Re: linux 3.3-pre-rc1: Starting domU fails with Error: Failed to query current memory allocation of dom0.

Re: linux 3.3-pre-rc1: Starting domU fails with Error: Failed to query current memory allocation of dom0.

[Konrad Rzeszutek Wilk]

On Thu, Jan 12, 2012 at 01:38:32PM +0100, Sander Eikelenboom wrote:
> Hi Konrad,
> 
> Today i tried linuses tree of today (last commit is 4c4d285ad5665bfbd983b95fde8d7a477d24a361).
> 
> It boots dom0 fine, but it fails to start any domU with: "Error: Failed to query current memory allocation of dom0."
> With my previous 3.1.5 kernel everything is fine, nothing else changed in config in between.

Hey Kay,

Your patch that converts the xen-balloon to use the regular device bus driver
(070680218379e15c1901f4bf21b98e3cbf12b527) has some not-so-happy consequences.

The toolstack (xen-tools) use:

/sys/devices/system/xen_memory/xen_memory0

But with the change, it is now:

/sys/devices/xen_memory0/target_kb

Which means that the tools can't find it now.

I did not see anything in feature-removal-schedule.txt so I don't know
exactly when the full sys_device structure is going away.

Is there any work-arounds that can be inserted in the kernel so that
the old directory still exists at least for 3.3 such that there will be
enough time for the tool-stack to be updated?

Re: linux 3.3-pre-rc1: Starting domU fails with Error: Failed to query current memory allocation of dom0.

[Kay Sievers]

On Thu, Jan 12, 2012 at 16:46, Konrad Rzeszutek Wilk
<konrad.wilk@oracle.com> wrote:
> On Thu, Jan 12, 2012 at 01:38:32PM +0100, Sander Eikelenboom wrote:

>> Today i tried linuses tree of today (last commit is 4c4d285ad5665bfbd983b95fde8d7a477d24a361).
>>
>> It boots dom0 fine, but it fails to start any domU with: "Error: Failed to query current memory allocation of dom0."
>> With my previous 3.1.5 kernel everything is fine, nothing else changed in config in between.
> Your patch that converts the xen-balloon to use the regular device bus driver
> (070680218379e15c1901f4bf21b98e3cbf12b527) has some not-so-happy consequences.
>
> The toolstack (xen-tools) use:
>
> /sys/devices/system/xen_memory/xen_memory0
>
> But with the change, it is now:
>
> /sys/devices/xen_memory0/target_kb

Urks, seems like a mistake on my side.

Please try if changing:
  bus_unregister(&balloon_subsys);
to:
  subsys_system_register(&balloon_subsys, NULL);
in:
  drivers/xen/xen-balloon.c
fixes the issue.

Sorry for that,
Kay

Re: linux 3.3-pre-rc1: Starting domU fails with Error: Failed to query current memory allocation of dom0.

[Konrad Rzeszutek Wilk]

On Thu, Jan 12, 2012 at 05:05:34PM +0100, Kay Sievers wrote:
> On Thu, Jan 12, 2012 at 16:46, Konrad Rzeszutek Wilk
> <konrad.wilk@oracle.com> wrote:
> > On Thu, Jan 12, 2012 at 01:38:32PM +0100, Sander Eikelenboom wrote:
> 
> >> Today i tried linuses tree of today (last commit is 4c4d285ad5665bfbd983b95fde8d7a477d24a361).
> >>
> >> It boots dom0 fine, but it fails to start any domU with: "Error: Failed to query current memory allocation of dom0."
> >> With my previous 3.1.5 kernel everything is fine, nothing else changed in config in between.
> > Your patch that converts the xen-balloon to use the regular device bus driver
> > (070680218379e15c1901f4bf21b98e3cbf12b527) has some not-so-happy consequences.
> >
> > The toolstack (xen-tools) use:
> >
> > /sys/devices/system/xen_memory/xen_memory0
> >
> > But with the change, it is now:
> >
> > /sys/devices/xen_memory0/target_kb
> 
> Urks, seems like a mistake on my side.
> 
> Please try if changing:
>   bus_unregister(&balloon_subsys);
> to:
>   subsys_system_register(&balloon_subsys, NULL);
> in:
>   drivers/xen/xen-balloon.c
> fixes the issue.

