x86: ioremap_nocache fix

This patch fixes a bug of ioremap_nocache. ioremap_nocache() will call
__ioremap() with flags != 0 to do the real work, which will call
change_page_attr_addr() if phys_addr + size - 1 < (end_pfn_map << PAGE_SHIFT).
But some pages between 0 ~ end_pfn_map << PAGE_SHIFT are not mapped by
identity map, this will make change_page_attr_addr failed.

This patch is based on latest x86 git and has been tested on x86_64 platform.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/x86/mm/ioremap_64.c b/arch/x86/mm/ioremap_64.c
index 2815ab60009b..0a05f024dc22 100644
--- a/arch/x86/mm/ioremap_64.c
+++ b/arch/x86/mm/ioremap_64.c
@@ -41,8 +41,15 @@ ioremap_change_attr(unsigned long phys_addr, unsigned long size,
         if (phys_addr + size - 1 < (end_pfn_map << PAGE_SHIFT)) {
                 unsigned long npages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
                 unsigned long vaddr = (unsigned long) __va(phys_addr);
+                int level;
 
                 /*
+                 * If there is no identity map for this address,
+                 * change_page_attr_addr is unnecessary
+                 */
+                if (!lookup_address(vaddr, &level))
+                        return err;
+                /*
                  * Must use a address here and not struct page because the phys addr
                  * can be a in hole between nodes and not have an memmap entry.
                  */