Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752750AbaKKJqf (ORCPT ); Tue, 11 Nov 2014 04:46:35 -0500 Received: from relay.parallels.com ([195.214.232.42]:56128 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751333AbaKKJqd (ORCPT ); Tue, 11 Nov 2014 04:46:33 -0500 Message-ID: <1415699189.15631.6.camel@tkhai> Subject: [PATCH] sched/numa: Init numa balancing fields of init_task From: Kirill Tkhai To: CC: Peter Zijlstra , Ingo Molnar , Kirill Tkhai Date: Tue, 11 Nov 2014 12:46:29 +0300 Organization: Parallels Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.8.5-2+b3 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Originating-IP: [10.30.26.172] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We do not initialize init_task.numa_preferred_nid, but this value is inherited by userspace "init" process: rest_init()->kernel_thread(kernel_init)->do_fork(CLONE_VM); __sched_fork() { if (clone_flags & CLONE_VM) p->numa_preferred_nid = current->numa_preferred_nid; else p->numa_preferred_nid = -1; } kernel_init() becomes userspace "init" process. So, we propagate garbage nid to userspace, and it may be used during numa balancing. Currently, we do not have reports about this brings a problem, but it seem we should set it for sure. Even if init_task.numa_preferred_nid is zero, we may meet a weird configuration without nid#0. On sparc64, where processors are numbered physically, I saw a machine without cpu#1, while cpu#2 existed. Possible, something similar may be with numa nodes. So, let's initialize it and be sure we're safe. Signed-off-by: Kirill Tkhai --- include/linux/init_task.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/include/linux/init_task.h b/include/linux/init_task.h index 77fc43f..5f30ac8 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -166,6 +166,15 @@ extern struct task_group root_task_group; # define INIT_RT_MUTEXES(tsk) #endif +#ifdef CONFIG_NUMA_BALANCING +# define INIT_NUMA_BALANCING(tsk) \ + .numa_preferred_nid = -1, \ + .numa_group = NULL, \ + .numa_faults = NULL, +#else +# define INIT_NUMA_BALANCING(tsk) +#endif + /* * INIT_TASK is used to set up the first task table, touch at * your own risk!. Base=0, limit=0x1fffff (=2MB) @@ -237,6 +246,7 @@ extern struct task_group root_task_group; INIT_CPUSET_SEQ(tsk) \ INIT_RT_MUTEXES(tsk) \ INIT_VTIME(tsk) \ + INIT_NUMA_BALANCING(tsk) \ } -- 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/