Message-ID: <91969FDC112D9742BC923801900F5661205D1B431F@EXGMBX01.sasken.com>
Date:	Mon, 25 Jul 2011 12:00:06 +0530
From:	Neha Singhal <neha.singhal@...ken.com>
To:	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Crash while using completions

Hi,

I am new to kernel programming. I am trying to use completion technique to synchronize two threads. But i am facing a crash due to NULL pointer reference. does anyone also face crash while using completion or have idea about it.  Crash seems to be like this:

[ 1120.334930] Unable to handle kernel NULL pointer dereference at virtual addre
ss 00000000
[ 1120.343078] pgd = c0004000
[ 1120.345855] [00000000] *pgd=00000000
[ 1120.349456] Internal error: Oops: 80000007 [#1] PREEMPT SMP
[ 1120.355072] last sysfs file: /sys/devices/platform/nmk-i2c.2/i2c-2/2-0018/dat
a
[ 1120.362335] Modules linked in: [last unloaded: cw1200_wlan]
[ 1120.367980] CPU: 1    Not tainted  (2.6.35.7+ #1)
[ 1120.372711] PC is at 0x0
[ 1120.375305] LR is at run_timer_softirq+0x264/0x388
[ 1120.380126] pc : [<00000000>]    lr : [<c0086d30>]    psr: 60000113
[ 1120.380157] sp : df863e90  ip : 00fdf000  fp : c06f4040
[ 1120.391662] r10: 00000000  r9 : c074bc30  r8 : 00000103
[ 1120.396911] r7 : c074bc20  r6 : df84a000  r5 : df862000  r4 : d9fb8500
[ 1120.403472] r3 : 00000000  r2 : 00000103  r1 : 00000000  r0 : 00000000
[ 1120.410034] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment kern
el
[ 1120.417388] Control: 10c57c7d  Table: 1eaa804a  DAC: 00000017
[ 1120.423156]
[ 1120.423187] LR: 0xc0086cb0:
[ 1120.427459] 6cb0  e1a00006 e5823004 e5832000 e59f2178 e8840006 eb11d757 e5973
044 e5958004
[ 1120.435821] 6cd0  e3530000 0a000013 e2883001 e5853004 e59f3158 e593b000 e35b0
000 0a000006
[ 1120.444152] 6cf0  e59b0004 e1a01004 e1a0e00f e59bf000 e5bb3008 e3530000 eafff
ff7 e5953004
[ 1120.452514] 6d10  e2433001 e5853004 e5953000 e3130002 0a000000 eb11cfab e59d0
024 e12fff3a
[ 1120.460845] 6d30  e5973064 e3530000 0a000014 e5953004 e2833001 e5853004 e59f1
0f4 e591b000
[ 1120.469177] 6d50  e35b0000 0a000006 e59b0004 e1a01004 e1a0e00f e59bf000 e5bb3
008 e3530000
[ 1120.477539] 6d70  eafffff7 e5953004 e2433001 e5853004 e5953000 e3130002 0a000
000 eb11cf91
[ 1120.485870] 6d90  e5953004 e1580003 0a00000f e59f20a4 e5523fb8 e3530001 0a000
00a e58d8000
[ 1120.494232]
[ 1120.494232] SP: 0xdf863e10:
[ 1120.498535] 3e10  ffffff00 ffffffff ffffc200 ffffffff 0000045c 00000000 00000
001 c1014cb0
[ 1120.506866] 3e30  00000100 ffffffff df863e7c df84a000 c074bc20 c0039370 00000
000 00000000
[ 1120.515228] 3e50  00000103 00000000 d9fb8500 df862000 df84a000 c074bc20 00000
103 c074bc30
[ 1120.523559] 3e70  00000000 c06f4040 00fdf000 df863e90 c0086d30 00000000 60000
113 ffffffff
[ 1120.531890] 3e90  c1014cb0 e7069d20 00000103 df863eb8 df863ef0 df84a814 df84a
a14 df84ac14
[ 1120.540252] 3eb0  df84ae14 00000000 df863eb8 df863eb8 00000000 df862000 00000
141 00000004
[ 1120.548583] 3ed0  c074bba0 00000001 00000103 c06f4044 c06f4040 c007eff4 c1014
c20 ffffffff
[ 1120.556915] 3ef0  0000000a c0035a10 00000001 00000001 00000000 00000000 c079f
760 0000001d
[ 1120.565277]
[ 1120.565277] FP: 0xc06f3fc0:
[ 1120.569580] 3fc0  c07e42cc 00000000 c002f038 c07095bc 0002d2d0 c0008b68 c0008
678 00000cdd
[ 1120.577911] 3fe0  00000100 c002f038 10c53c7d c075d538 c002f034 00008080 00000
000 00000000
