linux-kernel - Re: [Patch BUGFIX] kcore: fix its wrong size on x86

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Date:	Thu, 18 Jun 2009 11:00:51 +0800
From:	Amerigo Wang <xiyou.wangcong@...il.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	Américo Wang <xiyou.wangcong@...il.com>,
	Tao Ma <tao.ma@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Alexey Dobriyan <adobriyan@...il.com>
Subject: Re: [Patch BUGFIX] kcore: fix its wrong size on x86_64

On Tue, Jun 16, 2009 at 12:27:36PM -0700, Eric W. Biederman wrote:
>Américo Wang <xiyou.wangcong@...il.com> writes:
>>> I think a case can be made either way.  In practice neither answer
>>> gives us a dense offset space on x86_64 so I think I prefer the
>>> current definition which sets or clears the high bits as opposed
>>> to something that mangles the address more.
>>>
>>
>> I am trying to dig more... There must be something wrong there.
>
>How so?

See what you will get for kc_vaddr_to_offset(__va(0))?
It is supposed to be 0.


>
>>> It uses get_kcore_size and (size_t)high_memory - PAGE_OFFSET + PAGE_SIZE;
>>> The second definition being bogus as it has nothing to do with which
>>> offsets are accepted.
>>
>> Agreed. Maybe we can just remove the second one and update the doc?
>
>Yes.  It isn't critical but reducing confusion is good.
>Do you want to cook up the patch for that?

Yes, I am cooking a patch set... will send them when ready.
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