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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 A4CE6C2D0A8 for ; Mon, 28 Sep 2020 08:00:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1078522262 for ; Mon, 28 Sep 2020 08:00:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Wn1/p+6d" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726572AbgI1IAt (ORCPT ); Mon, 28 Sep 2020 04:00:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36256 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726440AbgI1IAs (ORCPT ); Mon, 28 Sep 2020 04:00:48 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 769C8C0613CE for ; Mon, 28 Sep 2020 01:00:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=cyiEBShF0+Den6Bat12B0wofEVTLd28sMsIoC8rXhVU=; b=Wn1/p+6dBt1I8+sPUEp4wfX2jV 82cDd2WB2SGyRCCisedLd5e9WVw/i325tuOE0bYmSeirLu7c14fnAGwD4nmz5jAwe6F88ZpYPhAQ1 nRAip7w99gP+wSuz8egplc5vBLJm+yy1tk0QyS9twm1HC5I6yRY1iQc7uDtCQ7z+x+UY+FyjVj8Il pGBulI/ri1AG9O7B2G43bjK+7FgzW5vT1B/kgCO6tFkkZlrXlr7s8T96Bn0foGq6HxPHxTj9GDLxF j0UEqIA6LjKgNM4E/uYFIuStFAHRXe8npMlnu/jjV/q8ul3P3SkbcTaHNMp80viQ1KNDTDqLIw0U/ GVvpBzmA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kMo5C-0001kK-2L; Mon, 28 Sep 2020 08:00:26 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 1E358300DB4; Mon, 28 Sep 2020 10:00:22 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id CBA21200DCAB1; Mon, 28 Sep 2020 10:00:22 +0200 (CEST) Date: Mon, 28 Sep 2020 10:00:22 +0200 From: Peter Zijlstra To: Joe Perches Cc: Chengming Zhou , linux-kernel@vger.kernel.org, pmladek@suse.com, sergey.senozhatsky@gmail.com, rostedt@goodmis.org, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, songmuchun@bytedance.com Subject: Re: [PATCH 2/2] sched: mark PRINTK_DEFERRED_CONTEXT_MASK in __schedule() Message-ID: <20200928080022.GD2611@hirez.programming.kicks-ass.net> References: <20200927161130.33172-1-zhouchengming@bytedance.com> <20200927161130.33172-2-zhouchengming@bytedance.com> <20200928073202.GA2611@hirez.programming.kicks-ass.net> <0e8e87e25c90339fe790252626855cbb47bc2c08.camel@perches.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0e8e87e25c90339fe790252626855cbb47bc2c08.camel@perches.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 28, 2020 at 12:52:44AM -0700, Joe Perches wrote: > On Mon, 2020-09-28 at 09:32 +0200, Peter Zijlstra wrote: > > On Mon, Sep 28, 2020 at 12:11:30AM +0800, Chengming Zhou wrote: > > > The WARN_ON/WARN_ON_ONCE with rq lock held in __schedule() should be > > > deferred by marking the PRINTK_DEFERRED_CONTEXT_MASK, or will cause > > > deadlock on rq lock in the printk path. > [] > > NAK printk_deferred is an abomination, kill that. > > Didn't you introduce it? > Should you be complaining to yourself? Yeah. I should've hacked around it then I suppose. Still, no reason to proliferate that crap. Afaik the new printk should be able to deal with this at some point. The thing we're not going to do it add a cache-miss to schedule just because.