Re: 'Interrupted system call' booting domains

[Mike Wray <mike.wray@hpl.hp.com>]

Tom Hibbert wrote:
> Hi all
>  
> I am a recent (as of this weekend) convert to Xen and I have to say I am 
> very, very impressed!
>  
> I am now planning a project to create a default Xen domain-0 
> installation CD based on Debian, providing an easy to use system for 
> creating
> additional domains at install time.
>  
> But first I need to iron out some issues with my personal Xen installation.
>  
> When I create the domains (xm create -f /etc/xen/auto/dom1 etc) I 
> sometimes get the error 'Interrupted system call'. Interrogating the 
> xend-debug.log file yeilds the following which is the only discernable 
> error:
>  
> ioctl: LOOP_SET_FD: Device or resource error
>  
> This would say to me that I am using all 8 loop devices. I upped the 
> max_loop parameter on boot to 255, but it hasnt fixed the issue.

Could you post the config file you are using to start the domain
when you get the problem? It also might be worth running losetup to
have a look at the state of the /dev/loop* devices:

for f in /dev/loop* ; do losetup $f ; done

I don't think increasing max_loop will create any more /dev/loop*
devices if you run out - you'd need to mknod them.

>  
> As I said before I only get this error sometimes. If i repeat the xm 
> create command, it usually starts the domain the second time. The 
> problem with this is that I cant rely on the domains to get 
> automatically restarted after reboot.
>  
> Here is the complete output from xend-debug.log if that helps.
>  
> network start bridge=xen-br0 netdev=eth0 antispoof=no
> VIRTUAL MEMORY ARRANGEMENT:
>  Loaded kernel: c0100000->c038ad18
>  Init. ramdisk: c038b000->c038b000
>  Phys-Mach map: c038b000->c039b000
>  Page tables:   c039b000->c039e000
>  Start info:    c039e000->c039f000
>  Boot stack:    c039f000->c03a0000
>  TOTAL:         c0000000->c0800000
>  ENTRY ADDRESS: c0100000
> ioctl: LOOP_SET_FD: Device or resource busy
> op_create> Deferred Exception creating domain: [Errno 4] Interrupted 
> system call
> Traceback (most recent call last):
>   File "/usr/lib/python2.3/site-packages/twisted/internet/defer.py", 
> line 338, in _runCallbacks
>     self.result = callback(self.result, *args, **kw)
>   File "/usr/lib/python2.3/site-packages/xen/xend/XendDomainInfo.py", 
> line 958, in <lambda>
>     d.addCallback(lambda x: self.create_devices())
>   File "/usr/lib/python2.3/site-packages/xen/xend/XendDomainInfo.py", 
> line 785, in create_devices
>     v = dev_handler(self, dev, dev_index)
>   File "/usr/lib/python2.3/site-packages/xen/xend/XendDomainInfo.py", 
> line 1085, in vm_dev_vbd
>     defer = ctrl.attachDevice(idx, val, recreate=recreate)
>   File "/usr/lib/python2.3/site-packages/xen/xend/server/blkif.py", line 
> 495, in attachDevice
>     d = dev.attach()
>   File "/usr/lib/python2.3/site-packages/xen/xend/server/blkif.py", line 
> 314, in attach
>     node = Blkctl.block('bind', self.type, self.params)
>   File "/usr/lib/python2.3/site-packages/xen/xend/Blkctl.py", line 40, 
> in block
>     output = out.readline()
> IOError: [Errno 4] Interrupted system call
> Hopefully I am doing something dumb somewhere and there is a quick fix 
> so I can get on to setting up my project page :)
>  
> Thanks in advance
>  
> Tom

Thanks,

Mike




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