[PATCH] Fix kunmap_atomic's use of kpte_clear_flush()

From: Jeremy Fitzhardinge
Date: Tue Nov 07 2006 - 19:22:38 EST


kunmap_atomic() will call kpte_clear_flush with vaddr/ptep arguments
which don't correspond if the vaddr is just a normal lowmem address
(ie, not in the KMAP area). This patch makes sure that the pte is
only cleared if kmap area was actually used for the mapping.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Zachary Amsden <zach@xxxxxxxxxx>

===================================================================
--- a/arch/i386/mm/highmem.c
+++ b/arch/i386/mm/highmem.c
@@ -56,22 +56,20 @@ void kunmap_atomic(void *kvaddr, enum km
unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();

-#ifdef CONFIG_DEBUG_HIGHMEM
- if (vaddr >= PAGE_OFFSET && vaddr < (unsigned long)high_memory) {
- pagefault_enable();
- return;
- }
-
- if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
- BUG();
-#endif
/*
* Force other mappings to Oops if they'll try to access this pte
* without first remap it. Keeping stale mappings around is a bad idea
* also, in case the page changes cacheability attributes or becomes
* a protected page in a hypervisor.
*/
- kpte_clear_flush(kmap_pte-idx, vaddr);
+ if (vaddr == __fix_to_virt(FIX_KMAP_BEGIN+idx))
+ kpte_clear_flush(kmap_pte-idx, vaddr);
+ else {
+#ifdef CONFIG_DEBUG_HIGHMEM
+ BUG_ON(vaddr < PAGE_OFFSET);
+ BUG_ON(vaddr >= (unsigned long)high_memory);
+#endif
+ }

pagefault_enable();
}

-
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