On Tuesday, 11 of November 2008, Ingo Molnar wrote:
>
> * Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
>
> > On 11/11, KOSAKI Motohiro wrote:
> > >
> > > it seem simple ABBA lock, right?
> > >
> > > -> #4 (&dev->mutex){--..}:
> > > [<c0160f87>] validate_chain+0x831/0xaa2
> > > [<c0161872>] __lock_acquire+0x67a/0x6e0
> > > [<c0161933>] lock_acquire+0x5b/0x81
> > > [<c0a660e4>] mutex_lock_interruptible_nested+0xde/0x2f8
> > > [<c0782d02>] input_register_handle+0x26/0x7a dev->mutex
> > ^^^^^^^^^^
> > > [<c04a62c9>] kbd_connect+0x64/0x8d
> > > [<c0782842>] input_attach_handler+0x38/0x6b
> > > [<c0784216>] input_register_handler+0x74/0xc3 input_mutex
> > > [<c0f54e4b>] kbd_init+0x66/0x91
> > > [<c0f54f7b>] vty_init+0xce/0xd7
> > > [<c0f54952>] tty_init+0x193/0x197
> > > [<c010112a>] do_one_initcall+0x42/0x133
> > > [<c0f2d5cb>] kernel_init+0x16e/0x1d5
> > > [<c0117c03>] kernel_thread_helper+0x7/0x10
> > > [<ffffffff>] 0xffffffff
> > >
> > > -> #3 (input_mutex){--..}:
> > > [<c0160f87>] validate_chain+0x831/0xaa2
> > > [<c0161872>] __lock_acquire+0x67a/0x6e0
> > > [<c0161933>] lock_acquire+0x5b/0x81
> > > [<c0a660e4>] mutex_lock_interruptible_nested+0xde/0x2f8
> > > [<c0783fbe>] input_register_device+0xff/0x17f input_mutex
> > > [<c048a889>] acpi_button_add+0x31e/0x429
> > > [<c04889f4>] acpi_device_probe+0x43/0xde
> > > [<c052c67f>] driver_probe_device+0xa5/0x120
> > > [<c052c73c>] __driver_attach+0x42/0x64 dev->sem
> > ^^^^^^^^
> > input_dev->mutex != device->sem
> >
> > > ...
> > > [<c0f2d201>] do_async_initcalls+0x1a/0x2a
> > > [<c0150eec>] run_workqueue+0xc3/0x193
> > > [<c015195d>] worker_thread+0xbb/0xc7
> > > [<c0153e2a>] kthread+0x40/0x66
> >
> > What is the kernel version, btw? I can't find do_async_initcalls
> > in 2.6.27 or 2.6.28.
>
> i suspect it's an older version of tip/master that still had async
> initcalls.
>
> > Anyway, this really looks like lockdep bug to me. Even if we really
> > have the circular dependency (will try to grep more) I can't
> > understand why lockdep claims that polldev_mutex depends on
> > cpu_add_remove_lock.
>
> ok, will re-report if i can trigger it again with latest kernels.
> Rafael, please close this bug as cannot-reproduce for now.
Done.
Thanks,
Rafael
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