From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752168AbdGGSsv (ORCPT ); Fri, 7 Jul 2017 14:48:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49590 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750848AbdGGSst (ORCPT ); Fri, 7 Jul 2017 14:48:49 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 973CD7D0CB Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=jglisse@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 973CD7D0CB Date: Fri, 7 Jul 2017 14:48:44 -0400 From: Jerome Glisse To: Igor Stoppa Cc: keescook@chromium.org, mhocko@kernel.org, jmorris@namei.org, labbott@redhat.com, hch@infradead.org, penguin-kernel@I-love.SAKURA.ne.jp, paul@paul-moore.com, sds@tycho.nsa.gov, casey@schaufler-ca.com, linux-security-module@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com Subject: Re: [PATCH 1/3] Protectable memory support Message-ID: <20170707184843.GA3113@redhat.com> References: <20170705134628.3803-1-igor.stoppa@huawei.com> <20170705134628.3803-2-igor.stoppa@huawei.com> <20170706162742.GA2919@redhat.com> <1665fd00-5908-2399-577d-1972c7d1c63b@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1665fd00-5908-2399-577d-1972c7d1c63b@huawei.com> User-Agent: Mutt/1.8.2 (2017-04-18) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Fri, 07 Jul 2017 18:48:49 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 07, 2017 at 11:42:09AM +0300, Igor Stoppa wrote: > On 06/07/17 19:27, Jerome Glisse wrote: > > On Wed, Jul 05, 2017 at 04:46:26PM +0300, Igor Stoppa wrote: [...] > > Yet another way is to use some of the free struct page fields ie > > when a page is allocated for vmalloc i think most of struct page > > fields are unuse (mapping, index, lru, ...). It would be better > > to use those rather than adding a page flag. > > Like introducing an unnamed union? Some sort of vmalloc_page_subtype? > If that is what you are proposing, I agree that it would work in a > similar fashion as what I have now, but without introducing the overhead > of the extra page flag. No need to introduce unamed union or anything. Just use one of the existing field for install you can make page->mapping point to the pmalloc pool structure. Or you can store a unique key value. I believe there is enough unuse field that for vmalloc pages that you should find one you can use. Just add some documentation in mm_types.h so people are aware of alternate use for the field you are using. Jérôme