linux-kernel - Re: /proc/kcore has a unreasonable size(281474974617600) in x86

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Date:	Fri, 05 Jun 2009 16:57:15 +0800
From:	Tao Ma <tao.ma@...cle.com>
To:	Amerigo Wang <xiyou.wangcong@...il.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: /proc/kcore has a unreasonable size(281474974617600) in x86_64
 2.6.30-rc8.



Amerigo Wang wrote:
> On Fri, Jun 05, 2009 at 02:59:46PM +0800, Tao Ma wrote:
>>
>> Andrew Morton wrote:
>>> On Fri, 05 Jun 2009 12:03:52 +0800 Tao Ma <tao.ma@...cle.com> wrote:
>>>
>>>> Hi list,
>>>>        In 2.6.30-rc8, /proc/kcore in x86_64's size is unreasonable 
>>>> large to be 281474974617600.
>>>> While in a x86 box, it is 931131392 which looks sane.
>>>>
>>>> [root@...t8 ~]# ll /proc/kcore
>>>> -r-------- 1 root root 281474974617600 Jun  5 11:15 /proc/kcore
>>>>
>>>> [root@...s2-test9 ~]$ ll /proc/kcore
>>>> -r-------- 1 root root 931131392 Jun  5 11:58 /proc/kcore
>>>>
>>>> I just noticed this when kexec fails in "Can't find kernel text map 
>>>> area from kcore".
>>>>
>>>> Is there something wrong?
>>>>
>>> fs/proc/kcore.c hasn't changed since October last year.  Was 2.6.29 OK?
>>> Earlier kernels?
>> with 2.6.29, ls shows the same output.
>> [root@...t8 ~]# ll /proc/kcore
>> -r-------- 1 root root 281474974617600 Jun  5 14:35 /proc/kcore
> 
> 
> Thanks.
> 
> It looks like the value of 'high_memory' is insane.. 
> 
> Can you get its value on your machine? You can add a printk() or use
> systemtap etc..
Just did that.
Also a strange number.
high memory 18446612137615818752.

Regards,
Tao
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