From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752455AbeCORcC (ORCPT ); Thu, 15 Mar 2018 13:32:02 -0400 Received: from mga14.intel.com ([192.55.52.115]:39465 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752011AbeCORb4 (ORCPT ); Thu, 15 Mar 2018 13:31:56 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.48,311,1517904000"; d="scan'208";a="42350261" Subject: Re: [PATCH v3] x86: treat pkey-0 special To: Ram Pai References: <1521061214-22385-1-git-send-email-linuxram@us.ibm.com> <20180315172129.GD1060@ram.oc3035372033.ibm.com> Cc: Thomas Gleixner , mingo@redhat.com, mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, x86@kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, benh@kernel.crashing.org, paulus@samba.org, khandual@linux.vnet.ibm.com, aneesh.kumar@linux.vnet.ibm.com, bsingharora@gmail.com, hbabu@us.ibm.com, mhocko@kernel.org, bauerman@linux.vnet.ibm.com, ebiederm@xmission.com, corbet@lwn.net, arnd@arndb.de, fweimer@redhat.com, msuchanek@suse.com, Ulrich.Weigand@de.ibm.com From: Dave Hansen Message-ID: <2bf8e659-5a8d-a2d5-ea52-e4d395ea2201@intel.com> Date: Thu, 15 Mar 2018 10:31:51 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20180315172129.GD1060@ram.oc3035372033.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/15/2018 10:21 AM, Ram Pai wrote: > On Thu, Mar 15, 2018 at 08:55:31AM -0700, Dave Hansen wrote: >> On 03/15/2018 02:46 AM, Thomas Gleixner wrote: >>>> + if (!pkey || !mm_pkey_is_allocated(mm, pkey)) >>> Why this extra check? mm_pkey_is_allocated(mm, 0) should not return true >>> ever. If it does, then this wants to be fixed. >> I was thinking that we _do_ actually want it to seem allocated. It just >> get "allocated" implicitly when an mm is created. I think that will >> simplify the code if we avoid treating it specially in as many places as >> possible. > I think, the logic that makes pkey-0 special must to go > in arch-neutral code. How about checking for pkey-0 in sys_pkey_free() > itself? This is for protection against shooting yourself in the foot? Yes, that can go in sys_pkey_free(). Does this need manpage and/or selftests updates?