[ag-automation] 2.6.29.6-rt23 - Locking API testsuite Fail

[taejin kim]

Hello.
I found the CONFIG_DEBUG_LOCKING_API_SELFTESTS hangs at (double
unlock)-(rlock) pair.

The kernel sources are at
www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.29.6.tar.bz2
rt.et.redhat.com/download/patch-2.6.29.6-rt23.bz2

They are OSADL's Latest Stable version
http://www.osadl.org/Latest-Stable.latest-stable-realtime-linux.0.html

We ported this kernel to ARM target. And we tested with our modules
which uses kernel semaphore API.
We found some mutex(semaphore) problems. So we activated “Locking API
test”option which is in kernel hacking menu.

How can I fix this problem? Is there some patch about this?


Here is log.
------------------------
| Locking API testsuite:
----------------------------------------------------------------------------
                                 | spin |wlock |rlock |mutex | wsem | rsem |
  --------------------------------------------------------------------------
                     A-A deadlock:  ok  |  ok  |  ok  |  ok  |  ok  |  ok  |
                 A-B-B-A deadlock:  ok  |  ok  |  ok  |  ok  |  ok  |  ok  |
             A-B-B-C-C-A deadlock:  ok  |  ok  |  ok  |  ok  |  ok  |  ok  |
             A-B-C-A-B-C deadlock:  ok  |  ok  |  ok  |  ok  |  ok  |  ok  |
         A-B-B-C-C-D-D-A deadlock:  ok  |  ok  |  ok  |  ok  |  ok  |  ok  |
         A-B-C-D-B-D-D-A deadlock:  ok  |  ok  |  ok  |  ok  |  ok  |  ok  |
         A-B-C-D-B-C-D-A deadlock:  ok  |  ok  |  ok  |  ok  |  ok  |  ok  |
                    double unlock:  ok  |  ok  |<2>kernel BUG at
kernel/rt.c:257!
Unable to handle kernel NULL pointer dereference at virtual address 00000000
pgd = c0004000
[00000000] *pgd=00000000
Internal error: Oops: 805 [#1] PREEMPT
Modules linked in:
CPU: 0    Not tainted  (2.6.29.6-rt23 #1)
PC is at __bug+0x20/0x2c
LR is at rt_up+0x48/0x64
pc : [<c0020ce0>]    lr : [<c005e7f8>]    psr: 00000153
sp : c021ff40  ip : c021fe58  fp : c021ff4c
r10: 20018e5c  r9 : 4117b362  r8 : 00000001
r7 : 00000002  r6 : 00000001  r5 : 00000000  r4 : c038ee20
r3 : 00000000  r2 : 00000001  r1 : 00000001  r0 : 00000022
Flags: nzcv  IRQs on  FIQs off  Mode SVC_32  ISA ARM  Segment kernel
Control: 00c5387d  Table: 20004008  DAC: 00000017
Process swapper (pid: 0, stack limit = 0xc021e268)
Stack: (0xc021ff40 to 0xc0220000)
ff40: c021ff64 c021ff50 c01ab07c c0020ccc c038ee20 c038ee20 c021ff7c c021ff68
ff60: c0104c68 c01ab04c c021ff58 c0104c3c c021ffa4 c021ff80 c0103818 c0104c48
ff80: c039727c c0397250 c039727c c038e3e8 c0222550 20018e90 c021ffc4 c021ffa8
ffa0: c0105c48 c01037d4 c01f5e20 c0397250 c039727c c001aee4 c021fff4 c021ffc8
