xen ballon errors in kernel logs even if I disabled it after kernel upgrade from 3.2 to 3.14

xen ballon errors in kernel logs even if I disabled it after kernel upgrade from 3.2 to 3.14

[Fabio Fantoni]

Yesterday I updated wheezy kernel (3.2) to 3.14 from wheezy-backports to 
solves one critical network problem with new windows pv driver.
Today I saw the kernel logs full of this error:
xen:balloon: reserve_additional_memory: add_memory() failed: -17

But I disabled the memory balloning:
in /etc/xen/xl.conf: autoballoon="0"
in grub.cfg: multiboot       /boot/xen.gz placeholder dom0_mem=2G,max:2G

Another rare problem that with new kernel happen more is xl create fails 
occasionally on high load with this error:
xl create /etc/xen/svn.cfg
Parsing config from /etc/xen/svn.cfg
libxl: error: libxl_device.c:945:device_backend_callback: unable to add 
device with path /local/domain/0/backend/vif/11/0
libxl: error: libxl_create.c:1357:domcreate_attach_vtpms: unable to add 
nic devices

Happen on both pv and hvm domUs but seems only when dom0 is an high 
load, always after windows domUs start.
I added this for to limit the high load (at least on auto start):
in /etc/default/xendomains: XENDOMAINS_CREATE_USLEEP=30000000
But new kernel probably have performance regression that seems increase 
load and happen more the problem.

If you need more informations or tests tell me and I'll post them.

Thanks for any reply and sorry for my bad english.

Re: xen ballon errors in kernel logs even if I disabled it after kernel upgrade from 3.2 to 3.14

[David Vrabel]

On 26/09/14 09:54, Fabio Fantoni wrote:
> Yesterday I updated wheezy kernel (3.2) to 3.14 from wheezy-backports to
> solves one critical network problem with new windows pv driver.
> Today I saw the kernel logs full of this error:
> xen:balloon: reserve_additional_memory: add_memory() failed: -17

Fixed by:

3dcf63677d4eb7fdfc13290c8558c301d2588fe8 (xen/balloon: cancel ballooning
if adding new memory failed)

Ballooned memory is required by backends which is why you're seeing it
even with auto-ballooning disabled.

David

Re: xen ballon errors in kernel logs even if I disabled it after kernel upgrade from 3.2 to 3.14

[Fabio Fantoni]

Il 26/09/2014 12:22, David Vrabel ha scritto:
> On 26/09/14 09:54, Fabio Fantoni wrote:
>> Yesterday I updated wheezy kernel (3.2) to 3.14 from wheezy-backports to
>> solves one critical network problem with new windows pv driver.
>> Today I saw the kernel logs full of this error:
>> xen:balloon: reserve_additional_memory: add_memory() failed: -17
> Fixed by:
>
> 3dcf63677d4eb7fdfc13290c8558c301d2588fe8 (xen/balloon: cancel ballooning
> if adding new memory failed)
>
> Ballooned memory is required by backends which is why you're seeing it
> even with auto-ballooning disabled.
>
> David
>

Thanks for your reply.
Is correct that show it also if dom0 have fixed memory size and xl.conf 
have balloning disabled?
Can this problem cause a crash or other important aftermath?
Can you apply or request the backport of this fix to stable branchs?

Thanks for any reply.

Re: xen ballon errors in kernel logs even if I disabled it after kernel upgrade from 3.2 to 3.14

[David Vrabel]

On 26/09/14 12:46, Fabio Fantoni wrote:
> Il 26/09/2014 12:22, David Vrabel ha scritto:
>> On 26/09/14 09:54, Fabio Fantoni wrote:
>>> Yesterday I updated wheezy kernel (3.2) to 3.14 from wheezy-backports to
>>> solves one critical network problem with new windows pv driver.
>>> Today I saw the kernel logs full of this error:
>>> xen:balloon: reserve_additional_memory: add_memory() failed: -17
>> Fixed by:
>>
>> 3dcf63677d4eb7fdfc13290c8558c301d2588fe8 (xen/balloon: cancel ballooning
>> if adding new memory failed)
>>
>> Ballooned memory is required by backends which is why you're seeing it
>> even with auto-ballooning disabled.
>>
>> David
>>
> 
> Thanks for your reply.
> Is correct that show it also if dom0 have fixed memory size and xl.conf
> have balloning disabled?

Yes.

