Re: [BUG/REGRESSION] Kernel 4.5-rc1 on Acube Sam460ex AMCC 460ex Power PC motherboards

[Julian Margetson <runaway@candw.ms>]

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On 1/26/2016 9:43 PM, Dan Williams wrote:
> On Mon, Jan 25, 2016 at 12:35 PM, Julian Margetson <runaway@candw.ms> wrote:
>> On 1/25/2016 3:20 PM, Dan Williams wrote:
> [..]
>> Hmm, this commit could only cause a behavior change if it modifies the
>> value of the pfn as seen by insert_pfn().  Can you try the attached
>> debug patch to see if that assumption is being violated?
>>
>> Had to manually delete the lines in the second part of the patch.
> Sorry about that I had based direct on that failing commit rather than
> 4.5-rc1.  A reflowed version in the attached.
>
>> [   42.557813] Oops: Machine check, sig: 7 [#1]
>> [   42.562350] PREEMPT Canyonlands
>> [   42.565692] Modules linked in:
>> [   42.568933] CPU: 0 PID: 495 Comm: Xorg Tainted: G        W
>> 4.5.0-rc1-Sam460ex #1
>> [   42.577291] task: ee3adcc0 ti: ee260000 task.ti: ee260000
>> [   42.582984] NIP: 1ff72480 LR: 1ff72404 CTR: 1ff724d0
>> [   42.588220] REGS: ee261f10 TRAP: 0214   Tainted: G        W
>> (4.5.0-rc1-Sam460ex)
>> [   42.596663] MSR: 0002d000 <CE,EE,PR,ME>  CR: 24004242  XER: 00000000
>> [   42.603512]
>> GPR00: 1f436134 bfc4dac0 b79cb6f0 b718dffc b69a4008 00000780 00000004
>> 00000000
>> GPR08: 00000000 b718dffc 00000000 bfc4da70 1ff72404 2080dff4 00000000
>> 00000780
>> GPR16: 00000000 00000020 00000000 00000000 00001e00 20aaa620 00000438
>> b69a4008
>> GPR24: 00000780 bfc4db18 20a94760 b718e000 b718e000 b69a4008 2007aff4
>> 00001e00
>> [   42.635363] NIP [1ff72480] 0x1ff72480
>> [   42.639225] LR [1ff72404] 0x1ff72404
>> [   42.642991] Call Trace:
>> [   42.798393] ---[ end trace 8fcfa5f0e9942055 ]---
> I'm not familiar with powerpc crash dumps, so there's not much
> information I can glean from this.  Any folks on the cc can translate
> a powerpc "Machine check"?
>
> I'm down to looking a differences between the passing and failing
> case.  Can you print out the value the pte entry and the in
> insert_pfn, like the following:
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 30991f83d0bf..c44e387130b2 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1521,6 +1521,8 @@ static int insert_pfn(struct vm_area_struct
> *vma, unsigned long addr,
>                 entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
>         else
>                 entry = pte_mkspecial(pfn_t_pte(pfn, prot));
> +       pr_info("%s: entry: %#llx pfn: %#lx\n", __func__,
> +                       (unsigned long long) entry, pfn_t_to_pfn(pfn));
>         set_pte_at(mm, addr, pte, entry);
>         update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
>
> ...of course for the passing case you'll need to drop the call to
> pfn_t_to_pfn() and just print the pfn directly.
>
> Thank you for the help tracking this down, it's much appreciated.
Happy to help out. Just need some guidance sometimes as I am relatively 
new at this.

