From nobody Mon Sep 15 07:37:26 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0AE39C54EBE for ; Fri, 13 Jan 2023 10:59:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241051AbjAMK7V (ORCPT ); Fri, 13 Jan 2023 05:59:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57008 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241576AbjAMK6q (ORCPT ); Fri, 13 Jan 2023 05:58:46 -0500 Received: from mx6.didiglobal.com (mx6.didiglobal.com [111.202.70.123]) by lindbergh.monkeyblade.net (Postfix) with SMTP id CC90459F9A for ; Fri, 13 Jan 2023 02:54:28 -0800 (PST) Received: from mail.didiglobal.com (unknown [10.79.65.12]) by mx6.didiglobal.com (Maildata Gateway V2.8) with ESMTPS id 4A6A611069780C; Fri, 13 Jan 2023 18:54:25 +0800 (CST) Received: from didi-ThinkCentre-M930t-N000 (10.79.64.101) by ZJY02-ACTMBX-02.didichuxing.com (10.79.65.12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.34; Fri, 13 Jan 2023 18:54:24 +0800 Date: Fri, 13 Jan 2023 18:54:13 +0800 X-MD-Sfrom: tiozhang@didiglobal.com X-MD-SrcIP: 10.79.65.12 From: Tio Zhang To: , , , CC: Subject: [PATCH] sched: print parent comm in sched_show_task() Message-ID: <20230113105413.GA30243@didi-ThinkCentre-M930t-N000> Mail-Followup-To: yu.c.chen@intel.com, pmladek@suse.com, zyhtheonly@gmail.com, linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) X-Originating-IP: [10.79.64.101] X-ClientProxiedBy: ZJY03-PUBMBX-01.didichuxing.com (10.79.71.12) To ZJY02-ACTMBX-02.didichuxing.com (10.79.65.12) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Knowing who the parent is might be useful for debugging. For example, we can sometimes resolve kernel hung tasks by stopping the person who begins those hung tasks. With the parent's name printed in sched_show_task(), it might be helpful to let people know which "service" should be operated. Also, we move the parent info to a following new line. It would better solve the situation when the task is not alive and we could not get information about the parent. Signed-off-by: Tio Zhang --- kernel/sched/core.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index cb2aa2b54c7a..5be3f476ee5b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8853,7 +8853,6 @@ SYSCALL_DEFINE2(sched_rr_get_interval_time32, pid_t, = pid, void sched_show_task(struct task_struct *p) { unsigned long free =3D 0; - int ppid; =20 if (!try_get_task_stack(p)) return; @@ -8865,14 +8864,16 @@ void sched_show_task(struct task_struct *p) #ifdef CONFIG_DEBUG_STACK_USAGE free =3D stack_not_used(p); #endif - ppid =3D 0; + pr_cont(" stack:%-5lu pid:%-5d flags:0x%08lx\n", + free, task_pid_nr(p), read_task_thread_flags(p)); + rcu_read_lock(); - if (pid_alive(p)) - ppid =3D task_pid_nr(rcu_dereference(p->real_parent)); + if (pid_alive(p)) { + struct task_struct *parent =3D rcu_dereference(p->real_parent); + + pr_info("parent:%-15.15s ppid:%-6d", parent->comm, task_pid_nr(parent)); + } rcu_read_unlock(); - pr_cont(" stack:%-5lu pid:%-5d ppid:%-6d flags:0x%08lx\n", - free, task_pid_nr(p), ppid, - read_task_thread_flags(p)); =20 print_worker_info(KERN_INFO, p); print_stop_info(KERN_INFO, p); --=20 2.17.1