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

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Message-ID: <20090605080019.GD8171@cr0.nay.redhat.com>
Date:	Fri, 5 Jun 2009 16:00:19 +0800
From:	Amerigo Wang <xiyou.wangcong@...il.com>
To:	Tao Ma <tao.ma@...cle.com>
Cc:	Amerigo Wang <xiyou.wangcong@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: /proc/kcore has a unreasonable size(281474974617600) in x86_64
	2.6.30-rc8.

On Fri, Jun 05, 2009 at 02:56:36PM +0800, Tao Ma wrote:
>
>
> Amerigo Wang wrote:
>> On Fri, Jun 05, 2009 at 02:07:58PM +0800, Tao Ma wrote:
>>>
>>> Amerigo Wang wrote:
>>>> On Fri, Jun 05, 2009 at 12:03:52PM +0800, Tao Ma 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
>>>> Hmm, what is your physical RAM size on test8?
>>>> /proc/kcore looks fine on my x86_64 box.
>>> Only 4G.
>>
>> Hmm, my x86_box has 8G mem, the size of kcore looks much
>> saner than the above huge number, but it is still wrong
>> according to what the man page describes...
>>
>> Please do what Andrew said, it will be helpful.
>>
>>>>> I just noticed this when kexec fails in "Can't find kernel text 
>>>>> map area  from kcore".
>>>>>
>>>>> Is there something wrong?
>>>> It looks like that error message is from userspace?
>>> I just started kdump and get the error message.
>>
>> IIRC, kdump should use /proc/vmcore, instead of /proc/kcore...
>> nothing related.
> in el5, when start kdump service it will do something like
> /sbin/kexec --args-linux -p '--command-line=ro root=LABEL=/ rhgb quiet  
> irqpoll maxcpus=1' --initrd=/boot/initrd-2.6.18-53.el5kdump.img  
> /boot/vmlinuz-2.6.18-53.el5
>
> And the error message is from there.

>From /sbin/kexec? I just checked the source code of kexec-tools,
I haven't found that message...
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