Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753739Ab2JIGVm (ORCPT ); Tue, 9 Oct 2012 02:21:42 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:64144 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753417Ab2JIGVk (ORCPT ); Tue, 9 Oct 2012 02:21:40 -0400 Date: Mon, 8 Oct 2012 23:21:37 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Tang Chen cc: mingo@redhat.com, peterz@infradead.org, miaox@cn.fujitsu.com, wency@cn.fujitsu.com, linux-kernel@vger.kernel.org, linux-numa@vger.kernel.org Subject: Re: [PATCH] Do not use cpu_to_node() to find an offlined cpu's node. In-Reply-To: <1349665183-11718-1-git-send-email-tangchen@cn.fujitsu.com> Message-ID: References: <1349665183-11718-1-git-send-email-tangchen@cn.fujitsu.com> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1838 Lines: 56 On Mon, 8 Oct 2012, Tang Chen wrote: > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 66b36ab..e76dce9 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -1263,18 +1263,24 @@ EXPORT_SYMBOL_GPL(kick_process); > */ > static int select_fallback_rq(int cpu, struct task_struct *p) > { > - const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(cpu)); > + int nid = cpu_to_node(cpu); > + const struct cpumask *nodemask = NULL; > enum { cpuset, possible, fail } state = cpuset; > int dest_cpu; > > - /* Look for allowed, online CPU in same node. */ > - for_each_cpu(dest_cpu, nodemask) { > - if (!cpu_online(dest_cpu)) > - continue; > - if (!cpu_active(dest_cpu)) > - continue; > - if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) > - return dest_cpu; > + /* If the cpu has been offlined, its nid was set to -1. */ > + if (nid != -1) { NUMA_NO_NODE. Eek, the nid shouldn't be -1 yet, though, for cpu hotplug since this should be called at CPU_DYING level and migrate_tasks() still sees a valid cpu. On x86, cpumask_of_node() is always guaranteed to return a valid cpumask after boot so presumably this is a problem in some non-x86 arch code and isn't actually a sched problem. > + nodemask = cpumask_of_node(nid); > + > + /* Look for allowed, online CPU in same node. */ > + for_each_cpu(dest_cpu, nodemask) { > + if (!cpu_online(dest_cpu)) > + continue; > + if (!cpu_active(dest_cpu)) > + continue; > + if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) > + return dest_cpu; > + } > } > > for (;;) { -- 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/