Messages in this thread | | | Date | Thu, 27 Apr 2006 10:00:34 +1000 | From | Nick Piggin <> | Subject | Re: [PATCH 2/2] I386 convert pae wmb to non smp |
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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 <zach@vmware.com> > >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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