Heh. I was *just* looking at d369a5d8fc70710236ae2d06a0e42dce483712df
("clocksource: convert sysdev_class to a regular subsystem") and typed up this patch
to try it out:


diff --git a/drivers/xen/xen-balloon.c b/drivers/xen/xen-balloon.c
index 3832e30..f0b206e 100644
--- a/drivers/xen/xen-balloon.c
+++ b/drivers/xen/xen-balloon.c
@@ -221,13 +221,13 @@ static int register_balloon(struct device *dev)
 {
 	int i, error;
 
-	error = bus_register(&balloon_subsys);
+	error = subsys_system_register(&balloon_subsys, NULL);
 	if (error)
 		return error;
-
+/*
 	dev->id = 0;
 	dev->bus = &balloon_subsys;
-
+*/
 	error = device_register(dev);
 	if (error) {
 		bus_unregister(&balloon_subsys);
> 
> Sorry for that,

That is OK. That is what rc0 is for.

Anyhow, let me see if that fixes the issue. Thanks for your quick reply.

Re: linux 3.3-pre-rc1: Starting domU fails with Error: Failed to query current memory allocation of dom0.

[Konrad Rzeszutek Wilk]

On Thu, Jan 12, 2012 at 11:12:04AM -0500, Konrad Rzeszutek Wilk wrote:
> On Thu, Jan 12, 2012 at 05:05:34PM +0100, Kay Sievers wrote:
> > On Thu, Jan 12, 2012 at 16:46, Konrad Rzeszutek Wilk
> > <konrad.wilk@oracle.com> wrote:
> > > On Thu, Jan 12, 2012 at 01:38:32PM +0100, Sander Eikelenboom wrote:
> > 
> > >> Today i tried linuses tree of today (last commit is 4c4d285ad5665bfbd983b95fde8d7a477d24a361).
> > >>
> > >> It boots dom0 fine, but it fails to start any domU with: "Error: Failed to query current memory allocation of dom0."
> > >> With my previous 3.1.5 kernel everything is fine, nothing else changed in config in between.
> > > Your patch that converts the xen-balloon to use the regular device bus driver
> > > (070680218379e15c1901f4bf21b98e3cbf12b527) has some not-so-happy consequences.
> > >
> > > The toolstack (xen-tools) use:
> > >
> > > /sys/devices/system/xen_memory/xen_memory0
> > >
> > > But with the change, it is now:
> > >
> > > /sys/devices/xen_memory0/target_kb
> > 
> > Urks, seems like a mistake on my side.
> > 
> > Please try if changing:
> >   bus_unregister(&balloon_subsys);
> > to:
> >   subsys_system_register(&balloon_subsys, NULL);
> > in:
> >   drivers/xen/xen-balloon.c
> > fixes the issue.
> 
> Heh. I was *just* looking at d369a5d8fc70710236ae2d06a0e42dce483712df
> ("clocksource: convert sysdev_class to a regular subsystem") and typed up this patch
> to try it out:

Kay, are you Acking this patch? (I can send it to Linus for rc0 or rc1)

commit 4e6f161986678a25c9e76af98df928408c734a27
Author: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date:   Thu Jan 12 11:35:50 2012 -0500

    xen/balloon: Move the registration from device to subsystem.
    
    With git commit 070680218379e15c1901f4bf21b98e3cbf12b527
    "xen-balloon: convert sysdev_class to a regular subsystem" we would
    end up with the attributes being put in:
    
     /sys/devices/xen_memory0/target_kb
    instead of
    /sys/devices/system/xen_memory/xen_memory0/target_kb
    
    Making the tools unable to deflate the kernel to make more space
    for launching another guest and printing:

    Error: Failed to query current memory allocation of dom0
    
    Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
    Suggested-by:  Kay Sievers <kay.sievers@vrfy.org>
    Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

diff --git a/drivers/xen/xen-balloon.c b/drivers/xen/xen-balloon.c
index 3832e30..596e6a7 100644
--- a/drivers/xen/xen-balloon.c
+++ b/drivers/xen/xen-balloon.c
@@ -221,7 +221,7 @@ static int register_balloon(struct device *dev)
 {
 	int i, error;
 
-	error = bus_register(&balloon_subsys);
+	error = subsys_system_register(&balloon_subsys, NULL);
 	if (error)
 		return error;
 

Re: linux 3.3-pre-rc1: Starting domU fails with Error: Failed to query current memory allocation of dom0.

