From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 426466B01B0 for ; Tue, 25 May 2010 01:06:00 -0400 (EDT) Message-ID: <4BFB5AAE.1060609@linux.intel.com> Date: Tue, 25 May 2010 13:05:50 +0800 From: Haicheng Li MIME-Version: 1.0 Subject: Re: [PATCH] cpu_up: hold zonelists_mutex when build_all_zonelists References: <201005192322.o4JNMu5v012158@imap1.linux-foundation.org> <4BF4AB24.7070107@linux.intel.com> <20100521130808.919ecb35.akpm@linux-foundation.org> In-Reply-To: <20100521130808.919ecb35.akpm@linux-foundation.org> Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: "linux-mm@kvack.org" , andi.kleen@intel.com, cl@linux-foundation.org, fengguang.wu@intel.com, mel@csn.ul.ie, tj@kernel.org, "linux-kernel@vger.kernel.org" , minskey guo List-ID: Andrew Morton wrote: > On Thu, 20 May 2010 11:23:16 +0800 > Haicheng Li wrote: > >> Here is another issue, we should always hold zonelists_mutex when calling build_all_zonelists >> unless system_state == SYSTEM_BOOTING. > > Taking a global mutex in the cpu-hotplug code is worrisome. Perhaps > because of the two years spent weeding out strange deadlocks between > cpu-hotplug and cpufreq. > > Has this change been carefully and fully tested with lockdep enabled > (please)? Yes, Andrew. I've tested it with lockdep enabled, and there was *no* issue found for this change in my testing. My test box: CPUs on node 1~3 are all offlined (16 cpus per node). Here are my test steps: on tty0: # cd /sys/devices/system/node/node1 # for i in cpu*; do echo 1 > $i/online; done on tty1: # cd /sys/devices/system/node/node2 # for i in cpu*; do echo 1 > $i/online; done on tty2: # cd /sys/devices/system/node/node3 # for i in cpu*; do echo 1 > $i/online; done on tty3: # cat zonelist #! /bin/bash set -x while ((1)); do echo n > /proc/sys/vm/numa_zonelist_order sleep 10 echo z > /proc/sys/vm/numa_zonelist_order sleep 10 done # ./zonelist Besides, I also ran some cpu online/offline tests from LTP/cpu_hotplug test suites. They worked fine too. >> --- a/kernel/cpu.c >> +++ b/kernel/cpu.c >> @@ -357,8 +357,11 @@ int __cpuinit cpu_up(unsigned int cpu) >> return -ENOMEM; >> } >> >> - if (pgdat->node_zonelists->_zonerefs->zone == NULL) >> + if (pgdat->node_zonelists->_zonerefs->zone == NULL) { >> + mutex_lock(&zonelists_mutex); >> build_all_zonelists(NULL); >> + mutex_unlock(&zonelists_mutex); >> + } > > Your email client is performing space-stuffing and it replaces tabs > with spaces. This requires me to edit the patches rather a lot, > which is dull. Really sorry for the inconvenience to you. I'll pay more attention next time. thank you! -haicheng -- 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