Zachary Amsden wrote:
Similar to the last bug, on set_pte, we don't want the compiler to re-order
the write of the PTE, even in non-SMP configurations, since if the write of
the low word occurs first, the TLB could prefetch a bad highmem mapping which
has been aliased into low memory.
wmb() means that it also orders IO memory. It is no difference for
i386, but smp_wmb() actually has the right semantics of the abstract
Linux memory model.
Signed-off-by: Zachary Amsden <[email protected]>
Index: linux-2.6.17-rc/include/asm-i386/pgtable-3level.h
===================================================================
--- linux-2.6.17-rc.orig/include/asm-i386/pgtable-3level.h 2006-04-26 08:38:57.000000000 -0700
+++ linux-2.6.17-rc/include/asm-i386/pgtable-3level.h 2006-04-26 14:45:12.000000000 -0700
@@ -53,7 +53,7 @@ static inline int pte_exec_kernel(pte_t
static inline void set_pte(pte_t *ptep, pte_t pte)
{
ptep->pte_high = pte.pte_high;
- smp_wmb();
+ wmb();
ptep->pte_low = pte.pte_low;
}
#define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)
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