[PATCH] mm: use symbolic names instead of indices for zone initialisation

Arch-independent zone-sizing is using indices instead of symbolic names to
offset within an array related to zones (max_zone_pfns).  The unintended
impact is that ZONE_DMA and ZONE_NORMAL is initialised on powerpc instead
of ZONE_DMA and ZONE_HIGHMEM when CONFIG_HIGHMEM is set.  As a result, the
the machine fails to boot but will boot with CONFIG_HIGHMEM turned off.

The following patch properly initialises the max_zone_pfns[] array and uses
symbolic names instead of indices in each architecture using
arch-independent zone-sizing.  Two users have successfully booted their
powerpcs with it (one an ibook G4).  It has also been boot tested on x86,
x86_64, ppc64 and ia64.  Please merge for 2.6.19-rc2.

Credit to Benjamin Herrenschmidt for identifying the bug and rolling the
first fix.  Additional credit to Johannes Berg and Andreas Schwab for
reporting the problem and testing on powerpc.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 3 deletions

diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c
index 19c72520a868..971dc1181e69 100644
--- a/arch/x86_64/mm/init.c
+++ b/arch/x86_64/mm/init.c
@@ -406,9 +406,12 @@ void __cpuinit zap_low_mappings(int cpu)
 #ifndef CONFIG_NUMA
 void __init paging_init(void)
 {
-        unsigned long max_zone_pfns[MAX_NR_ZONES] = {MAX_DMA_PFN,
-                                                        MAX_DMA32_PFN,
-                                                        end_pfn};
+        unsigned long max_zone_pfns[MAX_NR_ZONES];
+        memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
+        max_zone_pfns[ZONE_DMA] = MAX_DMA_PFN;
+        max_zone_pfns[ZONE_DMA32] = MAX_DMA32_PFN;
+        max_zone_pfns[ZONE_NORMAL] = end_pfn;
+
         memory_present(0, 0, end_pfn);
         sparse_init();
         free_area_init_nodes(max_zone_pfns);