From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

We need to reserve the brk segment before doing the pagetable
construction, so that it doesn't allocate the same memory.

Also, pre-initialize brk to _end (but still leave init_brk for cases
where that's not correct, like i386 (for now) and Xen).

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
 arch/x86/kernel/head64.c |    2 --
 arch/x86/kernel/setup.c  |   16 ++++++++++++----
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 4b29802..f5b2722 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -91,8 +91,6 @@ void __init x86_64_start_kernel(char * real_mode_data)
 	if (console_loglevel == 10)
 		early_printk("Kernel alive\n");
 
-	init_brk((unsigned long)&_end);
-
 	x86_64_start_reservations(real_mode_data);
 }
 
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 6a21423..c246dc4 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -113,7 +113,8 @@
 #endif
 
 unsigned int boot_cpu_id __read_mostly;
-__initdata unsigned long _brk_start, _brk_end;
+__initdata unsigned long _brk_start = (unsigned long)&_end;
+__initdata unsigned long _brk_end = (unsigned long)&_end;
 
 #ifdef CONFIG_X86_64
 int default_cpu_present_to_apicid(int mps_cpu)
@@ -356,6 +357,14 @@ void * __init extend_brk(size_t size, size_t align)
 	return ret;
 }
 
+static void __init reserve_brk(void)
+{
+	if (_brk_end > _brk_start)
+		reserve_early(__pa(_brk_start), __pa(_brk_end), "BRK");
+
+	_brk_end = _brk_start = 0xdeadb00c + POISON_POINTER_DELTA;
+}
+
 static void __init reserve_initrd(void)
 {
 	u64 ramdisk_image = boot_params.hdr.ramdisk_image;
@@ -856,6 +865,8 @@ void __init setup_arch(char **cmdline_p)
 	setup_bios_corruption_check();
 #endif
 
+	reserve_brk();
+
 	/* max_pfn_mapped is updated here */
 	max_low_pfn_mapped = init_memory_mapping(0, max_low_pfn<<PAGE_SHIFT);
 	max_pfn_mapped = max_low_pfn_mapped;
@@ -898,9 +909,6 @@ void __init setup_arch(char **cmdline_p)
 	acpi_numa_init();
 #endif
 
-	if (_brk_end > _brk_start)
-		reserve_early(__pa(_brk_start), __pa(_brk_end), "BRK");
-
 	initmem_init(0, max_pfn);
 
 #ifdef CONFIG_ACPI_SLEEP
-- 
1.6.0.6