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>

diff --git a/arch/x86/mm/ioremap_64.c b/arch/x86/mm/ioremap_64.c
index 2815ab60009b44f1797a84b2dc040927e229be5b..0a05f024dc221be8a692db2e1bac51b28b17456d 100644 (file)
--- a/arch/x86/mm/ioremap_64.c
+++ b/arch/x86/mm/ioremap_64.c
@@ -41,7 +41,14 @@ 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.