From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753612AbeAQPPQ (ORCPT + 1 other); Wed, 17 Jan 2018 10:15:16 -0500 Received: from mail-qt0-f182.google.com ([209.85.216.182]:35728 "EHLO mail-qt0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753586AbeAQPPO (ORCPT ); Wed, 17 Jan 2018 10:15:14 -0500 X-Google-Smtp-Source: ACJfBouaJUqWpQq8HsI461sGzpwQF6hI+EBNh/GHE1rv0bMtK4R2r2WjcAF9XvlDwrAIEQFxF+2SNw== Date: Wed, 17 Jan 2018 07:15:09 -0800 From: Tejun Heo To: Petr Mladek Cc: Steven Rostedt , Sergey Senozhatsky , Sergey Senozhatsky , akpm@linux-foundation.org, linux-mm@kvack.org, Cong Wang , Dave Hansen , Johannes Weiner , Mel Gorman , Michal Hocko , Vlastimil Babka , Peter Zijlstra , Linus Torvalds , Jan Kara , Mathieu Desnoyers , Tetsuo Handa , rostedt@home.goodmis.org, Byungchul Park , Pavel Machek , linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 0/2] printk: Console owner and waiter logic cleanup Message-ID: <20180117151509.GT3460072@devbig577.frc2.facebook.com> References: <20180110140547.GZ3668920@devbig577.frc2.facebook.com> <20180110130517.6ff91716@vmware.local.home> <20180111045817.GA494@jagdpanzerIV> <20180111093435.GA24497@linux.suse> <20180111103845.GB477@jagdpanzerIV> <20180111112908.50de440a@vmware.local.home> <20180111203057.5b1a8f8f@gandalf.local.home> <20180111215547.2f66a23a@gandalf.local.home> <20180116194456.GS3460072@devbig577.frc2.facebook.com> <20180117091208.ezvuhumnsarz5thh@pathway.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180117091208.ezvuhumnsarz5thh@pathway.suse.cz> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: Hello, On Wed, Jan 17, 2018 at 10:12:08AM +0100, Petr Mladek wrote: > IMHO, the bad scenario with OOM was that any printk() called in > the OOM report became console_lock owner and was responsible > for pushing all new messages to the console. There was a possible > livelock because OOM Killer was blocked in console_unlock() while > other CPUs repeatedly complained about failed allocations. I don't know why we're constantly back into this same loop on this topic but that's not the problem we've been seeing. There are no other CPUs involved. It's great that Steven's patches solve a good number of problems. It is also true that there's a class of problems that it doesn't solve, which other approaches do. The productive thing to do here is trying to solve the unsolved one too, especially given that it doesn't seem too difficuilt to do so on top of what's proposed. Thanks. -- tejun From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f198.google.com (mail-qt0-f198.google.com [209.85.216.198]) by kanga.kvack.org (Postfix) with ESMTP id 4AA056B0069 for ; Wed, 17 Jan 2018 10:15:15 -0500 (EST) Received: by mail-qt0-f198.google.com with SMTP id h32so9784809qtb.9 for ; Wed, 17 Jan 2018 07:15:15 -0800 (PST) Received: from mail-sor-f41.google.com (mail-sor-f41.google.com. [209.85.220.41]) by mx.google.com with SMTPS id q19sor2319616qta.61.2018.01.17.07.15.14 for (Google Transport Security); Wed, 17 Jan 2018 07:15:14 -0800 (PST) Date: Wed, 17 Jan 2018 07:15:09 -0800 From: Tejun Heo Subject: Re: [PATCH v5 0/2] printk: Console owner and waiter logic cleanup Message-ID: <20180117151509.GT3460072@devbig577.frc2.facebook.com> References: <20180110140547.GZ3668920@devbig577.frc2.facebook.com> <20180110130517.6ff91716@vmware.local.home> <20180111045817.GA494@jagdpanzerIV> <20180111093435.GA24497@linux.suse> <20180111103845.GB477@jagdpanzerIV> <20180111112908.50de440a@vmware.local.home> <20180111203057.5b1a8f8f@gandalf.local.home> <20180111215547.2f66a23a@gandalf.local.home> <20180116194456.GS3460072@devbig577.frc2.facebook.com> <20180117091208.ezvuhumnsarz5thh@pathway.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180117091208.ezvuhumnsarz5thh@pathway.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Petr Mladek Cc: Steven Rostedt , Sergey Senozhatsky , Sergey Senozhatsky , akpm@linux-foundation.org, linux-mm@kvack.org, Cong Wang , Dave Hansen , Johannes Weiner , Mel Gorman , Michal Hocko , Vlastimil Babka , Peter Zijlstra , Linus Torvalds , Jan Kara , Mathieu Desnoyers , Tetsuo Handa , rostedt@home.goodmis.org, Byungchul Park , Pavel Machek , linux-kernel@vger.kernel.org Hello, On Wed, Jan 17, 2018 at 10:12:08AM +0100, Petr Mladek wrote: > IMHO, the bad scenario with OOM was that any printk() called in > the OOM report became console_lock owner and was responsible > for pushing all new messages to the console. There was a possible > livelock because OOM Killer was blocked in console_unlock() while > other CPUs repeatedly complained about failed allocations. I don't know why we're constantly back into this same loop on this topic but that's not the problem we've been seeing. There are no other CPUs involved. It's great that Steven's patches solve a good number of problems. It is also true that there's a class of problems that it doesn't solve, which other approaches do. The productive thing to do here is trying to solve the unsolved one too, especially given that it doesn't seem too difficuilt to do so on top of what's proposed. Thanks. -- tejun -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org