[RFC][PATCH 01/15] mm, powerpc: Dont use tlb_flush for external tlb flushes

[Peter Zijlstra]

Both sparc64 and powerpc64 use tlb_flush() to flush their respective
hash-tables which is entirely different from what
flush_tlb_range()/flush_tlb_mm() would do.

Powerpc64 already uses arch_*_lazy_mmu_mode() to batch and flush these
so any tlb_flush() caller should already find an empty batch. So
remove this functionality from tlb_flush().

Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
---
 arch/powerpc/mm/tlb_hash64.c         |   10 ----------
 arch/sparc/include/asm/tlb_64.h      |    2 +-
 arch/sparc/include/asm/tlbflush_64.h |   13 +++++++++++++
 3 files changed, 14 insertions(+), 11 deletions(-)

Index: linux-2.6/arch/powerpc/mm/tlb_hash64.c
===================================================================
--- linux-2.6.orig/arch/powerpc/mm/tlb_hash64.c
+++ linux-2.6/arch/powerpc/mm/tlb_hash64.c
@@ -155,16 +155,6 @@ void __flush_tlb_pending(struct ppc64_tl
 
 void tlb_flush(struct mmu_gather *tlb)
 {
-	struct ppc64_tlb_batch *tlbbatch = &get_cpu_var(ppc64_tlb_batch);
-
-	/* If there's a TLB batch pending, then we must flush it because the
-	 * pages are going to be freed and we really don't want to have a CPU
-	 * access a freed page because it has a stale TLB
-	 */
-	if (tlbbatch->index)
-		__flush_tlb_pending(tlbbatch);
-
-	put_cpu_var(ppc64_tlb_batch);
 }
 
 /**


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