From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753375AbdE0Hrv (ORCPT ); Sat, 27 May 2017 03:47:51 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:43512 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753343AbdE0Hru (ORCPT ); Sat, 27 May 2017 03:47:50 -0400 Date: Sat, 27 May 2017 09:47:47 +0200 From: Sebastian Andrzej Siewior To: Anna-Maria Gleixner Cc: Haris Okanovic , linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, julia.cartwright@ni.com, gratian.crisan@ni.com Subject: Re: [PATCH] Revert "timers: Don't wake ktimersoftd on every tick" Message-ID: <20170527074746.6w7vakbuelurs245@linutronix.de> References: <20170203165151.qbpjothhaqctuzx5@linutronix.de> <20170203182112.18053-1-haris.okanovic@ni.com> <20170210170207.3kzfqyfa4ueh7mih@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170306 (1.8.0) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2017-05-26 19:16:07 [+0200], Anna-Maria Gleixner wrote: > This reverts commit 032f93cae150a. > > The problem is that the look ahead optimization from the tick timer > interrupt context can race with the softirq thread expiring timer. As > a consequence the temporary hlist heads which hold the to expire > timers are overwritten and the timers which are already removed from > the wheel bucket for expiry are now dangling w/o a list head. > > That means those timers never get expired. If one of those timers is > canceled the removal operation will result in a hlist corruption. > > Signed-off-by: Anna-Maria Gleixner Applied Sebastian