[Kay Sievers]

On Thu, Jan 12, 2012 at 17:40, Konrad Rzeszutek Wilk
<konrad.wilk@oracle.com> wrote:
> On Thu, Jan 12, 2012 at 11:12:04AM -0500, Konrad Rzeszutek Wilk wrote:
>> On Thu, Jan 12, 2012 at 05:05:34PM +0100, Kay Sievers wrote:
>> > On Thu, Jan 12, 2012 at 16:46, Konrad Rzeszutek Wilk
>> > <konrad.wilk@oracle.com> wrote:
>> > > On Thu, Jan 12, 2012 at 01:38:32PM +0100, Sander Eikelenboom wrote:
>> >
>> > >> Today i tried linuses tree of today (last commit is 4c4d285ad5665bfbd983b95fde8d7a477d24a361).
>> > >>
>> > >> It boots dom0 fine, but it fails to start any domU with: "Error: Failed to query current memory allocation of dom0."
>> > >> With my previous 3.1.5 kernel everything is fine, nothing else changed in config in between.
>> > > Your patch that converts the xen-balloon to use the regular device bus driver
>> > > (070680218379e15c1901f4bf21b98e3cbf12b527) has some not-so-happy consequences.
>> > >
>> > > The toolstack (xen-tools) use:
>> > >
>> > > /sys/devices/system/xen_memory/xen_memory0
>> > >
>> > > But with the change, it is now:
>> > >
>> > > /sys/devices/xen_memory0/target_kb
>> >
>> > Urks, seems like a mistake on my side.
>> >
>> > Please try if changing:
>> >   bus_unregister(&balloon_subsys);
>> > to:
>> >   subsys_system_register(&balloon_subsys, NULL);
>> > in:
>> >   drivers/xen/xen-balloon.c
>> > fixes the issue.
>>
>> Heh. I was *just* looking at d369a5d8fc70710236ae2d06a0e42dce483712df
>> ("clocksource: convert sysdev_class to a regular subsystem") and typed up this patch
>> to try it out:
>
> Kay, are you Acking this patch? (I can send it to Linus for rc0 or rc1)
>
> commit 4e6f161986678a25c9e76af98df928408c734a27
> Author: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Date:   Thu Jan 12 11:35:50 2012 -0500
>
>    xen/balloon: Move the registration from device to subsystem.
>
>    With git commit 070680218379e15c1901f4bf21b98e3cbf12b527
>    "xen-balloon: convert sysdev_class to a regular subsystem" we would
>    end up with the attributes being put in:
>
>     /sys/devices/xen_memory0/target_kb
>    instead of
>    /sys/devices/system/xen_memory/xen_memory0/target_kb
>
>    Making the tools unable to deflate the kernel to make more space
>    for launching another guest and printing:
>
>    Error: Failed to query current memory allocation of dom0
>
>    Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
>    Suggested-by:  Kay Sievers <kay.sievers@vrfy.org>
>    Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Sure, looks good.

Thanks for fixing this,
Kay

Re: linux 3.3-pre-rc1: Starting domU fails with Error: Failed to query current memory allocation of dom0.

