From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 18 Nov 2008 16:56:57 +0000 (GMT) From: Hugh Dickins Subject: Re: [PATCH mmotm] memcg: avoid using buggy kmap at swap_cgroup In-Reply-To: Message-ID: References: <20081118180721.cb2fe744.nishimura@mxp.nes.nec.co.jp><20081118182637.97ae0e48.kamezawa.hiroyu@jp.fujitsu.com><20081118192135.300803ec.nishimura@mxp.nes.nec.co.jp><20081118210838.c99887fd.nishimura@mxp.nes.nec.co.jp> <20081119001756.0a31b11e.d-nishimura@mtf.biglobe.ne.jp> <6023.10.75.179.61.1227024730.squirrel@webmail-b.css.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: KAMEZAWA Hiroyuki Cc: Daisuke Nishimura , Andrew Morton , linux-mm , Balbir Singh , Pavel Emelianov , LiZefan List-ID: On Tue, 18 Nov 2008, Hugh Dickins wrote: > On Wed, 19 Nov 2008, KAMEZAWA Hiroyuki wrote: > > > 2. later, add kmap_atomic + HighMem buffer support in explicit style. > > maybe KM_BOUNCE_READ...can be used..... > > It's hardly appropriate (there's no bouncing here), and you could only > use it if you disable interrupts. Oh, you do disable interrupts: > why's that? In fact, why do you even need the spinlock? I can see that you would need it if in future you reduce the size of the elements of the array from pointers; but at present, aren't you already in trouble if there's a race on the pointer? 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/ . Don't email: email@kvack.org