Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757384AbaDBDaL (ORCPT ); Tue, 1 Apr 2014 23:30:11 -0400 Received: from e23smtp04.au.ibm.com ([202.81.31.146]:32824 "EHLO e23smtp04.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756682AbaDBDaJ (ORCPT ); Tue, 1 Apr 2014 23:30:09 -0400 Message-ID: <533B8431.8090507@linux.vnet.ibm.com> Date: Wed, 02 Apr 2014 11:29:53 +0800 From: Michael wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: linuxppc-dev@lists.ozlabs.org, LKML , benh@kernel.crashing.org, paulus@samba.org, nfont@linux.vnet.ibm.com, sfr@canb.auug.org.au, Andrew Morton , rcj@linux.vnet.ibm.com, jlarrew@linux.vnet.ibm.com, srivatsa.bhat@linux.vnet.ibm.com, alistair@popple.id.au Subject: [PATCH] power, sched: stop updating inside arch_update_cpu_topology() when nothing to be update Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14040203-9264-0000-0000-000005C11422 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org During the testing, we encounter below WARN followed by Oops: WARNING: at kernel/sched/core.c:6218 ... NIP [c000000000101660] .build_sched_domains+0x11d0/0x1200 LR [c000000000101358] .build_sched_domains+0xec8/0x1200 PACATMSCRATCH [800000000000f032] Call Trace: [c00000001b103850] [c000000000101358] .build_sched_domains+0xec8/0x1200 [c00000001b1039a0] [c00000000010aad4] .partition_sched_domains+0x484/0x510 [c00000001b103aa0] [c00000000016d0a8] .rebuild_sched_domains+0x68/0xa0 [c00000001b103b30] [c00000000005cbf0] .topology_work_fn+0x10/0x30 ... Oops: Kernel access of bad area, sig: 11 [#1] ... NIP [c00000000045c000] .__bitmap_weight+0x60/0xf0 LR [c00000000010132c] .build_sched_domains+0xe9c/0x1200 PACATMSCRATCH [8000000000029032] Call Trace: [c00000001b1037a0] [c000000000288ff4] .kmem_cache_alloc_node_trace+0x184/0x3a0 [c00000001b103850] [c00000000010132c] .build_sched_domains+0xe9c/0x1200 [c00000001b1039a0] [c00000000010aad4] .partition_sched_domains+0x484/0x510 [c00000001b103aa0] [c00000000016d0a8] .rebuild_sched_domains+0x68/0xa0 [c00000001b103b30] [c00000000005cbf0] .topology_work_fn+0x10/0x30 ... This was caused by that 'sd->groups == NULL' after building groups, which was caused by the empty 'sd->span'. The cpu's domain contain nothing because the cpu was assigned to wrong node inside arch_update_cpu_topology() by calling update_lookup_table() with the uninitialized param, in the case when there is nothing to be update. Thus we should stop the updating in such cases, this patch will achieve this and fix the issue. CC: Benjamin Herrenschmidt CC: Paul Mackerras CC: Nathan Fontenot CC: Stephen Rothwell CC: Andrew Morton CC: Robert Jennings CC: Jesse Larrew CC: "Srivatsa S. Bhat" CC: Alistair Popple Signed-off-by: Michael Wang --- arch/powerpc/mm/numa.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c index 30a42e2..6757690 100644 --- a/arch/powerpc/mm/numa.c +++ b/arch/powerpc/mm/numa.c @@ -1591,6 +1591,14 @@ int arch_update_cpu_topology(void) cpu = cpu_last_thread_sibling(cpu); } + /* + * The 'cpu_associativity_changes_mask' could be cleared if + * all the cpus it indicates won't change their node, in + * which case the 'updated_cpus' will be empty. + */ + if (!cpumask_weight(&updated_cpus)) + goto out; + stop_machine(update_cpu_topology, &updates[0], &updated_cpus); /* @@ -1612,6 +1620,7 @@ int arch_update_cpu_topology(void) changed = 1; } +out: kfree(updates); return changed; } -- 1.7.9.5 -- 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/