Date: Fri, 26 Oct 2012 14:44:19 -0400
From: Rik van Riel <riel@redhat.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>, Michel Lespinasse <walken@google.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Andrea Arcangeli <aarcange@redhat.com>, Mel Gorman <mgorman@suse.de>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH 1/3] x86/mm: only do a local TLB flush in
 ptep_set_access_flags()
Message-ID: <20121026144419.7e666023@dull>
In-Reply-To: <20121026132601.GC9886@gmail.com>
References: <20121025121617.617683848@chello.nl>
	<20121025124832.840241082@chello.nl>
	<CA+55aFxRh43832cEW39t0+d1Sdz46Up6Za9w641jpWukmi4zFw@mail.gmail.com>
	<5089F5B5.1050206@redhat.com>
	<CA+55aFwcj=nh1RUmEXUk6W3XwfbdQdQofkkCstbLGVo1EoKryA@mail.gmail.com>
	<508A0A0D.4090001@redhat.com>
	<CA+55aFx2fSdDcFxYmu00JP9rHiZ1BjH3tO4CfYXOhf_rjRP_Eg@mail.gmail.com>
	<CANN689EHj2inp+wjJGcqMHZQUV3Xm+3dAkLPOsnV4RZU+Kq5nA@mail.gmail.com>
	<m2pq45qu0s.fsf@firstfloor.org>
	<508A8D31.9000106@redhat.com>
	<20121026132601.GC9886@gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1440
Lines: 41

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@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Michel Lespinasse <walken@google.com>
Cc: Ingo Molnar <mingo@kernel.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;


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/