[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>

2 files changed, 2 insertions, 0 deletions

diff --git a/arch/ia64/mm/contig.c b/arch/ia64/mm/contig.c
index daf977ff2920..82deaa3a7c48 100644
--- a/arch/ia64/mm/contig.c
+++ b/arch/ia64/mm/contig.c
@@ -233,6 +233,7 @@ paging_init (void)
         efi_memmap_walk(count_pages, &num_physpages);
 
         max_dma = virt_to_phys((void *) MAX_DMA_ADDRESS) >> PAGE_SHIFT;
+        memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
         max_zone_pfns[ZONE_DMA] = max_dma;
         max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
 
diff --git a/arch/ia64/mm/discontig.c b/arch/ia64/mm/discontig.c
index d497b6b0f5b2..96722cb1b49d 100644
--- a/arch/ia64/mm/discontig.c
+++ b/arch/ia64/mm/discontig.c
@@ -709,6 +709,7 @@ void __init paging_init(void)
                         max_pfn = mem_data[node].max_pfn;
         }
 
+        memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
         max_zone_pfns[ZONE_DMA] = max_dma;
         max_zone_pfns[ZONE_NORMAL] = max_pfn;
         free_area_init_nodes(max_zone_pfns);