linux-kernel - [tip:numa/core] mm: Only flush the TLB when clearing an accessible pte

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Date:	Mon, 19 Nov 2012 11:32:03 -0800
From:	tip-bot for Rik van Riel <riel@...hat.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	torvalds@...ux-foundation.org, a.p.zijlstra@...llo.nl,
	hughd@...gle.com, riel@...hat.com, akpm@...ux-foundation.org,
	aarcange@...hat.com, mgorman@...e.de, tglx@...utronix.de
Subject: [tip:numa/core] mm:
  Only flush the TLB when clearing an accessible pte

Commit-ID:  e29be43ba99182dc4f8ec4d305e51e62c8f1e1f9
Gitweb:     http://git.kernel.org/tip/e29be43ba99182dc4f8ec4d305e51e62c8f1e1f9
Author:     Rik van Riel <riel@...hat.com>
AuthorDate: Tue, 9 Oct 2012 15:31:59 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 19 Nov 2012 02:15:34 +0100

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@...hat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: Rik van Riel <riel@...hat.com>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Hugh Dickins <hughd@...gle.com>
Link: http://lkml.kernel.org/n/tip-vm3rkzevahelwhejx5uwm8ex@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 mm/pgtable-generic.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index d8397da..0c8323f 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
--
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