From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f178.google.com (mail-wi0-f178.google.com [209.85.212.178]) by kanga.kvack.org (Postfix) with ESMTP id 50D4D6B0255 for ; Mon, 27 Jul 2015 03:31:34 -0400 (EDT) Received: by wibxm9 with SMTP id xm9so103309913wib.1 for ; Mon, 27 Jul 2015 00:31:33 -0700 (PDT) Received: from mail-wi0-f182.google.com (mail-wi0-f182.google.com. [209.85.212.182]) by mx.google.com with ESMTPS id n7si29323841wjb.50.2015.07.27.00.31.32 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 27 Jul 2015 00:31:33 -0700 (PDT) Received: by wicmv11 with SMTP id mv11so127120933wic.0 for ; Mon, 27 Jul 2015 00:31:32 -0700 (PDT) Date: Mon, 27 Jul 2015 10:31:29 +0300 From: "Kirill A. Shutemov" 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> Sender: owner-linux-mm@kvack.org List-ID: 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 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, 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