[Pkg-xen-devel] Bug#912975: xen-hypervisor-4.8-amd64: Dom0 crashes randomly without logs on Debian Stretch with Xen 4.8.4

[Roalt Zijlstra]

Package: src:xen
Version: 4.8.4+xsa273+shim4.10.1+xsa273-1+deb9u10
Severity: important

Updating Xen to the latest 4.8 version from the security repo makes servers unstable. The servers randomly reset without any logs.
We have serveral Debian Stretch servers running Xen 4.8 and only the ones updated to the 4.8.4+xsa273+shim4.10.1+xsa273-1+deb9u10
version tend to crash ranging from 'twice a day' to 'once every two weeks'. We have already ruled out if hardware was an 
issue, since we have 4 individual servers which are different in hardware setup and also were bought at different times. 
And these servers ran stable with the previsous version 4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9.
These servers are acting exactly the same. Every thing works as it should, but without any logs it crashes and resets at 
a certain point.

It looks like it could have something to do with DomUs running older (3.16) Linux kernels. As a test we applied 4.9 kernels to 
all Jessie DomU servers and so far it runs for 13 days (but this server did crash twice on a day). 
We have seen this behaviour with Xen on CentOS6 and 7 too, but the trouble seems to be fixed after some more updates.

As said.. I cannot provide logs since it simply resets without notice.


-- System Information:
Debian Release: 9.5
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.9.0-8-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US:en (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

xen-hypervisor-4.8-amd64 depends on no packages.

Versions of packages xen-hypervisor-4.8-amd64 recommends:
ii  xen-utils-4.8  4.8.4+xsa273+shim4.10.1+xsa273-1+deb9u10

xen-hypervisor-4.8-amd64 suggests no packages.

-- Configuration Files:
/etc/default/grub.d/xen.cfg changed:
echo "Including Xen overrides from /etc/default/grub.d/xen.cfg"
GRUB_CMDLINE_XEN="dom0_mem=3072M,max:4096M loglvl=all guest_loglvl=all dom0_max_vcpus=4 dom0_vcpus_pin noreboot"
if [ "$XEN_OVERRIDE_GRUB_DEFAULT" = "" ]; then
	echo "WARNING: GRUB_DEFAULT changed to boot into Xen by default!"
	echo "         Edit /etc/default/grub.d/xen.cfg to avoid this warning."
	XEN_OVERRIDE_GRUB_DEFAULT=1
fi
if [ "$XEN_OVERRIDE_GRUB_DEFAULT" = "1" ]; then
	GRUB_DEFAULT="Debian GNU/Linux, with Xen hypervisor"
fi


-- no debconf information