[PATCH] i386: clear_fixmap() should not use set_pte()

While not strictly required with the current code (as the upper half of
page table entries generated by __set_fixmap() cannot be non-zero due
to the second parameter of this function being 'unsigned long'), the
use of set_pte() in __set_fixmap() in the context of clear_fixmap() is
still improper with CONFIG_X86_PAE (see the respective comment in
include/asm-i386/pgtable-3level.h) and would turn into a bug if that
second parameter ever gets changed to a 64-bit type.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>

diff --git a/arch/i386/mm/pgtable.c b/arch/i386/mm/pgtable.c
index 10126e3f81745f5591eab2e66dc4426394c3c2cb..65b5c0959033d44324d1cda1c10a60f2818c8329 100644 (file)
--- a/arch/i386/mm/pgtable.c
+++ b/arch/i386/mm/pgtable.c
@@ -95,8 +95,11 @@ static void set_pte_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
                return;
        }
        pte = pte_offset_kernel(pmd, vaddr);
-       /* <pfn,flags> stored as-is, to permit clearing entries */
-       set_pte(pte, pfn_pte(pfn, flags));
+       if (pgprot_val(flags))
+               /* <pfn,flags> stored as-is, to permit clearing entries */
+               set_pte(pte, pfn_pte(pfn, flags));
+       else
+               pte_clear(&init_mm, vaddr, pte);
 
        /*
         * It's enough to flush this one mapping.