> Can this problem cause a crash or other important aftermath?

No. It's harmless.

> Can you apply or request the backport of this fix to stable branchs?

No. A fix for a harmless log message is not critical enough for stable.

David

Re: xen ballon errors in kernel logs even if I disabled it after kernel upgrade from 3.2 to 3.14

[Fabio Fantoni]

Il 26/09/2014 14:02, David Vrabel ha scritto:
> On 26/09/14 12:46, Fabio Fantoni wrote:
>> Il 26/09/2014 12:22, David Vrabel ha scritto:
>>> On 26/09/14 09:54, Fabio Fantoni wrote:
>>>> Yesterday I updated wheezy kernel (3.2) to 3.14 from wheezy-backports to
>>>> solves one critical network problem with new windows pv driver.
>>>> Today I saw the kernel logs full of this error:
>>>> xen:balloon: reserve_additional_memory: add_memory() failed: -17
>>> Fixed by:
>>>
>>> 3dcf63677d4eb7fdfc13290c8558c301d2588fe8 (xen/balloon: cancel ballooning
>>> if adding new memory failed)
>>>
>>> Ballooned memory is required by backends which is why you're seeing it
>>> even with auto-ballooning disabled.
>>>
>>> David
>>>
>> Thanks for your reply.
>> Is correct that show it also if dom0 have fixed memory size and xl.conf
>> have balloning disabled?
> Yes.
>
>> Can this problem cause a crash or other important aftermath?
> No. It's harmless.
>
>> Can you apply or request the backport of this fix to stable branchs?
> No. A fix for a harmless log message is not critical enough for stable.
>
> David

Thanks for your reply.
New debian kernel is freezed to 3.16 version without this fix 
(3.16.7-ckt2-1), I not found a workaround for it, even with dom0 mem 
fixed and autoballoning  disabled I still have big syslog and kern.log 
full of these messages when I start 1 or more domUs that make difficult 
see other parts of logs.
And another strange thing that I not understand is why older kernel 
(3.2) not have this problem.
Someone has advices about it please?

Thanks for any reply and sorry for my bad english.

Re: xen ballon errors in kernel logs even if I disabled it after kernel upgrade from 3.2 to 3.14

[David Vrabel]

On 11/12/14 09:40, Fabio Fantoni wrote:
> Il 26/09/2014 14:02, David Vrabel ha scritto:
>> On 26/09/14 12:46, Fabio Fantoni wrote:
>>> Il 26/09/2014 12:22, David Vrabel ha scritto:
>>>> On 26/09/14 09:54, Fabio Fantoni wrote:
>>>>> Yesterday I updated wheezy kernel (3.2) to 3.14 from
>>>>> wheezy-backports to
>>>>> solves one critical network problem with new windows pv driver.
>>>>> Today I saw the kernel logs full of this error:
>>>>> xen:balloon: reserve_additional_memory: add_memory() failed: -17
>>>> Fixed by:
>>>>
>>>> 3dcf63677d4eb7fdfc13290c8558c301d2588fe8 (xen/balloon: cancel
>>>> ballooning
>>>> if adding new memory failed)
>>>>
>>>> Ballooned memory is required by backends which is why you're seeing it
>>>> even with auto-ballooning disabled.
>>>>
>>>> David
>>>>
>>> Thanks for your reply.
>>> Is correct that show it also if dom0 have fixed memory size and xl.conf
>>> have balloning disabled?
>> Yes.
>>
>>> Can this problem cause a crash or other important aftermath?
>> No. It's harmless.
>>
>>> Can you apply or request the backport of this fix to stable branchs?
>> No. A fix for a harmless log message is not critical enough for stable.
>>
>> David
> 
> Thanks for your reply.
> New debian kernel is freezed to 3.16 version without this fix
> (3.16.7-ckt2-1), I not found a workaround for it, even with dom0 mem
> fixed and autoballoning  disabled I still have big syslog and kern.log
> full of these messages when I start 1 or more domUs that make difficult
> see other parts of logs.
> And another strange thing that I not understand is why older kernel
> (3.2) not have this problem.
> Someone has advices about it please?

You can workaround it by pre-ballooning dom0 with a Xen command line
option such as dom0_mem=4G,max:5G

Don't have too much ballooned memory or dom0 may run out of memory and
not boot or run very slowly.

You can also disable XEN_BALLOON_MEMORY_HOTPLUG.

David