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,URIBL_BLOCKED,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 ADAF6C433DF for ; Thu, 21 May 2020 09:51:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 73C4F206BE for ; Thu, 21 May 2020 09:51:47 +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="QD+yMqR+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728902AbgEUJvq (ORCPT ); Thu, 21 May 2020 05:51:46 -0400 Received: from mail27.static.mailgun.info ([104.130.122.27]:11839 "EHLO mail27.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728834AbgEUJvq (ORCPT ); Thu, 21 May 2020 05:51:46 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1590054705; h=In-Reply-To: Content-Type: MIME-Version: References: Message-ID: Subject: Cc: To: From: Date: Sender; bh=VUInLX2WLl7cD+RkohFnAqEctPK4dVI0lt7ZdhVDzps=; b=QD+yMqR+ZGtfyNsRHAP6N/Gi24IMFdc6NX4C/yxF6sJaUWWiJJRlbhB17ITNdqVP2pW6djir 49Ud6Bva0UGum5ntJgdLVh04/to+oePHi5YvhK8a7D4HeX5rr4fJb3OR3sujkjyAK1ikvbkD GJsNcLbkrNL+DO0tZrXgHNEPmpc= 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 5ec64f24.7f2addeafa08-smtp-out-n01; Thu, 21 May 2020 09:51:32 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 52DFBC433CA; Thu, 21 May 2020 09:51:32 +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 C2E77C433C6; Thu, 21 May 2020 09:51:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org C2E77C433C6 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 15:21:25 +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: <20200521095125.GD31725@codeaurora.org> References: <1589975710-9283-1-git-send-email-pkondeti@codeaurora.org> <20200520181858.GA343493@kroah.com> <20200521013544.GC31725@codeaurora.org> <20200521055639.GA2337399@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200521055639.GA2337399@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 Thu, May 21, 2020 at 07:56:39AM +0200, Greg Kroah-Hartman wrote: > On Thu, May 21, 2020 at 07:05:44AM +0530, Pavan Kondeti wrote: > > 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. > > Do you have a pointer to that specific change? > Here it is https://source.codeaurora.org/quic/la/kernel/msm-4.19/commit/drivers/staging/android/ion/ion_system_heap.c?h=LA.UM.8.12.r1-11300-sm8250.0&id=0734b477f1e77cb9f91f5e5c0d7742d3113f2cd3 > > 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. > > Just go fix that code, it sounds like it's in your tree already :) > Yes, we will fix it. 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.