From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751340AbdH1Vvc (ORCPT ); Mon, 28 Aug 2017 17:51:32 -0400 Received: from mail-qt0-f196.google.com ([209.85.216.196]:37208 "EHLO mail-qt0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751182AbdH1Vvb (ORCPT ); Mon, 28 Aug 2017 17:51:31 -0400 Date: Mon, 28 Aug 2017 14:51:27 -0700 From: Tejun Heo To: Linus Torvalds , Andrew Morton Cc: linux-kernel@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH] cpumask: fix spurious cpumask_of_node() on non-NUMA multi-node configs Message-ID: <20170828215127.GC491396@devbig577.frc2.facebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When !CONFIG_NUMA, cpumask_of_node(@node) equals cpu_online_mask regardless of @node. The assumption seems that if !NUMA, there shouldn't be more than one node and thus reporting cpu_online_mask regardless of @node is correct. However, that assumption was broken years ago to support CONFIG_DISCONTIGMEM and whether a system has multiple nodes or not is separately controlled by CONFIG_NEED_MULTIPLE_NODES. This means that, on a system with !CONFIG_NUMA && CONFIG_NEED_MULTIPLE_NODES, cpumask_of_node() will report cpu_online_mask for all possible nodes, indicating that the CPUs are associated with multiple nodes which is an impossible configuration. This bug has been around forever but doesn't look like it has caused any noticeable symptoms. However, it triggers a WARN recently added to workqueue to verify NUMA affinity configuration. Fix it by reporting empty cpumask on non-zero nodes if !NUMA. Signed-off-by: Tejun Heo Reported-and-tested-by: Geert Uytterhoeven Cc: stable@vger.kernel.org --- include/asm-generic/topology.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/include/asm-generic/topology.h b/include/asm-generic/topology.h index fc824e2..5d2add1 100644 --- a/include/asm-generic/topology.h +++ b/include/asm-generic/topology.h @@ -48,7 +48,11 @@ #define parent_node(node) ((void)(node),0) #endif #ifndef cpumask_of_node -#define cpumask_of_node(node) ((void)node, cpu_online_mask) + #ifdef CONFIG_NEED_MULTIPLE_NODES + #define cpumask_of_node(node) ((node) == 0 ? cpu_online_mask : cpu_none_mask) + #else + #define cpumask_of_node(node) ((void)node, cpu_online_mask) + #endif #endif #ifndef pcibus_to_node #define pcibus_to_node(bus) ((void)(bus), -1)