Re: WARN... Device 'cpu1' does not have a release() function, it is broken and must be fixed. when doing 'xl vcpu-set <guest_id> 1'

[Maciej Rutecki <maciej.rutecki@gmail.com>]

I created a Bugzilla entry at 
https://bugzilla.kernel.org/show_bug.cgi?id=42683
for your bug report, please add your address to the CC list in there, thanks!

On poniedziałek, 23 stycznia 2012 o 19:06:01 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@suse.de>
> 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.
> 
> The guest config is quite simple:
> extra="console=hvc0 debug earlyprintk=xen memblock=debug"
> kernel="/mnt/lab/bootstrap-x86_64/vmlinuz"
> ramdisk="/mnt/lab/bootstrap-x86_64/initramfs.cpio.gz"
> memory=1024
> maxmem=2048
> vcpus=2
> name="bootstrap-x86_64"
> on_crash="preserve"
> vfb = [ 'vnc=1, vnclisten=0.0.0.0,vncunused=1']
> --
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-- 
Maciej Rutecki
http://www.mrutecki.pl