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Date: Wed, 22 Aug 2012 15:49:08 +0800
From: Feng Tang <feng.tang@...el.com>
To: Fengguang Wu <fengguang.wu@...el.com>
Cc: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Steven Rostedt <rostedt@...dmis.org>,
Avi Kivity <avi@...hat.com>,
Steven Rostedt <srostedt@...hat.com>,
LKML <linux-kernel@...r.kernel.org>,
"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
Yinghai Lu <yinghai@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
<linux-pci@...r.kernel.org>
Subject: Re: pci_get_subsys: GFP_KERNEL allocations with IRQs disabled
Hi Fengguang,
On Wed, 22 Aug 2012 10:50:08 +0800
Fengguang Wu <fengguang.wu@...el.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@...el.com>
> AuthorDate: Wed May 30 23:15:41 2012 +0800
> Commit: Ingo Molnar <mingo@...nel.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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