Re: /proc/kcore has a unreasonable size(281474974617600) in x86_64 2.6.30-rc8.

Eric W. Biederman
2009-06-09T04:10:23Z

Américo Wang <xiyou.wangcong@gmail.com> writes:

> On Mon, Jun 8, 2009 at 4:00 PM, Tao Ma<tao.ma@oracle.com> wrote:
>>>>
>>>> But the result is the same
>>>
>>> Yes?
>>> Your printk() shows kcore size is: 5301604352, and in your subject it is
>>> 281474974617600...
>>>
>>> Or they happened in the same time?
>>
>> yes. the same box and the same linux version.
>> A bit strange.
>>
>> [taoma@ocfs2-test2 ~]$ dmesg|grep "high memory"
>> high memory ffff88013c000000, size 5301604352
>> [taoma@ocfs2-test2 ~]$ ll /proc/kcore
>> -r-------- 1 root root 281474974617600 Jun  8 15:20 /proc/kcore
>
> Really weird...
> They should be the same. This means we have some problem in our procfs.
>
> And, we have no problem on i386, I, myself, even can't reproduce this on my
> x86_64 box...
>
> Drop Cc to x86 people, add some Cc to proc people. :)
>
> Eric, Alexey, any ideas?
>
> Tao, would you like to send us your .config? Thanks.

Short of some strange patch applied I would guess that a non-sense /proc/kcore
size is related to a kernel memory stomp, stepping on the high_memory variable.

Eric