LWP 29452)):
>> #0  0x000003ff99abe2c0 in raise () from /lib64/libc.so.6
>> #1  0x000003ff99abfc26 in abort () from /lib64/libc.so.6
>> #2  0x0000000080427d80 in qemu_coroutine_enter (co=0x9c5a4120, opaque=0x0)
>> at /root/kvmdev/qemu/util/qemu-coroutine.c:112
>> #3  0x000000008032246e in nbd_restart_write (opaque=0x9c5897b0) at
>> /root/kvmdev/qemu/block/nbd-client.c:114
>> #4  0x00000000802b3a1c in aio_dispatch (ctx=0x9c530770) at
>> /root/kvmdev/qemu/aio-posix.c:341
>> #5  0x00000000802b4332 in aio_poll (ctx=0x9c530770, blocking=true) at
>> /root/kvmdev/qemu/aio-posix.c:479
>> #6  0x0000000080155aba in iothread_run (opaque=0x9c530200) at
>> /root/kvmdev/qemu/iothread.c:46
>> #7  0x000003ff99c87c2c in start_thread () from /lib64/libpthread.so.0
>> #8  0x000003ff99b8ec9a in thread_start () from /lib64/libc.so.6
>
> This is the continuation of write request to the NBD target....
>
>> Thread 1 (Thread 0x3ff9a6f2a90 (LWP 29433)):
>> #0  0x000003ff99c8d68a in pthread_cond_wait@@GLIBC_2.3.2 () from
>> /lib64/libpthread.so.0
>> #1  0x000000008040932e in qemu_cond_wait (cond=0x9c530800, mutex=0x9c5307d0)
>> at /root/kvmdev/qemu/util/qemu-thread-posix.c:123
>> #2  0x0000000080426a38 in rfifolock_lock (r=0x9c5307d0) at
>> /root/kvmdev/qemu/util/rfifolock.c:59
>> #3  0x00000000802a1f72 in aio_context_acquire (ctx=0x9c530770) at
>> /root/kvmdev/qemu/async.c:373
>> #4  0x00000000802b3f54 in aio_poll (ctx=0x9c530770, blocking=true) at
>> /root/kvmdev/qemu/aio-posix.c:415
>> #5  0x000000008031e7ac in bdrv_flush (bs=0x9c59b5c0) at
>> /root/kvmdev/qemu/block/io.c:2470
>> #6  0x00000000802a8e6e in bdrv_close (bs=0x9c59b5c0) at
>> /root/kvmdev/qemu/block.c:2134
>> #7  0x00000000802a9966 in bdrv_delete (bs=0x9c59b5c0) at
>> /root/kvmdev/qemu/block.c:2341
>> #8  0x00000000802ac7c6 in bdrv_unref (bs=0x9c59b5c0) at
>> /root/kvmdev/qemu/block.c:3376
>> #9  0x0000000080315340 in mirror_exit (job=0x9c956ed0, opaque=0x9c9570d0) at
>> /root/kvmdev/qemu/block/mirror.c:494
>> #10 0x00000000802afb52 in block_job_defer_to_main_loop_bh
>> (opaque=0x9c90dc10) at /root/kvmdev/qemu/blockjob.c:476
>
> ... while this is the completion of mirror. They are not supposed to happen
> together. Either the job is completed too early, or the nbd_restart_write
> function is invoked incorrectly.
>
> I'll see if I can reproduce it here.
>
> Fam
>

Hi Fam,
Have you had any luck reproducing this?


-- 
-- Jason J. Herne (jjherne@linux.vnet.ibm.com)