memblock: Allow memblock_init to be called early

The Xen setup code needs to call memblock_x86_reserve_range() very early,
so allow it to initialize the memblock subsystem before doing so.  The
second memblock_init() is ignored.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
LKML-Reference: <4CACFDAD.3090900@goop.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

2 files changed, 9 insertions, 0 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 7d46c8441418..63b83ceebd1a 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -30,6 +30,7 @@
 #include <linux/console.h>
 #include <linux/pci.h>
 #include <linux/gfp.h>
+#include <linux/memblock.h>
 
 #include <xen/xen.h>
 #include <xen/interface/xen.h>
@@ -1183,6 +1184,8 @@ asmlinkage void __init xen_start_kernel(void)
         local_irq_disable();
         early_boot_irqs_off();
 
+        memblock_init();
+
         xen_raw_console_write("mapping kernel into physical memory\n");
         pgd = xen_setup_kernel_pagetable(pgd, xen_start_info->nr_pages);
 
diff --git a/mm/memblock.c b/mm/memblock.c
index 9ad39690a2bd..ae8b06c828c7 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -752,6 +752,12 @@ void __init memblock_analyze(void)
 
 void __init memblock_init(void)
 {
+        static int init_done __initdata = 0;
+
+        if (init_done)
+                return;
+        init_done = 1;
+
         /* Hookup the initial arrays */
         memblock.memory.regions = memblock_memory_init_regions;
         memblock.memory.max             = INIT_MEMBLOCK_REGIONS;