[Crash-utility] Broken vtop on kernel 2.6.20?

[David Anderson]

David Anderson wrote:

> Alex Sidorenko wrote:
>
>> Hi Dave,
>>
>> when I try to use 'vtop' for process pages on 2.6.20 kernel 
>> (Ubuntu/Feisty) on x86 architecture, I get error messages about page 
>> table. The easiest way to reproduce is to run 'ps -a' on a live kernel:
>>
>>
>> PID: 0      TASK: c03a2440  CPU: 0   COMMAND: "swapper"
>> ps: no user stack
>>
>> PID: 0      TASK: df838560  CPU: 1   COMMAND: "swapper"
>> ps: no user stack
>>
>> PID: 1      TASK: df838a90  CPU: 1   COMMAND: "init"
>> ps: read error: physical address: 7f2f0000  type: "page table"
>>
>>
>> Running crash with -d8:
>>
>> PID: 1      TASK: df838a90  CPU: 1   COMMAND: "init"
>> <readmem: df838a90, KVADDR, "fill_task_struct", 1328, (ROE|Q), 8d2eac0>
>> <readmem: dfb71e40, KVADDR, "fill_mm_struct", 432, (ROE|Q), 8d8bf80>
>>  GETBUF(128 -> 1)
>>  FREEBUF(1)
>>  GETBUF(128 -> 1)
>>  FREEBUF(1)
>>  GETBUF(128 -> 1)
>>  FREEBUF(1)
>>  GETBUF(128 -> 1)
>>  FREEBUF(1)
>> arg_start: bf991ecf arg_end: bf991ee1 (18)
>> env_start: bf991ee1 env_end: bf991ff1 (272)
>>  GETBUF(291 -> 1)
>> <readmem: dfb6f000, KVADDR, "pgd page", 4096, (FOE), 843cf90>
>> <readmem: dfb6f000, KVADDR, "pmd page", 4096, (FOE), 843cf90>
>> <readmem: 7f2f0000, PHYSADDR, "page table", 4096, (FOE), 843efa0>
>> ps: read error: physical address: 7f2f0000  type: "page table"
>>
>> The same crash-4.0-4.1 works fine on live 2.6.15 kernel. Did the page 
>> table layout change between 2.6.15 and 2.6.20 ?
>>
>> Regards,
>> Alex
>>
> I don't know.  I don't have an x86 2.6.20 live system or dumpfile 
> readily available,
> so I'll need some help from the "outside world" here...
>
> Anybody else know anything about this?

It would be something post-2.6.18 (RHEL5)

Dave