From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753780AbZEJNST (ORCPT ); Sun, 10 May 2009 09:18:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752225AbZEJNSE (ORCPT ); Sun, 10 May 2009 09:18:04 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:45384 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751673AbZEJNSD (ORCPT ); Sun, 10 May 2009 09:18:03 -0400 Subject: Re: [PATCH -mm] vmscan: make mapped executable pages the first class citizen From: Peter Zijlstra To: KOSAKI Motohiro Cc: Wu Fengguang , Alan Cox , Andrew Morton , "hannes@cmpxchg.org" , "riel@redhat.com" , "linux-kernel@vger.kernel.org" , "tytso@mit.edu" , "linux-mm@kvack.org" , "elladan@eskimo.com" , "npiggin@suse.de" , "cl@linux-foundation.org" , "minchan.kim@gmail.com" In-Reply-To: <2f11576a0905100539l1512170oc64f7aee2864e8d5@mail.gmail.com> References: <20090508081608.GA25117@localhost> <2f11576a0905100159m32c36a9ep9fb7cc5604c60b2@mail.gmail.com> <20090510092053.GA7651@localhost> <2f11576a0905100229m2c5e6a67md555191dc8c374ae@mail.gmail.com> <20090510100335.GC7651@localhost> <2f11576a0905100315j2c810e96mc29b84647dc565c2@mail.gmail.com> <20090510112149.GA8633@localhost> <2f11576a0905100439u38c8bccak355ec23953950d6@mail.gmail.com> <20090510114454.GA8891@localhost> <1241957948.9562.2.camel@laptop> <2f11576a0905100539l1512170oc64f7aee2864e8d5@mail.gmail.com> Content-Type: text/plain Date: Sun, 10 May 2009 15:17:21 +0200 Message-Id: <1241961441.9562.63.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.26.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2009-05-10 at 21:39 +0900, KOSAKI Motohiro wrote: > >> > They always use mmap(PROT_READ | PROT_WRITE | PROT_EXEC) for anycase. > >> > Please google it. you can find various example. > >> > >> How widely is PROT_EXEC abused? Would you share some of your google results? > > > > That's a security bug right there and should be fixed regardless of our > > heuristics. > > Yes, should be. but it's not security issue. it doesn't make any security hole. > Plus, this claim doesn't help to solve end-user problems. Having more stuff executable than absolutely needed is always a security issue. > I think the basic concept of the patch is right. > - executable mapping is important for good latency > - executable file is relatively small > > The last problem is, The patch assume executable mappings is rare, but > it isn't guranteed. > How do we separate truth executable mapping and mis-used PROT_EXEC usage? One could possibly limit the size, but I don't think it pays to bother about this until we really run into it, again as Andrew already said, there's more ways to screw reclaim if you really want to. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id BEAED6B00A1 for ; Sun, 10 May 2009 09:17:23 -0400 (EDT) Subject: Re: [PATCH -mm] vmscan: make mapped executable pages the first class citizen From: Peter Zijlstra In-Reply-To: <2f11576a0905100539l1512170oc64f7aee2864e8d5@mail.gmail.com> References: <20090508081608.GA25117@localhost> <2f11576a0905100159m32c36a9ep9fb7cc5604c60b2@mail.gmail.com> <20090510092053.GA7651@localhost> <2f11576a0905100229m2c5e6a67md555191dc8c374ae@mail.gmail.com> <20090510100335.GC7651@localhost> <2f11576a0905100315j2c810e96mc29b84647dc565c2@mail.gmail.com> <20090510112149.GA8633@localhost> <2f11576a0905100439u38c8bccak355ec23953950d6@mail.gmail.com> <20090510114454.GA8891@localhost> <1241957948.9562.2.camel@laptop> <2f11576a0905100539l1512170oc64f7aee2864e8d5@mail.gmail.com> Content-Type: text/plain Date: Sun, 10 May 2009 15:17:21 +0200 Message-Id: <1241961441.9562.63.camel@laptop> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: Wu Fengguang , Alan Cox , Andrew Morton , "hannes@cmpxchg.org" , "riel@redhat.com" , "linux-kernel@vger.kernel.org" , "tytso@mit.edu" , "linux-mm@kvack.org" , "elladan@eskimo.com" , "npiggin@suse.de" , "cl@linux-foundation.org" , "minchan.kim@gmail.com" List-ID: On Sun, 2009-05-10 at 21:39 +0900, KOSAKI Motohiro wrote: > >> > They always use mmap(PROT_READ | PROT_WRITE | PROT_EXEC) for anycase. > >> > Please google it. you can find various example. > >> > >> How widely is PROT_EXEC abused? Would you share some of your google results? > > > > That's a security bug right there and should be fixed regardless of our > > heuristics. > > Yes, should be. but it's not security issue. it doesn't make any security hole. > Plus, this claim doesn't help to solve end-user problems. Having more stuff executable than absolutely needed is always a security issue. > I think the basic concept of the patch is right. > - executable mapping is important for good latency > - executable file is relatively small > > The last problem is, The patch assume executable mappings is rare, but > it isn't guranteed. > How do we separate truth executable mapping and mis-used PROT_EXEC usage? One could possibly limit the size, but I don't think it pays to bother about this until we really run into it, again as Andrew already said, there's more ways to screw reclaim if you really want to. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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