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Message-ID: <86802c440804172206k7533e7d1kf1f355f6a97a4412@mail.gmail.com>
Date: Thu, 17 Apr 2008 22:06:22 -0700
From: "Yinghai Lu" <yhlu.kernel@gmail.com>
To: "Johannes Weiner" <hannes@saeurebad.de>
Subject: Re: [RFC][patch 2/5] mm: Node-setup agnostic free_bootmem()
Cc: "Ingo Molnar" <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>,
       "Linux MM" <linux-mm@kvack.org>, "Andi Kleen" <andi@firstfloor.org>,
       "Yasunori Goto" <y-goto@jp.fujitsu.com>,
       "KAMEZAWA Hiroyuki" <kamezawa.hiroyu@jp.fujitsu.com>,
       "Christoph Lameter" <clameter@sgi.com>,
       "Andrew Morton" <akpm@linux-foundation.org>,
       "Siddha, Suresh B" <suresh.b.siddha@intel.com>
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On Wed, Apr 16, 2008 at 12:17 PM, Johannes Weiner <hannes@saeurebad.de> wrote:
> Hi,
>
>
>
>  Ingo Molnar <mingo@elte.hu> writes:
>
>  > * Yinghai Lu <yhlu.kernel@gmail.com> wrote:
>  >
>  >> >  Yes, it should work well with cross nodes case.
>  >> >
>  >> >  but please add boundary check on free_bootmem_node too.
>  >>
>  >> also please note: it will have problem span nodes box.
>  >>
>  >> for example: node 0: 0-2g, 4-6g, node1: 2-4g, 6-8g. and if ramdisk sit
>  >> creoss 2G boundary. you will only free the range before 2g.
>  >
>  > yes. Such systems _will_ become more common - so the "this is rare"
>  > arguments are incorrect. bootmem has to be robust enough to deal with
>  > it.
>
>  Ingo, I never doubted any of this, I was just asking more than once if
>  and when this might happen.  And I don't want the allocator become
>  fragile, just not completely ignorant about bogus input.
>
>  But the situation is still not clear for me.  Ingo, how are these
>  node spanning pfn ranges represented in the kernel?  How many node
>  descriptors will you have in the case Yinghai described and how will
>  they look like?

according to patch from Suresh in x86.git, one node still only have one bdata.

YH