jffs2, 2.6.28-git8 : Weird problem.

[Jonathan Cameron]

> Jonathan Cameron wrote:
>> Having applied a few board specific patches on top of
>> Linus' tree (around 2.6.28-git8)
>> run into the following.
>>
>> Anyone have an ideas or seeing anything similar?
> 
> Yes, I think the same thing just happened on my avr32 board
> (ATSTK1006)...see below.
> 
>> Works fine on 2.6.28 so git bisection underway, but
>> will take a while given speed of flashing this device
>> (intelmote 2)
> 
> Please let me know the result, or if you need any help.
> 
> Haavard
> 
> Unable to handle kernel NULL pointer dereference at virtual address 00000150
> ptbr = 93a9b000 pgd = 93b45000
> Oops: Kernel access of bad area, sig: 11 [#1]
> FRAME_POINTER chip: 0x01f:0x1e82 rev 2
> Modules linked in:
> PC is at set_dumpable+0x16/0x5e
> LR is at commit_creds+0x86/0x10c
> pc : [<9005bfc6>]    lr : [<9002e4fe>]    Not tainted
> sp : 93bbff00  r12: 00000000  r11: 00000000
> r10: ffffffff  r9 : 00000000  r8 : 00000150
> r7 : 93bbff00  r6 : 939b9420  r5 : 901eca58  r4 : 00000000
> r3 : 939e02e0  r2 : 90021494  r1 : 900a40c4  r0 : 93b52400
> Flags: qvnzC
> Mode bits: hjmde....G
> CPU Mode: Supervisor
> Process: jffs2_gcd_mtd1 [281] (task: 939e02e0 thread: 93bbe000)
> Stack: (0x93bbff00 to 0x93bc0000)
> ff00: 9002e4fe 93bbff14 939b9420 901eca58 00000000 90021b00 93bbff44 93bbe000 
> ff20: 901ea8b0 00000000 00000000 90021494 900a40c4 93b52400 ffffffff ffffffff 
> ff40: 93bbff58 900a40da 93bbffdc 00000000 93b52400 00000000 00000001 038e300c 
> ff60: b3ec22cd 11c4148c b11833cc 338d19ec 77ca338c 734831ec 23dc63cc 33ec334c 
> ff80: 33cc33cd 338c30cc 37cc338c b3fcb68d 9001be6c 93bbffa4 90204640 939e05c0 
> ffa0: 93b5248c 90014166 93badcfc 90204640 939e05c0 93b5248c 00400000 900180e0 
> ffc0: 900180e0 93bc0000 00000000 00000000 00000000 00000000 00000000 90021494 
> ffe0: 00000000 00000000 00000000 00000000 00000000 90021494 900a40c4 93b52400 
> Call trace:
>  [<9002e4fe>] commit_creds+0x86/0x10c
>  [<90021b00>] daemonize+0x14c/0x16c
>  [<900a40da>] jffs2_garbage_collect_thread+0x16/0x108
>  [<90021494>] do_exit+0x0/0x488
> 
Hi All, 

Results of git bisection are in.  The patch highlighted as
causing the problem is:

d84f4f992cbd76e8f39c488cf0c5d123843923b1 is first bad commit                              
commit d84f4f992cbd76e8f39c488cf0c5d123843923b1                                           
Author: David Howells <dhowells at redhat.com>                                               
Date:   Fri Nov 14 10:39:23 2008 +1100                                                    

    CRED: Inaugurate COW credentials
                                    
( lots of info ).

So now for the remaining question of why?

The setup I'm using is now in Linus' tree anyway
(intelmote2 see arm/mach-pxa/imote2.c)

Jonathan