Not sure if it's an unrelated warning, but anyway.

commit: c2865bb326476f031ce7121e876c656cdc12c894 [13/18] x86, um/x86: switch to generic sys_execve and kernel_execve

i386-randconfig-b006        B______B___B_Bc_BBB

0:	B 9acb172  2012-09-10 kvm-xgwo     [  144.142996] WARNING: at /c/kernel-tests/src/linux/kernel/lockdep.c:2739 lockdep_trace_alloc+0x92/0xd0() [lockdep_trace_alloc kmem_cache_alloc_trace bus_find_device pci_get_subsys put_device pci_get_subsys pci_get_device mach_reboot_fixups native_machine_emergency_restart native_machine_restart machine_restart kernel_restart sys_reboot trace_hardirqs_off local_clock lock_release_holdtime do_page_fault up_read do_page_fault do_raw_spin_unlock restore_all arch_init_optprobes trace_hardirqs_on_caller trace_hardirqs_on_thunk sysenter_do_call]
1:	  574ebc5  
--
6:	  b2d5514  
7:	B 14b2cae  2012-09-10 kvm-inn      [  145.724087] WARNING: at /c/kernel-tests/src/linux/kernel/lockdep.c:2739 lockdep_trace_alloc+0x92/0xd0() 
8:	  f4df8d3  
--
10:	  c5cbf44  
11:	B aec81ea  2012-09-10 kvm-inn      [  143.248463] WARNING: at /c/kernel-tests/src/linux/kernel/lockdep.c:2739 lockdep_trace_alloc+0x92/0xd0() 
12:	  f411932  
13:	B c2865bb  2012-09-10 kvm-fat      [   21.121919] WARNING: at /c/kernel-tests/src/linux/kernel/lockdep.c:2623 trace_hardirqs_off_caller+0x56/0x90() [trace_hardirqs_off_caller error_code smp_threshold_interrupt trace_hardirqs_off_caller trace_hardirqs_off_thunk error_code do_trap int3 smp_threshold_interrupt]
14:	  549bf9c  
15:	  4e382ff  
16:	B 23ddf94  2012-09-10 kvm-tyan     [  141.023385] WARNING: at /c/kernel-tests/src/linux/kernel/lockdep.c:2623 trace_hardirqs_off_caller+0x56/0x90() [trace_hardirqs_off_caller error_code smp_threshold_interrupt trace_hardirqs_off_caller trace_hardirqs_off_thunk error_code smp_threshold_interrupt]
17:	B f117e2a  2012-09-10 kvm-bay      [   25.803351] WARNING: at /c/kernel-tests/src/linux/kernel/lockdep.c:2623 trace_hardirqs_off_caller+0x56/0x90() [trace_hardirqs_off_caller error_code smp_threshold_interrupt trace_hardirqs_off_caller trace_hardirqs_off_thunk error_code do_trap int3 smp_threshold_interrupt]
18:	B a392720  2012-09-10 kvm-bay      [   27.113234] WARNING: at /c/kernel-tests/src/linux/kernel/lockdep.c:2623 trace_hardirqs_off_caller+0x56/0x90() 
18:	B a392720  2012-09-10 kvm-fat      [   23.173063] WARNING: at /c/kernel-tests/src/linux/kernel/lockdep.c:2623 trace_hardirqs_off_caller+0x56/0x90() 
18:	B a392720  2012-09-10 kvm-fat      [   23.399061] WARNING: at /c/kernel-tests/src/linux/kernel/lockdep.c:2623 trace_hardirqs_off_caller+0x56/0x90() 
18:	B a392720  2012-09-10 kvm-xbm      [   24.642647] WARNING: at /c/kernel-tests/src/linux/kernel/lockdep.c:2623 trace_hardirqs_off_caller+0x56/0x90() 
18:	B a392720  2012-09-10 kvm-xbm      [   24.497886] WARNING: at /c/kernel-tests/src/linux/kernel/lockdep.c:2623 trace_hardirqs_off_caller+0x56/0x90() 
18:	B a392720  2012-09-10 kvm-xbm      [   25.248386] WARNING: at /c/kernel-tests/src/linux/kernel/lockdep.c:2623 trace_hardirqs_off_caller+0x56/0x90() 
18:	B a392720  2012-09-10 kvm-xbm      [   24.769405] WARNING: at /c/kernel-tests/src/linux/kernel/lockdep.c:2623 trace_hardirqs_off_caller+0x56/0x90() 
18:	B a392720  2012-09-10 kvm-xgwo     [   24.148032] WARNING: at /c/kernel-tests/src/linux/kernel/lockdep.c:2623 trace_hardirqs_off_caller+0x56/0x90() 

[   21.076021] hwclock (454) used greatest stack depth: 6468 bytes left
[   21.121238] ------------[ cut here ]------------
[   21.121919] WARNING: at /c/kernel-tests/src/linux/kernel/lockdep.c:2623 trace_hardirqs_off_caller+0x56/0x90()
[   21.123259] Hardware name: Bochs
[   21.123784] Modules linked in:
[   21.124344] Pid: 477, comm: modprobe Not tainted 3.6.0-rc3-00182-gc2865bb #50
[   21.125262] Call Trace:
[   21.125695]  [<c1036fa7>] warn_slowpath_common+0x87/0xb0
[   21.126411]  [<c108be46>] ? trace_hardirqs_off_caller+0x56/0x90
[   21.127217]  [<c108be46>] ? trace_hardirqs_off_caller+0x56/0x90
[   21.127984]  [<c131fe8b>] ? error_code+0x5b/0x64
[   21.128633]  [<c10037b0>] ? smp_threshold_interrupt+0x10/0x10
[   21.129421]  [<c1036ff2>] warn_slowpath_null+0x22/0x30
[   21.130118]  [<c108be46>] trace_hardirqs_off_caller+0x56/0x90
[   21.130870]  [<c11c4f88>] trace_hardirqs_off_thunk+0xc/0x14
[   21.131627]  [<c131fe8b>] ? error_code+0x5b/0x64
[   21.132247]  [<c132007b>] ? do_trap+0x2b/0xd0
[   21.132846]  [<c1320000>] ? int3+0x4/0x34
[   21.133503]  [<c10037b0>] ? smp_threshold_interrupt+0x10/0x10

Thanks,
Fengguang