Subject: [BUG?] numa required on x86_64?
From: Ian Kumlien <pomac@vapor.com>
Reply-To: pomac@vapor.com
To: linux-kernel@vger.kernel.org
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Date: Sat, 25 Jun 2011 00:00:58 +0200
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Hi all,

Just found this when wanting to play with development kernels again.
Since there is no -gitXX snapshots anymore, I cloned the git =3D)...

But, it failed to build properly with my config:

mm/page_cgroup.c line 308: node_start_pfn and node_end_pfn is only
defined under NUMA on x86_64.

The commit that changed the use of this was introduced recently while
the mmzone_64.h hasn't been changed since april.

commit 37573e8c718277103f61f03741bdc5606d31b07e
Author: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Date:   Wed Jun 15 15:08:42 2011 -0700

    memcg: fix init_page_cgroup nid with sparsemem
   =20
    Commit 21a3c9646873 ("memcg: allocate memory cgroup structures in local
    nodes") makes page_cgroup allocation as NUMA aware.  But that caused a
    problem https://bugzilla.kernel.org/show_bug.cgi?id=3D36192.
   =20
    The problem was getting a NID from invalid struct pages, which was not
    initialized because it was out-of-node, out of [node_start_pfn,
    node_end_pfn)
   =20
    Now, with sparsemem, page_cgroup_init scans pfn from 0 to max_pfn.  But
    this may scan a pfn which is not on any node and can access memmap whic=
h
    is not initialized.
   =20
    This makes page_cgroup_init() for SPARSEMEM node aware and remove a cod=
e
    to get nid from page->flags.  (Then, we'll use valid NID always.)
   =20
    [akpm@linux-foundation.org: try to fix up comments]
    Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>


--=20
Ian Kumlien  -- http://demius.net || http://pomac.netswarm.net

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