diff --git a/arch/i386/kernel/cpu/mtrr/main.c b/arch/i386/kernel/cpu/mtrr/main.c
index 1cf466d..b4b3ea8 100644
--- a/arch/i386/kernel/cpu/mtrr/main.c
+++ b/arch/i386/kernel/cpu/mtrr/main.c
@@ -38,8 +38,8 @@
 #include <linux/cpu.h>
 #include <linux/mutex.h>
 
+#include <asm/e820.h>
 #include <asm/mtrr.h>
-
 #include <asm/uaccess.h>
 #include <asm/processor.h>
 #include <asm/msr.h>
@@ -47,7 +47,8 @@
 
 u32 num_var_ranges = 0;
 
-unsigned int *usage_table;
+#define MAX_MTRR_RANGES 255
+unsigned int usage_table[MAX_MTRR_RANGES];
 static DEFINE_MUTEX(mtrr_mutex);
 
 u64 size_or_mask, size_and_mask;
@@ -121,11 +122,6 @@ static void __init init_table(void)
 	int i, max;
 
 	max = num_var_ranges;
-	if ((usage_table = kmalloc(max * sizeof *usage_table, GFP_KERNEL))
-	    == NULL) {
-		printk(KERN_ERR "mtrr: could not allocate\n");
-		return;
-	}
 	for (i = 0; i < max; i++)
 		usage_table[i] = 1;
 }
@@ -631,6 +627,29 @@ static struct sysdev_driver mtrr_sysdev_driver = {
 	.resume		= mtrr_restore,
 };
 
+void __init mtrr_trim_uncached_memory(void)
+{
+	unsigned long i, base, size, highest_addr = 0;
+	mtrr_type type;
+
+	/* Find highest cached pfn */
+	for (i = 0; i < num_var_ranges; i++) {
+		mtrr_if->get(i, &base, &size, &type);
+		if (type != MTRR_TYPE_WRBACK)
+			continue;
+		base <<= PAGE_SHIFT;
+		size <<= PAGE_SHIFT;
+		if (highest_addr < base + size)
+			highest_addr = base + size;
+	}
+
+	if ((highest_addr >> PAGE_SHIFT) != end_pfn) {
+		printk(KERN_WARNING "Warning:  MTRRs don't cover all of "
+		       "memory, trimmed %ld pages\n", end_pfn -
+		       (highest_addr >> PAGE_SHIFT));
+		end_pfn = highest_addr >> PAGE_SHIFT;
+	}
+}
 
 /**
  * mtrr_bp_init - initialize mtrrs on the boot CPU
diff --git a/arch/x86_64/kernel/bugs.c b/arch/x86_64/kernel/bugs.c
index c3c6b91..c138eac 100644
--- a/arch/x86_64/kernel/bugs.c
+++ b/arch/x86_64/kernel/bugs.c
@@ -14,7 +14,6 @@
 void __init check_bugs(void)
 {
 	identify_cpu(&boot_cpu_data);
-	mtrr_bp_init();
 #if !defined(CONFIG_SMP)
 	printk("CPU: ");
 	print_cpu_info(&boot_cpu_data);
diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c
index eb6524f..409b63c 100644
--- a/arch/x86_64/kernel/setup.c
+++ b/arch/x86_64/kernel/setup.c
@@ -266,6 +266,10 @@ void __init setup_arch(char **cmdline_p)
 	 * we are rounding upwards:
 	 */
 	end_pfn = e820_end_of_ram();
+	/* Trim memory not covered by WB MTRRs */
+	mtrr_bp_init();
+	mtrr_trim_uncached_memory();
+
 	num_physpages = end_pfn;
 
 	check_efer();
diff --git a/include/asm-i386/mtrr.h b/include/asm-i386/mtrr.h
diff --git a/include/asm-x86_64/mtrr.h b/include/asm-x86_64/mtrr.h
index b557c48..cc62bd8 100644
--- a/include/asm-x86_64/mtrr.h
+++ b/include/asm-x86_64/mtrr.h
@@ -78,6 +78,7 @@ extern int mtrr_add_page (unsigned long base, unsigned long size,
 		     unsigned int type, char increment);
 extern int mtrr_del (int reg, unsigned long base, unsigned long size);
 extern int mtrr_del_page (int reg, unsigned long base, unsigned long size);
+extern void mtrr_trim_uncached_memory(void);
 #  else
 static __inline__ int mtrr_add (unsigned long base, unsigned long size,
 				unsigned int type, char increment)