From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751109AbcFAShK (ORCPT ); Wed, 1 Jun 2016 14:37:10 -0400 Received: from tex.lwn.net ([70.33.254.29]:37124 "EHLO vena.lwn.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750742AbcFAShI (ORCPT ); Wed, 1 Jun 2016 14:37:08 -0400 Date: Wed, 1 Jun 2016 12:37:05 -0600 From: Jonathan Corbet To: Dave Hansen Cc: linux-kernel@vger.kernel.org, x86@kernel.org, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, dave.hansen@linux.intel.com Subject: Re: [PATCH 5/8] x86, pkeys: allocation/free syscalls Message-ID: <20160601123705.72a606e7@lwn.net> In-Reply-To: <20160531152822.FE8D405E@viggo.jf.intel.com> References: <20160531152814.36E0B9EE@viggo.jf.intel.com> <20160531152822.FE8D405E@viggo.jf.intel.com> Organization: LWN.net MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sorry, I have one more obnoxious question... > +static inline > +int mm_pkey_free(struct mm_struct *mm, int pkey) > +{ > + /* > + * pkey 0 is special, always allocated and can never > + * be freed. > + */ > + if (!pkey || !validate_pkey(pkey)) > + return -EINVAL; > + if (!mm_pkey_is_allocated(mm, pkey)) > + return -EINVAL; > + > + mm_set_pkey_free(mm, pkey); > + > + return 0; > +} If I read this right, it doesn't actually remove any pkey restrictions that may have been applied while the key was allocated. So there could be pages with that key assigned that might do surprising things if the key is reallocated for another use later, right? Is that how the API is intended to work? Thanks, jon