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    SubjectRe: pci_get_subsys: GFP_KERNEL allocations with IRQs disabled
    Hi Fengguang,


    On Wed, 22 Aug 2012 10:50:08 +0800
    Fengguang Wu <fengguang.wu@intel.com> wrote:

    > Feng,
    >
    > > I think it's pci_get_subsys() triggered this assert:
    > >
    > > /*
    > > * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
    > > */
    > > if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
    > > return;
    >
    > It's bisected down to this commit:
    >
    > commit 55c844a4dd16a4d1fdc0cf2a283ec631a02ec448
    > Author: Feng Tang <feng.tang@intel.com>
    > AuthorDate: Wed May 30 23:15:41 2012 +0800
    > Commit: Ingo Molnar <mingo@kernel.org>
    > CommitDate: Wed Jun 6 12:03:23 2012 +0200
    >
    > x86/reboot: Fix a warning message triggered by stop_other_cpus()
    >
    > Thanks,
    > Fengguang

    Thanks for the bisection.

    Revert my commit should be a solution, but can we simply make the pci_device_id
    a local on stack one instead of using sleepable kmalloc for it, as this
    sounds fragile when pci_get_subsys get called in a late system reboot stage?

    Thanks,
    Feng

    ------------
    diff --git a/drivers/pci/search.c b/drivers/pci/search.c
    index 993d4a0..e5ccede 100644
    --- a/drivers/pci/search.c
    +++ b/drivers/pci/search.c
    @@ -246,7 +246,7 @@ struct pci_dev *pci_get_subsys(unsigned int vendor, unsigned int device,
    struct pci_dev *from)
    {
    struct pci_dev *pdev;
    - struct pci_device_id *id;
    + struct pci_device_id id;

    /*
    * pci_find_subsys() can be called on the ide_setup() path,
    @@ -257,17 +257,12 @@ struct pci_dev *pci_get_subsys(unsigned int vendor, unsigned int device,
    if (unlikely(no_pci_devices()))
    return NULL;

    - id = kzalloc(sizeof(*id), GFP_KERNEL);
    - if (!id)
    - return NULL;
    - id->vendor = vendor;
    - id->device = device;
    - id->subvendor = ss_vendor;
    - id->subdevice = ss_device;
    -
    - pdev = pci_get_dev_by_id(id, from);
    - kfree(id);
    + id.vendor = vendor;
    + id.device = device;
    + id.subvendor = ss_vendor;
    + id.subdevice = ss_device;

    + pdev = pci_get_dev_by_id(&id, from);
    return pdev;
    }


    >
    > > [ 91.282131] machine restart
    > > [ 91.283895] ------------[ cut here ]------------
    > > [ 91.284731] WARNING: at /c/wfg/linux/kernel/lockdep.c:2739 lockdep_trace_alloc+0x1fb/0x210()
    > > [ 91.286132] Modules linked in:
    > > [ 91.286703] Pid: 697, comm: reboot Not tainted 3.5.0-00024-g01ff5db-dirty #4
    > > [ 91.287859] Call Trace:
    > > [ 91.288289] [<81050148>] warn_slowpath_common+0xb8/0x100
    > > [ 91.289338] [<8110acdb>] ? lockdep_trace_alloc+0x1fb/0x210
    > > [ 91.290264] [<8110acdb>] ? lockdep_trace_alloc+0x1fb/0x210
    > > [ 91.291161] [<810501ce>] warn_slowpath_null+0x3e/0x50
    > > [ 91.292042] [<8110acdb>] lockdep_trace_alloc+0x1fb/0x210
    > > [ 91.292934] [<81228e25>] kmem_cache_alloc_trace+0x55/0x600
    > > [ 91.292934] [<813025ca>] ? kobject_put+0x9a/0x160
    > > [ 91.292934] [<814e95e0>] ? klist_iter_exit+0x30/0x50
    > > [ 91.292934] [<81405881>] ? bus_find_device+0xf1/0x120
    > > [ 91.292934] [<81361a3c>] ? pci_get_subsys+0x11c/0x1b0
    > > [ 91.292934] [<81361a3c>] pci_get_subsys+0x11c/0x1b0
    > > [ 91.292934] [<81361afe>] pci_get_device+0x2e/0x40
    > > [ 91.292934] [<81033e25>] mach_reboot_fixups+0xa5/0xd0
    > > [ 91.292934] [<81027611>] native_machine_emergency_restart+0x1f1/0x590
    > > [ 91.292934] [<814f2e00>] ? printk+0x4b/0x5b
    > > [ 91.292934] [<810269ef>] native_machine_restart+0x6f/0x80
    > > [ 91.292934] [<810271cc>] machine_restart+0x1c/0x30
    > > [ 91.292934] [<810886e0>] kernel_restart+0x70/0xc0
    > > [ 91.292934] [<81088a85>] sys_reboot+0x325/0x380
    > > [ 91.292934] [<811f796c>] ? handle_pte_fault+0xdc/0x1740
    > > [ 91.292934] [<811f93e7>] ? handle_mm_fault+0x417/0x4a0
    > > [ 91.292934] [<8103e07b>] ? do_page_fault+0x7fb/0xb30
    > > [ 91.292934] [<810b33e7>] ? up_read+0x37/0x70
    > > [ 91.292934] [<8103e07b>] ? do_page_fault+0x7fb/0xb30
    > > [ 91.292934] [<8123c063>] ? do_sys_open+0x3a3/0x3f0
    > > [ 91.292934] [<8123c063>] ? do_sys_open+0x3a3/0x3f0
    > > [ 91.292934] [<810b0270>] ? update_rmtp+0xe0/0xe0
    > > [ 91.292934] [<8150376e>] ? restore_all+0xf/0xf
    > > [ 91.292934] [<8103d880>] ? vmalloc_sync_all+0x320/0x320
    > > [ 91.292934] [<81109fca>] ? trace_hardirqs_on_caller+0x28a/0x380
    > > [ 91.292934] [<81311594>] ? trace_hardirqs_on_thunk+0xc/0x10
    > > [ 91.292934] [<81503735>] syscall_call+0x7/0xb
    > >
    > > Thanks,
    > > Fengguang


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