[PATCH] x86_64: allocate sparsemem memmap above 4G

On systems with huge amount of physical memory, VFS cache and memory memmap
may eat all available system memory under 4G, then the system may fail to
allocate swiotlb bounce buffer.

There was a fix for this issue in arch/x86_64/mm/numa.c, but that fix dose
not cover sparsemem model.

This patch add fix to sparsemem model by first try to allocate memmap above
4G.
Signed-off-by: Zou Nan hai <nanhai.zou@intel.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[chrisw: trivial backport]
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/x86_64/mm/init.c

@@ -776,3 +776,9 @@ int in_gate_area_no_task(unsigned long addr)
 {
 	return (addr >= VSYSCALL_START) && (addr < VSYSCALL_END);
 }
+
+void *alloc_bootmem_high_node(pg_data_t *pgdat, unsigned long size)
+{
+	return __alloc_bootmem_core(pgdat->bdata, size,
+			SMP_CACHE_BYTES, (4UL*1024*1024*1024), 0);
+}

include/linux/bootmem.h

@@ -59,6 +59,7 @@ extern void *__alloc_bootmem_core(struct bootmem_data *bdata,
 				  unsigned long align,
 				  unsigned long goal,
 				  unsigned long limit);
+extern void *alloc_bootmem_high_node(pg_data_t *pgdat, unsigned long size);
 
 #ifndef CONFIG_HAVE_ARCH_BOOTMEM_NODE
 extern void reserve_bootmem(unsigned long addr, unsigned long size);

mm/sparse.c

@@ -209,6 +209,12 @@ static int sparse_init_one_section(struct mem_section *ms,
 	return 1;
 }
 
+__attribute__((weak))
+void *alloc_bootmem_high_node(pg_data_t *pgdat, unsigned long size)
+{
+	return NULL;
+}
+
 static struct page *sparse_early_mem_map_alloc(unsigned long pnum)
 {
 	struct page *map;
@@ -219,6 +225,11 @@ static struct page *sparse_early_mem_map_alloc(unsigned long pnum)
 	if (map)
 		return map;
 
+  	map = alloc_bootmem_high_node(NODE_DATA(nid),
+                       sizeof(struct page) * PAGES_PER_SECTION);
+	if (map)
+		return map;
+
 	map = alloc_bootmem_node(NODE_DATA(nid),
 			sizeof(struct page) * PAGES_PER_SECTION);
 	if (map)