[patch 18/29] i386: avoid temporarily inconsistent pte-s

Greg Kroah-Hartman
2007-11-20T18:33:48Z

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2.6.23-stable review patch. If anyone has any objections, please let us
know.

------------------
From: Jan Beulich <jbeulich@novell.com>

patch aa506dc7b12d03fbf8fd11aab752aed1aadd9c07 in mainline.

i386: avoid temporarily inconsistent pte-s

One more of these issues (which were considered fixed a few releases
back): other than on x86-64, i386 allows set_fixmap() to replace
already present mappings. Consequently, on PAE, care must be taken to
not update the high half of a pte while the low half is still holding
the old value.

[ tglx: arch/x86 adaptation ]

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
arch/i386/mm/pgtable.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

--- a/arch/i386/mm/pgtable.c
+++ b/arch/i386/mm/pgtable.c
@@ -97,8 +97,7 @@ static void set_pte_pfn(unsigned long va
}
pte = pte_offset_kernel(pmd, vaddr);
if (pgprot_val(flags))
- /* <pfn,flags> stored as-is, to permit clearing entries */
- set_pte(pte, pfn_pte(pfn, flags));
+ set_pte_present(&init_mm, vaddr, pte, pfn_pte(pfn, flags));
else
pte_clear(&init_mm, vaddr, pte);

--