Re: [Xen-devel] [BUG] invocation of xl create with insufficient memory for new domU causes system reboot

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2014-04-01 at 14:17 +0400, Georgy V. Repin wrote:
> 01.04.2014 13:52, Ian Campbell ÐÐÑÐÑ:
> > On Tue, 2014-04-01 at 13:35 +0400, Georgy V. Repin wrote:
> >> Hello!
> >>
> >> 1. Problem: invocation of xl create when there is not enough memory to
> >> create new domU causes oom to select process to kiill; when oom selects
> >> to kill quemu-system-* process, this causes kernel panic (it's my
> >> suppose, because i see no message "kernel panic" in log, but i do see
> >> "CPU: 0 PID: 7899 Comm: qemu-system-i38 Not tainted 3.10.17-gentoo #1" +
> >> failed call trace), and, therefore (assuming default settings) kernel
> >> reboot (see log at "4.")
> >> Couple of remarks:
> >> - fix checking of available memory for new domU in xl toolstack could
> >> serve as workaround
> >> - real cause is not clear to me, maybe it's not even a xen bug (quemu ?
> >> kernel ?)
> >
> > Are you using dom0_mem= together with auto ballooning enabled in the
> > toolstack?
> 
> informika-xen-3 ~ # cat /proc/cmdline
> placeholder root=/dev/sda1 ro

dom0_mem is a hypervisor command line option, not a Linux one. Although
given that you have show autobaloon=auto that is moot since it implies
the automatic functionality was indeed added in the version you have.

> 
> part of grub.cfg
> 
>                       if [ "$grub_platform" = "pc" -o "$grub_platform" = "" 
> ]; then
>                           xen_rm_opts=
>                       else
>                           xen_rm_opts="no-real-mode edd=off"
>                       fi
>                       multiboot       /boot/xen-4.gz placeholder   
> ${xen_rm_opts}
>                       echo    'Loading Linux 3.10.17-gentoo ...'
>                       module  /boot/vmlinuz-3.10.17-gentoo placeholder 
> root=/dev/sda1 ro
> 
> xl.conf:
> # Control whether dom0 is ballooned down when xen doesn't have enough
> # free memory to create a domain.  "auto" means only balloon if dom0
> # starts with all the host's memory.
> #autoballoon="auto"
> 
> So:
>       - no dom0_mem= as boot param
>       - autobaloon is set to default ("auto", i suppose)

Correct, the default is auto.

Please can you show us the output of "xl info" and your guest cfg file
as well as the full output of "xl -vvv create $cfg".

Thanks,
Ian.





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