Hi all, Just found this when wanting to play with development kernels again. Since there is no -gitXX snapshots anymore, I cloned the git =)... 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 Date: Wed Jun 15 15:08:42 2011 -0700 memcg: fix init_page_cgroup nid with sparsemem 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=36192. 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) 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 which is not initialized. This makes page_cgroup_init() for SPARSEMEM node aware and remove a code to get nid from page->flags. (Then, we'll use valid NID always.) [akpm@linux-foundation.org: try to fix up comments] Signed-off-by: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds -- Ian Kumlien -- http://demius.net || http://pomac.netswarm.net