Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753879Ab1DRBVj (ORCPT ); Sun, 17 Apr 2011 21:21:39 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:51514 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751985Ab1DRBVd (ORCPT ); Sun, 17 Apr 2011 21:21:33 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 From: KOSAKI Motohiro To: Hugh Dickins Subject: Re: mm: convert vma->vm_flags to 64bit Cc: kosaki.motohiro@jp.fujitsu.com, LKML , linux-mm , Andrew Morton , Benjamin Herrenschmidt , Dave Hansen , KAMEZAWA Hiroyuki , Paul Mundt , Russell King In-Reply-To: References: <20110412151116.B50D.A69D9226@jp.fujitsu.com> Message-Id: <20110418102128.933A.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.56.05 [ja] Date: Mon, 18 Apr 2011 10:21:29 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2470 Lines: 66 Hi > On Tue, 12 Apr 2011, KOSAKI Motohiro wrote: > > > > Benjamin, Hugh, I hope to add your S-O-B to this one because you are original author. > > Can I do? > > Well, now you've fixed the mm/fremap.c omission, you're welcome to my > Acked-by: Hugh Dickins Thank you! > I happen not to shared Ben's aversion to unsigned long long, I just > don't really care one way or another on that; but I do get irritated by > obfuscatory types which we then have to cast or unfold all over the place, > I don't know if vm_flags_t would have been in that category or not. I agree. > You've made a few different choices than I did, okay: the only place > where it might be worth disagreeing with you, is on mm->def_flags: > I would rather make that an unsigned int than an unsigned long long, > to save 4 bytes on 64-bit (if it were moved) rather than waste 4 bytes > on 32-bit - in the unlikely event that someone adds a high VM_flag to > def_flags, I'd rather hope they would test its effect. However, > it's every mm not every vma, so maybe not worth worrying about. Yeap. I thought it is one of typical easy-read-code vs memory-footprint trade-off. And after I looked size of task_struct, I was lost interest to spned my time to keep small mm_struct size. ;-) off-topic, if mm_struct size is performance important, we have to get rid of mm->cpu_vm_mask from mm_struct at first. cpumask_t use NR_CPUS/8 bytes and NR_CPUS==4096 when we use recent distros. it's one of root cause of mm_struct bloat. > I am surprised that > #define VM_EXEC 0x00000004ULL > does not cause trouble for arch/arm/kernel/asm-offsets.c, > but you tried cross-building it which I never did. > > Does your later addition of __nocast on vm_flags not make trouble > for the unsigned long casts in arch/arm/include/asm/cacheflush.h? > (And if it does not, then just what does __nocast do?) If my understanding is correct, __nocast mean warn _implicit_ narrowing conversion. Thus, arm defconfig cross build doesn't make any warn nor error. :) side note: honestly says, I know arm defconfig doesn't build many subarch specific cacheflush code. But I have no way to confirm it. ;) > > Thanks for seeing this through, > Hugh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/