From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx203.postini.com [74.125.245.203]) by kanga.kvack.org (Postfix) with SMTP id AC6DE6B005C for ; Wed, 18 Jul 2012 20:21:07 -0400 (EDT) Received: by pbbrp2 with SMTP id rp2so4298715pbb.14 for ; Wed, 18 Jul 2012 17:21:07 -0700 (PDT) Date: Wed, 18 Jul 2012 17:21:02 -0700 From: Tejun Heo Subject: Re: + memory-hotplug-fix-kswapd-looping-forever-problem-fix-fix.patch added to -mm tree Message-ID: <20120719002102.GN24336@google.com> References: <20120717233115.A8E411E005C@wpzn4.hot.corp.google.com> <20120718012200.GA27770@bbox> <20120718143810.b15564b3.akpm@linux-foundation.org> <20120719001002.GA6579@bbox> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120719001002.GA6579@bbox> Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Andrew Morton , Ralf Baechle , aaditya.kumar.30@gmail.com, kamezawa.hiroyu@jp.fujitsu.com, linux-mm@kvack.org, Johannes Weiner , Yinghai Lu (cc'ing Yinghai, hi!) Hello, On Thu, Jul 19, 2012 at 09:10:02AM +0900, Minchan Kim wrote: > On Wed, Jul 18, 2012 at 02:38:10PM -0700, Andrew Morton wrote: > > On Wed, 18 Jul 2012 10:22:00 +0900 > > Minchan Kim wrote: > > > > > > > > > > Is this really necessary? Does the zone start out all-zeroes? If not, can we > > > > make it do so? > > > > > > Good point. > > > It can remove zap_zone_vm_stats and zone->flags = 0, too. > > > More important thing is that we could remove adding code to initialize > > > zero whenever we add new field to zone. So I look at the code. > > > > > > In summary, IMHO, all is already initialie zero out but we need double > > > check in mips. > > > > > > > Well, this is hardly a performance-critical path. So rather than > > groveling around ensuring that each and every architectures does the > > right thing, would it not be better to put a single memset() into core > > MM if there is an appropriate place? > > I think most good place is free_area_init_node but at a glance, > bootmem_data is set up eariler than free_area_init_node so shouldn't we > keep that pointer still? I don't think zapping node_data that late is a good idea. It's used from very early in the boot and its usage during early boot is fairly platform dependent. Dunno whether there's a good solution for this. Maybe trigger warning if some fields which have to be zero aren't? Thanks. -- tejun -- 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