SMP issues on ARM11 MPCore

[Dirk Behme]

2010/1/7 Uwe Kleine-König <u.kleine-koenig at pengutronix.de>:
> Hi Dirk,
>
> On Thu, Jan 07, 2010 at 02:45:11PM +0100, Dirk Behme wrote:
>> >  Unable to handle kernel NULL pointer dereference at virtual address 00000000
>> >  pgd = cc37c000
>> >  [00000000] *pgd=8c38f031, *pte=00000000, *ppte=00000000
>> >  Internal error: Oops: 17 [#1] SMP
>> >  last sysfs file:
>> >  Modules linked in: [last unloaded: module]
>> >  CPU: 0    Not tainted  (2.6.32-00012-g89b993e-dirty #17)
>> >  PC is at strcmp+0x8/0x34
>> >  LR is at sysfs_find_dirent+0x18/0x38
>> >  pc : [<c094bd8c>]    lr : [<c08ede4c>]    psr: a0000013
>> >  sp : cc26bef8  ip : 00000000  fp : 00000000
>> >  r10: 40025000  r9 : cc26a000  r8 : 00000880
>> >  r7 : cc26bf44  r6 : 00000000  r5 : 00000000  r4 : cc326428
>> >  r3 : 000009b3  r2 : 00000000  r1 : 00000000  r0 : 00000000
>> >  Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
>> >  Control: 08c5787d  Table: 8c37c00a  DAC: 00000015
>> >  Process rmmod (pid: 378, stack limit = 0xcc26a270)
>> >  Stack: (0xcc26bef8 to 0xcc26c000)
>> >  bee0:                                                       cc3263f8 00000000
>> >  bf00: 00000000 c08ec918 cc3263f8 00000000 00000000 00000000 00000000 ccd961e0
>> >  bf20: 00000000 c087de50 bf000074 bf000074 00000000 c087e214 00000000 c087e550
>> >  bf40: 00000001 75646f6d cc00656c cc37d000 cc25ba20 cc25ba64 cc25ba54 00000000
>> >  bf60: 40025000 00000000 40025000 00000001 cc26a000 4002501c bef869c4 0089e8e8
>> >  bf80: bf000074 00000880 cc26bf8c 00000000 be00656c 400256c0 00000000 00000081
>> >  bfa0: c0842224 c08420a0 be00656c 400256c0 bef86b80 00000880 00000000 75646f6d
>> >  bfc0: be00656c 400256c0 00000000 00000081 00000059 00000000 40025000 00000000
>> >  bfe0: bef86b80 bef86b70 00012fe0 400e7740 60000010 bef86b80 00000000 00000000
>> >  [<c094bd8c>] (strcmp+0x8/0x34) from [<c08ede4c>] (sysfs_find_dirent+0x18/0x38)
>> >  [<c08ede4c>] (sysfs_find_dirent+0x18/0x38) from [<c08ec918>]
>> > (sysfs_hash_and_remove+0x28/0x60)
>> >  [<c08ec918>] (sysfs_hash_and_remove+0x28/0x60) from [<c087de50>]
>> > (free_notes_attrs+0x2c/0x4c)
>> >  [<c087de50>] (free_notes_attrs+0x2c/0x4c) from [<c087e214>]
>> > (free_module+0x2c/0xdc)
>> >  [<c087e214>] (free_module+0x2c/0xdc) from [<c087e550>]
>> > (sys_delete_module+0x214/0x250)
>> >  [<c087e550>] (sys_delete_module+0x214/0x250) from [<c08420a0>]
>> > (ret_fast_syscall+0x0/0x2c)
>>
>> Debugging of above call stack shows:
>>
>> strcmp() fails due to both parameters, cs and ct being NULL.
>>
>> Function free_module() gets 'struct module *mod' as parameter. This
>> has an element
>>
>> mod->notes_attrs->attrs[0].attr.name
>>
>> In case of module's init and exit function are _both_ marked with
>> __init/__exit, this name is NULL. This is then parsed down by above
>> call stack and let strcmp() fail.
>>
>> In case init and/or exit function in above module don't have
>> __init/__exit, name is a valid pointer.
>>
>> Any idea what might cause this?
>>
>> Many thanks and best regards
> does
>
>        http://svn.debian.org/wsvn/kernel/dists/trunk/linux-2.6/debian/patches/bugfix/all/modules-Skip-empty-section-notes.patch
>
> help you?

Yes :) Thanks.

Having this patch applied and having mkl lin's test module working
now, it seems to me that I'm not able to reproduce mkl lin's issues,
though. I will do some additional tests.

Best regards

Dirk