PREEMPT ISSUE - 805

[manoelramon]

Please, I running Android JB on my IMX6 and I've seeing the following crash sometimes (it is random)

Unable to handle kernel NULL pointer dereference at virtual address 00000001
pgd = d04f4000
[00000001] *pgd=00000000
Internal error: Oops: 805 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 Tainted: G W (3.0.35 #4)
PC is at _raw_spin_unlock+0x8/0x3c
LR is at inotify_merge+0x3c/0xf0
pc : [<c068ec84>] lr : [<c01844dc>] psr: 200b0013
sp : d0371db0 ip : 00000001 fp : 00000000
r10: 0000eed0 r9 : 00000000 r8 : 00000000
r7 : d006a7a0 r6 : 00000000 r5 : 00000001 r4 : 00000000
r3 : 00000000 r2 : 00000f80 r1 : 00001000 r0 : 00000001
Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
Control: 10c53c7d Table: 204f404a DAC: 00000015

PC: 0xc068ec04:
ec04 e3310000 1afffffa e3530000 1a000001 f57ff04f e320f004 e1a0100d e3c13d7f
ec24 e3c3303f e1a00002 e5932004 e2422001 e5832004 e49de004 eae89351 e52de004
ec44 f57ff05f e3a03000 e5803000 f57ff04f e320f004 e1a0100d e3c13d7f e3c3303f
ec64 e1a0000e e5932004 e2422001 e5832004 e49de004 eae89342 f57ff05f e3a03000
ec84 e5803000 f57ff04f e320f004 e1a0200d e3c23d7f e3c3303f e5932004 e2422001
eca4 e5832004 e5933000 e3130002 012fff1e eafff88c f57ff05f e3a03000 e5803000
ecc4 f57ff04f e320f004 e121f001 e1a0200d e3c23d7f e3c3303f e5932004 e2422001
ece4 e5832004 e5933000 e3130002 012fff1e eafff87c f57ff05f e3a03000 e5803000

LR: 0xc018445c:
445c e1a00005 e34c1018 eb0504db e1a00005 eb05053d e1a00005 eb050339 e5943080
447c e2832014 e1921f9f e2411001 e1820f91 e3300000 1afffffa e5940080 e8bd4038
449c eafce05c e92d4070 e281500c e1a04000 e1a06001 e1a00005 eb142b1f e5943004
44bc e5962028 e5134004 e5943028 e1530002 0a000004 e3a04000 e1a00005 eb1429e7
44dc e1a00004 e8bd8070 e5941014 e5962014 e1510002 1afffff6 e5942020 e5961020
44fc e1520001 1afffff2 e5941034 e5960034 e1510000 1affffee e3520001 0a000013
451c e3520002 0a000009 e3520000 1affffe8 e2132901 1a000002 e3130902 11a04002
453c 1affffe4 e1a00004 ebfff7a8 eaffffe1 e3510000 0afffffa e5940030 e5961030

SP: 0xd0371d30:
1d30 c06b8a48 ffffffff 00000020 c02cf230 00000000 0000000a ffffffff ffffffff
1d50 000000d0 0000040f 00000005 00000000 d006a7a0 c006b2d0 00000001 00001000
1d70 00000f80 00000000 00000000 00000001 00000000 d006a7a0 00000000 00000000
1d90 0000eed0 00000000 00000001 d0371db0 c01844dc c068ec84 200b0013 ffffffff
1db0 000005aa 00000000 000000d8 00000000 0000046b 00000000 00001591 00000000
1dd0 000000a6 00000000 00000000 00000000 00000006 00000000 00000000 00000000
1df0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
1e10 00000000 00000000 00001591 00000000 000000a6 00000000 00000000 00000000