-----------------------------------------------------------------------------------------------------------------------------
15.802615] systemd[1]: Started Journal Service.
[   44.263074] Oops: Machine check, sig: 7 [#1]
[   44.267603] PREEMPT Canyonlands
[   44.270938] Modules linked in:
[   44.274182] CPU: 0 PID: 586 Comm: Xorg Tainted: G        W       4.5.0-rc1-Sam460ex #2
[   44.282538] task: ecd505c0 ti: efff2000 task.ti: ecd76000
[   44.288239] NIP: c0000cec LR: 1fb81404 CTR: 1fb814d0
[   44.293483] REGS: efff3f10 TRAP: 0214   Tainted: G        W        (4.5.0-rc1-Sam460ex)
[   44.301926] MSR: 00021000 <CE,ME>  CR: 84004242  XER: 00000000
[   44.308185]
GPR00: 1f045134 bfd0ce80 b7e7b6f0 b763dffc b6e54008 00000780 00000004 00000000
GPR08: 00000000 b763dffc b6e54010 ecf50000 ecf50000 00000009 00000000 00000780
GPR16: 00000000 00000020 00000000 00000000 00001e00 2079b638 00000438 b6e54008
GPR24: 00000780 bfd0ced8 20785770 b763e000 b763e000 b6e54008 1fc89ff4 00001e00
[   44.340039] NIP [c0000cec] DataTLBError44x+0x6c/0x90
[   44.345279] LR [1fb81404] 0x1fb81404
[   44.349053] Call Trace:
[   44.351631] Instruction dump:
[   44.354776] 7d7342a6 816b0040 7d92eaa6 7db00aa6 51ac063e 7d92eba6 7d9e0aa6 39a00009
[   44.363081] 518d57bc 554c6cfa 7d6c582e 556c0029 <4182003c> 514cbd38 816c0000 818c0004
[   44.524699] ---[ end trace 439fa29153308785 ]---
[   44.529322]
[   47.216536] insert_pfn: entry: 0x80ed246b pfn: 0x80ed2
[   47.221777] insert_pfn: entry: 0x80ed346b pfn: 0x80ed3
[   47.228485] insert_pfn: entry: 0x80ed446b pfn: 0x80ed4
[   47.237798] insert_pfn: entry: 0x80ed546b pfn: 0x80ed5
[   47.249809] insert_pfn: entry: 0x80ed646b pfn: 0x80ed6
[   47.257588] insert_pfn: entry: 0x80ed746b pfn: 0x80ed7
[   47.265879] insert_pfn: entry: 0x80ed846b pfn: 0x80ed8
[   47.275825] insert_pfn: entry: 0x80ed946b pfn: 0x80ed9
[   47.281437] insert_pfn: entry: 0x80eda46b pfn: 0x80eda
[   47.288113] insert_pfn: entry: 0x80edb46b pfn: 0x80edb
[   47.293660] insert_pfn: entry: 0x80edc46b pfn: 0x80edc
[   47.299834] insert_pfn: entry: 0x80edd46b pfn: 0x80edd
[   47.305223] insert_pfn: entry: 0x80ede46b pfn: 0x80ede
[   47.314891] insert_pfn: entry: 0x80edf46b pfn: 0x80edf
[   47.329777] insert_pfn: entry: 0x80ee046b pfn: 0x80ee0
[   47.339769] insert_pfn: entry: 0x80ee146b pfn: 0x80ee1
[   47.349777] Machine check in kernel mode.
[   47.353814] Data Write PLB Error
[   47.357049] Vector: 214  at [efff3f10]
[   47.360799]     pc: c0000cec: DataTLBError44x+0x6c/0x90
[   47.366085]     lr: 2008f404
[   47.369002]     sp: bfe76110
[   47.371885]    msr: 21000
[   47.374506]   current = 0xeced85c0
[   47.377910]     pid   = 668, comm = Xorg
[   47.381835] Linux version 4.5.0-rc1-Sam460ex (root@julian-VirtualBox) (gcc version 4.8.2 (Ubuntu 4.8.2-16ubuntu3) ) #2 PREEMPT Wed Jan 27 06:07:01 AST 2016
[   47.395758] enter ? for help
[   47.398638] mon>  <no input ...>
[   49.401927] Oops: Machine check, sig: 7 [#2]
[   49.406450] PREEMPT Canyonlands
[   49.409783] Modules linked in:
[   49.413026] CPU: 0 PID: 668 Comm: Xorg Tainted: G      D W       4.5.0-rc1-Sam460ex #2
[   49.421383] task: eced85c0 ti: efff2000 task.ti: ecf8c000
[   49.427075] NIP: c0000cec LR: 2008f404 CTR: 2008f4d0
[   49.432311] REGS: efff3f10 TRAP: 0214   Tainted: G      D W        (4.5.0-rc1-Sam460ex)
[   49.440755] MSR: 00021000 <CE,ME>  CR: 88004262  XER: 00000000
[   49.447013]
GPR00: 1f553134 bfe76110 b7d6d6f0 b752fffc b6d46008 00000780 00000004 00000000
GPR08: 00000000 b752fffc b6d46010 ecef9000 ecef9000 00000009 00000000 00000780
GPR16: 00000000 00000020 00000000 00000000 00001e00 20eb5650 00000438 b6d46008
GPR24: 00000780 bfe76168 20e9f728 b7530000 b7530000 b6d46008 20197ff4 00001e00
[   49.478867] NIP [c0000cec] DataTLBError44x+0x6c/0x90
[   49.484108] LR [2008f404] 0x2008f404
[   49.487881] Call Trace:
[   49.490460] Instruction dump:
[   49.493603] 7d7342a6 816b0040 7d92eaa6 7db00aa6 51ac063e 7d92eba6 7d9e0aa6 39a00009
[   49.501909] 518d57bc 554c6cfa 7d6c582e 556c0029 <4182003c> 514cbd38 816c0000 818c0004
[   49.510404] ---[ end trace 439fa29153308786 ]---
[   49.515026]




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