From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4C893C433DF for ; Thu, 21 May 2020 01:36:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 11D45206BE for ; Thu, 21 May 2020 01:36:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="vF1L5jp+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727869AbgEUBgC (ORCPT ); Wed, 20 May 2020 21:36:02 -0400 Received: from mail27.static.mailgun.info ([104.130.122.27]:43356 "EHLO mail27.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726840AbgEUBgA (ORCPT ); Wed, 20 May 2020 21:36:00 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1590024960; h=In-Reply-To: Content-Type: MIME-Version: References: Message-ID: Subject: Cc: To: From: Date: Sender; bh=vyiFP+qGMYV+Am54Ab6TSEgSEpSd01azXhoSKWjYyKc=; b=vF1L5jp+MokLkTwdztu22DpD9dkah6rhqtd3vB4QwmaqMvCk8wp16HDwXS/J6f2YgqnHO+pq 764ixX0+id27LsNIg3IIfnDLWSARoADhzMkYheidVwLFExxGfEhZYpjYN14JESmyX2nZp9Fi v67UKRVvQvZGvubfQP34clEy0AU= X-Mailgun-Sending-Ip: 104.130.122.27 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by mxa.mailgun.org with ESMTP id 5ec5daf7.7f84b2e0de68-smtp-out-n02; Thu, 21 May 2020 01:35:51 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id C4EA0C43391; Thu, 21 May 2020 01:35:50 +0000 (UTC) Received: from codeaurora.org (blr-c-bdr-fw-01_GlobalNAT_AllZones-Outside.qualcomm.com [103.229.19.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: pkondeti) by smtp.codeaurora.org (Postfix) with ESMTPSA id 6464DC433C6; Thu, 21 May 2020 01:35:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 6464DC433C6 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=none smtp.mailfrom=pkondeti@codeaurora.org Date: Thu, 21 May 2020 07:05:44 +0530 From: Pavan Kondeti To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, Vinayak Menon , Ben Dooks , "Peter Zijlstra (Intel)" , Thomas Gleixner , "Steven Rostedt (VMware)" , Liang Chen Subject: Re: [PATCH] kthread: Use TASK_IDLE state for newly created kernel threads Message-ID: <20200521013544.GC31725@codeaurora.org> References: <1589975710-9283-1-git-send-email-pkondeti@codeaurora.org> <20200520181858.GA343493@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200520181858.GA343493@kroah.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 20, 2020 at 08:18:58PM +0200, Greg Kroah-Hartman wrote: > On Wed, May 20, 2020 at 05:25:09PM +0530, Pavankumar Kondeti wrote: > > When kernel threads are created for later use, they will be in > > TASK_UNINTERRUPTIBLE state until they are woken up. This results > > in increased loadavg and false hung task reports. To fix this, > > use TASK_IDLE state instead of TASK_UNINTERRUPTIBLE when > > a kernel thread schedules out for the first time. > > > > Signed-off-by: Pavankumar Kondeti > > --- > > kernel/kthread.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/kernel/kthread.c b/kernel/kthread.c > > index bfbfa48..b74ed8e 100644 > > --- a/kernel/kthread.c > > +++ b/kernel/kthread.c > > @@ -250,7 +250,7 @@ static int kthread(void *_create) > > current->vfork_done = &self->exited; > > > > /* OK, tell user we're spawned, wait for stop or wakeup */ > > - __set_current_state(TASK_UNINTERRUPTIBLE); > > + __set_current_state(TASK_IDLE); > > create->result = current; > > /* > > * Thread is going to call schedule(), do not preempt it, > > @@ -428,7 +428,7 @@ static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state) > > > > void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask) > > { > > - __kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE); > > + __kthread_bind_mask(p, mask, TASK_IDLE); > > } > > > > /** > > @@ -442,7 +442,7 @@ void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask) > > */ > > void kthread_bind(struct task_struct *p, unsigned int cpu) > > { > > - __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE); > > + __kthread_bind(p, cpu, TASK_IDLE); > > } > > EXPORT_SYMBOL(kthread_bind); > > It's as if people never read mailing lists: > https://lore.kernel.org/r/DM6PR11MB3531D3B164357B2DC476102DDFC90@DM6PR11MB3531.namprd11.prod.outlook.com > > Given that this is an identical resend of the previous patch, why are > you doing so, and what has changed since that original rejection? > I did not know that it is attempted before. Thanks for pointing to the previous discussion. We have seen hung task reports from customers and it is due to a downstream change which create bunch of kernel threads for later use. From Peter's reply, I understood that one must wake up the kthread after creation and put it in INTERRUPTIBLE sleep. I will pass on the message. Thanks, Pavan -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.