Re: WARN... Device 'cpu1' does not have a release() function, it isbroken and must be fixed. when doing 'xl vcpu-set <guest_id> 1'
From: Konrad Rzeszutek Wilk
Date: Thu Feb 02 2012 - 12:46:43 EST
On Wed, Feb 01, 2012 at 02:22:50PM -0800, Greg KH wrote:
> On Mon, Jan 23, 2012 at 01:06:01PM -0500, Konrad Rzeszutek Wilk wrote:
> > When I bring a CPU down in a guest (which should be the same as bringing a
> > CPU down using the ACPI framework), I get this:
> >
> > [ 14.484206] SMP alternatives: switching to UP code
> > [ 14.514287] ------------[ cut here ]------------
> > [ 14.514318] WARNING: at /home/konrad/linux-linus/drivers/base/core.c:194 device_release+0x82/0x90()
> > [ 14.514354] Device 'cpu1' does not have a release() function, it is broken and must be fixed.
> > [ 14.514386] Modules linked in: radeon fbcon tileblit font ttm bitblit softcursor drm_kms_helper xen_blkfront xen_netfront xen_fbfront fb_sys_fops sysimgblt sysfillrect syscopyarea xen_kbdfront xenfs xen_privcmd
> > [ 14.514557] Pid: 22, comm: xenwatch Not tainted 3.3.0-rc1 #1
> > [ 14.514586] Call Trace:
> > [ 14.515094] [<ffffffff810897fa>] warn_slowpath_common+0x7a/0xb0
> > [ 14.515094] [<ffffffff810898d1>] warn_slowpath_fmt+0x41/0x50
> > [ 14.515094] [<ffffffff813dea02>] device_release+0x82/0x90
> > [ 14.515094] [<ffffffff812dfb85>] kobject_release+0x45/0x90
> > [ 14.515094] [<ffffffff812dfa4c>] kobject_put+0x2c/0x60
> > [ 14.515094] [<ffffffff813de6a2>] put_device+0x12/0x20
> > [ 14.515094] [<ffffffff813df409>] device_unregister+0x19/0x20
> > [ 14.515094] [<ffffffff813e4edf>] unregister_cpu+0x4f/0x80
> > [ 14.515094] [<ffffffff81052c7c>] arch_unregister_cpu+0x1c/0x20
> > [ 14.515094] [<ffffffff8137f787>] handle_vcpu_hotplug_event+0xc7/0xd0
> > [ 14.515094] [<ffffffff8137b900>] xenwatch_thread+0xb0/0x180
> > [ 14.515094] [<ffffffff810ad3f0>] ? wake_up_bit+0x40/0x40
> > [ 14.515094] [<ffffffff8137b850>] ? split+0xf0/0xf0
> > [ 14.515094] [<ffffffff810acd16>] kthread+0x96/0xa0
> > [ 14.515094] [<ffffffff816151e4>] kernel_thread_helper+0x4/0x10
> > [ 14.515094] [<ffffffff8160cc80>] ? retint_restore_args+0x5/0x6
> > [ 14.515094] [<ffffffff816151e0>] ? gs_change+0x13/0x13
> > [ 14.515094] ---[ end trace 8f70af51a2e2611f ]---
> >
> > Looking at "commit e032d80774315869aa2285b217fdbbfed86c0b49
> > Author: Greg Kroah-Hartman <gregkh@xxxxxxx>
> > Date: Mon Jan 16 14:40:28 2012 -0800
> >
> > mce: fix warning messages about static struct mce_device
> > "
> >
> > it looks like the corret fix is to make the 'cpu_devices' in
> > arch/x86/kernel/topology.c to be changed to be more dynamic
> > (or perhaps have an empty release function)?
> >
> > Is anybody else hitting this with ACPI CPU hot-unplug? Or do I have
> > the privilige of being the first? Oh, I hadn't done a full bisection
> > but v3.2 does not have this.
>
> Does the patch below solve the problem for you?
Hey Greg,
Indeed it does.
For the patch below, please put 'Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>'
Thanks!
>
> thanks,
>
> greg k-h
>
>
> diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
> index db87e78..23f2c4c 100644
> --- a/drivers/base/cpu.c
> +++ b/drivers/base/cpu.c
> @@ -208,6 +208,25 @@ static ssize_t print_cpus_offline(struct device *dev,
> }
> static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
>
> +static void cpu_device_release(struct device *dev)
> +{
> + /*
> + * This is an empty function to prevent the driver core from spitting a
> + * warning at us. Yes, I know this is directly opposite of what the
> + * documentation for the driver core and kobjects say, and the author
> + * of this code has already been publically ridiculed for doing
> + * something as foolish as this. However, at this point in time, it is
> + * the only way to handle the issue of statically allocated cpu
> + * devices. The different architectures will have their cpu device
> + * code reworked to properly handle this in the near future, so this
> + * function will then be changed to correctly free up the memory held
> + * by the cpu device.
> + *
> + * Never copy this way of doing things, or you too will be made fun of
> + * on the linux-kerenl list, you have been warned.
> + */
> +}
> +
> /*
> * register_cpu - Setup a sysfs device for a CPU.
> * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
> @@ -223,6 +242,7 @@ int __cpuinit register_cpu(struct cpu *cpu, int num)
> cpu->node_id = cpu_to_node(num);
> cpu->dev.id = num;
> cpu->dev.bus = &cpu_subsys;
> + cpu->dev.release = cpu_device_release;
> error = device_register(&cpu->dev);
> if (!error && cpu->hotpluggable)
> register_cpu_control(cpu);
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/