From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mt1.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id mA61xsZO024213 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Thu, 6 Nov 2008 10:59:54 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 6377C45DD7C for ; Thu, 6 Nov 2008 10:59:54 +0900 (JST) Received: from s8.gw.fujitsu.co.jp (s8.gw.fujitsu.co.jp [10.0.50.98]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 3633845DD79 for ; Thu, 6 Nov 2008 10:59:54 +0900 (JST) Received: from s8.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s8.gw.fujitsu.co.jp (Postfix) with ESMTP id 1E4E31DB803C for ; Thu, 6 Nov 2008 10:59:54 +0900 (JST) Received: from ml13.s.css.fujitsu.com (ml13.s.css.fujitsu.com [10.249.87.103]) by s8.gw.fujitsu.co.jp (Postfix) with ESMTP id C070C1DB8037 for ; Thu, 6 Nov 2008 10:59:53 +0900 (JST) Date: Thu, 6 Nov 2008 10:59:18 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [linux-pm] [PATCH] hibernation should work ok with memory hotplug Message-Id: <20081106105918.e64b7afb.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20081106105453.b2c1b0fc.kamezawa.hiroyu@jp.fujitsu.com> References: <20081029105956.GA16347@atrey.karlin.mff.cuni.cz> <1225817945.12673.602.camel@nimitz> <20081105093837.e073c373.kamezawa.hiroyu@jp.fujitsu.com> <200811051208.26628.rjw@sisk.pl> <20081106091441.6517c072.kamezawa.hiroyu@jp.fujitsu.com> <20081106101751.14113f24.kamezawa.hiroyu@jp.fujitsu.com> <1225935787.6216.12.camel@nigel-laptop> <20081106105453.b2c1b0fc.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: KAMEZAWA Hiroyuki Cc: Nigel Cunningham , "Rafael J. Wysocki" , Dave Hansen , Yasunori Goto , Matt Tolentino , linux-pm@lists.osdl.org, Dave Hansen , linux-kernel@vger.kernel.org, linux-mm@kvack.org, pavel@suse.cz, Mel Gorman , Andy Whitcroft , Andrew Morton List-ID: On Thu, 6 Nov 2008 10:54:53 +0900 KAMEZAWA Hiroyuki wrote: > On Thu, 06 Nov 2008 12:43:07 +1100 > Nigel Cunningham wrote: > > > Hi. > > > > On Thu, 2008-11-06 at 10:17 +0900, KAMEZAWA Hiroyuki wrote: > > > On Thu, 6 Nov 2008 09:14:41 +0900 > > > KAMEZAWA Hiroyuki wrote: > > > > > > > Ok, please consider "when memory hotplug happens." > > > > > > > > In general, it happens when > > > > 1. memory is inserted to slot. > > > > 2. the firmware notifes the system to enable already inserted memory. > > > > > > > > To trigger "1", you have to open cover of server/pc. Do you open pc while the system > > > > starts hibernation ? for usual people, no. > > > > > > > > To trigger "2", the user have special console to tell firmware "enable this memory". > > > > Such firmware console or users have to know "the system works well." And, more important, > > > > when the system is suspended, the firmware can't do hotplug because the kernel is sleeping. > > > > So, such firmware console or operator have to know the system status. > > > > > > > > Am I missing some ? Current linux can know PCI/USB hotplug while the system is suspended ? > > > > > > > *OFFTOPIC* > > > > > > I hear following answer from my friend. > > > > > > - hibernate the system > > > => plug USB memory > > > => wake up the system > > > => panic. > > > - hibernate the system > > > => unplug USB memory > > > => wake up the sytem > > > => panic. > > > > We currently check that the number of physical pages is the same when > > starting to load the image, so neither of these issues cause real > > problems. > > > Hmm? this doesn't come from lost of hotplug interrupt ? > the memory plugged while the system is sleeping can be recognized when the system wakes up ? > > My point is the firmware/operator has to know "the system is sleeping or not" to do *any* hotplug. > (I'm not sure but removing a cpu while the system is under hibernation may cause panic, too.) > In my point of view, this is operator's problem, not hibernation's. IOW, please just remove !HIBERNATION in Kconfig and add "WARNING" to Documentaion. for *now*. I hope some notifier_call_chain from hibernation will be added. Thanks, -Kame -- 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