[Sander Eikelenboom]

Hello Konrad,

Thursday, January 12, 2012, 5:40:25 PM, you wrote:

> On Thu, Jan 12, 2012 at 11:12:04AM -0500, Konrad Rzeszutek Wilk wrote:
>> On Thu, Jan 12, 2012 at 05:05:34PM +0100, Kay Sievers wrote:
>> > On Thu, Jan 12, 2012 at 16:46, Konrad Rzeszutek Wilk
>> > <konrad.wilk@oracle.com> wrote:
>> > > On Thu, Jan 12, 2012 at 01:38:32PM +0100, Sander Eikelenboom wrote:
>> > 
>> > >> Today i tried linuses tree of today (last commit is 4c4d285ad5665bfbd983b95fde8d7a477d24a361).
>> > >>
>> > >> It boots dom0 fine, but it fails to start any domU with: "Error: Failed to query current memory allocation of dom0."
>> > >> With my previous 3.1.5 kernel everything is fine, nothing else changed in config in between.
>> > > Your patch that converts the xen-balloon to use the regular device bus driver
>> > > (070680218379e15c1901f4bf21b98e3cbf12b527) has some not-so-happy consequences.
>> > >
>> > > The toolstack (xen-tools) use:
>> > >
>> > > /sys/devices/system/xen_memory/xen_memory0
>> > >
>> > > But with the change, it is now:
>> > >
>> > > /sys/devices/xen_memory0/target_kb
>> > 
>> > Urks, seems like a mistake on my side.
>> > 
>> > Please try if changing:
>> >   bus_unregister(&balloon_subsys);
>> > to:
>> >   subsys_system_register(&balloon_subsys, NULL);
>> > in:
>> >   drivers/xen/xen-balloon.c
>> > fixes the issue.
>> 
>> Heh. I was *just* looking at d369a5d8fc70710236ae2d06a0e42dce483712df
>> ("clocksource: convert sysdev_class to a regular subsystem") and typed up this patch
>> to try it out:

> Kay, are you Acking this patch? (I can send it to Linus for rc0 or rc1)

> commit 4e6f161986678a25c9e76af98df928408c734a27
> Author: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Date:   Thu Jan 12 11:35:50 2012 -0500

>     xen/balloon: Move the registration from device to subsystem.
>     
>     With git commit 070680218379e15c1901f4bf21b98e3cbf12b527
>     "xen-balloon: convert sysdev_class to a regular subsystem" we would
>     end up with the attributes being put in:
>     
>      /sys/devices/xen_memory0/target_kb
>     instead of
>     /sys/devices/system/xen_memory/xen_memory0/target_kb
>     
>     Making the tools unable to deflate the kernel to make more space
>     for launching another guest and printing:

>     Error: Failed to query current memory allocation of dom0
>     
>     Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
>     Suggested-by:  Kay Sievers <kay.sievers@vrfy.org>
>     Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

> diff --git a/drivers/xen/xen-balloon.c b/drivers/xen/xen-balloon.c
> index 3832e30..596e6a7 100644
> --- a/drivers/xen/xen-balloon.c
> +++ b/drivers/xen/xen-balloon.c
> @@ -221,7 +221,7 @@ static int register_balloon(struct device *dev)
>  {
>         int i, error;
>  
> -       error = bus_register(&balloon_subsys);
> +       error = subsys_system_register(&balloon_subsys, NULL);
>         if (error)
>                 return error;
>  


Shouldn't the

if (error) {
        bus_unregister(&balloon_subsys);
        return error;
}

right below it also be changed ?

Re: linux 3.3-pre-rc1: Starting domU fails with Error: Failed to query current memory allocation of dom0.

[Konrad Rzeszutek Wilk]

