pci_get_subsys: GFP_KERNEL allocations with IRQs disabled

From: Fengguang Wu <fengguang.wu@intel.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>, Avi Kivity <avi@redhat.com>,
	Steven Rostedt <srostedt@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>,
	Yinghai Lu <yinghai@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	linux-pci@vger.kernel.org
Subject: pci_get_subsys: GFP_KERNEL allocations with IRQs disabled
Date: Wed, 1 Aug 2012 08:43:19 +0800	[thread overview]
Message-ID: <20120801004319.GA7043@localhost> (raw)
In-Reply-To: <20120801001811.GX2422@linux.vnet.ibm.com>

On Tue, Jul 31, 2012 at 05:18:11PM -0700, Paul E. McKenney wrote:
> On Tue, Jul 31, 2012 at 08:09:38PM -0400, Steven Rostedt wrote:
> > On Tue, 2012-07-31 at 16:57 -0700, Paul E. McKenney wrote:
> > 
> > > > What was the next lines? I bet you it was "PASSED". Which means it did
> > > > not fail. This is the second bug you found that has to do with RCU being
> > > > called in 'idle'. The one that Paul posted a patch for.
> > > 
> > > Though it needs another patch to actually use it in the right place...
> > 
> > Right. Something like this:
> 
> Looks good to me!

With all 3 patches applied, the warning on __update_max_tr finally
goes away. Thanks!

However, this unrelated warning still reliably remains (the same config).
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;

[   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