From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E99CDC3A59E for ; Tue, 20 Aug 2019 18:01:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C4A3F22D6D for ; Tue, 20 Aug 2019 18:01:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730423AbfHTSBW (ORCPT ); Tue, 20 Aug 2019 14:01:22 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:52791 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727006AbfHTSBW (ORCPT ); Tue, 20 Aug 2019 14:01:22 -0400 Received: from p5de0b6c5.dip0.t-ipconnect.de ([93.224.182.197] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1i08RX-0004FB-JJ; Tue, 20 Aug 2019 20:01:15 +0200 Date: Tue, 20 Aug 2019 20:01:14 +0200 (CEST) From: Thomas Gleixner To: Matthew Wilcox cc: Sebastian Siewior , LKML , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, Peter Zijlstra , Ingo Molnar , Anna-Maria Gleixner , Steven Rostedt , Julia Cartwright , Jan Kara , Theodore Tso , Alexander Viro , Jan Kara , Mark Fasheh , Joseph Qi , Christoph Hellwig , Joel Becker Subject: Re: [PATCH] fs/buffer: Make BH_Uptodate_Lock bit_spin_lock a regular spinlock_t In-Reply-To: <20190820171721.GA4949@bombadil.infradead.org> Message-ID: References: <20190820170818.oldsdoumzashhcgh@linutronix.de> <20190820171721.GA4949@bombadil.infradead.org> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Tue, 20 Aug 2019, Matthew Wilcox wrote: > On Tue, Aug 20, 2019 at 07:08:18PM +0200, Sebastian Siewior wrote: > > Bit spinlocks are problematic if PREEMPT_RT is enabled, because they > > disable preemption, which is undesired for latency reasons and breaks when > > regular spinlocks are taken within the bit_spinlock locked region because > > regular spinlocks are converted to 'sleeping spinlocks' on RT. So RT > > replaces the bit spinlocks with regular spinlocks to avoid this problem. > > Bit spinlocks are also not covered by lock debugging, e.g. lockdep. > > > > Substitute the BH_Uptodate_Lock bit spinlock with a regular spinlock. > > > > Signed-off-by: Thomas Gleixner > > [bigeasy: remove the wrapper and use always spinlock_t] > > Uhh ... always grow the buffer_head, even for non-PREEMPT_RT? Why? Christoph requested that: https://lkml.kernel.org/r/20190802075612.GA20962@infradead.org Thanks, tglx