Always use CLFLUSH instead of WBINVD for change_page_attr

CLFLUSH is a lot faster than WBINVD so avoid it if at all
possible.

Signed-off-by: Andi Kleen <ak@suse.de>

---
 arch/x86_64/mm/pageattr.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Index: linux/arch/x86_64/mm/pageattr.c
===================================================================
--- linux.orig/arch/x86_64/mm/pageattr.c
+++ linux/arch/x86_64/mm/pageattr.c
@@ -64,8 +64,9 @@ static struct page *split_large_page(uns
 
 static void flush_kernel_map(void *address) 
 {
-	if (0 && address && cpu_has_clflush) {
-		/* is this worth it? */ 
+	/* When clflush is available always use it because it is
+	   much cheaper than WBINVD */
+	if (cpu_has_clflush) {
 		int i;
 		for (i = 0; i < PAGE_SIZE; i += boot_cpu_data.x86_clflush_size) 
 			asm volatile("clflush (%0)" :: "r" (address + i)); 
@@ -77,7 +78,6 @@ static void flush_kernel_map(void *addre
 		__flush_tlb_all();
 }
 
-
 static inline void flush_map(unsigned long address)
 {	
 	on_each_cpu(flush_kernel_map, (void *)address, 1, 1);
@@ -213,7 +213,7 @@ void global_flush_tlb(void)
 	dpage = xchg(&deferred_pages, NULL);
 	up_read(&init_mm.mmap_sem);
 
-	flush_map((dpage && !dpage->lru.next) ? (unsigned long)page_address(dpage) : 0);
+	flush_map((unsigned long)page_address(dpage));
 	while (dpage) {
 		struct page *tmp = dpage;
 		dpage = (struct page *)dpage->lru.next;