From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f69.google.com (mail-oi0-f69.google.com [209.85.218.69]) by kanga.kvack.org (Postfix) with ESMTP id F1C856B040B for ; Thu, 6 Apr 2017 07:03:50 -0400 (EDT) Received: by mail-oi0-f69.google.com with SMTP id l132so27710509oia.10 for ; Thu, 06 Apr 2017 04:03:50 -0700 (PDT) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [2001:e42:101:1:202:181:97:72]) by mx.google.com with ESMTPS id o84si563314oib.304.2017.04.06.04.03.49 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 06 Apr 2017 04:03:49 -0700 (PDT) Subject: Re: [PATCH v8] mm: Add memory allocation watchdog kernel thread. From: Tetsuo Handa References: <1489578541-81526-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> In-Reply-To: <1489578541-81526-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> Message-Id: <201704062002.FAE18212.OJOFOHLStFVFQM@I-love.SAKURA.ne.jp> Date: Thu, 6 Apr 2017 20:02:24 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, mhocko@kernel.org, hannes@cmpxchg.org, mgorman@techsingularity.net, david@fromorbit.com, apolyakov@beget.ru, lists@wiesinger.com, hughd@google.com Andrew, anything else I can do? Tetsuo Handa wrote: > Regarding maintenance burden, I consider this patch is least invasive > because it does not make __GFP_NOWARN flag's semantic confusing while > providing administrators some hints [4]. Also, this patch will remain > useful because we might overlook something that can cause infinite > loop (or significant delay) in future changes, and we can remove this > patch when we achieve safe and robust memory management subsystem. > > Changes from v7 [11]: > > (1) Reflect review comments from Andrew Morton. (Convert "u8 type" to > "bool report", use CPUHP_PAGE_ALLOC_DEAD event and replace > for_each_possible_cpu() with for_each_online_cpu(), reuse existing > rcu_lock_break() and hung_timeout_jiffies() for now, update comments). We are still sometimes overlooking unexpected delays like http://lkml.kernel.org/r/alpine.LSU.2.11.1704051331420.4288@eggly.anvils and http://lkml.kernel.org/r/da13c3c7-b514-67b0-2eb9-6d6af277901b@wiesinger.com and I think we will in the future. I believe that this patch is helpful for catching such cases. -- 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