Re: [2.6.33-rc4] sysfs lockdep warnings on cpu hotplug

[Heiko Carstens <heiko.carstens@de.ibm.com>]

On Fri, Jan 22, 2010 at 12:42:22PM +0800, Américo Wang wrote:
> On Thu, Jan 21, 2010 at 11:53 PM, Heiko Carstens
> <heiko.carstens@de.ibm.com> wrote:
> > Hi Eric,
> >
> > rumours are that you could be responsible for the following lockdep message:
> >
> > Happens on cpu hotplug on s390:
> >
> > =============================================
> > [ INFO: possible recursive locking detected ]
> > 2.6.33-rc4-00399-g24bc734 #1
> > ---------------------------------------------
> > bash/2576 is trying to acquire lock:
> >  (s_active){++++.+}, at: [<000000000016c506>] sysfs_addrm_finish+0x5a/0xa8
> >
> > but task is already holding lock:
> >  (s_active){++++.+}, at: [<000000000016c90c>] sysfs_get_active_two+0x64/0x88
> >
> > other info that might help us debug this:
> > 5 locks held by bash/2576:
> >  #0:  (&buffer->mutex){+.+.+.}, at: [<000000000016a912>] sysfs_write_file+0x4a/0x1a8
> >  #1:  (s_active){++++.+}, at: [<000000000016c90c>] sysfs_get_active_two+0x64/0x88
> >  #2:  (s_active){++++.+}, at: [<000000000016c8e6>] sysfs_get_active_two+0x3e/0x88
> >  #3:  (cpu_add_remove_lock){+.+.+.}, at: [<00000000003dd318>] cpu_down+0x44/0x88
> >  #4:  (cpu_hotplug.lock){+.+.+.}, at: [<0000000000056eee>] cpu_hotplug_begin+0x3e/0x74
> >
> 
> I think this is the same with the problem we met some days ago,
> 
> http://lkml.org/lkml/2010/1/10/282
> 
> does this patch from Erich help?

No, it doesn't help.