[PATCH] stop NULL pointer dereference in __alloc_pages

[PATCH] stop NULL pointer dereference in __alloc_pages

[Martin J. Bligh]

This trivial patch will apply to both 2.4.19-pre7 and 2.5.8 with just line 
offsets. It stops us from following a NULL pointer in classzone in the case 
where there is a pgdat without a fully populated zone list (ie a node with 
no ZONE_NORMAL on an ia32 NUMA machine). Without this patch, ia32 
NUMA machines won't even boot - we dereference the classzone ptr
a few lines further down (or try to ;-) ).

Please apply ...

Thanks,

Martin.

--- linux-2.4.18-memalloc/mm/page_alloc.c.old	Fri Mar  8 18:21:41 2002
+++ linux-2.4.18-memalloc/mm/page_alloc.c	Fri Mar  8 18:23:27 2002
@@ -317,6 +317,8 @@
 
 	zone = zonelist->zones;
 	classzone = *zone;
+	if (classzone == NULL)
+		return NULL;
 	min = 1UL << order;
 	for (;;) {
 		zone_t *z = *(zone++);