[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, 5 deletions

diff --git a/arch/i386/mm/discontig.c b/arch/i386/mm/discontig.c
index 455597db84d..ddbdb0336f2 100644
--- a/arch/i386/mm/discontig.c
+++ b/arch/i386/mm/discontig.c
@@ -356,11 +356,12 @@ void __init numa_kva_reserve(void)
 void __init zone_sizes_init(void)
 {
         int nid;
-        unsigned long max_zone_pfns[MAX_NR_ZONES] = {
-                virt_to_phys((char *)MAX_DMA_ADDRESS) >> PAGE_SHIFT,
-                max_low_pfn,
-                highend_pfn
-        };
+        unsigned long max_zone_pfns[MAX_NR_ZONES];
+        memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
+        max_zone_pfns[ZONE_DMA] =
+                virt_to_phys((char *)MAX_DMA_ADDRESS) >> PAGE_SHIFT;
+        max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
+        max_zone_pfns[ZONE_HIGHMEM] = highend_pfn;
 
         /* If SRAT has not registered memory, register it now */
         if (find_max_pfn_with_active_regions() == 0) {