[PATCH] Fix bootmem breakage on ARM

Russell King reports:
 "With previous kernels, the nodes are added to the list in reverse order,
  so architecture code knew we had to add the highest PFN first and the
  lowest PFN node last.

  Unfortunately, init_bootmem_core() now sorts the nodes according to
  their start pfn. This active sorting broke ARM discontig memory support."

Andrew Morton chimes in:
 "It looks to be bogus on ia64 as well, for which the patch was written"

Yep, I think it is bogus.  There's only one caller on ia64 that would be
affected--swiotlb_init(), and afaik multi-node systems won't be using
that code (except maybe NEC?), so even if the pgdat list is out of order
we should be ok.  If not I'll fix the ia64 discontig code.

diff --git a/mm/bootmem.c b/mm/bootmem.c
index 1d5c1de81fbad9fe91f9d0b1be286a19a6465684..ec2862a9244b8f1b2575d2122d74e5cf0860b592 100644 (file)
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -48,24 +48,8 @@ static unsigned long __init init_bootmem_core (pg_data_t *pgdat,
        bootmem_data_t *bdata = pgdat->bdata;
        unsigned long mapsize = ((end - start)+7)/8;
 
-
-       /*
-        * sort pgdat_list so that the lowest one comes first,
-        * which makes alloc_bootmem_low_pages work as desired.
-        */
-       if (!pgdat_list || pgdat_list->node_start_pfn > pgdat->node_start_pfn) {
-               pgdat->pgdat_next = pgdat_list;
-               pgdat_list = pgdat;
-       } else {
-               pg_data_t *tmp = pgdat_list;
-               while (tmp->pgdat_next) {
-                       if (tmp->pgdat_next->node_start_pfn > pgdat->node_start_pfn)
-                               break;
-                       tmp = tmp->pgdat_next;
-               }
-               pgdat->pgdat_next = tmp->pgdat_next;
-               tmp->pgdat_next = pgdat;
-       }
+       pgdat->pgdat_next = pgdat_list;
+       pgdat_list = pgdat;
 
        mapsize = (mapsize + (sizeof(long) - 1UL)) & ~(sizeof(long) - 1UL);
        bdata->node_bootmem_map = phys_to_virt(mapstart << PAGE_SHIFT);