Re: [RFC][PATCH 00/26] sched/numa

[Peter Zijlstra]

On Fri, 2012-03-23 at 18:41 -0700, Nish Aravamudan wrote:
> [2012-03-20 00:46:33]   Unable to handle kernel paging request for data at address 0x00001688
> [2012-03-20 00:46:33]   Faulting instruction address: 0xc000000000168338
> [2012-03-20 00:46:33]   Oops: Kernel access of bad area, sig: 11 [#1]
> [2012-03-20 00:46:33]   SMP NR_CPUS=32 NUMA pSeries
> [2012-03-20 00:46:33]   Modules linked in:
> [2012-03-20 00:46:33]   NIP: c000000000168338 LR: c0000000001b523c CTR: 0000000000000000
> [2012-03-20 00:46:33]   REGS: c00000013d887700 TRAP: 0300   Not tainted (3.3.0-rc7)
> [2012-03-20 00:46:33]   MSR: 8000000000009032 <SF,EE,ME,IR,DR,RI>  CR: 24004022  XER: 00000008
> [2012-03-20 00:46:33]   CFAR: 0000000000005374
> [2012-03-20 00:46:33]   DAR: 0000000000001688, DSISR: 40000000
> [2012-03-20 00:46:33]   TASK = c00000013d888000[1] 'swapper/0' THREAD: c00000013d884000 CPU: 0
> [2012-03-20 00:46:33]   GPR00: 0000000000000000 c00000013d887980 c000000000ce7990 00000000000012d0
> [2012-03-20 00:46:33]   GPR04: 0000000000000000 0000000000001680 0000000000000000 0003005500000001
> [2012-03-20 00:46:33]   GPR08: 0000000000000001 0000000000000000 c000000000d25000 0000000000000010
> [2012-03-20 00:46:33]   GPR12: 0000000044004024 c00000000fffa000 0000000000000000 0000000000000060
> [2012-03-20 00:46:33]   GPR16: c000000000a69040 c000000000a66828 0000000002e317f0 0000000001a3f930
> [2012-03-20 00:46:33]   GPR20: 0000000000000000 0000000000001680 0000000000000001 0000000000210d00
> [2012-03-20 00:46:33]   GPR24: c000000000d193a0 0000000000000000 0000000000001680 00000000000012d0
> [2012-03-20 00:46:33]   GPR28: 0000000000000000 0000000000000000 c000000000c5d6e8 c00000013e009200
> [2012-03-20 00:46:33]   NIP [c000000000168338] .__alloc_pages_nodemask+0xb8/0x860
> [2012-03-20 00:46:33]   LR [c0000000001b523c] .new_slab+0xcc/0x3d0
> [2012-03-20 00:46:33]   Call Trace:
> [2012-03-20 00:46:33]   [c00000013d887980] [c0000000001683dc] .__alloc_pages_nodemask+0x15c/0x860 (unreliable)
> [2012-03-20 00:46:33]   [c00000013d887b00] [c0000000001b523c] .new_slab+0xcc/0x3d0
> [2012-03-20 00:46:33]   [c00000013d887bb0] [c0000000007fc780] .__slab_alloc+0x388/0x4e0
> [2012-03-20 00:46:33]   [c00000013d887cd0] [c0000000001b5af8] .kmem_cache_alloc_node_trace+0x98/0x230
> [2012-03-20 00:46:33]   [c00000013d887d90] [c000000000b83ed0] .numa_init+0x90/0x1d0
> [2012-03-20 00:46:33]   [c00000013d887e20] [c00000000000ab60] .do_one_initcall+0x60/0x1e0
> [2012-03-20 00:46:33]   [c00000013d887ee0] [c000000000b5cad4] .kernel_init+0xf0/0x1e0
> [2012-03-20 00:46:33]   [c00000013d887f90] [c000000000021e14] .kernel_thread+0x54/0x70
> [2012-03-20 00:46:33]   Instruction dump:
> [2012-03-20 00:46:33]   0b000000 eb1e8000 3ba00000 801800a8 2f800000 409e001c 7860efe3 38000000
> [2012-03-20 00:46:33]   41820008 38000002 7b7d6fe2 7fbd0378 <e81a0008> 827800a4 3be00000 2fa00000
> [2012-03-20 00:46:33]   ---[ end trace 31fd0ba7d8756001 ]--- 

Can't say I've ever seen that one before.. that looks to be the
kzalloc() in numa_init() which is ran as an early_initcall(), which is
way after mm_init() and numa_policy_init() in init/main.c.

Where exactly in __alloc_pages_nodemask() is this?

The only thing I can think of is that the policy returned by
get_task_policy() is wonky and we get a weird zone_list, but that would
mean this is the first kmalloc() ever.. also all that should be set up
by now.

Hmm..
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