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=-2.5 required=3.0 tests=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 1E0A2C04EB9 for ; Mon, 3 Dec 2018 14:17:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DED4A20850 for ; Mon, 3 Dec 2018 14:17:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DED4A20850 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.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 S1726622AbeLCOSv (ORCPT ); Mon, 3 Dec 2018 09:18:51 -0500 Received: from mx2.suse.de ([195.135.220.15]:57226 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725914AbeLCOSu (ORCPT ); Mon, 3 Dec 2018 09:18:50 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 78A6BAD48; Mon, 3 Dec 2018 14:17:38 +0000 (UTC) Date: Mon, 3 Dec 2018 15:17:37 +0100 From: Michal Hocko To: Pavel Machek Cc: Oleg Nesterov , Ingo Molnar , Linus Torvalds , Linux List Kernel Mailing , "Rafael J. Wysocki" , Chanho Min , Thomas Gleixner , Peter Zijlstra Subject: Re: [PATCH] Revert "exec: make de_thread() freezable (was: Re: Linux 4.20-rc4) Message-ID: <20181203141737.GY31738@dhcp22.suse.cz> References: <20181203074700.GA21240@gmail.com> <20181203083942.GF31738@dhcp22.suse.cz> <20181203123149.GB31795@redhat.com> <20181203123857.GS31738@dhcp22.suse.cz> <20181203131006.GA10054@amd> <20181203135351.GU31738@dhcp22.suse.cz> <20181203141459.GA14789@amd> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181203141459.GA14789@amd> 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 03-12-18 15:14:59, Pavel Machek wrote: > On Mon 2018-12-03 14:53:51, Michal Hocko wrote: > > On Mon 03-12-18 14:10:06, Pavel Machek wrote: > > > On Mon 2018-12-03 13:38:57, Michal Hocko wrote: > > > > On Mon 03-12-18 13:31:49, Oleg Nesterov wrote: > > > > > On 12/03, Michal Hocko wrote: > > > > > > > > > > > > Now, I wouldn't mind to revert this because the code is really old and > > > > > > we haven't seen many bug reports about failing suspend yet. But what is > > > > > > the actual plan to make this work properly? > > > > > > > > > > I don't see a simple solution... > > > > > > > > > > But we need to fix exec/de_thread anyway, then we can probably reconsider > > > > > this patch. > > > > > > > > My concern is that de_thread fix might be too disruptive for stable > > > > kernels while we might want to have a simple enough fix for the the > > > > suspend issue in the meantime. That was actually the primary reason I've > > > > acked the hack even though I didn't like it. > > > > > > Do we care about failing sleep in stable? Does someone hit the issue there? > > > > > > This sounds like issue only Android is hitting, and they run very > > > heavily patched kernels, far away from mainline or stable. > > > > But the underlying issue is the same and independent on their patches > > AFAIU. And is this really a common problem to care about in stable? I > > dunno to be honest but it sounds annoying for sure. Failing suspend is > > something that doesn't make your day when you are in hurry and want > > find out only later when your laptop heats up your bag ;) > > In general, yes. In practice, if it happens 1 in 1000000 suspends, you > don't care that much (but Android cares). This argument just doesn't make any sense. Rare bugs are maybe even more annoying because you do not expect them to happen. But I would be more interested to see whether they are any downside. Is there any actual risk to silence the lockup detector that you can see? > Do we actually have reports of this happening for people outside > Android? Not that I am aware of. -- Michal Hocko SUSE Labs