From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751660Ab1KCVHH (ORCPT ); Thu, 3 Nov 2011 17:07:07 -0400 Received: from home.keithp.com ([63.227.221.253]:41910 "EHLO keithp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751027Ab1KCVHG (ORCPT ); Thu, 3 Nov 2011 17:07:06 -0400 From: Keith Packard To: Daniel Vetter Cc: Daniel Vetter , Chris Wilson , Daniel Vetter , intel-gfx , stable@kernel.org, linux-kernel , "Morton\, Andrew" Subject: Re: [Intel-gfx] [PATCH 2/2] drm/i915: properly prefault for pread/pwrite In-Reply-To: <20111023221157.GH2953@phenom.ffwll.local> References: <1317203844-2930-1-git-send-email-daniel.vetter@ffwll.ch> <1317203844-2930-2-git-send-email-daniel.vetter@ffwll.ch> <20111023101830.GE2953@phenom.ffwll.local> <20111023221157.GH2953@phenom.ffwll.local> User-Agent: Notmuch/0.6.1-66-ga900dda (http://notmuchmail.org) Emacs/23.3.1 (i486-pc-linux-gnu) Date: Thu, 03 Nov 2011 14:06:55 -0700 Message-ID: MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-=-= Content-Transfer-Encoding: quoted-printable On Mon, 24 Oct 2011 00:11:57 +0200, Daniel Vetter wrote: > This patch only fixes things up so that we prefault the entire page range > and not just the first PAGE_SIZE bytes (i.e. at most 2 pages). So I don't > see the risk of extending the current behaviour to all pages. Userspace > can already see these zero writes, but only when doing something stupid. When we posted a patch to instead fix fault_in_pages_writeable, Andrew complained that we'd have modified memory even on a short read, which wasn't considered polite. Could we read/write the same value and avoid that problem? Also, we should be fixing fault_in_pages_* going forward, rather than kludging in more code. And, we'd get to remove the version in ntfs, which should end in a patch that removes more code than it adds... =2D-=20 keith.packard@intel.com --=-=-= Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQIVAwUBTrMCbzYtFsjWk68qAQgrfRAAsCZyxc9aaWTYWh6nm0TFXUiSbe3mhIRn p1l3BgsiJ+ATp53HaCFSHgG54HGNk3bxnMiUGeWg9K79UHnf8CAE3ZGWJyJmzS+t 1UOhy0lWtLl3UHmujk6jFPNgoqsAkP0KCZHXkfDr8s17JWWf5Az5kFFUg7gIzSEQ FKdQ5EMlVX+Y/yWdMIzwqCjI4UV/tKmShRDWHT64olYERFzCppOfM6SoXLijmyhV jTXTG92K2r1dw44YBDTonEVjqThaHE+rsKkVyHeZavTt3xQ1b2ug80Cv4nnbThdV swjwCpaCs7KElVRnurqJplQQWWDNVRwTRvKNzCau2D1Ji3klOTPZUZ8Xm4w2n5eP qYzerWSlEuCm/yD5eGLAD+pVBxcxltrXGTfFLtzjD4AfPCR9Bvdb4bntUgBrN4OC HmavzwPeHU6e965mHgxqWr+ZQcaFr0FG1ukEueiqbmZJi8pJYZwlkcjswMrvW/Xs y+IHyFuDYcXq9spUXEcSaz7FkL57KIwtLov98nHYvKIHTiM0ssz02ajZpcr1JLXX PPLIAAm6X8+3HrhS7Nffl4RMKQQq6xk3RqNGH86aXIwqSL1azjZMO+QsMmAaH+zI MPz+IVjRoNJF57FwwlyrmpGReIYEq+88wU1JDjr2pd8/p66Tr+U61m328P1P/07u 6w636prxbKA= =gH6w -----END PGP SIGNATURE----- --=-=-=--