Re: [Xen-devel] [BUG][4.5.1]xl cpupool-create segfault (with config file parameter)

[Dario Faggioli <dario.faggioli@xxxxxxxxxx>]

On Wed, 2015-08-12 at 12:28 +0100, Ian Campbell wrote:
> On Wed, 2015-08-12 at 13:03 +0200, Benjamin Beier wrote:

> > You never get any output apart from "segmentation fault".
> > If you create exactly the same cpupool without using a config file it 
> > works absolutely fine.
> > Tested on multiple systems and it seems to be reproducible for everyone.
> > STrace shows that the command fails right after reading the content of 
> > the config file.
> 
> Please can you capture a backtrace by running it under gdb. Valgrind might
> also have something interesting to say.
> 
Yep, a gdb backtrace would be really helpful.

I've 'played' with cpupools quite a bit in the last few months (during
the whole Xen 4.6 release cycle), and I don't remember seeing anything
like this... :-/

> FWIW this doesn't happen on the current development branch:
>     # cat foo
>     Testing
>     # xl cpupool-create foo
>     foo:1: config parsing error near `Testing': lexical error
>     Failed to parse config file: Invalid argument
> 
Just tried with the example cpupool config file, from /etc/xen/cpupool,
and it works. I'm also on staging (i.e., 4-6.-rc1):

  root@Zhaman:~# cat /etc/xen/cpupool  
  #============================================================================
  # Configuration setup for 'xm cpupool-create' or 'xl cpupool-create'.
  # This script sets the parameters used when a cpupool is created using
  # 'xm cpupool-create' or 'xl cpupool-create'.
  # You use a separate script for each cpupool you want to create, or 
  # you can set the parameters for the cpupool on the xm command line.
  #============================================================================

  # the name of the new cpupool
  name = "Example-Cpupool"

  # the scheduler to use: valid are e.g. credit, credit2 and rtds
  sched = "credit"

  # list of cpus to use
  cpus = ["2", "3"]

  root@Zhaman:~# xl cpupool-create /etc/xen/cpupool
  cpu 2 illegal or not free
  root@Zhaman:~# xl cpupool-cpu-remove Pool-0 2,3
  root@Zhaman:~# xl cpupool-create /etc/xen/cpupool
  Using config file "/etc/xen/cpupool"
  cpupool name:   Example-Cpupool
  scheduler:      credit
  number of cpus: 2
  root@Zhaman:~# xl cpupool-list 
  Name               CPUs   Sched     Active   Domain count
  Pool-0              14    credit       y          1
  Example-Cpupool      2    credit       y          0

> But I don't see any obviously related looking fixes in the commit log.
> 
Since 4.5, there has been changes touching both xl and libxl bits of
cpupools. E.g.:

  commit a86eecbbf5155aa5b4ec02b6c5e41baf1a7f49de
  xl: enable using ranges of pCPUs when creating cpupools

However, as I said, I don't remember facing (and fixing) such error.

> Was 4.5.0 ok?
> 
> Ian.

-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)

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