Re: [Bug #10713] ehci splatter in 2.6.26-rc2

From: Lennert Buytenhek
Date: Mon May 19 2008 - 19:11:48 EST


On Sun, May 18, 2008 at 01:13:56PM +0200, Rafael J. Wysocki wrote:

> This message has been generated automatically as a part of a report
> of recent regressions.
>
> The following bug entry is on the current list of known regressions
> from 2.6.25. Please verify if it still should be listed.
>
>
> Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=10713
> Subject : ehci splatter in 2.6.26-rc2
> Submitter : Lennert Buytenhek <buytenh@xxxxxxxxxxxxxx>
> Date : 2008-05-14 11:24 (5 days old)
> References : http://marc.info/?l=linux-kernel&amp;m=121076435420129&amp;w=4
> Handled-By : David Brownell <david-b@xxxxxxxxxxx>

Just re-checked, and this device (a USB to dual PS/2 cable) works
fine on 2.6.25 on this hardware:

usb 1-1: new low speed USB device using orion-ehci and address 2
usb 1-1: configuration #1 chosen from 1 choice
input: PS2 to USB AdapterA3 as /class/input/input0
input: USB HID v1.10 Keyboard [PS2 to USB AdapterA3] on usb-orion-ehci.0-1
input: PS2 to USB AdapterA3 as /class/input/input1
input: USB HID v1.10 Mouse [PS2 to USB AdapterA3] on usb-orion-ehci.0-1

But on 2.6.26-rc3 it just gives me:

usb 1-1: new low speed USB device using orion-ehci and address 2
Unable to handle kernel NULL pointer dereference at virtual address 00000000
pgd = c0004000
[00000000] *pgd=00000000
Internal error: Oops: 5 [#1] PREEMPT
Modules linked in:
CPU: 0 Not tainted (2.6.26-rc3 #347)
PC is at qh_append_tds+0x24c/0x47c
LR is at ehci_qtd_alloc+0x30/0x5c
pc : [<c0242374>] lr : [<c0241d48>] psr: 00000093
sp : c7cfdcb0 ip : c7e3c4c0 fp : c7cfdcfc
r10: ffc83080 r9 : 00000008 r8 : c7d12240
r7 : 80000080 r6 : 00000080 r5 : 00000000 r4 : 00000002
r3 : c7d3f000 r2 : 00000000 r1 : 40800000 r0 : 08085000
Flags: nzcv IRQs off FIQs on Mode SVC_32 ISA ARM Segment kernel
Control: 0005317f Table: 00004000 DAC: 00000017
Process khubd (pid: 79, stack limit = 0xc7cfc268)
Stack: (0xc7cfdcb0 to 0xc7cfe000)
[...]
Backtrace:
[<c0242128>] (qh_append_tds+0x0/0x47c) from [<c0243ca0>] (ehci_urb_enqueue+0x100/0xff4)
[<c0243ba0>] (ehci_urb_enqueue+0x0/0xff4) from [<c0234c30>] (usb_hcd_submit_urb+0x824/0x91c)
[<c023440c>] (usb_hcd_submit_urb+0x0/0x91c) from [<c0235098>] (usb_submit_urb+0x224/0x260)
[<c0234e74>] (usb_submit_urb+0x0/0x260) from [<c0235b5c>] (usb_start_wait_urb+0x44/0xac)
r6:c7d12240 r5:c7cfde80 r4:00000000
[<c0235b18>] (usb_start_wait_urb+0x0/0xac) from [<c0235dac>] (usb_control_msg+0xc8/0xec)
r8:00000000 r7:00000100 r6:fffffff4 r5:00000040 r4:c7e3dc20
[<c0235ce4>] (usb_control_msg+0x0/0xec) from [<c0230854>] (hub_port_init+0x274/0x5e4)
[<c02305e0>] (hub_port_init+0x0/0x5e4) from [<c0231bec>] (hub_thread+0x608/0xc10)
[<c02315e4>] (hub_thread+0x0/0xc10) from [<c0059e20>] (kthread+0x5c/0x94)
[<c0059dc4>] (kthread+0x0/0x94) from [<c0047908>] (do_exit+0x0/0x67c)
r6:00000000 r5:00000000 r4:00000000
Code: e51bc040 e5932000 e51c309c e1520003 (15923000)
---[ end trace ce1992535f2e8e4d ]---
note: khubd[79] exited with preempt_count 1

If you have no idea what might have caused this to creep in, I guess
I'll have to bisect it?
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