[ 1120.586273] 4000  00000000 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.594604] 4020  00000000 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.602935] 4040  c007ea0c c0086acc c03f1718 c03f310c c01f4820 c01f4f38 c007e
b58 c0075210
[ 1120.611267] 4060  c0097af8 c00bd3b0 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.619598] 4080  00013ee2 00000001 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.627960] 40a0  00000000 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.636291]
[ 1120.636291] R4: 0xd9fb8480:
[ 1120.640594] 8480  00000000 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.648925] 84a0  00000000 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.657257] 84c0  00000000 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.665618] 84e0  00000000 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.673950] 8500  00000000 00200200 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.682281] 8520  00000000 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.690612] 8540  00000000 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.698974] 8560  00000000 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.707305]
[ 1120.707305] R5: 0xdf861f80:
[ 1120.711608] 1f80  00797474 57babae3 22b30b8a a926e3eb aeaa6be6 aafb2ba6 aca8b
aaa a4e2ea9e
[ 1120.719940] 1fa0  00797474 eee6aa09 8ba27eae 06abc2eb 2baa3abb baca202a fa328
ac3 22ca6ae1
[ 1120.728302] 1fc0  76697264 00737265 23656e9a aaa16cab 3ae28a00 024a2aaa ec2aa
88a 2caaa8b8
[ 1120.736633] 1fe0  76697264 00737265 b62bc6bb abea286f 2a8ab80a 481baeba a6b2b
aae aaaabea7
[ 1120.744995] 2000  00000002 00000105 00000000 df84f5a0 c0716614 00000001 00000
017 c1016820
[ 1120.753326] 2020  df84f5a0 df862000 c07e4564 df82e040 df84f808 00000000 df863
fdc df863f80
[ 1120.761657] 2040  c04fa928 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.769989] 2060  00000000 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.778350]
[ 1120.778350] R6: 0xdf849f80:
[ 1120.782653] 9f80  a44c63de 00000000 c0033958 c0037820 c071a6f0 00000000 df849
fcc c00b7c28
[ 1120.790985] 9fa0  c1014d70 df831f20 df849fcc c00b7c28 c1014d70 00000000 00000
000 00000000
[ 1120.799316] 9fc0  00000000 c0093a9c 00000000 00000000 00000000 00000000 df849
fd8 df849fd8
[ 1120.807678] 9fe0  00000000 df831f20 c0093a24 c003a8fc 00000013 c003a8fc a6b2b
8ae a2aab2a7
[ 1120.816009] a000  00000000 00000000 d9fb8500 00013edb 00000000 df84a014 df84a
014 df84a01c
[ 1120.824340] a020  df84a01c df84a024 df84a024 df84a02c df84a02c df84a034 df84a
034 df84a03c
[ 1120.832702] a040  df84a03c df84a044 df84a044 df84a04c df84a04c df84a054 df84a
054 df84a05c
[ 1120.841033] a060  df84a05c df84a064 df84a064 df84a06c df84a06c df84a074 df84a
074 df84a07c
[ 1120.849395]
[ 1120.849395] R7: 0xc074bba0:
[ 1120.853698] bba0  c06a6148 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.862030] bbc0  c06a6158 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.870361] bbe0  c06a6120 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.878692] bc00  c06a6134 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.887054] bc20  c06a61a8 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.895385] bc40  c06a6168 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.903717] bc60  c06a6180 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.912048] bc80  c06a6194 00000000 00000000 00000000 00000000 00000000 00000
