Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754674AbdHZAbz (ORCPT ); Fri, 25 Aug 2017 20:31:55 -0400 Received: from mail-oi0-f67.google.com ([209.85.218.67]:34736 "EHLO mail-oi0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754171AbdHZAby (ORCPT ); Fri, 25 Aug 2017 20:31:54 -0400 MIME-Version: 1.0 In-Reply-To: References: <83f675ad385d67760da4b99cd95ee912ca7c0b44.1503677178.git.tim.c.chen@linux.intel.com> From: Linus Torvalds Date: Fri, 25 Aug 2017 17:31:52 -0700 X-Google-Sender-Auth: WPQ5A23ZF1zlGRUUjXwuvfGMhGo Message-ID: Subject: Re: [PATCH 2/2 v2] sched/wait: Introduce lock breaker in wake_up_page_bit To: Tim Chen Cc: Mel Gorman , Peter Zijlstra , Ingo Molnar , Andi Kleen , Kan Liang , Andrew Morton , Johannes Weiner , Jan Kara , Christopher Lameter , "Eric W . Biederman" , Davidlohr Bueso , linux-mm , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 661 Lines: 18 On Fri, Aug 25, 2017 at 4:03 PM, Linus Torvalds wrote: > > Let this be a lesson in just *how* little tested, and *how* crap that > patch probably still is. I haven't had time to look at it any more (trying to merge the pull requests that came in today instead), but the more I think about it, the more I think it was a mistake to do that page_wait_struct allocation on the stack. It made it way more fragile and complicated, having to rewrite things so carefully. A simple slab cache would likely be a lot cleaner and simpler. So even if that thing can be made to work, it's probably not worth the pain. Linus