From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 84A586B005C for ; Sat, 9 May 2009 06:19:55 -0400 (EDT) Received: from m2.gw.fujitsu.co.jp ([10.0.50.72]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n49AKBl1012917 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Sat, 9 May 2009 19:20:11 +0900 Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 470ED45DE51 for ; Sat, 9 May 2009 19:20:11 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 2382145DE69 for ; Sat, 9 May 2009 19:20:11 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id F3C881DB803A for ; Sat, 9 May 2009 19:20:10 +0900 (JST) Received: from ml14.s.css.fujitsu.com (ml14.s.css.fujitsu.com [10.249.87.104]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 6C91E1DB803E for ; Sat, 9 May 2009 19:20:10 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [PATCH -mm] vmscan: make mapped executable pages the first class citizen In-Reply-To: References: <20090508034054.GB1202@eskimo.com> Message-Id: <20090509191818.3AD8.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Sat, 9 May 2009 19:20:09 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: kosaki.motohiro@jp.fujitsu.com, Elladan , Rik van Riel , Lee Schermerhorn , Peter Zijlstra , Wu Fengguang , Andrew Morton , "linux-kernel@vger.kernel.org" , "tytso@mit.edu" , "linux-mm@kvack.org" , Nick Piggin , Johannes Weiner List-ID: > On Thu, 7 May 2009, Elladan wrote: > > > > Nobody (except you) is proposing that we completely disable > > > the eviction of executable pages. I believe that your idea > > > could easily lead to a denial of service attack, with a user > > > creating a very large executable file and mmaping it. > > The amount of mlockable pages is limited via ulimit. We can already make > the pages unreclaimable through mlock(). > > > I don't know of any distro that applies default ulimits, so desktops are > > already susceptible to the far more trivial "call malloc a lot" or "fork bomb" > > attacks. Plus, ulimits don't help, since they only apply per process - you'd > > need a default mem cgroup before this mattered, I think. > > The point remains that the proposed patch does not solve the general > problem that we encounter with exec pages of critical components of the > user interface being evicted from memory. > > Do we have test data that shows a benefit? The description is minimal. Rik > claimed on IRC that tests have been done. If so then the patch description > should include the tests. Which loads benefit from this patch? > > A significant change to the reclaim algorithm also needs to > have a clear description of the effects on reclaim behavior which is also > lacking. btw, This is very good news to me. Recently I've taked sevaral time for reproducing this issue. but I have no luck. I'm interesting its test-case. Thanks. -- 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