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=-5.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 5B4CBC3A59E for ; Tue, 20 Aug 2019 17:17:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 25C9822CF7 for ; Tue, 20 Aug 2019 17:17:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Gml1tOhZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730473AbfHTRR0 (ORCPT ); Tue, 20 Aug 2019 13:17:26 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:54588 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729852AbfHTRR0 (ORCPT ); Tue, 20 Aug 2019 13:17:26 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=oHwVFXFTd/4J3FUGeiOCXpDuyqqKxUu9Uqvxt0jCufw=; b=Gml1tOhZGhEvUuyIfqUo3p3+e saftgBze6Guzy9ncyc4b+AB/n7VrfDXKku9z2zRtgEdRVIhRbxeIRxIittvFu8wOk/9TBrQvfi93g nhbfy25U75aW0qZjIMywMpc2dX675S2ScjoLdBF7qkLTi8uOpuhZy+Vk6ryvWOFR/MryUCGhmOPJ5 q6/jfAbdrwXlFNEc3TMptLDkMsEMwyDkDOsALHFKkksAfKjVQDqEXwhnw0ts++VLjHXlpEwCtzBR6 ry2fUWXdPD4/jOuMPJ4ifPilscj3I+4NIuFK3IF6NCxZ+BJ1UZeTj5VgVpM0oSqXTa9rbS+6V3Dcf Ohr12cOCA==; Received: from willy by bombadil.infradead.org with local (Exim 4.92 #3 (Red Hat Linux)) id 1i07l3-0001ii-DJ; Tue, 20 Aug 2019 17:17:21 +0000 Date: Tue, 20 Aug 2019 10:17:21 -0700 From: Matthew Wilcox To: Sebastian Siewior Cc: LKML , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, Thomas Gleixner , 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 Message-ID: <20190820171721.GA4949@bombadil.infradead.org> References: <20190820170818.oldsdoumzashhcgh@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190820170818.oldsdoumzashhcgh@linutronix.de> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 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?