From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754031Ab2IXFut (ORCPT ); Mon, 24 Sep 2012 01:50:49 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:39723 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751325Ab2IXFur (ORCPT ); Mon, 24 Sep 2012 01:50:47 -0400 X-IronPort-AV: E=Sophos;i="4.80,474,1344182400"; d="scan'208";a="5901320" Message-ID: <505FF518.2050008@cn.fujitsu.com> Date: Mon, 24 Sep 2012 13:52:24 +0800 From: Tang Chen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120430 Thunderbird/12.0.1 MIME-Version: 1.0 To: mingo@redhat.com, peterz@infradead.org CC: linux-kernel@vger.kernel.org, x86@kernel.org, linux-numa@vger.kernel.org, wency@cn.fujitsu.com, Tang Chen Subject: Re: [PATCH] Update sched_domains_numa_masks when new cpus are onlined. References: <1347963128-25942-1-git-send-email-tangchen@cn.fujitsu.com> In-Reply-To: <1347963128-25942-1-git-send-email-tangchen@cn.fujitsu.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/09/24 13:51:00, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/09/24 13:51:01, Serialize complete at 2012/09/24 13:51:01 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Would you please help to review this patch ? Thanks. :) On 09/18/2012 06:12 PM, Tang Chen wrote: > Once array sched_domains_numa_masks is defined, it is never updated. > When a new cpu on a new node is onlined, the coincident member in > sched_domains_numa_masks is not initialized, and all the masks are 0. > As a result, the build_overlap_sched_groups() will initialize a NULL > sched_group for the new cpu on the new node, which will lead to kernel panic. > > [ 3189.403280] Call Trace: > [ 3189.403286] [] warn_slowpath_common+0x7f/0xc0 > [ 3189.403289] [] warn_slowpath_null+0x1a/0x20 > [ 3189.403292] [] build_sched_domains+0x467/0x470 > [ 3189.403296] [] partition_sched_domains+0x307/0x510 > [ 3189.403299] [] ? partition_sched_domains+0x142/0x510 > [ 3189.403305] [] cpuset_update_active_cpus+0x83/0x90 > [ 3189.403308] [] cpuset_cpu_active+0x38/0x70 > [ 3189.403316] [] notifier_call_chain+0x67/0x150 > [ 3189.403320] [] ? native_cpu_up+0x18a/0x1b5 > [ 3189.403328] [] __raw_notifier_call_chain+0xe/0x10 > [ 3189.403333] [] __cpu_notify+0x20/0x40 > [ 3189.403337] [] _cpu_up+0xe9/0x131 > [ 3189.403340] [] cpu_up+0xdb/0xee > [ 3189.403348] [] store_online+0x9c/0xd0 > [ 3189.403355] [] dev_attr_store+0x20/0x30 > [ 3189.403361] [] sysfs_write_file+0xa3/0x100 > [ 3189.403368] [] vfs_write+0xd0/0x1a0 > [ 3189.403371] [] sys_write+0x54/0xa0 > [ 3189.403375] [] system_call_fastpath+0x16/0x1b > [ 3189.403377] ---[ end trace 1e6cf85d0859c941 ]--- > [ 3189.403398] BUG: unable to handle kernel NULL pointer dereference at 0000000000000018 > > This patch registers a new notifier for cpu hotplug notify chain, and > updates sched_domains_numa_masks every time a new cpu is onlined or offlined. > > Signed-off-by: Tang Chen > --- > kernel/sched/core.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 files changed, 62 insertions(+), 0 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index fbf1fd0..66b36ab 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -6711,6 +6711,14 @@ static void sched_init_numa(void) > * numbers. > */ > > + /* > + * Since sched_domains_numa_levels is also used in other functions as > + * an index for sched_domains_numa_masks[][], we should reset it here in > + * case sched_domains_numa_masks[][] fails to be initialized. And set it > + * to 'level' when sched_domains_numa_masks[][] is fully initialized. > + */ > + sched_domains_numa_levels = 0; > + > sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL); > if (!sched_domains_numa_masks) > return; > @@ -6765,11 +6773,64 @@ static void sched_init_numa(void) > } > > sched_domain_topology = tl; > + > + sched_domains_numa_levels = level; > +} > + > +static void sched_domains_numa_masks_set(int cpu) > +{ > + int i, j; > + int node = cpu_to_node(cpu); > + > + for (i = 0; i< sched_domains_numa_levels; i++) > + for (j = 0; j< nr_node_ids; j++) > + if (node_distance(j, node)<= sched_domains_numa_distance[i]) > + cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]); > +} > + > +static void sched_domains_numa_masks_clear(int cpu) > +{ > + int i, j; > + for (i = 0; i< sched_domains_numa_levels; i++) > + for (j = 0; j< nr_node_ids; j++) > + cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]); > +} > + > +/* > + * Update sched_domains_numa_masks[level][node] array when new cpus > + * are onlined. > + */ > +static int sched_domains_numa_masks_update(struct notifier_block *nfb, > + unsigned long action, > + void *hcpu) > +{ > + int cpu = (int)hcpu; > + > + switch (action& ~CPU_TASKS_FROZEN) { > + case CPU_ONLINE: > + sched_domains_numa_masks_set(cpu); > + break; > + > + case CPU_DEAD: > + sched_domains_numa_masks_clear(cpu); > + break; > + > + default: > + return NOTIFY_DONE; > + } > + return NOTIFY_OK; > } > #else > static inline void sched_init_numa(void) > { > } > + > +static int sched_domains_numa_masks_update(struct notifier_block *nfb, > + unsigned long action, > + void *hcpu) > +{ > + return 0; > +} > #endif /* CONFIG_NUMA */ > > static int __sdt_alloc(const struct cpumask *cpu_map) > @@ -7218,6 +7279,7 @@ void __init sched_init_smp(void) > mutex_unlock(&sched_domains_mutex); > put_online_cpus(); > > + hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE); > hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE); > hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE); >