From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f72.google.com (mail-it0-f72.google.com [209.85.214.72]) by kanga.kvack.org (Postfix) with ESMTP id 146506B0038 for ; Wed, 14 Sep 2016 10:41:11 -0400 (EDT) Received: by mail-it0-f72.google.com with SMTP id 186so58668514itf.2 for ; Wed, 14 Sep 2016 07:41:11 -0700 (PDT) Received: from g2t2354.austin.hpe.com (g2t2354.austin.hpe.com. [15.233.44.27]) by mx.google.com with ESMTPS id d139si10266611oih.268.2016.09.14.07.40.53 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 14 Sep 2016 07:40:53 -0700 (PDT) Subject: Re: [kernel-hardening] [RFC PATCH v2 2/3] xpfo: Only put previous userspace pages into the hot cache References: <20160902113909.32631-1-juerg.haefliger@hpe.com> <20160914071901.8127-1-juerg.haefliger@hpe.com> <20160914071901.8127-3-juerg.haefliger@hpe.com> <57D95FA3.3030103@intel.com> From: Juerg Haefliger Message-ID: <7badeb6c-e343-4327-29ed-f9c9c0b6654b@hpe.com> Date: Wed, 14 Sep 2016 16:40:49 +0200 MIME-Version: 1.0 In-Reply-To: <57D95FA3.3030103@intel.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="MvDRGgCgUqFIL4RSGlCO7Xs24fkENiwV2" Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen , kernel-hardening@lists.openwall.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-x86_64@vger.kernel.org Cc: vpk@cs.columbia.edu This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --MvDRGgCgUqFIL4RSGlCO7Xs24fkENiwV2 Content-Type: multipart/mixed; boundary="O1CtIAVv6aLLWs1NIc0rmG57UUaBW7E7P"; protected-headers="v1" From: Juerg Haefliger To: Dave Hansen , kernel-hardening@lists.openwall.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-x86_64@vger.kernel.org Cc: vpk@cs.columbia.edu Message-ID: <7badeb6c-e343-4327-29ed-f9c9c0b6654b@hpe.com> Subject: Re: [kernel-hardening] [RFC PATCH v2 2/3] xpfo: Only put previous userspace pages into the hot cache References: <20160902113909.32631-1-juerg.haefliger@hpe.com> <20160914071901.8127-1-juerg.haefliger@hpe.com> <20160914071901.8127-3-juerg.haefliger@hpe.com> <57D95FA3.3030103@intel.com> In-Reply-To: <57D95FA3.3030103@intel.com> --O1CtIAVv6aLLWs1NIc0rmG57UUaBW7E7P Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Hi Dave, On 09/14/2016 04:33 PM, Dave Hansen wrote: > On 09/14/2016 12:19 AM, Juerg Haefliger wrote: >> Allocating a page to userspace that was previously allocated to the >> kernel requires an expensive TLB shootdown. To minimize this, we only >> put non-kernel pages into the hot cache to favor their allocation. >=20 > Hi, I had some questions about this the last time you posted it. Maybe= > you want to address them now. I did reply: https://lkml.org/lkml/2016/9/5/249 =2E..Juerg > -- >=20 > But kernel allocations do allocate from these pools, right? Does this > just mean that kernel allocations usually have to pay the penalty to > convert a page? >=20 > So, what's the logic here? You're assuming that order-0 kernel > allocations are more rare than allocations for userspace? >=20 --O1CtIAVv6aLLWs1NIc0rmG57UUaBW7E7P-- --MvDRGgCgUqFIL4RSGlCO7Xs24fkENiwV2 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 iQIcBAEBCAAGBQJX2WFxAAoJEHVMOpb5+LSMrQoP/jtdf3Fbc1bSXJXL93ntuPf7 i3r1RKdrhfJgT8ScBPMs4PUahWaZMA/ktMfteu53+HXIIThGZNc5N5+T7VIrt7Xn rj594vhVfeXftedOqjlRIO2r2LRubX6qD+7oRHf5yLHhdr7W1wgFv7cZModu6Nuj h61J5RZoKGzogN0/Tn5hOoe6s6MS3qdcBaPNDFBTs0ZJz4s0X+i70pz9ysIH2jgS kgxuQJ1bWnvZztlkzGJZLiK1CNBezHHy58zFyFx7HJTNR4G5FW+2nNyqVUUXIRvi GddECUJaPPIIuIyNfeuiFqiJ5oYjuzhWKDbMfZXTaRfZr1mCtmUcwSjuiv/NlOJI ynuq+A+GnTxSiXqQtenuARSzgz8QCkBi9ZuDzHU6wlSY3/GVO3XVf0yhqpYwEbQF pHV3Rjrwkx+rOa35wTYkdR+JCEZZQoxQj9tXyGpctxrbZStc5eOuIRHzJu2mZo7P eiGy4UsdNR+RtClauD+4QMLb4udStmFMG3RMwA78ioJYZE4j93QHGJN7+HBq/e7d FuEkuWcAk/UsNVJdfuBjHyATNin+wjxrllEcPA4OPzHEbMevsXO4AE8ucmDSNGvD hWa50Ahf8x/Zx/FvyBUSD7+g5c5CK9wNLdE70WwWUkphFGEhbJFhIm7wrTv0700g KGlgI1DsXBwxzIzvnv/8 =T/wt -----END PGP SIGNATURE----- --MvDRGgCgUqFIL4RSGlCO7Xs24fkENiwV2-- -- 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