000 00000000
[ 1120.920379]
[ 1120.920410] R9: 0xc074bbb0:
[ 1120.924682] bbb0  00000000 00000000 00000000 00000000 c06a6158 00000000 00000
000 00000000
[ 1120.933044] bbd0  00000000 00000000 00000000 00000000 c06a6120 00000000 00000
000 00000000
[ 1120.941375] bbf0  00000000 00000000 00000000 00000000 c06a6134 00000000 00000
000 00000000
[ 1120.949707] bc10  00000000 00000000 00000000 00000000 c06a61a8 00000000 00000
000 00000000
[ 1120.958038] bc30  00000000 00000000 00000000 00000000 c06a6168 00000000 00000
000 00000000
[ 1120.966369] bc50  00000000 00000000 00000000 00000000 c06a6180 00000000 00000
000 00000000
[ 1120.974731] bc70  00000000 00000000 00000000 00000000 c06a6194 00000000 00000
000 00000000
[ 1120.983062] bc90  00000000 00000000 00000000 00000000 c06a6174 00000000 00000
000 00000000
[ 1120.991394] Process swapper (pid: 0, stack limit = 0xdf8622f0)
[ 1120.997283] Stack: (0xdf863e90 to 0xdf864000)
[ 1121.001678] 3e80:                                     c1014cb0 e7069d20 00000
103 df863eb8
[ 1121.009918] 3ea0: df863ef0 df84a814 df84aa14 df84ac14 df84ae14 00000000 df863
eb8 df863eb8
[ 1121.018127] 3ec0: 00000000 df862000 00000141 00000004 c074bba0 00000001 00000
103 c06f4044
[ 1121.026367] 3ee0: c06f4040 c007eff4 c1014c20 ffffffff 0000000a c0035a10 00000
001 00000001
[ 1121.034606] 3f00: 00000000 00000000 c079f760 0000001d 00000002 00000001 df862
000 00000000
[ 1121.042846] 3f20: c06f4080 c007f154 00000000 c00383c8 ffffffff fa410100 00000
01d c003920c
[ 1121.051055] 3f40: e66e2f98 60000013 60000013 ffffffff c1014cb0 00000001 c1012
050 00013ed9
[ 1121.059295] 3f60: 00013ed9 c07a0e50 00000000 c06f4080 00000488 df863f88 c0074
c54 c00a2890
[ 1121.067535] 3f80: 40000013 ffffffff 00000000 00000000 00000001 0000737b e75f8
c84 60000013
[ 1121.075775] 3fa0: e66e2f98 00000103 e5af4a80 00000103 e66e2f98 00000103 00000
000 df862000
[ 1121.083984] 3fc0: c07095c4 c075d424 c0500c38 90017040 412fc091 0000001f 00000
000 c003ac18
[ 1121.092224] 3fe0: 1f86406a 0000001f 10c03c7d c075d5a4 90017040 00008080 abe49
0e8 b2aaaea3
[ 1121.100524] [<c0086d30>] (run_timer_softirq+0x264/0x388) from [<c007eff4>] (_
_do_softirq+0x114/0x228)
[ 1121.109802] [<c007eff4>] (__do_softirq+0x114/0x228) from [<c007f154>] (irq_ex
it+0x4c/0xb0)
[ 1121.118164] [<c007f154>] (irq_exit+0x4c/0xb0) from [<c00383c8>] (do_local_tim
er+0x50/0x80)
[ 1121.126495] [<c00383c8>] (do_local_timer+0x50/0x80) from [<c003920c>] (__irq_
svc+0x4c/0xe4)
[ 1121.134887] Exception stack(0xdf863f40 to 0xdf863f88)
[ 1121.139984] 3f40: e66e2f98 60000013 60000013 ffffffff c1014cb0 00000001 c1012
050 00013ed9
[ 1121.148223] 3f60: 00013ed9 c07a0e50 00000000 c06f4080 00000488 df863f88 c0074
c54 c00a2890
[ 1121.156433] 3f80: 40000013 ffffffff
[ 1121.159973] [<c003920c>] (__irq_svc+0x4c/0xe4) from [<c00a2890>] (tick_nohz_s
top_sched_tick+0x3e4/0x444)
[ 1121.169525] [<c00a2890>] (tick_nohz_stop_sched_tick+0x3e4/0x444) from [<c003a
c18>] (cpu_idle+0x28/0xf0)
[ 1121.178985] [<c003ac18>] (cpu_idle+0x28/0xf0) from [<00008080>] (0x8080)
[ 1121.185729] Code: bad PC value
[ 1121.188934] CPU 0 will stop doing anything useful since another CPU has crash
ed
[ 1121.196777] Loading crashdump kernel...
[ 1121.200683] Bye!



Thanks in advance
Neha Singhal

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