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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 E8234C64EB1 for ; Fri, 7 Dec 2018 09:22:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AAAD320868 for ; Fri, 7 Dec 2018 09:22:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="koyp6/x6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AAAD320868 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726035AbeLGJWE (ORCPT ); Fri, 7 Dec 2018 04:22:04 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:53766 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725976AbeLGJWD (ORCPT ); Fri, 7 Dec 2018 04:22:03 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=Sh3bp5HViOL6B4pX3LYPzliLYMoGh1xLBt60hl5qof8=; b=koyp6/x6okHEK/ND7ppHmFxGj XsJbebbKzTwufxyuPp4TxKCq6mAKUC+GwbGmNtwja99NCWSY+9kFMpTgDKbveUi9lhgbrYyDOV0h5 ux1Fqp4RzuQhl5fqAagjE7OC7ptrpwUtHtiNCtnIJjZ4BfhMG4ne+23EIHAG5dARVrl69yaHiem+y JvamTtFQdEZTKm74QwgyODxtC/+P1Z0RVCNvzjCUBG+5gaE0h0vZc5ezQyDvughILwC+0myw25Ttq h7peczCTThBYbhqdSdGs+az/Gan6usIfhoCMLFYLeKuSuMmp3wt3QfG7tm7sQ6cQRJxyLiXejpWmj OfQsFOLeQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gVCKc-0007K5-5o; Fri, 07 Dec 2018 09:21:58 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id AD3372072617E; Fri, 7 Dec 2018 10:21:56 +0100 (CET) Date: Fri, 7 Dec 2018 10:21:56 +0100 From: Peter Zijlstra To: Waiman Long Cc: Ingo Molnar , Will Deacon , Thomas Gleixner , linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Petr Mladek , Sergey Senozhatsky , Andrey Ryabinin , Tejun Heo , Andrew Morton Subject: Re: [PATCH v2 07/17] debugobjects: Move printk out of db lock critical sections Message-ID: <20181207092156.GE2237@hirez.programming.kicks-ass.net> References: <1542653726-5655-1-git-send-email-longman@redhat.com> <1542653726-5655-8-git-send-email-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1542653726-5655-8-git-send-email-longman@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 19, 2018 at 01:55:16PM -0500, Waiman Long wrote: > The db->lock is a raw spinlock and so the lock hold time is supposed > to be short. This will not be the case when printk() is being involved > in some of the critical sections. In order to avoid the long hold time, > in case some messages need to be printed, the debug_object_is_on_stack() > and debug_print_object() calls are now moved out of those critical > sections. That's not why you did this patch though; you want to make these locks terminal locks and that means no printk() inside, as that uses locks again. Please write relevant changelogs.