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Subject[PATCH] x86: ioremap_nocache fix
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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>

---
arch/x86/mm/ioremap_64.c | 7 +++++++
1 file changed, 7 insertions(+)

--- a/arch/x86/mm/ioremap_64.c
+++ b/arch/x86/mm/ioremap_64.c
@@ -41,8 +41,15 @@ ioremap_change_attr(unsigned long phys_a
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.
*/


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