Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753689AbbG0Nlb (ORCPT ); Mon, 27 Jul 2015 09:41:31 -0400 Received: from prod-mail-xrelay02.akamai.com ([72.246.2.14]:60291 "EHLO prod-mail-xrelay02.akamai.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751632AbbG0Nl2 (ORCPT ); Mon, 27 Jul 2015 09:41:28 -0400 Date: Mon, 27 Jul 2015 09:41:26 -0400 From: Eric B Munson To: "Kirill A. Shutemov" 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: <20150727134126.GB17133@akamai.com> References: <1437773325-8623-1-git-send-email-emunson@akamai.com> <1437773325-8623-6-git-send-email-emunson@akamai.com> <20150727073129.GE11657@node.dhcp.inet.fi> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="H1spWtNR+x+ondvy" Content-Disposition: inline In-Reply-To: <20150727073129.GE11657@node.dhcp.inet.fi> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2538 Lines: 63 --H1spWtNR+x+ondvy Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, 27 Jul 2015, Kirill A. Shutemov wrote: > 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. > >=20 > > 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. >=20 > As I mentioned before, I don't think this interface is justified. >=20 > MAP_LOCKED has known issues[1]. The MAP_LOCKED problem is not necessary > affects MAP_LOCKONFAULT, but still. >=20 > Let's not add new interface unless it's demonstrably useful. >=20 > [1] http://lkml.kernel.org/g/20150114095019.GC4706@dhcp22.suse.cz I understand and should have been more explicit. This patch is still included becuase I have an internal user that wants to see it added. The problem discussed in the thread you point out does not affect MAP_LOCKONFAULT because we do not attempt to populate the region with MAP_LOCKONFAULT. As I told Vlastimil, if this is a hard NAK with the patch I can work with that. Otherwise I prefer it stays. --H1spWtNR+x+ondvy Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJVtjUGAAoJELbVsDOpoOa9FEQP/0tZqvE9r1cDWHP2fRNfVeMA 4SA6NwWvWAlS3Jyzwqin6jEPfTp5mp9XmBs2OSFCUtRM4gheS+V0qm4UMCoUUe8V 1biXRm6JAcqlQ9RaQsIleuwtu6rfq/VmPvyXfoh2VzHtHkfJH1es+IuzyMvN8rB2 +dMOrDXpr0TGzV2pUXmpqvJV9XCuJJqC2EUp3ygCjCsxtir7que+hBurNHk6V37o SJPg+1fOfKlZC2JoH1e3nlaNa8E7Tgn3CcaS95PJGtjp3B3B/WFHyQsV7ICDCPph p1DS8lNn1AHvC8Ia1b9q9k6iuPVpunFRthVyXLfDtb7UVDxyDBAbBArQMlSqdS98 7s+Am4nRAqQ4hyvCrfFbkXyplihX34uwmi263r7pAPizwJRx/ArnJk+EJK6Qclp+ aiL2BO8PJR2vPi7BfsPSBcgd68iEeCCsOpNGD3GyQ3C5tdtZK/MaDmZm2cCdzaZg pWkEgj3oi8jiTD59NskpqqsmtWahucR6HVXAF6DNvZXypigq+uvnaqImEOxpOEQR h1zR5O8L5jnZO1BYAHpJO1+16ZAPcNa2tF20OcxsAvcGvblbFNYG1jzAE6w9FGbz Qr4VU8B1u/IiDGuHNroiwrTOlN7Tn7wYN0/bstOPk3UavEmg3wEuOaaQat2CU7pC rLymWmGP9Rc0+NgO/vMz =Leis -----END PGP SIGNATURE----- --H1spWtNR+x+ondvy-- -- 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/