From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx179.postini.com [74.125.245.179]) by kanga.kvack.org (Postfix) with SMTP id 163616B007B for ; Fri, 26 Oct 2012 14:49:10 -0400 (EDT) Received: by mail-we0-f169.google.com with SMTP id u3so1930015wey.14 for ; Fri, 26 Oct 2012 11:49:08 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20121026144615.2276cd59@dull> References: <20121025121617.617683848@chello.nl> <20121025124832.840241082@chello.nl> <5089F5B5.1050206@redhat.com> <508A0A0D.4090001@redhat.com> <508A8D31.9000106@redhat.com> <20121026132601.GC9886@gmail.com> <20121026144615.2276cd59@dull> From: Linus Torvalds Date: Fri, 26 Oct 2012 11:48:48 -0700 Message-ID: Subject: Re: [PATCH 3/3] mm,generic: only flush the local TLB in ptep_set_access_flags Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Rik van Riel Cc: Ingo Molnar , Andi Kleen , Michel Lespinasse , Peter Zijlstra , Andrea Arcangeli , Mel Gorman , Johannes Weiner , Thomas Gleixner , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Fri, Oct 26, 2012 at 11:46 AM, Rik van Riel wrote: > > The function ptep_set_access_flags is only ever used to upgrade > access permissions to a page. NOTE: It's *not* "access permissions". It's "access flags". Big difference. This is not about permissions at all. The access flags are the Accessed and Dirty bits. And the dirty bit is never *cleared* by this function, it's only ever potentially set. That, together with the fact that the accessed flag is "best effort" rather than exact, is what makes this function so special to begin with. Linus -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org