Re: [Qemu-devel] [Problem] qemu crash when vhost_net_start

[Marc-André Lureau]

Hi

----- Original Message -----
> Hi, all
> Recently, I have a VM with a vhost-user network card created by qemu 2.6.0.
> Once, I restart OpenVSwitch service
> and start this VM in the same time. I found qemu may probably crash with
> following stack:
> 
> (gdb) bt
> #0  0x00007f0f9179a5d7 in raise () from /usr/lib64/libc.so.6
> #1  0x00007f0f9179bcc8 in abort () from /usr/lib64/libc.so.6
> #2  0x000000000045a202 in kvm_io_ioeventfd_add ()
> #3  0x000000000045cffc in address_space_add_del_ioeventfds ()
> #4  0x000000000045fa0e in address_space_update_ioeventfds ()
> #5  0x0000000000460f40 in memory_region_transaction_commit ()
> #6  0x0000000000461ce5 in memory_region_add_eventfd ()
> #7  0x000000000066a1e5 in virtio_pci_set_host_notifier_internal ()
> #8  0x00000000004ae08a in vhost_dev_enable_notifiers ()
> #9  0x0000000000492743 in vhost_net_start_one ()
> #10 0x00000000004930bf in vhost_net_start ()
> #11 0x000000000048efd4 in virtio_net_vhost_status ()
> #12 0x000000000048f16a in virtio_net_set_status ()
> #13 0x0000000000686bcd in qmp_set_link ()
> #14 0x000000000068dcc3 in net_vhost_user_event ()
> #15 0x000000000051f043 in tcp_chr_new_client ()
> #16 0x000000000051f10f in qemu_chr_socket_connected ()
> #17 0x000000000073cb10 in qio_task_complete ()
> #18 0x000000000073cb7b in gio_task_thread_result ()
> #19 0x00007f0f929fb99a in g_main_context_dispatch () from
> /usr/lib64/libglib-2.0.so.0
> #20 0x00000000006d2275 in os_host_main_loop_wait ()
> #21 0x00000000006d2393 in main_loop_wait ()
> #22 0x000000000052a0f2 in main_loop ()
> #23 0x000000000041bcd3 in main ()
> 
> This seems a bug triggering when backend starts vhost_net and meanwhile the
> frontend rmmod/modprobe virtio-net.
> Is this a known issue or any patch can fix this?
> 


Thanks for the report.

Could you provide step-by-step instructions on how to reproduce?

(if you could bisect qemu.git that would be also helpful !)

thanks