Re: xcs segfaults on vm shutdown

[Anthony Liguori <aliguori@us.ibm.com>]

Richard Sterling Cox wrote:

>hi,
>
>I'm experiencing regular seg-faults of the xcs daemon during vm
>shutdown operations (occurring somewhere between 5 and 25 VMs run,
>typically).
>  
>
I've seen xcs crash a number of times with vm-tools.  What arguments 
were you passing to vm-shutdown?  The default operation is to simply 
send a CMSG_SHUTDOWN to the domain.

If you're doing a '-d' which invokes xc_destroy, I think that perhaps 
what's happening is that xcs is not gracefully handling a disappearing VM.

Regards,

>xen: unstable patched through 2005-03-07
>dom0: linux-2.6.10-xen0 / Fedora Core 3
>gcc: 3.4.2 20041017 (Red Hat 3.4.2-6.fc3)
>vmtools: 0.0.3 I believe, but they report (-V) 0.0.1, which is not
>         true
>(not using xend)
>
>The errors usually seem to occur while running 'vm-shutdown'.
>
>I have been running 'xcs -i' under gdb and found that, at least twice,
>the error is at xen/tools/xcs/ctrl_interface.c:143. Here is the output
>of one such session (the error is repeatable enough that I should be
>able to provide other info if anyone is interested):
>
>Program received signal SIGSEGV, Segmentation fault.
>0x080490b9 in ctrl_chan_request_to_read (cc=0x8050a60) at ctrl_interface.c:143
>143         return (RING_HAS_UNCONSUMED_REQUESTS(CTRL_RING, &cc->tx_ring));
>
>(gdb) bt
>#0  0x080490b9 in ctrl_chan_request_to_read (cc=0x8050a60) at ctrl_interface.c:143
>#1  0x0804a8d7 in handle_ctrl_if () at xcs.c:550
>#2  0x0804ae93 in main (argc=2, argv=0xbffffa74) at xcs.c:737
>(gdb) print cc
>$1 = (control_channel_t *) 0x8050a60
>(gdb) print *cc
>$2 = {connected = 1, ref_count = 1, type = 0, remote_dom = 26, local_port = 73, remote_port = 1,
>  interface = 0xb7ff0800, tx_ring = {rsp_prod_pvt = 0, req_cons = 0, sring = 0xb7ff0800},
>  rx_ring = {req_prod_pvt = 0, rsp_cons = 0, sring = 0xb7ff0a08}, virq = 0}
>(gdb) print *(cc->tx_ring->sring)
>Cannot access memory at address 0xb7ff0800
>(gdb) up
>#1  0x0804a8d7 in handle_ctrl_if () at xcs.c:550
>550             while (ctrl_chan_request_to_read(cc))
>(gdb) print chan
>$4 = 73
>(gdb) print cc_list[chan]
>$6 = (control_channel_t *) 0x8050a60
>
>
>rick
>
>
>
>-------------------------------------------------------
>SF email is sponsored by - The IT Product Guide
>Read honest & candid reviews on hundreds of IT Products from real users.
>Discover which products truly live up to the hype. Start reading now.
>http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click
>_______________________________________________
>Xen-devel mailing list
>Xen-devel@lists.sourceforge.net
>https://lists.sourceforge.net/lists/listinfo/xen-devel
>
>  
>



-------------------------------------------------------
SF email is sponsored by - The IT Product Guide
Read honest & candid reviews on hundreds of IT Products from real users.
Discover which products truly live up to the hype. Start reading now.
http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click