Re: [2.6.26] kobject_add_internal failed for 2:0 with -EEXIST / unable to handle kernel NULL pointer dereference in sysfs_create_link

[Kay Sievers]

On Wed, Oct 29, 2008 at 11:01, Bryan Wu <cooloney@xxxxxxxxxx> wrote:
> On Wed, Oct 29, 2008 at 5:40 PM, Folkert van Heusden
> <folkert@xxxxxxxxxxxxxx> wrote:
>>> > While running my http://vanheusden.com/pyk/ script (which randomly
>>> > inserts and removes modules) I triggered the folllowing oops in a 2.6.26
>>> > kernel on an IBM xSeries 260. This oops (in fact no oops at all) did not
>>> > get triggered in a 2.6.18 kernel on that system.
>>> >
>>> > [   42.507375] FDC 0 is a National Semiconductor PC87306
>>> > [   42.509057] kobject_add_internal failed for 2:0 with -EEXIST, don't try to register things with the same name in the same directory.
>>> > [   42.509291] Pid: 5301, comm: modprobe Not tainted 2.6.26-1-amd64 #1
>>> > [   42.509431]
>>> > [   42.509433] Call Trace:
>>> > [   42.509685]  [<ffffffff8031b031>] kobject_add_internal+0x13f/0x17e
>>> > [   42.509823]  [<ffffffff8031b46e>] kobject_add+0x74/0x7c
>>> > [   42.509969]  [<ffffffff802e2470>] sysfs_addrm_finish+0x19/0x1ea
>>> > [   42.510141]  [<ffffffff802e21b4>] sysfs_find_dirent+0x1b/0x2f
>>> > [   42.510331]  [<ffffffff802e2741>] create_dir+0x5a/0x87
>>> > [   42.510466]  [<ffffffff8031ae88>] kobject_get+0x12/0x17
>>> > [   42.510614]  [<ffffffff80382771>] get_device+0x17/0x20
>>> > [   42.510754]  [<ffffffff80382d81>] device_add+0x9b/0x53f
>>> > [   42.510915]  [<ffffffff8031acf2>] kobject_init+0x41/0x69
>>> > [   42.511374]  [<ffffffff803832d1>] device_create_vargs+0x9a/0xc6
>>> > [   42.511519]  [<ffffffff8027d23b>] bdi_register+0x57/0xb4
>>>
>>> Looks like bdi sees two devices with the same devnum, or didn't
>>> cleanup an old entry.
>>> What does: ls -l "/sys/class/bdi/" print?
...
>> drwxr-xr-x 3 root root 0 2008-10-28 18:32 2:0
>> drwxr-xr-x 3 root root 0 2008-10-28 18:32 2:1
...
>> drwxr-xr-x 3 root root 0 2008-10-28 18:32 default
>>
>>> How many floppies (or emulated floppies) does this system have?
>>
>> 1 physical.

> Hi guys,
>
> I found similar issue on Blackfin board and I believe it is a common bug for bdi
> http://lkml.org/lkml/2008/10/16/126
>
> But there is no response about this bug, although I am working on it.

Peter, any idea? BDI seems to try to create duplicate devices.

Thanks,
Kay
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