From nobody Sun Sep 14 18:30:09 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 59B6FC00A5A for ; Thu, 19 Jan 2023 11:06:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229776AbjASLGz (ORCPT ); Thu, 19 Jan 2023 06:06:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52748 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229542AbjASLGx (ORCPT ); Thu, 19 Jan 2023 06:06:53 -0500 Received: from mx5.didiglobal.com (mx5.didiglobal.com [111.202.70.122]) by lindbergh.monkeyblade.net (Postfix) with SMTP id BEB2DE3 for ; Thu, 19 Jan 2023 03:06:51 -0800 (PST) Received: from mail.didiglobal.com (unknown [10.79.65.12]) by mx5.didiglobal.com (Maildata Gateway V2.8) with ESMTPS id 1C818B008082F; Thu, 19 Jan 2023 19:06:49 +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; Thu, 19 Jan 2023 19:06:48 +0800 Date: Thu, 19 Jan 2023 19:06:42 +0800 X-MD-Sfrom: tiozhang@didiglobal.com X-MD-SrcIP: 10.79.65.12 From: Tio Zhang To: , CC: , , , , , , , , Subject: [PATCH v2] sched: print parent comm in sched_show_task() Message-ID: <20230119110642.GA6463@didi-ThinkCentre-M930t-N000> Mail-Followup-To: pmladek@suse.com, yu.c.chen@intel.com, juri.lelli@redhat.com, mingo@redhat.com, peterz@infradead.org, vincent.guittot@linaro.org, linux-kernel@vger.kernel.org, zyhtheonly@gmail.com, zwp10758@gmail.com, zyhtheonly@yeah.net 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 while keeping the original line the same. And we would print "parent:unknown ppid:" when the task is not alive. Signed-off-by: Tio Zhang --- kernel/sched/core.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index cb2aa2b54c7a..5690a5700f9e 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8854,6 +8854,7 @@ void sched_show_task(struct task_struct *p) { unsigned long free =3D 0; int ppid; + char *pcomm =3D NULL; =20 if (!try_get_task_stack(p)) return; @@ -8867,13 +8868,22 @@ void sched_show_task(struct task_struct *p) #endif ppid =3D 0; 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); + + ppid =3D task_pid_nr(parent); + pcomm =3D parent->comm; + } 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 + if (!ppid) + pr_info("parent:unknown ppid:\n"); + else + pr_info("parent:%-15.15s ppid:%-6d\n", pcomm, ppid); + print_worker_info(KERN_INFO, p); print_stop_info(KERN_INFO, p); show_stack(p, NULL, KERN_INFO); --=20 2.17.1