Re: [ACPI/PCI] possible recursive locking detected

[Fengguang Wu]

On Sat, Sep 22, 2012 at 12:04:51AM -0700, Yinghai Lu wrote:
> On Fri, Sep 21, 2012 at 9:53 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> > On Fri, Sep 21, 2012 at 5:35 PM, Fengguang Wu <fengguang.wu@xxxxxxxxx> wrote:
> >> Hi Taku,
> >>
> >> The below oops is pretty reproducible, and shows up first in:
> >>
> >> tree:   git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git pci/taku-acpi-pci-host-bridge-v3
> >> head:   e3faec8ea9c8aa683c56fa20ff2c58a4c5857960
> >> commit: d3c663236318a43fed5d86a643e6ea2534e9220e [5/7] PCI/ACPI: Protect acpi_pci_roots list with mutex
> >>
> >> [    8.613239]  (acpi_pci_root_lock){+.+.+.}, at: [<ffffffff81741e5f>] acpi_get_pci_rootbridge_handle+0x22/0x63
> >> [    8.613239]  (acpi_pci_root_lock){+.+.+.}, at: [<ffffffff81741e5f>] acpi_get_pci_rootbridge_handle+0x22/0x63
> >> [    8.613239]  (acpi_pci_root_lock){+.+.+.}, at: [<ffffffff81742398>] acpi_pci_register_driver+0x21/0x79
> >> [    8.613239]   lock(acpi_pci_root_lock);
> >> [    8.613239]   lock(acpi_pci_root_lock);
> >> [    8.613239]  #0:  (acpi_pci_root_lock){+.+.+.}, at: [<ffffffff81742398>] acpi_pci_register_driver+0x21/0x79
> >> [    8.613239]  [<ffffffff81741e5f>] ? acpi_get_pci_rootbridge_handle+0x22/0x63
> >> [    8.613239]  [<ffffffff81741e5f>] ? acpi_get_pci_rootbridge_handle+0x22/0x63
> >> [    8.613239]  [<ffffffff81741e5f>] ? acpi_get_pci_rootbridge_handle+0x22/0x63
> >> [    8.613239]  [<ffffffff81741e5f>] acpi_get_pci_rootbridge_handle+0x22/0x63
> >>
> >> [    8.610859]
> >> [    8.611385] =============================================
> >> [    8.612505] [ INFO: possible recursive locking detected ]
> >> [    8.613239] 3.6.0-rc1-00022-gd3c6632 #7512 Not tainted
> >> [    8.613239] ---------------------------------------------
> >> [    8.613239] swapper/0/1 is trying to acquire lock:
> >> [    8.613239]  (acpi_pci_root_lock){+.+.+.}, at: [<ffffffff81741e5f>] acpi_get_pci_rootbridge_handle+0x22/0x63
> >> [    8.613239]
> >> [    8.613239] but task is already holding lock:
> >> [    8.613239]  (acpi_pci_root_lock){+.+.+.}, at: [<ffffffff81742398>] acpi_pci_register_driver+0x21/0x79
> >> [    8.613239]
> >> [    8.613239] other info that might help us debug this:
> >> [    8.613239]  Possible unsafe locking scenario:
> >> [    8.613239]
> >> [    8.613239]        CPU0
> >> [    8.613239]        ----
> >> [    8.613239]   lock(acpi_pci_root_lock);
> >> [    8.613239]   lock(acpi_pci_root_lock);
> >> [    8.613239]
> >> [    8.613239]  *** DEADLOCK ***
> >> [    8.613239]
> >> [    8.613239]  May be due to missing lock nesting notation
> >> [    8.613239]
> >> [    8.613239] 1 lock held by swapper/0/1:
> >> [    8.613239]  #0:  (acpi_pci_root_lock){+.+.+.}, at: [<ffffffff81742398>] acpi_pci_register_driver+0x21/0x79
> >> [    8.613239]

> > Please check attached patch that should fix the problem.
> 
> updated more aggressive version. two patches.

Yes they work nicely. Thank you very much!

Thanks,
Fengguang
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