ffc0: c0008a34 c010586c c0008398 00000000 00000000 c001aee4 00000000 00c5387d
ffe0: c03972e0 c001b2e8 00000000 c021fff8 20008038 c0008888 00000000 00000000
Backtrace:
[<c0020cc0>] (__bug+0x0/0x2c) from [<c01ab07c>] (rt_read_unlock+0x3c/0x60)
[<c01ab040>] (rt_read_unlock+0x0/0x60) from [<c0104c68>]
(double_unlock_rlock+0x2c/0x34)
 r4:c038ee20
[<c0104c3c>] (double_unlock_rlock+0x0/0x34) from [<c0103818>]
(dotest+0x50/0x4f8)
 r4:c0104c3c
[<c01037c8>] (dotest+0x0/0x4f8) from [<c0105c48>] (locking_selftest+0x3e8/0x8b0)
 r8:20018e90 r7:c0222550 r6:c038e3e8 r5:c039727c r4:c0397250
[<c0105860>] (locking_selftest+0x0/0x8b0) from [<c0008a34>]
(start_kernel+0x1b8/0x308)
 r6:c001aee4 r5:c039727c r4:c0397250
[<c000887c>] (start_kernel+0x0/0x308) from [<20008038>] (0x20008038)
 r6:c001b2e8 r5:c03972e0 r4:00c5387d
Code: e1a01000 e59f000c eb0050a9 e3a03000 (e5833000)
---[ end trace 1b75b31a2719ed1c ]---
Kernel panic - not syncing: Attempted to kill the idle task!
[<c0021330>] (dump_stack+0x0/0x14) from [<c0034054>] (panic+0x54/0x130)
[<c0034000>] (panic+0x0/0x130) from [<c003711c>] (do_exit+0x68/0x648)
 r3:00000000 r2:00000001 r1:00000001 r0:c01f41d4
[<c00370b4>] (do_exit+0x0/0x648) from [<c0021230>] (die+0x1ac/0x1fc)
[<c0021084>] (die+0x0/0x1fc) from [<c00234c4>] (__do_kernel_fault+0x6c/0x7c)
[<c0023458>] (__do_kernel_fault+0x0/0x7c) from [<c00236fc>]
(do_page_fault+0x228/0x248)
 r7:c021fef8 r6:c0220c80 r5:c022294c r4:ffffffff
[<c00234d4>] (do_page_fault+0x0/0x248) from [<c00237bc>]
(do_translation_fault+0x1c/0x84)
[<c00237a0>] (do_translation_fault+0x0/0x84) from [<c001c23c>]
(do_DataAbort+0x3c/0xa0)
 r6:00000805 r5:c022294c r4:ffffffff
[<c001c200>] (do_DataAbort+0x0/0xa0) from [<c001c9ec>] (__dabt_svc+0x4c/0x60)
Exception stack(0xc021fef8 to 0xc021ff40)
fee0:                                                       00000022 00000001
ff00: 00000001 00000000 c038ee20 00000000 00000001 00000002 00000001 4117b362
ff20: 20018e5c c021ff4c c021fe58 c021ff40 c005e7f8 c0020ce0 00000153 ffffffff
 r8:00000001 r7:00000002 r6:00000001 r5:c021ff2c r4:ffffffff
[<c0020cc0>] (__bug+0x0/0x2c) from [<c01ab07c>] (rt_read_unlock+0x3c/0x60)
[<c01ab040>] (rt_read_unlock+0x0/0x60) from [<c0104c68>]
(double_unlock_rlock+0x2c/0x34)
 r4:c038ee20
[<c0104c3c>] (double_unlock_rlock+0x0/0x34) from [<c0103818>]
(dotest+0x50/0x4f8)
 r4:c0104c3c
[<c01037c8>] (dotest+0x0/0x4f8) from [<c0105c48>] (locking_selftest+0x3e8/0x8b0)
 r8:20018e90 r7:c0222550 r6:c038e3e8 r5:c039727c r4:c0397250
[<c0105860>] (locking_selftest+0x0/0x8b0) from [<c0008a34>]
(start_kernel+0x1b8/0x308)
 r6:c001aee4 r5:c039727c r4:c0397250
[<c000887c>] (start_kernel+0x0/0x308) from [<20008038>] (0x20008038)
 r6:c001b2e8 r5:c03972e0 r4:00c5387d

Thank you
taejin