Re: [Bugme-new] [Bug 13690] New: nodes_clear cause hugepage unusable on non-NUMA machine

[Yinghai Lu <yinghai@kernel.org>]

Alex Shi wrote:
> The new patch works for my stoakley i386 machine. But for x86_64 machine
> the specjbb2005 still can not run with hugepage. The specjbb2005 use the
> same java setting as i386 system. After apply your patch, the iomem of
> x86_64 is:

please check

[PATCH] x86: don't clear nodes_states[N_NORMAL_MEMORY] when numa is not compiled in

Alex found:
for x86_64 machine the specjbb2005 still can not run with hugepage

only happens when numa is not compiled in

the root cause: node_set_state will not set it back for us in that case

so don't clear that when numa is not select in config

Reported-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 arch/x86/mm/init_64.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Index: linux-2.6/arch/x86/mm/init_64.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/init_64.c
+++ linux-2.6/arch/x86/mm/init_64.c
@@ -598,8 +598,14 @@ void __init paging_init(void)
 
 	sparse_memory_present_with_active_regions(MAX_NUMNODES);
 	sparse_init();
-	/* clear the default setting with node 0 */
+#if MAX_NUMNODES > 1
+	/*
+	 * clear the default setting with node 0
+	 * note: don't clear it, node_set_state will do nothing
+	 *	 (aka set it back) when numa support is not compiled in
+	 */
 	nodes_clear(node_states[N_NORMAL_MEMORY]);
+#endif
 	free_area_init_nodes(max_zone_pfns);
 }