From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3zqvjD1mX6zDrL0 for ; Tue, 27 Feb 2018 08:14:38 +1100 (AEDT) Subject: Re: [PATCH v12 2/3] mm, powerpc, x86: introduce an additional vma bit for powerpc pkey To: Ram Pai , mpe@ellerman.id.au, mingo@redhat.com, akpm@linux-foundation.org References: <1519257138-23797-1-git-send-email-linuxram@us.ibm.com> <1519257138-23797-3-git-send-email-linuxram@us.ibm.com> Cc: linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, x86@kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.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 From: Dave Hansen Message-ID: Date: Mon, 26 Feb 2018 13:14:34 -0800 MIME-Version: 1.0 In-Reply-To: <1519257138-23797-3-git-send-email-linuxram@us.ibm.com> Content-Type: text/plain; charset=utf-8 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 02/21/2018 03:52 PM, Ram Pai wrote: > diff --git a/include/linux/mm.h b/include/linux/mm.h > index ad207ad..d534f46 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -231,9 +231,10 @@ extern int overcommit_kbytes_handler(struct ctl_table *, int, void __user *, > #ifdef CONFIG_ARCH_HAS_PKEYS > # define VM_PKEY_SHIFT VM_HIGH_ARCH_BIT_0 > # define VM_PKEY_BIT0 VM_HIGH_ARCH_0 /* A protection key is a 4-bit value */ > -# define VM_PKEY_BIT1 VM_HIGH_ARCH_1 > +# define VM_PKEY_BIT1 VM_HIGH_ARCH_1 /* on x86 and 5-bit value on ppc64 */ > # define VM_PKEY_BIT2 VM_HIGH_ARCH_2 > # define VM_PKEY_BIT3 VM_HIGH_ARCH_3 > +# define VM_PKEY_BIT4 VM_HIGH_ARCH_4 > #endif /* CONFIG_ARCH_HAS_PKEYS */ I think I would prefer if VM_PKEY_BIT4 was unusable on x86, or #defined to 0. We don't want folks using a bit that can not be programmed into the hardware.