Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751632AbbG0Hbh (ORCPT ); Mon, 27 Jul 2015 03:31:37 -0400 Received: from mail-wi0-f179.google.com ([209.85.212.179]:35924 "EHLO mail-wi0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750854AbbG0Hbd (ORCPT ); Mon, 27 Jul 2015 03:31:33 -0400 Date: Mon, 27 Jul 2015 10:31:29 +0300 From: "Kirill A. Shutemov" To: Eric B Munson Cc: Andrew Morton , Michal Hocko , Vlastimil Babka , Paul Gortmaker , Chris Metcalf , Guenter Roeck , linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mips@linux-mips.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org Subject: Re: [PATCH V5 5/7] mm: mmap: Add mmap flag to request VM_LOCKONFAULT Message-ID: <20150727073129.GE11657@node.dhcp.inet.fi> References: <1437773325-8623-1-git-send-email-emunson@akamai.com> <1437773325-8623-6-git-send-email-emunson@akamai.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1437773325-8623-6-git-send-email-emunson@akamai.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 969 Lines: 24 On Fri, Jul 24, 2015 at 05:28:43PM -0400, Eric B Munson wrote: > The cost of faulting in all memory to be locked can be very high when > working with large mappings. If only portions of the mapping will be > used this can incur a high penalty for locking. > > Now that we have the new VMA flag for the locked but not present state, > expose it as an mmap option like MAP_LOCKED -> VM_LOCKED. As I mentioned before, I don't think this interface is justified. MAP_LOCKED has known issues[1]. The MAP_LOCKED problem is not necessary affects MAP_LOCKONFAULT, but still. Let's not add new interface unless it's demonstrably useful. [1] http://lkml.kernel.org/g/20150114095019.GC4706@dhcp22.suse.cz -- Kirill A. Shutemov -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/