Date:	Fri, 24 Apr 2009 10:38:12 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Dmitry Adamushko <dmitry.adamushko@...il.com>
Cc:	Greg KH <greg@...ah.com>,
	Andreas Herrmann <andreas.herrmann3@....com>,
	Hugh Dickins <hugh@...itas.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Zdenek Kabelac <zdenek.kabelac@...il.com>,
	linux-kernel@...r.kernel.org, "Rafael J. Wysocki" <rjw@...k.pl>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Kay Sievers <kay.sievers@...y.org>
Subject: Re: WARNING: at fs/sysfs/group.c:138 sysfs_remove_group


* Dmitry Adamushko <dmitry.adamushko@...il.com> wrote:

> 2009/4/24 Ingo Molnar <mingo@...e.hu>:
> >
> > (more people Cc:-ed - some microcode driver sysdev badness)
> >
> > * Greg KH <greg@...ah.com> wrote:
> >
> >> On Thu, Apr 23, 2009 at 01:09:30PM -0700, Andrew Morton wrote:
> >> > On Fri, 17 Apr 2009 11:13:08 +0200
> >> > Zdenek Kabelac <zdenek.kabelac@...il.com> wrote:
> >> >
> >> > > Hi
> >> > >
> >> > >
> >> > > When I've checked  2.6.30-rc2 kernel and  I've got among other errors
> >> > > with Wifi message below.
> >> > > As I've noticed - some people were reporting this problem already earlier:
> >> > >
> >> > > http://www.gossamer-threads.com/lists/linux/kernel/1058276?page=last
> >> > >
> >> > > But for me - it started with 2.6.30-rc kernels.
> >> > > I've T61, 4GB, C2D, X86_64.
> >> > >
> >> > >
> >> > >
> >> > > Zdenek
> >> > >
> >> > >
> >> > > platform microcode: firmware: requesting intel-ucode/06-0f-0a
> >> > > platform microcode: firmware: requesting intel-ucode/06-0f-0a
> >> >
> >> > Lots of people are reporting this.  One person reported that each
> >> > attempt takes 60 seconds, thus delaying boot be several minutes.
> >> >
> >> > > Microcode Update Driver: v2.00 <tigran@...azian.fsnet.co.uk>, Peter Oruba
> >> > > ------------[ cut here ]------------
> >> > > WARNING: at fs/sysfs/group.c:138 sysfs_remove_group+0x10b/0x110()
> >> > > Hardware name: 6464CTO
> >> > > sysfs group ffffffffa038d900 not found for kobject 'cpu0'
> >> > > Modules linked in: microcode(-) binfmt_misc dm_mirror dm_region_hash
> >> > > dm_log dm_mod kvm_intel kvm i915 dr
> >> > > m i2c_algo_bit uinput btusb bluetooth arc4 ecb cryptomgr aead
> >> > > pcompress thinkpad_acpi snd_hda_codec_analog crypto_blkcipher
> >> > > crypto_hash snd_hda_intel cry
> >> > > pto_algapi snd_hda_codec iwl3945 snd_seq_oss iwlcore
> >> > > snd_seq_midi_event mac80211 snd_seq rfkill backlight i2c_i801 psmouse
> >> > > intel_agp snd_seq_device snd_p
> >> > > cm_oss rtc_cmos rtc_core sr_mod cdrom i2c_core sdhci_pci sdhci
> >> > > mmc_core serio_raw led_class iTCO_wdt iTCO_vendor_support nvram
> >> > > cfg80211 snd_mixer_oss e10
> >> > > 00e rtc_lib snd_pcm snd_timer snd evdev soundcore button ac battery
> >> > > snd_page_alloc uhci_hcd ohci_hcd ehci_hcd usbcore [last unloaded:
> >> > > scsi_wait_scan]
> >> > > Pid: 1983, comm: rmmod Not tainted 2.6.30-rc2-00076-g3ee8da8 #51
> >> > > Call Trace:
> >> > >  [<ffffffff802434bf>] warn_slowpath+0xaf/0xf0
> >> > >  [<ffffffff8039c3dd>] ? kobject_release+0x5d/0xa0
> >> > >  [<ffffffff80333f7b>] sysfs_remove_group+0x10b/0x110
> >> > >  [<ffffffffa038b3f8>] mc_sysdev_remove+0x38/0x50 [microcode]
> >> > >  [<ffffffff8043c08f>] sysdev_driver_unregister+0x5f/0xa0
> >> > >  [<ffffffffa038bee8>] microcode_exit+0x39/0x65 [microcode]
> >> > >  [<ffffffff8026e974>] sys_delete_module+0x1b4/0x280
> >> > >  [<ffffffff8039ff18>] ? __up_write+0xd8/0x150
> >> > >  [<ffffffff8053e35f>] ? trace_hardirqs_on_thunk+0x3a/0x3c
> >> > >  [<ffffffff8020c19b>] system_call_fastpath+0x16/0x1b
> >> >
> >> > ugh, where to start?
> >> >
> >> > sysdev_driver_register() calls all the ->add methods and cheerily drops
> >> > their return codes on the floor.  Consequently
> >> > sysdev_driver_unregister() will call the ->remove method on objects
> >> > which were not successfully add()ed.
> >>
> >> Ugh, the sysdev code sucks so badly it's not funny.  It's next on my
> >> chopping block for cleanups, need to still do some driver core rework
> >> first though :(
> >>
> >> > mc_sysdev_add() will return an error if microcode_init_cpu() failed but
> >> > fails to remove its attr_group in that case.  So if
> >> > sysdev_driver_register()/sysdev_driver_unregister() get fixed,
> >> > microcode will misbehave.
> >> >
> >> > This patch:
> >> >
> >> > : commit af5c820a3169e81af869c113e18ec7588836cd50
> >> > : Author:     Rusty Russell <rusty@...tcorp.com.au>
> >> > : AuthorDate: Wed Mar 11 16:32:36 2009 +1030
> >> > : Commit:     Ingo Molnar <mingo@...e.hu>
> >> > : CommitDate: Wed Mar 18 13:50:47 2009 +0100
> >> > :
> >> > :     x86: cpumask: use work_on_cpu in arch/x86/kernel/microcode_core.c
> >> > :
> >> >
> >> > attempted to fix things up a bit:
> >> >
> >> > : @@ -379,8 +390,11 @@ static int mc_sysdev_add(struct sys_device *sys_dev)
> >> > :         if (err)
> >> > :                 return err;
> >> > :
> >> > : -       microcode_init_cpu(cpu);
> >> > : -       return 0;
> >> > : +       err = microcode_init_cpu(cpu);
> >> > : +       if (err)
> >> > : +               sysfs_remove_group(&sys_dev->kobj, &mc_attr_group);
> >> > : +
> >> > : +       return err;
> >> > :  }
> >> > :
> >> > :  static int mc_sysdev_remove(struct sys_device *sys_dev)
> >> >
> >> > But it seems that the sysfs_remove_group() later got removed again.
> >>
> >> So, this is a microcode specific issue?
> >
> > Hm, it really doesnt do anything fancy. I've Cc:-ed a few more
> > folks. There's a patch to try in this thread on lkml:
> 
> The following commit addresses this issue.
> 
> 0917798d82212f884fff650e7e520de3b438f947
> 
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=0917798d82212f884fff650e7e520de3b438f947

Ah, i thought people have already tested with -rc3 which has this 
fix.

So ... can anyone reproduce badness with 2.6.30-rc3?

	Ingo
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