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Date: Wed, 13 Sep 2006 14:44:48 -0400 (EDT)
From: Alan Stern <stern@rowland.harvard.edu>
X-X-Sender: stern@iolanthe.rowland.org
To: "Rafael J. Wysocki" <rjw@sisk.pl>
cc: Pete Zaitcev <zaitcev@redhat.com>, Andrew Morton <akpm@osdl.org>,
       Kernel development list <linux-kernel@vger.kernel.org>,
       USB development list <linux-usb-devel@lists.sourceforge.net>
Subject: Re: 2.6.18-rc6-mm2: rmmod ohci_hcd oopses on HPC 6325
In-Reply-To: <200609131558.03391.rjw@sisk.pl>
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On Wed, 13 Sep 2006, Rafael J. Wysocki wrote:

> 'rmmod ohci_hcd' causes the following oops to appear on my HPC 6325 every
> time (happens also on -rc6-mm1, does not happen on -rc7):
> 
> Unable to handle kernel NULL pointer dereference at 0000000000000274 RIP:
>  [<ffffffff8822c185>] :ohci_hcd:ohci_hub_status_data+0x25/0x27b
> PGD 35ca9067 PUD 369a4067 PMD 0

> Call Trace:
>  [<ffffffff8818e03f>] :usbcore:usb_hcd_poll_rh_status+0x40/0x13b
>  [<ffffffff8822c01b>] :ohci_hcd:ohci_irq+0xcb/0x210
>  [<ffffffff8818e78b>] :usbcore:usb_hcd_irq+0x2f/0x5f
>  [<ffffffff8020ef13>] handle_IRQ_event+0x33/0x66
>  [<ffffffff802af5f8>] handle_fasteoi_irq+0x9d/0xe3
>  [<ffffffff80267c85>] do_IRQ+0x104/0x11f
>  [<ffffffff80259621>] ret_from_intr+0x0/0xa
> DWARF2 unwinder stuck at ret_from_intr+0x0/0xa
> 
> Leftover inexact backtrace:
> 
>  <IRQ>  <EOI>  [<ffffffff802ee4ac>] sysfs_hash_and_remove+0x9/0x137
>  [<ffffffff802eed13>] sysfs_remove_file+0x10/0x12
>  [<ffffffff8038baf7>] class_device_remove_file+0x12/0x14
>  [<ffffffff8822aa02>] :ohci_hcd:ohci_stop+0xf5/0x17b
>  [<ffffffff8818d9d2>] :usbcore:usb_remove_hcd+0xdc/0x114
>  [<ffffffff8040f8eb>] klist_release+0x0/0x82
>  [<ffffffff88197f45>] :usbcore:usb_hcd_pci_remove+0x1e/0x7d
>  [<ffffffff803204d8>] pci_device_remove+0x25/0x3c
>  [<ffffffff8038b1b5>] __device_release_driver+0x80/0x9c
>  [<ffffffff8038b617>] driver_detach+0xac/0xee
>  [<ffffffff8038ad92>] bus_remove_driver+0x75/0x98
>  [<ffffffff8038b696>] driver_unregister+0x15/0x21
>  [<ffffffff80320686>] pci_unregister_driver+0x13/0x8e
>  [<ffffffff8822cd1c>] :ohci_hcd:ohci_hcd_pci_cleanup+0x10/0x12
>  [<ffffffff8029b281>] sys_delete_module+0x1b5/0x1e6
>  [<ffffffff8025910e>] system_call+0x7e/0x83
> 
> 
> Code: 8a 98 74 02 00 00 e8 d6 3b 03 f8 48 89 45 d0 41 8b 84 24 e4
> RIP  [<ffffffff8822c185>] :ohci_hcd:ohci_hub_status_data+0x25/0x27b
>  RSP <ffffffff805c7e18>
> CR2: 0000000000000274
>  <0>Kernel panic - not syncing: Aiee, killing interrupt handler!
> 
> where
> 
> (gdb) l *ohci_hub_status_data+0x25
> 0x4185 is in ohci_hub_status_data (drivers/usb/host/ohci-hub.c:316).
> 311             struct ohci_hcd *ohci = hcd_to_ohci (hcd);
> 312             int             i, changed = 0, length = 1;
> 313             int             can_suspend;
> 314             unsigned long   flags;
> 315
> 316             can_suspend = device_may_wakeup(&hcd->self.root_hub->dev);
> 317             spin_lock_irqsave (&ohci->lock, flags);
> 318
> 319             /* handle autosuspended root:  finish resuming before
> 320              * letting khubd or root hub timer see state changes.
> 
> I guess it may be related to the suspend issues?

No, this is completely separate.  The suspend issue involved ehci-hcd, not 
ohci-hcd.

This problem has already been identified by Pete Zaitcev in this thread:

	http://marc.theaimsgroup.com/?t=115769512800001&r=1&w=2

Perhaps Pete has an updated patch to fix the problem.  If not, I could 
write one.

Alan Stern

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