[PATCH 2/8] Add better comment on careful_allocation()

[Dave Hansen <dave@linux.vnet.ibm.com>]

The behavior in careful_allocation() really confused me
at first.  Add a comment to hopefully make it easier
on the next doofus that looks at it.

Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
---

 linux-2.6.git-dave/arch/powerpc/mm/numa.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff -puN arch/powerpc/mm/numa.c~cleanup-careful_allocation4 arch/powerpc/mm/numa.c
--- linux-2.6.git/arch/powerpc/mm/numa.c~cleanup-careful_allocation4	2008-12-09 10:16:05.000000000 -0800
+++ linux-2.6.git-dave/arch/powerpc/mm/numa.c	2008-12-09 10:16:05.000000000 -0800
@@ -840,8 +840,16 @@ static void __init *careful_allocation(i
 		      size, nid);
 
 	/*
-	 * If the memory came from a previously allocated node, we must
-	 * retry with the bootmem allocator.
+	 * We initialize the nodes in numeric order: 0, 1, 2...
+	 * and hand over control from the LMB allocator to the
+	 * bootmem allocator.  If this function is called for
+	 * node 5, then we know that all nodes <5 are using the
+	 * bootmem allocator instead of the LMB allocator.
+	 *
+	 * So, check the nid from which this allocation came
+	 * and double check to see if we need to use bootmem
+	 * instead of the LMB.  We don't free the LMB memory
+	 * since it would be useless.
 	 */
 	new_nid = early_pfn_to_nid(ret >> PAGE_SHIFT);
 	if (new_nid < nid) {
_