Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754711AbZIVFdN (ORCPT ); Tue, 22 Sep 2009 01:33:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754576AbZIVFdM (ORCPT ); Tue, 22 Sep 2009 01:33:12 -0400 Received: from mga11.intel.com ([192.55.52.93]:15140 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754385AbZIVFdL (ORCPT ); Tue, 22 Sep 2009 01:33:11 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.44,429,1249282800"; d="scan'208";a="495634365" Subject: Re: + generic-ipi-fix-the-race-between-generic_smp_call_function_-and-hotplug_cfd.patch added to -mm tree From: Suresh Siddha Reply-To: Suresh Siddha To: Xiao Guangrong Cc: Peter Zijlstra , "akpm@linux-foundation.org" , "mm-commits@vger.kernel.org" , "jens.axboe@oracle.com" , "mingo@elte.hu" , "nickpiggin@yahoo.com.au" , "rusty@rustcorp.com.au" , LKML In-Reply-To: <4AB6FB62.3000605@cn.fujitsu.com> References: <200907310030.n6V0Uqgw001644@imap1.linux-foundation.org> <1252616988.7205.102.camel@laptop> <4AAA0001.2060703@cn.fujitsu.com> <1252696132.3756.21.camel@sbs-t61.sc.intel.com> <4AADEF2F.5080504@cn.fujitsu.com> <1252973802.2899.88.camel@sbs-t61.sc.intel.com> <4AAEF5DC.4070308@cn.fujitsu.com> <1253067602.2667.13.camel@sbs-t61.sc.intel.com> <4AB1A652.1010000@cn.fujitsu.com> <1253326599.3948.732.camel@sbs-t61.sc.intel.com> <4AB6EB1C.5090106@cn.fujitsu.com> <1253502682.2528.4.camel@sbs-t61> <4AB6FB62.3000605@cn.fujitsu.com> Content-Type: text/plain Organization: Intel Corp Date: Mon, 21 Sep 2009 22:32:33 -0700 Message-Id: <1253597553.2519.8.camel@sbs-t61> Mime-Version: 1.0 X-Mailer: Evolution 2.26.3 (2.26.3-1.fc11) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1106 Lines: 27 On Sun, 2009-09-20 at 21:04 -0700, Xiao Guangrong wrote: > > Suresh Siddha wrote: > > > > I am referring to the missing csd_lock_wait() here that you had in the > > first version of your patch. Let's say, if cpu X is going offline, we > > need to ensure that the smp_call_function() initiated by cpu X (i.e., > > smp_call_function IPI sent to some other cpu's from cpu X) got serviced > > before cpu X goes offline. We can't do csd_lock_wait() here, as that > > might deadlock (as all the other cpu's are already in stop machine with > > interrupts disabled). > > > > It not happen because the preemption is disabled while send IPI request and > can't schedule to stop machine path, it also stop cpu down. Xiao, I am getting confused. I am referring to case '1' mentioned by you here http://marc.info/?l=linux-kernel&m=125265516529139&w=2 thanks, suresh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/