linux-kernel - Re: [RESEND Patch] kcore: remove its pointless size

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Message-Id: <20090721110924.39a93078.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Tue, 21 Jul 2009 11:09:24 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	ebiederm@...ssion.com, xiyou.wangcong@...il.com, tao.ma@...cle.com,
	linux-kernel@...r.kernel.org, adobriyan@...il.com,
	mtk.manpages@...il.com, y-goto@...fujitsu.com
Subject: Re: [RESEND Patch] kcore: remove its pointless size

On Fri, 17 Jul 2009 15:29:55 -0700
Andrew Morton <akpm@...ux-foundation.org> wrote:

> On Thu, 2 Jul 2009 09:41:38 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> wrote:
> I think I'm about to forget about the above issues.  If everyone else
> does the same, they won't get addressed.  Oh well.
> 
> And I still need to decide whether
> kcore-fix-proc-kcores-statst_size.patch fixes things up sufficiently
> well to justify merging it.
>

Hmm, I read fs/proc/kcore.c and feel followng, now.

- kclist doesn't handle memory hole, then, it will never be "correct" size.
  For example, arch/x86/mm/init.c calls kclist_add() as following

  715         kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
  716                    VMALLOC_END-VMALLOC_START);

  Wow, extremely big anyway.

- Then, yes. Size of /proc/kcode is pointless. Anyway, what's important is
  not "size", but ELF phder of kcore.

To this patch,
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>

BTW, I'd like to look into handling physical memory range for /proc/kcore.
IMHO, kclist for physical memory is not necessary...it's handled by /proc/iomem.
"kdump" uses this information and it's properly maintained by memory hotplug.
I'd like to try some pathces and make kclist_add() for physical memory cleaner,
later.

Thanks,
-Kame







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