From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id 6DB7C6B007E for ; Wed, 1 Jun 2016 14:37:09 -0400 (EDT) Received: by mail-wm0-f71.google.com with SMTP id e3so15999832wme.3 for ; Wed, 01 Jun 2016 11:37:09 -0700 (PDT) Received: from vena.lwn.net (tex.lwn.net. [70.33.254.29]) by mx.google.com with ESMTPS id s10si49919951wjm.110.2016.06.01.11.37.08 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 01 Jun 2016 11:37:08 -0700 (PDT) Date: Wed, 1 Jun 2016 12:37:05 -0600 From: Jonathan Corbet 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> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: 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 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org