On Thu, Jan 12, 2012 at 06:05:46PM +0100, Sander Eikelenboom wrote:
> Hello Konrad,
> 
> Thursday, January 12, 2012, 5:40:25 PM, you wrote:
> 
> > On Thu, Jan 12, 2012 at 11:12:04AM -0500, Konrad Rzeszutek Wilk wrote:
> >> On Thu, Jan 12, 2012 at 05:05:34PM +0100, Kay Sievers wrote:
> >> > On Thu, Jan 12, 2012 at 16:46, Konrad Rzeszutek Wilk
> >> > <konrad.wilk@oracle.com> wrote:
> >> > > On Thu, Jan 12, 2012 at 01:38:32PM +0100, Sander Eikelenboom wrote:
> >> > 
> >> > >> Today i tried linuses tree of today (last commit is 4c4d285ad5665bfbd983b95fde8d7a477d24a361).
> >> > >>
> >> > >> It boots dom0 fine, but it fails to start any domU with: "Error: Failed to query current memory allocation of dom0."
> >> > >> With my previous 3.1.5 kernel everything is fine, nothing else changed in config in between.
> >> > > Your patch that converts the xen-balloon to use the regular device bus driver
> >> > > (070680218379e15c1901f4bf21b98e3cbf12b527) has some not-so-happy consequences.
> >> > >
> >> > > The toolstack (xen-tools) use:
> >> > >
> >> > > /sys/devices/system/xen_memory/xen_memory0
> >> > >
> >> > > But with the change, it is now:
> >> > >
> >> > > /sys/devices/xen_memory0/target_kb
> >> > 
> >> > Urks, seems like a mistake on my side.
> >> > 
> >> > Please try if changing:
> >> >   bus_unregister(&balloon_subsys);
> >> > to:
> >> >   subsys_system_register(&balloon_subsys, NULL);
> >> > in:
> >> >   drivers/xen/xen-balloon.c
> >> > fixes the issue.
> >> 
> >> Heh. I was *just* looking at d369a5d8fc70710236ae2d06a0e42dce483712df
> >> ("clocksource: convert sysdev_class to a regular subsystem") and typed up this patch
> >> to try it out:
> 
> > Kay, are you Acking this patch? (I can send it to Linus for rc0 or rc1)
> 
> > commit 4e6f161986678a25c9e76af98df928408c734a27
> > Author: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> > Date:   Thu Jan 12 11:35:50 2012 -0500
> 
> >     xen/balloon: Move the registration from device to subsystem.
> >     
> >     With git commit 070680218379e15c1901f4bf21b98e3cbf12b527
> >     "xen-balloon: convert sysdev_class to a regular subsystem" we would
> >     end up with the attributes being put in:
> >     
> >      /sys/devices/xen_memory0/target_kb
> >     instead of
> >     /sys/devices/system/xen_memory/xen_memory0/target_kb
> >     
> >     Making the tools unable to deflate the kernel to make more space
> >     for launching another guest and printing:
> 
> >     Error: Failed to query current memory allocation of dom0
> >     
> >     Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
> >     Suggested-by:  Kay Sievers <kay.sievers@vrfy.org>
> >     Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> 
> > diff --git a/drivers/xen/xen-balloon.c b/drivers/xen/xen-balloon.c
> > index 3832e30..596e6a7 100644
> > --- a/drivers/xen/xen-balloon.c
> > +++ b/drivers/xen/xen-balloon.c
> > @@ -221,7 +221,7 @@ static int register_balloon(struct device *dev)
> >  {
> >         int i, error;
> >  
> > -       error = bus_register(&balloon_subsys);
> > +       error = subsys_system_register(&balloon_subsys, NULL);
> >         if (error)
> >                 return error;
> >  
> 
> 
> Shouldn't the
> 
> if (error) {
>         bus_unregister(&balloon_subsys);
>         return error;
> }
> 
> right below it also be changed ?

I thought so too, but looking at how the subsys_system_register it looks
to be OK. Kay, thoughts?

Re: linux 3.3-pre-rc1: Starting domU fails with Error: Failed to query current memory allocation of dom0.

[Kay Sievers]

On Thu, Jan 12, 2012 at 18:10, Konrad Rzeszutek Wilk
<konrad.wilk@oracle.com> wrote:
> On Thu, Jan 12, 2012 at 06:05:46PM +0100, Sander Eikelenboom wrote:

>> Shouldn't the
>>
>> if (error) {
>>         bus_unregister(&balloon_subsys);
>>         return error;
>> }
>>
>> right below it also be changed ?
>
> I thought so too, but looking at how the subsys_system_register it looks
> to be OK. Kay, thoughts?

No, it's fine, there is nothing else.

The subsys_system_register() fucrtion is a new function (for compat
with old sysdev rules only) that registers a bus. The counterpart is
the bus_unregister.

The long-term picture is that 'struct bus_type' and 'struct class'
will be merged and everything will be called 'subsys'.

Kay