From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750800AbVHHKOr (ORCPT ); Mon, 8 Aug 2005 06:14:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750804AbVHHKOr (ORCPT ); Mon, 8 Aug 2005 06:14:47 -0400 Received: from [81.2.110.250] ([81.2.110.250]:3029 "EHLO localhost.localdomain") by vger.kernel.org with ESMTP id S1750800AbVHHKOr (ORCPT ); Mon, 8 Aug 2005 06:14:47 -0400 Subject: Re: overcommit verses MAP_NORESERVE From: Alan Cox To: Nicholas Miell Cc: linux-kernel@vger.kernel.org In-Reply-To: <1123485777.17857.10.camel@localhost.localdomain> References: <1123386755.26540.9.camel@localhost.localdomain> <1123415381.9464.29.camel@localhost.localdomain> <1123485777.17857.10.camel@localhost.localdomain> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Mon, 08 Aug 2005 11:41:01 +0100 Message-Id: <1123497662.28681.2.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.2.2 (2.2.2-5) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Llu, 2005-08-08 at 00:22 -0700, Nicholas Miell wrote: > I don't think you can forcibly reclaim MAP_NORESERVE objects (I'm > assuming you mean completely throwing away dirty pages). In which case there is no real difference between MAP_NORESERVE and not setting it when doing zero overcommit as we do the accounting currently. > not other errors) and individual writes to unallocated pages in a > MAP_NORESERVE region should either allocate a new page if possible or > send a SIGSEGV without triggering the OOM killer. You'd need to track vma cost seperately which we don't do now and adjust it for such mappings in the page faulting cases. Certainly practical - send a patch