From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (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 40d9qK1S35zDrDT for ; Sat, 5 May 2018 11:13:00 +1000 (AEST) Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w4518oeP043595 for ; Fri, 4 May 2018 21:12:58 -0400 Received: from e06smtp15.uk.ibm.com (e06smtp15.uk.ibm.com [195.75.94.111]) by mx0b-001b2d01.pphosted.com with ESMTP id 2hs21n13gj-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 04 May 2018 21:12:57 -0400 Received: from localhost by e06smtp15.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Sat, 5 May 2018 02:12:56 +0100 Date: Fri, 4 May 2018 18:12:43 -0700 From: Ram Pai To: Dave Hansen Cc: mpe@ellerman.id.au, mingo@redhat.com, akpm@linux-foundation.org, 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 Subject: Re: [PATCH v13 3/3] mm, powerpc, x86: introduce an additional vma bit for powerpc pkey Reply-To: Ram Pai References: <1525471183-21277-1-git-send-email-linuxram@us.ibm.com> <1525471183-21277-3-git-send-email-linuxram@us.ibm.com> <1e37895e-5a18-11c1-58f1-834f96dfd4d5@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1e37895e-5a18-11c1-58f1-834f96dfd4d5@intel.com> Message-Id: <20180505011243.GB5617@ram.oc3035372033.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, May 04, 2018 at 03:57:33PM -0700, Dave Hansen wrote: > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > > index 0c9e392..3ddddc7 100644 > > --- a/fs/proc/task_mmu.c > > +++ b/fs/proc/task_mmu.c > > @@ -679,6 +679,7 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma) > > [ilog2(VM_PKEY_BIT1)] = "", > > [ilog2(VM_PKEY_BIT2)] = "", > > [ilog2(VM_PKEY_BIT3)] = "", > > + [ilog2(VM_PKEY_BIT4)] = "", > > #endif /* CONFIG_ARCH_HAS_PKEYS */ > ... > > +#if defined(CONFIG_PPC) > > +# define VM_PKEY_BIT4 VM_HIGH_ARCH_4 > > +#else > > +# define VM_PKEY_BIT4 0 > > +#endif > > #endif /* CONFIG_ARCH_HAS_PKEYS */ > > That new line boils down to: > > [ilog2(0)] = "", > > on x86. It wasn't *obvious* to me that it is OK to do that. The other > possibly undefined bits (VM_SOFTDIRTY for instance) #ifdef themselves > out of this array. > > I would just be a wee bit worried that this would overwrite the 0 entry > ("??") with "". Yes it would :-( and could potentially break anything that depends on 0th entry being "??" Is the following fix acceptable? #if VM_PKEY_BIT4 [ilog2(VM_PKEY_BIT4)] = "", #endif -- Ram Pai