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

["Georgy V. Repin" <grep@xxxxxxxxxxxx>]

01.04.2014 14:17, Georgy V. Repin ÐÐÑÐÑ:
> 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
>
> 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)
Any other suggestions what to "do" with this "bug" ?
(Captain Obvious definetly says "you should not start new domU when you 
don't have enough memory")
> > I think it was Xen 4.4 which gained the ability to detect dom0_mem= and
> > disable ballooning automatically in that case, but I might be
> > misremembering.
> >
> > Ian.
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