Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753009Ab0BWBtV (ORCPT ); Mon, 22 Feb 2010 20:49:21 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:54908 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752667Ab0BWBtU (ORCPT ); Mon, 22 Feb 2010 20:49:20 -0500 Message-ID: <4B833404.2010807@cn.fujitsu.com> Date: Tue, 23 Feb 2010 09:48:52 +0800 From: Miao Xie Reply-To: miaox@cn.fujitsu.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.1.5) Gecko/20091204 Thunderbird/3.0 MIME-Version: 1.0 To: Nick Piggin CC: David Rientjes , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Lee Schermerhorn Subject: Re: [regression] cpuset,mm: update tasks' mems_allowed in time (58568d2) References: <20100218134921.GF9738@laptop> <20100219033126.GI9738@laptop> <4B827043.3060305@cn.fujitsu.com> <20100222120605.GU9738@laptop> In-Reply-To: <20100222120605.GU9738@laptop> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3664 Lines: 121 on 2010-2-22 20:06, Nick Piggin wrote: >>>>> guarantee_online_cpus() truly does require callback_mutex, the >>>>> cgroup_scan_tasks() iterator locking can protect changes in the cgroup >>>>> hierarchy but it doesn't protect a store to cs->cpus_allowed or for >>>>> hotplug. >>>> >>>> Right, but the callback_mutex was being removed by this patch. >>>> >>> >>> I was making the case for it to be readded :) >> >> But cgroup_mutex is held when someone changes cs->cpus_allowed or doing hotplug, >> so I think callback_mutex is not necessary in this case. > > So long as that's done consistently (and we should update the comments > too). I will update the comments. >> --- >> diff --git a/init/main.c b/init/main.c >> index 4cb47a1..512ba15 100644 >> --- a/init/main.c >> +++ b/init/main.c >> @@ -846,7 +846,7 @@ static int __init kernel_init(void * unused) >> /* >> * init can allocate pages on any node >> */ >> - set_mems_allowed(node_possible_map); >> + set_mems_allowed(node_states[N_HIGH_MEMORY]); >> /* >> * init can run on any cpu. >> */ >> diff --git a/kernel/cpuset.c b/kernel/cpuset.c >> index ba401fa..e29b440 100644 >> --- a/kernel/cpuset.c >> +++ b/kernel/cpuset.c >> @@ -935,10 +935,12 @@ static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from, >> struct task_struct *tsk = current; >> >> tsk->mems_allowed = *to; >> + wmb(); >> >> do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL); >> >> guarantee_online_mems(task_cs(tsk),&tsk->mems_allowed); >> + wmb(); >> } >> >> /* > > You always need to comment barriers (and use smp_ variants unless you're > doing mmio). It's my mistake. I'll remake a new patch and change it. Thanks. Miao > > >> @@ -1391,11 +1393,10 @@ static void cpuset_attach(struct cgroup_subsys *ss, struct cgroup *cont, >> >> if (cs == &top_cpuset) { >> cpumask_copy(cpus_attach, cpu_possible_mask); >> - to = node_possible_map; >> } else { >> guarantee_online_cpus(cs, cpus_attach); >> - guarantee_online_mems(cs, &to); >> } >> + guarantee_online_mems(cs, &to); >> >> /* do per-task migration stuff possibly for each in the threadgroup */ >> cpuset_attach_task(tsk, &to, cs); >> @@ -2090,15 +2091,19 @@ static int cpuset_track_online_cpus(struct notifier_block *unused_nb, >> static int cpuset_track_online_nodes(struct notifier_block *self, >> unsigned long action, void *arg) >> { >> + nodemask_t oldmems; >> + >> cgroup_lock(); >> switch (action) { >> case MEM_ONLINE: >> - case MEM_OFFLINE: >> + oldmems = top_cpuset.mems_allowed; >> mutex_lock(&callback_mutex); >> top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY]; >> mutex_unlock(&callback_mutex); >> - if (action == MEM_OFFLINE) >> - scan_for_empty_cpusets(&top_cpuset); >> + update_tasks_nodemask(&top_cpuset, &oldmems, NULL); >> + break; >> + case MEM_OFFLINE: >> + scan_for_empty_cpusets(&top_cpuset); >> break; >> default: >> break; >> diff --git a/kernel/kthread.c b/kernel/kthread.c >> index fbb6222..84c7f99 100644 >> --- a/kernel/kthread.c >> +++ b/kernel/kthread.c >> @@ -219,7 +219,7 @@ int kthreadd(void *unused) >> set_task_comm(tsk, "kthreadd"); >> ignore_signals(tsk); >> set_cpus_allowed_ptr(tsk, cpu_all_mask); >> - set_mems_allowed(node_possible_map); >> + set_mems_allowed(node_states[N_HIGH_MEMORY]); >> >> current->flags |= PF_NOFREEZE | PF_FREEZER_NOSIG; >> > > > -- 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/