linux-kernel - [PATCH 1/3] x86/mm: only do a local TLB flush in ptep_set_access

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Message-ID: <20121026144419.7e666023@dull>
Date:	Fri, 26 Oct 2012 14:44:19 -0400
From:	Rik van Riel <riel@...hat.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Michel Lespinasse <walken@...gle.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Mel Gorman <mgorman@...e.de>,
	Johannes Weiner <hannes@...xchg.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH 1/3] x86/mm: only do a local TLB flush in
 ptep_set_access_flags()

Here are the TLB patches as requested:
---8<---
    
The function ptep_set_access_flags() is only ever invoked to upgrade
access permissions on a PTE. That makes it safe to skip flushing the
TLBs on remote TLBs. The worst that can happen is a spurious page
fault on other CPUs, which would flush that TLB entry.

Lazily letting another CPU incur a spurious page fault occasionally
is (much!) cheaper than aggressively flushing everybody else's TLB.

Signed-off-by: Rik van Riel <riel@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Michel Lespinasse <walken@...gle.com>
Cc: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/mm/pgtable.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 8573b83..b3b852c 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -310,7 +310,7 @@ int ptep_set_access_flags(struct vm_area_struct *vma,
 	if (changed && dirty) {
 		*ptep = entry;
 		pte_update_defer(vma->vm_mm, address, ptep);
-		flush_tlb_page(vma, address);
+		__flush_tlb_one(address);
 	}
 
 	return changed;


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