From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id 2F37E6B0005 for ; Thu, 15 Mar 2018 13:50:02 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id j12so3535987pff.18 for ; Thu, 15 Mar 2018 10:50:02 -0700 (PDT) Received: from mga11.intel.com (mga11.intel.com. [192.55.52.93]) by mx.google.com with ESMTPS id q4-v6si4344273plr.365.2018.03.15.10.50.00 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 15 Mar 2018 10:50:01 -0700 (PDT) Subject: Re: [PATCH v3] x86: treat pkey-0 special References: <1521061214-22385-1-git-send-email-linuxram@us.ibm.com> <20180315172129.GD1060@ram.oc3035372033.ibm.com> From: Dave Hansen Message-ID: <2bf8e659-5a8d-a2d5-ea52-e4d395ea2201@intel.com> Date: Thu, 15 Mar 2018 10:31:51 -0700 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: owner-linux-mm@kvack.org List-ID: To: Ram Pai 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 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?