On 01/11/2015 12:57 PM, Chris Clayton wrote:
> Thanks Konstantin.
>
> [snip]
>
>>>>
>>>> Looks like degree (%edx) is 1 on anon-vma desruction.
>>>> Probably I've overlooked some weird conrner case in vma splitting/merging.
>>>>
>>>> Could you try this patch. It disables vma merging end eliminates half
>>>> of complicated paths.
>>>> As I see merging is optional, everything should work fine without it.
>>>>
>>>> --- a/mm/mmap.c
>>>> +++ b/mm/mmap.c
>>>> @@ -1048,7 +1048,7 @@ struct vm_area_struct *vma_merge(struct mm_struct
>>>> *mm,
>>>> * We later require that vma->vm_flags == vm_flags,
>>>> * so this tests vma->vm_flags & VM_SPECIAL, too.
>>>> */
>>>> - if (vm_flags & VM_SPECIAL)
>>>> + if (1)
>>>> return NULL;
>>>>
>>>> if (prev)
>>>>
>>>>
>>>>
>>>>
>>>> Code from your oops.
>>>>
>>>> Code: 00 ad de 48 89 43 18 e8 c5 f9 00 00 48 8b 45 10 48 8d 55 10 48
>>>> 83 e8 10 49 39 d6 74 54 48 8b 7d 08 48 89 eb 8b 57 34 85 d2 74 9e <0f>
>>>> 0b 0f 1f 40 00 e8 6b fc ff ff eb 9a 66 0f 1f 84 00 00 00 00
>>>> All code
>>>> ========
>>>> 0: 00 ad de 48 89 43 add %ch,0x438948de(%rbp)
>>>> 6: 18 e8 sbb %ch,%al
>>>> 8: c5 f9 00 (bad)
>>>> b: 00 48 8b add %cl,-0x75(%rax)
>>>> e: 45 10 48 8d adc %r9b,-0x73(%r8)
>>>> 12: 55 push %rbp
>>>> 13: 10 48 83 adc %cl,-0x7d(%rax)
>>>> 16: e8 10 49 39 d6 callq 0xffffffffd639492b
>>>> 1b: 74 54 je 0x71
>>>> 1d: 48 8b 7d 08 mov 0x8(%rbp),%rdi
>>>> 21: 48 89 eb mov %rbp,%rbx
>>>> 24: 8b 57 34 mov 0x34(%rdi),%edx
>>>> 27: 85 d2 test %edx,%edx
>>>> 29: 74 9e je 0xffffffffffffffc9
>>>> 2b:* 0f 0b ud2 <-- trapping instruction
>>>> 2d: 0f 1f 40 00 nopl 0x0(%rax)
>>>> 31: e8 6b fc ff ff callq 0xfffffffffffffca1
>>>> 36: eb 9a jmp 0xffffffffffffffd2
>>>> 38: 66 data16
>>>> 39: 0f .byte 0xf
>>>> 3a: 1f (bad)
>>>> 3b: 84 00 test %al,(%rax)
>>>> 3d: 00 00 add %al,(%rax)
>>>> ...
>>>>
>>>> Code starting with the faulting instruction
>>>> ===========================================
>>>> 0: 0f 0b ud2
>>>> 2: 0f 1f 40 00 nopl 0x0(%rax)
>>>> 6: e8 6b fc ff ff callq 0xfffffffffffffc76
>>>> b: eb 9a jmp 0xffffffffffffffa7
>>>> d: 66 data16
>>>> e: 0f .byte 0xf
>>>> f: 1f (bad)
>>>> 10: 84 00 test %al,(%rax)
>>>> 12: 00 00 add %al,(%rax)
>>>>
>>>>
>>>> +Added Oded Gabbay <oded.gab...@amd.com> into cc, he's reported this
>>>> problem too.
>>>>
>>> Thanks for the fast reply.
>>>
>>> I applied the patch and tested it. I wasn't able to reproduce *my* problem,
>>> so you are definitely in the right direction :)
>>
>> Ok. I've found something. Try patch from attachment.
>>
>
> Your patch has fixed the BUG for me. Thank you.
>
> Tested-by: Chris Clayton <chris2...@googlemail.com>
>
Same for me. Thanks.
Tested-by: Oded Gabbay <oded.gab...@amd.com>
Oded
>>>
>>> Oded
>>>
>>>>>
>>>>> In case it helps, I've attached the xz-compressed related config file.
>>>>>
>>>>> Chris
>>>>>
>>>>>>
>>>>>> I've attached the full kernel log file for that boot.
>>>>>>
>>>>>> Chris
>>>>>>
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>>>>
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