From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: WARN... Device 'cpu1' does not have a release() function, it is broken and must be fixed. when doing 'xl vcpu-set 1' Date: Thu, 2 Feb 2012 12:43:30 -0500 Message-ID: <20120202174330.GA9311@phenom.dumpdata.com> References: <20120123180601.GA24553@phenom.dumpdata.com> <20120201222250.GA3854@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20120201222250.GA3854@kroah.com> Sender: linux-kernel-owner@vger.kernel.org To: Greg KH Cc: Linus Torvalds , gregkh@suse.de, linux-kernel@vger.kernel.org, kay.sievers@vrfy.org, bp@amd64.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, lenb@kernel.org, xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org 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] [] warn_slowpath_common+0x7a/0xb0 > > [ 14.515094] [] warn_slowpath_fmt+0x41/0x50 > > [ 14.515094] [] device_release+0x82/0x90 > > [ 14.515094] [] kobject_release+0x45/0x90 > > [ 14.515094] [] kobject_put+0x2c/0x60 > > [ 14.515094] [] put_device+0x12/0x20 > > [ 14.515094] [] device_unregister+0x19/0x20 > > [ 14.515094] [] unregister_cpu+0x4f/0x80 > > [ 14.515094] [] arch_unregister_cpu+0x1c/0x20 > > [ 14.515094] [] handle_vcpu_hotplug_event+0xc7/0xd0 > > [ 14.515094] [] xenwatch_thread+0xb0/0x180 > > [ 14.515094] [] ? wake_up_bit+0x40/0x40 > > [ 14.515094] [] ? split+0xf0/0xf0 > > [ 14.515094] [] kthread+0x96/0xa0 > > [ 14.515094] [] kernel_thread_helper+0x4/0x10 > > [ 14.515094] [] ? retint_restore_args+0x5/0x6 > > [ 14.515094] [] ? gs_change+0x13/0x13 > > [ 14.515094] ---[ end trace 8f70af51a2e2611f ]--- > > > > Looking at "commit e032d80774315869aa2285b217fdbbfed86c0b49 > > Author: Greg Kroah-Hartman > > 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 ' 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);