From: Rik van Riel <riel@redhat.com>
Date: Tue, 9 Oct 2012 13:31:59 +0000 (+0200)
Subject: mm: Only flush the TLB when clearing an accessible pte
X-Git-Tag: next-20121029~34^2^2~24
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=6fe64360a759f3cbbff4835da4c226d6cb78c34d;p=karo-tx-linux.git

mm: Only flush the TLB when clearing an accessible pte

If ptep_clear_flush() is called to clear a page table entry that is
accessible anyway by the CPU, eg. a _PAGE_PROTNONE page table entry,
there is no need to flush the TLB on remote CPUs.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-vm3rkzevahelwhejx5uwm8ex@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index d8397da42fe6..0c8323fe6c8f 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -88,7 +88,8 @@ pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long address,
 {
 	pte_t pte;
 	pte = ptep_get_and_clear((vma)->vm_mm, address, ptep);
-	flush_tlb_page(vma, address);
+	if (pte_accessible(pte))
+		flush_tlb_page(vma, address);
 	return pte;
 }
 #endif