[OOPS] hugetlbfs tests with 2.6.30-rc8-git1

While executing Hugetlbfs tests against 2.6.30-rc8-git1 on a
Power 6 box observed the following OOPS message.

Oops: Kernel access of bad area, sig: 11 [#1]
SMP NR_CPUS=1024 DEBUG_PAGEALLOC NUMA pSeries
Modules linked in: ipv6 fuse loop dm_mod sg sd_mod crc_t10dif ibmvscsic
scsi_transport_srp scsi_tgt scsi_mod
NIP: c000000000038240 LR: c0000000000380f0 CTR: c00000000025d050
REGS: c0000000fa8ff490 TRAP: 0300   Not tainted  (2.6.30-rc8-git1-autotest)
MSR: 8000000000009032 <EE,ME,IR,DR>  CR: 44022422  XER: 00000001
DAR: c000000084340480, DSISR: 0000000040000000
TASK = c0000000facf40a0[10514] 'shm-fork' THREAD: c0000000fa8fc000 CPU: 2
GPR00: 0000000000000000 c0000000fa8ff710 c000000000a9d900 0000000000000004 GPR04: 000003fff0000000 c000000084338480 0000168008000393 0000000000000001 GPR08: 0000000000000004 c000000084348480 000000000003fff0 0000000000000350 GPR12: 0000000044022422 c000000000b72800 00000000ffffffff ffffffffffffffff GPR16: 000000004c8d6470 0000000000000000 ffffffffffff9010 0000000000000000 GPR20: 0000000000000000 0000040000000000 c000000084338480 0000000000760000 GPR24: 0000000000000000 0000168008000393 c000000084379700 0000000000000004 GPR28: c000000000890430 0000000000000001 c000000000ff0430 f9c3d6fff0000000 NIP [c000000000038240] .hpte_need_flush+0x1bc/0x2d8
LR [c0000000000380f0] .hpte_need_flush+0x6c/0x2d8
Call Trace:
[c0000000fa8ff710] [c000000000038264] .hpte_need_flush+0x1e0/0x2d8 (unreliable)
[c0000000fa8ff7d0] [c000000000039fa4] .huge_ptep_get_and_clear+0x40/0x5c
[c0000000fa8ff850] [c00000000012d46c] .__unmap_hugepage_range+0x178/0x2b8
[c0000000fa8ff940] [c00000000012d600] .unmap_hugepage_range+0x54/0x88
[c0000000fa8ff9e0] [c0000000001173a0] .unmap_vmas+0x178/0x8f4
[c0000000fa8ffb30] [c00000000011cab8] .unmap_region+0xfc/0x1e4
[c0000000fa8ffc00] [c00000000011e248] .do_munmap+0x2f4/0x38c
[c0000000fa8ffcc0] [c0000000002f6d74] .SyS_shmdt+0xc0/0x188
[c0000000fa8ffd70] [c00000000000c430] .sys_ipc+0x274/0x2fc
[c0000000fa8ffe30] [c000000000008534] syscall_exit+0x0/0x40
Instruction dump:
78090220 2fbd0000 409e0010 7929e0e4 7be00120 4800000c 792945c6 7be00600 7d3f0378 7c1cb82e 3d360001 2f800000 <eb898000> 409e0028 7fe3fb78 7f24cb78

I first noticed this with 2.6.30-rc7-git3 on a power6 machine,
but could not recreate again on the same machine. Now the problem
has resurfaced again with 2.6.30-rc8 (and with git1 as well) on
another Power6 box.

I had seen similar failures(although the back trace was different,
crash point was same) with older kernels and Mel submitted a patch
to fix that issue. Here is the link to that patch.

http://lists.ozlabs.org/pipermail/linuxppc-dev/2009-May/071395.html

I have attached the .config.

Thanks
-Sachin

-- 

---------------------------------
Sachin Sant
IBM Linux Technology Center
India Systems and Technology Labs
Bangalore, India
---------------------------------