From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx196.postini.com [74.125.245.196]) by kanga.kvack.org (Postfix) with SMTP id 301606B005D for ; Mon, 23 Jul 2012 00:58:40 -0400 (EDT) Date: Mon, 23 Jul 2012 13:58:55 +0900 From: Minchan Kim Subject: Re: + memory-hotplug-fix-kswapd-looping-forever-problem-fix-fix.patch added to -mm tree Message-ID: <20120723045855.GC6832@bbox> References: <20120717233115.A8E411E005C@wpzn4.hot.corp.google.com> <20120718012200.GA27770@bbox> <20120718143810.b15564b3.akpm@linux-foundation.org> <20120719001002.GA6579@bbox> <20120719002102.GN24336@google.com> <20120719004845.GA7346@bbox> <20120719165750.GP24336@google.com> <20120719235057.GA21012@bbox> <20120720142213.f4a4a68e.akpm@linux-foundation.org> <20120720213641.GA6823@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120720213641.GA6823@google.com> Sender: owner-linux-mm@kvack.org List-ID: To: Tejun Heo Cc: Andrew Morton , Ralf Baechle , aaditya.kumar.30@gmail.com, kamezawa.hiroyu@jp.fujitsu.com, linux-mm@kvack.org, Johannes Weiner , Yinghai Lu On Fri, Jul 20, 2012 at 02:36:41PM -0700, Tejun Heo wrote: > Hello, Andrew. > > On Fri, Jul 20, 2012 at 02:22:13PM -0700, Andrew Morton wrote: > > My point is that having to ensure that each arch zeroes out this > > structure is difficult/costly/unreliable/fragile. It would be better > > if we can reliably clear it at some well-known place in core MM. > > > > That might mean that the memory gets cleared twice on some > > architectures, but I doubt if that matters - it's a once-off thing. > > Clearing twice isn't the problem here. The problem is the risk of > zapping fields which are already in use. That would be way more > unexpected and difficult to track down than garbage value in whatever > field. I would like to know what fields you are concerning because most of field in pg_data_t are generic except bdata so they would be initialized by free_area_init_node. So IMHO, reset pg_data_t except bdata would be no problem and clean approach. If some arch needs some fields in pg_data_t , we have to declare new variable struct arch_data in pg_data_t and generic functions doesn't need to touch them. Of course, we can skip reset of that structure, too. Please let me know it if I am missing something. -- Kind regards, Minchan Kim -- 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