From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757958AbYGDCCc (ORCPT ); Thu, 3 Jul 2008 22:02:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753491AbYGDCCX (ORCPT ); Thu, 3 Jul 2008 22:02:23 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:54281 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753459AbYGDCCX (ORCPT ); Thu, 3 Jul 2008 22:02:23 -0400 Date: Thu, 3 Jul 2008 19:01:23 -0700 From: Andrew Morton To: balbir@linux.vnet.ibm.com Cc: Hugh Dickins , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 2.6.26-rc8-mm1] memrlimit: fix mmap_sem deadlock Message-Id: <20080703190123.1d72e9d1.akpm@linux-foundation.org> In-Reply-To: <486D81B9.9030704@linux.vnet.ibm.com> References: <20080703160117.b3781463.akpm@linux-foundation.org> <486D81B9.9030704@linux.vnet.ibm.com> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.5; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 04 Jul 2008 07:19:45 +0530 Balbir Singh wrote: > Andrew Morton wrote: > > There doesn't seem to have been much discussion regarding your recent > > objections to the memrlimit patches. But it caused me to put a big > > black mark on them. Perhaps sending it all again would be helpful. > > Black marks are not good, but there have been some silly issues found with them. > I have been addressing/answering concerns raised so far. Would you like me to > fold all patches and fixes and send them out for review again? > > I was referring to the below (which is where the conversation ended). It questions the basis of the whole feature. On Wed, 25 Jun 2008 06:31:05 +0530 Balbir Singh wrote: > Hugh Dickins wrote: > > ... > > > (In passing, I'll add that I'm not a great fan of these memrlimits: > > to me it's loony to be charging people for virtual address space, > > it's _virtual_, and process A can have as much as it likes without > > affecting process B in any way. You're following the lead of RLIMIT_AS, > > but I've always thought RLIMIT_AS a lame attempt to move into the mmap > > decade, after RLIMIT_DATA and RLIMIT_STACK no longer made sense. > > > > Taking Alan Cox's Committed_AS as a limited resource charged per mm makes > > much more sense to me: but yes, it's not perfect, and it is a lot harder > > to get its accounting right, and to maintain that down the line. Okay, > > you've gone for the easier option of tracking total_vm, getting that > > right is a more achievable target. And I accept that I may be too > > pessimistic about it: total_vm may often enough give a rough > > approximation to something else worth limiting.) > > You seem to have read my mind, my motivation for memrlimits is > > 1. Administrators to set a limit and be sure that a cgroup cannot consume more > swap + RSS than the assigned virtual memory limit > 2. It allows applications to fail gracefully or decide what parts to free up > to get more memory or change their allocation pattern (a scientific application > deciding what size of matrix to allocate for example). >