From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id ED6F1900086 for ; Sun, 17 Apr 2011 21:21:33 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp (unknown [10.0.50.73]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id 4FCD13EE0BB for ; Mon, 18 Apr 2011 10:21:30 +0900 (JST) Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 34F1145DE93 for ; Mon, 18 Apr 2011 10:21:30 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 160DD45DE8F for ; Mon, 18 Apr 2011 10:21:30 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 04374E08002 for ; Mon, 18 Apr 2011 10:21:30 +0900 (JST) Received: from ml13.s.css.fujitsu.com (ml13.s.css.fujitsu.com [10.240.81.133]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id C2B711DB8038 for ; Mon, 18 Apr 2011 10:21:29 +0900 (JST) From: KOSAKI Motohiro Subject: Re: mm: convert vma->vm_flags to 64bit 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 Date: Mon, 18 Apr 2011 10:21:29 +0900 (JST) Sender: owner-linux-mm@kvack.org List-ID: To: Hugh Dickins Cc: kosaki.motohiro@jp.fujitsu.com, LKML , linux-mm , Andrew Morton , Benjamin Herrenschmidt , Dave Hansen , KAMEZAWA Hiroyuki , Paul Mundt , Russell King 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, 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org