Hi Raghavendra,
On Saturday 25 June 2011 21:19:29 Raghavendra D Prabhu wrote:
> Hi,
>
> While modprobing uvcvideo I am getting the following oops. This is
> on a kernel built with latest linus master
> (536142f950f7ea4f3d146a138ad6938f28a34f33). I have also attached the
> full dmesg.
>
> =============================================================
> [ 1985.732475] uvcvideo: Found UVC 1.00 device Laptop_Integrated_Webcam_2HDM
> (0408:2fb1)
Could you please send me the output of
lsusb -v -d 0408:2fb1
running as root if possible ?
> [ 1985.759844] uvcvideo: No streaming interface found for terminal 6.
> [ 1985.759863] BUG: unable to handle kernel NULL pointer dereference at
> 0000000000000050
> [ 1985.759871] IP: [<ffffffffa0da23e0>] media_entity_init+0x40/0xa0 [media]
[snip]
> I was able to observe this at boot and also reproduce it later.
>
> Further analyzing the oops revealed this:
> ========================================================
> perl scripts/markup_oops.pl < ~/oops
>
> No vmlinux specified, assuming /lib/modules/3.0.0-rc4-LYM/build/vmlinux
> unsigned int max_links = num_pads + extra_links;
> unsigned int i;
>
> links = kzalloc(max_links * sizeof(links[0]), GFP_KERNEL);
> ffffffffa01573d2: 48 c1 e7 05 shl $0x5,%rdi | %edi
> => ffff88013ac31200 ffffffffa01573d6: e8 00 00 00 00 callq
> ffffffffa01573db <media_entity_init+0x3b> if (links == NULL)
> ffffffffa01573db: 48 85 c0 test %rax,%rax | %eax
> => ffff88013ac311e0 ffffffffa01573de: 74 56 je
> ffffffffa0157436 <media_entity_init+0x96> entity->max_links = max_links;
> entity->num_links = 0;
> entity->num_backlinks = 0;
> entity->num_pads = num_pads;
> entity->pads = pads;
> entity->links = links;
> *ffffffffa01573e0: 48 89 43 50 mov %rax,0x50(%rbx) |
> %eax = ffff88013ac311e0 <--- faulting instruction
It looks like entity is NULL.
> for (i = 0; i < num_pads; i++) {
> pads[i].entity = entity;
> pads[i].index = i;
> }
>
> return 0;
> ffffffffa01573e4: 31 c0 xor %eax,%eax
> entity->num_backlinks = 0;
> entity->num_pads = num_pads;
> entity->pads = pads;
> entity->links = links;
> ==================================================================
I can't reproduce the problem with my webcams. Can you try a diagnosis patch
if needed ?
--
Regards,
Laurent Pinchart
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