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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 BDAB6C33CB7 for ; Mon, 20 Jan 2020 07:23:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 937BC20684 for ; Mon, 20 Jan 2020 07:23:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579504980; bh=sE0YgHR3/69NR2b6qoAvqiX5z6zce0Lt3KatTtwtWW8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=KmQ1utsTTSOueHPsyDAhBkOiRpWcEH38eAUGIkW3Mg78H1fryDTAGxdeHl5kRWBDj ynLsXtGJeUwe1t59BceSgr8gJU4eRJYH4SWwgm2UjmGsynzAinZuqzhXq0RmYbDFdb pwLOsU04lxARz4qsanR/ABysgY/eMNT9PdkND99c= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726626AbgATHW7 (ORCPT ); Mon, 20 Jan 2020 02:22:59 -0500 Received: from mail-wr1-f66.google.com ([209.85.221.66]:42914 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725851AbgATHW7 (ORCPT ); Mon, 20 Jan 2020 02:22:59 -0500 Received: by mail-wr1-f66.google.com with SMTP id q6so28224180wro.9 for ; Sun, 19 Jan 2020 23:22:57 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=XoV6O0m1pCknJULeMQsOZ3LratNUtl8Q4pIJIVCq2CQ=; b=DvTdshZAJbi/lGBOdwq1woVHsmt2NbhSFnb9V8oCDeIxvqDfzSpjak4KXsST02bY9u DxLGrGD7hPOS4YUVebApmIJr+sw0xXfUZC86BZbwBg/KDqjrV7E7tnb5C8F8VeGqmqSI csXh40so+jZxcEMCqnJEzu/ZDZjvM9tFfVFsMSc+Cn6iZCW44wMcjd+wOH4DaF3TuUGH ujA7bPaS4+Ie2t++Kcb9itrpDnefVVbI8x15Dug1o1/l4eqNl1g4ZwFBXk84eLUGjQfN 7QEaJTm+tK4NlrX8lfdTa5wzW04C5cjj2/tK3sQJdOW+b58JR2RasX9OLinNLycQ036r lqaw== X-Gm-Message-State: APjAAAW/FY7fxxgDu8/YUrNemz26vDS9FcMwUteZ72hzJ1gxszWrctk0 G/Fxo6JF+Cg6GaNaYxnDTg9+XAc1 X-Google-Smtp-Source: APXvYqzywx/yRIN+ucM+OPGKSntfCeJSJma/U31vPXTCEzmOaR/EBCEa8L89Pjw6tvf1P8OKlGk/mw== X-Received: by 2002:adf:fd87:: with SMTP id d7mr17305260wrr.226.1579504977148; Sun, 19 Jan 2020 23:22:57 -0800 (PST) Received: from localhost (ip-37-188-138-155.eurotel.cz. [37.188.138.155]) by smtp.gmail.com with ESMTPSA id g25sm1849534wmh.3.2020.01.19.23.22.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 Jan 2020 23:22:56 -0800 (PST) Date: Mon, 20 Jan 2020 08:22:55 +0100 From: Michal Hocko To: Qian Cai Cc: David Hildenbrand , akpm@linux-foundation.org, sergey.senozhatsky.work@gmail.com, pmladek@suse.com, rostedt@goodmis.org, peterz@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH -next v5] mm/hotplug: silence a lockdep splat with printk() Message-ID: <20200120072255.GB18451@dhcp22.suse.cz> References: <5abf5440-7c1c-b9e9-9770-b89759771a44@redhat.com> <587CD165-FAA4-4369-9F30-CB8F9C03F062@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <587CD165-FAA4-4369-9F30-CB8F9C03F062@lca.pw> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 17-01-20 11:35:08, Qian Cai wrote: > > > > On Jan 17, 2020, at 11:27 AM, David Hildenbrand wrote: > > > > the "int" should go onto the next line as well > > [...] > > Yes. > > > apart from that looks good to me. I hope we won't have a whac-a-mole > > with printk() (including WARN_ON() etc?) under the zone lock. This all > > screams for a better fix. > > WARN_ON() is normally not a concern. Once it happens here, we will > figure out the reason why it happens in the first place and shut it > off there instead. It is very much the same concern as any other printk which might deadlock. It is true this is WARN_ONCE so the likelyhood is much smaller. But you know, probability is not going to help you if you are unlucky ;) -- Michal Hocko SUSE Labs