mm: use alloc_bootmem_node_nopanic() on really needed path

Stefan found nobootmem does not work on his system that has only 8M of
RAM.  This causes an early panic:

  BIOS-provided physical RAM map:
   BIOS-88: 0000000000000000 - 000000000009f000 (usable)
   BIOS-88: 0000000000100000 - 0000000000840000 (usable)
  bootconsole [earlyser0] enabled
  Notice: NX (Execute Disable) protection missing in CPU or disabled in BIOS!
  DMI not present or invalid.
  last_pfn = 0x840 max_arch_pfn = 0x100000
  init_memory_mapping: 0000000000000000-0000000000840000
  8MB LOWMEM available.
    mapped low ram: 0 - 00840000
    low ram: 0 - 00840000
  Zone PFN ranges:
    DMA      0x00000001 -> 0x00001000
    Normal   empty
  Movable zone start PFN for each node
  early_node_map[2] active PFN ranges
      0: 0x00000001 -> 0x0000009f
      0: 0x00000100 -> 0x00000840
  BUG: Int 6: CR2 (null)
       EDI c034663c  ESI (null)  EBP c0329f38  ESP c0329ef4
       EBX c0346380  EDX 00000006  ECX ffffffff  EAX fffffff4
       err (null)  EIP c0353191   CS c0320060  flg 00010082
  Stack: (null) c030c533 000007cd (null) c030c533 00000001 (null) (null)
         00000003 0000083f 00000018 00000002 00000002 c0329f6c c03534d6 (null)
         (null) 00000100 00000840 (null) c0329f64 00000001 00001000 (null)
  Pid: 0, comm: swapper Not tainted 2.6.36 #5
  Call Trace:
   [<c02e3707>] ? 0xc02e3707
   [<c035e6e5>] 0xc035e6e5
   [<c0353191>] ? 0xc0353191
   [<c03534d6>] 0xc03534d6
   [<c034f1cd>] 0xc034f1cd
   [<c034a824>] 0xc034a824
   [<c03513cb>] ? 0xc03513cb
   [<c0349432>] 0xc0349432
   [<c0349066>] 0xc0349066

It turns out that we should ignore the low limit of 16M.

Use alloc_bootmem_node_nopanic() in this case.

[akpm@linux-foundation.org: less mess]
Signed-off-by: NYinghai LU <yinghai@kernel.org>
Reported-by: NStefan Hellermann <stefan@the2masters.de>
Tested-by: NStefan Hellermann <stefan@the2masters.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@kernel.org>		[2.6.34+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

include/linux/bootmem.h

@@ -111,6 +111,8 @@ extern void *__alloc_bootmem_low_node(pg_data_t *pgdat,
 	__alloc_bootmem_nopanic(x, PAGE_SIZE, __pa(MAX_DMA_ADDRESS))
 #define alloc_bootmem_node(pgdat, x) \
 	__alloc_bootmem_node(pgdat, x, SMP_CACHE_BYTES, __pa(MAX_DMA_ADDRESS))
+#define alloc_bootmem_node_nopanic(pgdat, x) \
+	__alloc_bootmem_node_nopanic(pgdat, x, SMP_CACHE_BYTES, __pa(MAX_DMA_ADDRESS))
 #define alloc_bootmem_pages_node(pgdat, x) \
 	__alloc_bootmem_node(pgdat, x, PAGE_SIZE, __pa(MAX_DMA_ADDRESS))
 #define alloc_bootmem_pages_node_nopanic(pgdat, x) \

mm/page_alloc.c

@@ -3564,7 +3564,7 @@ int zone_wait_table_init(struct zone *zone, unsigned long zone_size_pages)
 
 	if (!slab_is_available()) {
 		zone->wait_table = (wait_queue_head_t *)
-			alloc_bootmem_node(pgdat, alloc_size);
+			alloc_bootmem_node_nopanic(pgdat, alloc_size);
 	} else {
 		/*
 		 * This case means that a zone whose size was 0 gets new memory
@@ -4141,7 +4141,8 @@ static void __init setup_usemap(struct pglist_data *pgdat,
 	unsigned long usemapsize = usemap_size(zonesize);
 	zone->pageblock_flags = NULL;
 	if (usemapsize)
-		zone->pageblock_flags = alloc_bootmem_node(pgdat, usemapsize);
+		zone->pageblock_flags = alloc_bootmem_node_nopanic(pgdat,
+								   usemapsize);
 }
 #else
 static inline void setup_usemap(struct pglist_data *pgdat,
@@ -4307,7 +4308,7 @@ static void __init_refok alloc_node_mem_map(struct pglist_data *pgdat)
 		size =  (end - start) * sizeof(struct page);
 		map = alloc_remap(pgdat->node_id, size);
 		if (!map)
-			map = alloc_bootmem_node(pgdat, size);
+			map = alloc_bootmem_node_nopanic(pgdat, size);
 		pgdat->node_mem_map = map + (pgdat->node_start_pfn - start);
 	}
 #ifndef CONFIG_NEED_MULTIPLE_NODES