From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756180Ab2CRWHx (ORCPT ); Sun, 18 Mar 2012 18:07:53 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:49236 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755198Ab2CRWHw (ORCPT ); Sun, 18 Mar 2012 18:07:52 -0400 Date: Sun, 18 Mar 2012 22:07:51 +0000 From: Al Viro To: Linus Torvalds Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [rfc][patches] fix for munmap/truncate races Message-ID: <20120318220751.GD6589@ZenIV.linux.org.uk> References: <20120318190744.GA6589@ZenIV.linux.org.uk> <20120318220610.GC6589@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120318220610.GC6589@ZenIV.linux.org.uk> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Mar 18, 2012 at 10:06:10PM +0000, Al Viro wrote: > On Sun, Mar 18, 2012 at 03:01:08PM -0700, Linus Torvalds wrote: > > On Sun, Mar 18, 2012 at 12:07 PM, Al Viro wrote: > > > - ? ? ? tlb_finish_mmu(&tlb, 0, end); > > > + ? ? ? tlb_finish_mmu(&tlb, 0, -1); > > > > Hmm. The fact that you drop the end pointer means that some > > architectures that optimize the TLB flushing for ranges now > > effectively can't do it any more. > > > > Now, I think it's only ia64 that really is affected, but it *might* matter. > > > > In particular, ia64 has some logic for "if you only flush one single > > region, you can optimize it", and the region sizes are in the > > terabytes. And I'm pretty sure you broke that - I'm just not entirely > > sure how much we care. > > Nope - ia64 check explicitly for precisely that case: [snip] ... and everything else doesn't look at start or end at all.