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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 68579C31E40 for ; Tue, 6 Aug 2019 06:11:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3EAE12086D for ; Tue, 6 Aug 2019 06:11:31 +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="ia9qAdq6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731759AbfHFGL1 (ORCPT ); Tue, 6 Aug 2019 02:11:27 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:57880 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731708AbfHFGL1 (ORCPT ); Tue, 6 Aug 2019 02:11:27 -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=aB60sYFkleC6hpDylnEldYGmLHnG+9pRYw06I4nxy6M=; b=ia9qAdq6lNwFYo7OVTZPsfhxv vfOjSEbe9ZkOiaAOKXdKACSVtb7rMX+i3fcKh0974MqVDFqWUVvEtfnry2a+ezfxHcDX+r+jgSl50 4z8jVldTjbUVRJWVBZXrw753MjgEsLKG3pAdolC1PYVTAIiRMZaCUjvDi4ZbEkre5vaoTQXo1KETI OlBxF2ExoFKfBRpc+TrCOYdxFhwlgpmKi5cuPacGG26m5p0pT+N+pjxlSVyd3pSxk1WRTuDcWdOw8 nXuhTXz7wF2qZXGAy1lH72pgTQdZ+NgIHLkPSCgb3p7NxvwYBxpElWC7GCA+TdWg9Dr2qPPVGqCcv JHcSj4RBQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.92 #3 (Red Hat Linux)) id 1husgp-0005nR-Nj; Tue, 06 Aug 2019 06:11:19 +0000 Date: Mon, 5 Aug 2019 23:11:19 -0700 From: Christoph Hellwig To: Thomas Gleixner Cc: Christoph Hellwig , LKML , Peter Zijlstra , Ingo Molnar , Sebastian Siewior , Anna-Maria Gleixner , Steven Rostedt , Julia Cartwright , Jan Kara , Theodore Tso , Matthew Wilcox , Alexander Viro , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, Jan Kara , Mark Fasheh , Joseph Qi , Joel Becker Subject: Re: [patch V2 0/7] fs: Substitute bit-spinlocks for PREEMPT_RT and debugging Message-ID: <20190806061119.GA17492@infradead.org> References: <20190801010126.245731659@linutronix.de> <20190802075612.GA20962@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.4 (2019-03-13) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri, Aug 02, 2019 at 11:07:53AM +0200, Thomas Gleixner wrote: > Last time I did, there was resistance :) Do you have a pointer? Note that in the buffer head case maybe a hash lock based on the page address is even better, as we only ever use the lock in the first buffer head of a page anyway.. > What about the page lock? > > mm/slub.c: bit_spin_lock(PG_locked, &page->flags); One caller ouf of a gazillion that spins on the page lock instead of sleepign on it like everyone else. That should not have passed your smell test to start with :)