From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751246AbdBOIIw (ORCPT ); Wed, 15 Feb 2017 03:08:52 -0500 Received: from mail-wm0-f65.google.com ([74.125.82.65]:34788 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750800AbdBOIIv (ORCPT ); Wed, 15 Feb 2017 03:08:51 -0500 Date: Wed, 15 Feb 2017 09:08:47 +0100 From: Ingo Molnar To: Aleksa Sarai Cc: Johannes Weiner , Ingo Molnar , Peter Zijlstra , Andrew Morton , Michal Hocko , Oleg Nesterov , linux-kernel@vger.kernel.org, linux-mm@kvack.org, cyphar@cyphar.com Subject: Re: [PATCH] oom_reaper: switch to struct list_head for reap queue Message-ID: <20170215080847.GA28090@gmail.com> References: <20170214150714.6195-1-asarai@suse.de> <20170214163005.GA2450@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Aleksa Sarai wrote: > >>Rather than implementing an open addressing linked list structure > >>ourselves, use the standard list_head structure to improve consistency > >>with the rest of the kernel and reduce confusion. > >> > >>Cc: Michal Hocko > >>Cc: Oleg Nesterov > >>Signed-off-by: Aleksa Sarai > >>--- > >> include/linux/sched.h | 6 +++++- > >> kernel/fork.c | 4 ++++ > >> mm/oom_kill.c | 24 +++++++++++++----------- > >> 3 files changed, 22 insertions(+), 12 deletions(-) > >> > >>diff --git a/include/linux/sched.h b/include/linux/sched.h > >>index e93594b88130..d8bcd0f8c5fe 100644 > >>--- a/include/linux/sched.h > >>+++ b/include/linux/sched.h > >>@@ -1960,7 +1960,11 @@ struct task_struct { > >> #endif > >> int pagefault_disabled; > >> #ifdef CONFIG_MMU > >>- struct task_struct *oom_reaper_list; > >>+ /* > >>+ * List of threads that have to be reaped by OOM (rooted at > >>+ * &oom_reaper_list in mm/oom_kill.c). > >>+ */ > >>+ struct list_head oom_reaper_list; > > > >This is an extra pointer to task_struct and more lines of code to > >accomplish the same thing. Why would we want to do that? > > I don't think it's more "actual" lines of code (I think the wrapping is > inflating the line number count), but switching it means that it's more in > line with other queues in the kernel (it took me a bit to figure out what > was going on with oom_reaper_list beforehand). It's still an extra pointer and extra generated code to do the same thing - a clear step backwards. Thanks, Ingo