R7: 0xd006a720:
a720 d006a71c 00000000 00000000 00000000 00000000 00000000 00000000 00000000
a740 000068c9 d006a744 d006a744 00000003 d006a6f0 00000000 00000000 d46f4000
a760 00000000 00000000 00000000 00000000 40eb4ab8 414158bc 00001fe0 d006a77c
a780 d006a77c 00000000 00000000 00000000 00000000 00000000 00000000 00000000
a7a0 d11be000 00001000 00000000 00000082 00000000 00000000 00000000 00000000
a7c0 00000000 00000000 00000000 00000000 00000000 d006a7d4 d006a7d4 d41a0080
a7e0 d03c9a80 00000000 00000000 00000000 00000000 00000000 00000000 00000000
a800 d006a800 d006a800 d006a808 d006a808 d006a810 d006a810 00000000 00000000
Process ActivityManager (pid: 2583, stack limit = 0xd03702f0)
Stack: (0xd0371db0 to 0xd0372000)
1da0: 000005aa 00000000 000000d8 00000000
1dc0: 0000046b 00000000 00001591 00000000 000000a6 00000000 00000000 00000000
1de0: 00000006 00000000 00000000 00000000 00000000 00000000 00000000 00000000
1e00: 00000000 00000000 00000000 00000000 00000000 00000000 00001591 00000000
1e20: 000000a6 00000000 00000000 00000000 00000006 00000000 00000000 00000000
1e40: 00000000 00000000 000005aa 00000000 000000d8 00000000 0000046b 00000000
1e60: 00000006 00000000 00000000 00000000 00000000 00000000 0000eed0 00000000
1e80: 0001ac29 00000000 d006a7a0 c00631c8 c0913b1c 589e648f 589e648f 27425d39
1ea0: 00000000 000029e5 00000001 00000000 00000000 00000000 00007af2 00000c82
1ec0: 00000004 00003d72 00000000 d006a7a0 00000001 00000000 00000001 d0371f08
1ee0: d11bfcc0 00000000 00000000 c016caf4 00000041 000000ff d0371f88 69177b14
1f00: d006a7c8 00000000 00000000 00000000 d2001800 d2324e78 00000101 d45e97c0
1f20: d11bfcc0 c016c930 d0371f88 000000ff d0370000 69177b14 00000000 c0193480
1f40: d0371f88 d11bfcc0 000000ff 69177b14 d0371f88 000000ff 00000000 c014f468
1f60: 00000000 c015092c d11bfcc0 69177b14 00000000 00000000 000000ff c014f534
1f80: 00000024 00000001 00000000 00000000 630f8ce8 69177b14 6dc00009 00000003
1fa0: c006ba84 c006b900 630f8ce8 69177b14 000000c7 69177b14 000000ff 00000000
1fc0: 630f8ce8 69177b14 6dc00009 00000003 f7200001 66594fa8 000000c7 00000000
1fe0: 4011f1f4 69177af0 4023485f 400ef060 200b0010 000000c7 5e9fb5f5 f7fffffa
[<c068ec84>] (_raw_spin_unlock+0x8/0x3c) from [<c01844dc>] (inotify_merge+0x3c/0xf0)
[<c01844dc>] (inotify_merge+0x3c/0xf0) from [<00000000>] ( (null))
Code: e49de004 eae89342 f57ff05f e3a03000 (e5803000)

Have you guys seen simular problem with error 805 on _raw_spin_unlock ? I do not have JTAG available.

[weidong_sun]

Hello Manoel,

    The issue should be caused by empty pointer in kernel. you don't need Simulator with JTAG to debug it. Cross Compiler's path is at "/myandroid/prebuilts/gcc/linux-x86/arm/arm-eabi-4.6/bin/", see below:

...

./prebuilts/gcc/linux-x86/arm/arm-eabi-4.6/bin/arm-eabi-gdb

...

   you can use the gdb to locate where erros ocurred like following steps:

(1) Running gdb to debug related vmlinux

# arm-eabi-gdb vmlinux

(2) setting breakpoint

(gdb) b*0xc068ec04   ( See above logs: PC: 0xc068ec04: )

Then you will konw which file and wihch line caused errors.

(3)If you don't want to open the file, you can use the follwing setting to show lines including error one.

(gdb) set listsize 60 

(gdb) list *0xc068ec04

Hope above advice can help you!

Best Regards,

Weidong