From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752088AbcEKLSM (ORCPT ); Wed, 11 May 2016 07:18:12 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:51666 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751372AbcEKLSL (ORCPT ); Wed, 11 May 2016 07:18:11 -0400 Subject: Re: [PATCH 1/2] mmap.2: clarify MAP_LOCKED semantic To: Michal Hocko , Michael Kerrisk References: <1431527892-2996-1-git-send-email-miso@dhcp22.suse.cz> <1431527892-2996-2-git-send-email-miso@dhcp22.suse.cz> <57331275.9000805@infradead.org> Cc: Andrew Morton , Linus Torvalds , David Rientjes , LKML , Linux API , linux-mm@kvack.org, Michal Hocko From: Peter Zijlstra Message-ID: <573314ED.4090704@infradead.org> Date: Wed, 11 May 2016 13:18:05 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.2 MIME-Version: 1.0 In-Reply-To: <57331275.9000805@infradead.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/11/2016 01:07 PM, Peter Zijlstra wrote: > On 05/13/2015 04:38 PM, Michal Hocko wrote: >> >> This patch makes the semantic of MAP_LOCKED explicit and suggest using >> mmap + mlock as the only way to guarantee no later major page faults. >> > > URGH, this really blows chunks. It basically means MAP_LOCKED is > pointless cruft and we might as well remove it. > > Why not fix it proper? OK; after having been pointed at this discussion, it seems I reacted rather too hasty in that I didn't read all the previous threads. From that it appears fixing this proper is indeed rather hard, and we should indeed consider MAP_LOCKED broken. At which point I would've worded the manpage update stronger, but alas. Sorry for the noise.