Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753651AbbKMINY (ORCPT ); Fri, 13 Nov 2015 03:13:24 -0500 Received: from mail-ig0-f174.google.com ([209.85.213.174]:36536 "EHLO mail-ig0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750878AbbKMINW (ORCPT ); Fri, 13 Nov 2015 03:13:22 -0500 Subject: Re: [PATCH v3 01/17] mm: support madvise(MADV_FREE) To: Minchan Kim References: <1447302793-5376-1-git-send-email-minchan@kernel.org> <1447302793-5376-2-git-send-email-minchan@kernel.org> <564421DA.9060809@gmail.com> <20151113061511.GB5235@bbox> <56458056.8020105@gmail.com> <20151113063802.GF5235@bbox> <56458720.4010400@gmail.com> <20151113070356.GG5235@bbox> Cc: Andy Lutomirski , Andrew Morton , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , Michael Kerrisk , Linux API , Hugh Dickins , Johannes Weiner , Rik van Riel , Mel Gorman , KOSAKI Motohiro , Jason Evans , "Kirill A. Shutemov" , Shaohua Li , Michal Hocko , yalin wang From: Daniel Micay X-Enigmail-Draft-Status: N1110 Message-ID: <56459B9A.7080501@gmail.com> Date: Fri, 13 Nov 2015 03:13:14 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20151113070356.GG5235@bbox> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="ecsUtC3W8kFJ8SxDviaGGgFSqHrMGNiT1" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3004 Lines: 68 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --ecsUtC3W8kFJ8SxDviaGGgFSqHrMGNiT1 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable On 13/11/15 02:03 AM, Minchan Kim wrote: > On Fri, Nov 13, 2015 at 01:45:52AM -0500, Daniel Micay wrote: >>> And now I am thinking if we use access bit, we could implment MADV_FR= EE_UNDO >>> easily when we need it. Maybe, that's what you want. Right? >> >> Yes, but why the access bit instead of the dirty bit for that? It coul= d >> always be made more strict (i.e. access bit) in the future, while goin= g >> the other way won't be possible. So I think the dirty bit is really th= e >> more conservative choice since if it turns out to be a mistake it can = be >> fixed without a backwards incompatible change. >=20 > Absolutely true. That's why I insist on dirty bit until now although > I didn't tell the reason. But I thought you wanted to change for using > access bit for the future, too. It seems MADV_FREE start to bloat > over and over again before knowing real problems and usecases. > It's almost same situation with volatile ranges so I really want to > stop at proper point which maintainer should decide, I hope. > Without it, we will make the feature a lot heavy by just brain storming= > and then causes lots of churn in MM code without real bebenfit > It would be very painful for us. Well, I don't think you need more than a good API and an implementation with no known bugs, kernel security concerns or backwards compatibility issues. Configuration and API extensions are something for later (i.e. land a baseline, then submit stuff like sysctl tunables). Just my take on it though... --ecsUtC3W8kFJ8SxDviaGGgFSqHrMGNiT1 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJWRZuaAAoJEPnnEuWa9fIqlKwP/RMTaGkNLQ9TdIGkFDZTbPG5 zOLwhzEg751X4CA+4b25bVAKoVq39rhLrnQD2BDyPbptDKXPCQ0f8Z++0lnk5qZg tybT+TJLs9SK3CA9pCHQjWtc9Dy1ekqTYkrNY0P4rcCPbxVDYaqKSwnf+O+7SZss w6jnMjLEu23zjQamBcU5dwTrvmQRXwX4Gw0jCKcRzmhECOZvKfstBEnfIDBc9glJ vytE/lXER5B3rTnp5k7NSrgE9EfNv/TTXrtbYVVAUatEhq0MBtHQ8LQdmTSgU3EA 3vk1/pXDvMa1atOw7eQdgkmDcD/dxhHFT5jsEfAV452JdVdpnRsPQYTU62rqXru+ Tnl6sej264zgSQMEWTLPbUvpPC6y9CFRIqYHLjNF5Uni8c08R7dtWaf+39r2cPXA j4gISD6Y7KxhXdewbmVnDPJEBsnM7C9AKgcs3qrOlBK824p0VqhJNF2xaryBzrF2 xfOrsg5rJuS9nJRBx254WiUa1atHhgUx8kyNx3pZLKBrsVe1pL3MbZMED73j8bv7 cyfOzYcElo3OknSsMRkkLERGD9lC+OOEADfbQGKt7NgZlf2Uxv6HR2GIOaWG9i/P T6Hk884xMmKQLl59+6s699XcYpMYJ4Tt5IdZLxghmZvBTb2/IpOn0IZI0At6dlzd hoR8O/tiXi4hxoMMW4x4 =31Tg -----END PGP SIGNATURE----- --ecsUtC3W8kFJ8SxDviaGGgFSqHrMGNiT1-- -- 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/