[Pkg-xen-devel] Bug#994870: Bug#994870: Bug#994870: Memory allocation problem for VM after xen security update

[Alexander Dahl]

Hello,

Am 22.09.21 um 20:54 schrieb Hans van Kranenburg:
> Hi Ruediger,
> 
> On 9/22/21 11:37 AM, H.-R. Oberhage wrote:
>> Package: xen-system-amd64
>> Version: 4.14.3-1~deb11u1
>>
>> After applying the buster security update to xen, my VM won't start
>> any longer, complaining about a memory allocation error.
> 
> Can you confirm that this is a virtual machine that tries to boot a
> 32-bit kernel as PV type?

I can confirm this for three of my virtual machines.

> The error message you are seeing is not particularly helpful, but it is
> most likely related to this.
> 
> The fact that with this package update 32-bit PV guests fail to start is
> indeed a regression problem, which is quite inconvenient for you, right now.

And for me. :-/

> At this point I would really recommend to not wait for a fix to arrive
> which makes it start again, but change your VM to use a 64-bit kernel.

How?

> Let me know if you need help or run into problems while making this change.
> 
> Running 32-bit PV at all is already 'on life support' upstream for quite
> a while now, and it also not under security support any more.

Ack.

FWIW, Debian 10 VMs with 32 bit running with PVH work fine. My important 
VM is still Debian 9 however due to a software I can not simply upgrade.

> In the long run, I'd suggest working towards having 64-bit guests in PVH
> mode, since that's one of the best options we have these days.

Ack.

> If there's a reason you really cannot switch to a 64-bit kernel or move
> the functionality of this virtual machine to a new fully 64 bit system,
> switching the virtualization type from PV to HVM would also be an option.

Thanks for your support.

Greets
Alex

>> Switching back to the previous version 4.14.2+25-gb6a8c4f72d-2 lets
>> the VM start (again,) normally.
>>
>> /var/log/libvirt/libxl/libxl-driver.log:
>> 2021-09-21 14:01:44.645+0000: xc: panic: xc_dom_boot.c:120:
>> xc_dom_boot_mem_init: can't allocate low memory for domain: Out of
>> memory
>> 2021-09-21 14:01:44.653+0000: libxl: libxl_dom.c:593:libxl__build_dom:
>> xc_dom_boot_mem_init failed: Die Operation wird nicht unterstützt
>> [means: the operation is not supported]
>> 2021-09-21 14:01:44.662+0000: libxl:
>> libxl_create.c:1576:domcreate_rebuild_done: Domain 1:cannot (re-)build
>> domain: -3
>>
>> The error is triggered, regardless if there was a boot-parameter
>> "dom0_mem=1024M:max=2048M" set or not.
>> /etc/xen/xl.conf was unaltered, i.e. 'autoballoon' was implicitely set
>> to "auto".
>>
>> I am "on" Buster, kernel 5.10.0-8-amd64 (5.10.46-4), all relevant fixes
>> included.
> 
> Apologies for the inconvenience,
> 
> Hans
> 
> _______________________________________________
> Pkg-xen-devel mailing list
> Pkg-xen-devel at alioth-lists.debian.net
> https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/pkg-xen-devel
>