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=-7.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_PASS,USER_AGENT_MUTT 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 EC8D9C43219 for ; Tue, 30 Apr 2019 14:30:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BB25C20835 for ; Tue, 30 Apr 2019 14:30:00 +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="qeO0cllV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726291AbfD3O3z (ORCPT ); Tue, 30 Apr 2019 10:29:55 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:36004 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725942AbfD3O3z (ORCPT ); Tue, 30 Apr 2019 10:29:55 -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=H4+KAPmjx58DIhwVOO8DsRJgwzL0afbdwEtz43iN/Dw=; b=qeO0cllVcOA1oaf4HAuMfdckj RhFwPVYQGDmsZMoFiuGNTaPt8hExZGUfXOVhRnw8/zlURThnFPBTtWt5mOOXPYbSfTLIQJn4aW9Qe T0eL5b6B3mFexBBD3j97bCKiumW6TnRblkqCsJPhVr972iJXUUxIArSb7OS8sSpr3Whe4gZyVYDDs JRNjh4TAkjvvlg3/FuYPsV8+JSqtyufQCyoMR2gP5h/TBNy/02iyCVOsEYKNDuJpj7iH03oK85KWi AFSd4bpfLifmlNvRSG0Z/LxbfrrT8NS3MYhdjKi9AsNGxMKxobuAsT40q1IQ7odBi04Fh2xXXi2/Q i5gUL2gLQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hLTlY-00087M-Cx; Tue, 30 Apr 2019 14:29:52 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 6CFBA29D226A0; Tue, 30 Apr 2019 16:29:50 +0200 (CEST) Date: Tue, 30 Apr 2019 16:29:50 +0200 From: Peter Zijlstra To: Oleg Nesterov Cc: Sebastian Andrzej Siewior , linux-rt-users , LKML , Thomas Gleixner , Daniel Bristot de Oliveira , Clark Williams , Juri Lelli , jack@suse.com Subject: Re: [RT WARNING] DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current) with fsfreeze (4.19.25-rt16) Message-ID: <20190430142950.GG2589@hirez.programming.kicks-ass.net> References: <20190326093421.GA29508@localhost.localdomain> <20190419085627.GI4742@localhost.localdomain> <20190430125130.uw7mhdnsoqr2v3gf@linutronix.de> <20190430132811.GB2589@hirez.programming.kicks-ass.net> <20190430141500.GE23020@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190430141500.GE23020@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-rt-users-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org On Tue, Apr 30, 2019 at 04:15:01PM +0200, Oleg Nesterov wrote: > Sorry, I don't understand... So the problem is that on -RT rwsem uses PI mutexes, and the below just cannot work. Also see: https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/tree/include/linux/rwsem_rt.h?h=linux-5.0.y-rt https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/tree/kernel/locking/rwsem-rt.c?h=linux-5.0.y-rt > On 04/30, Peter Zijlstra wrote: > > > > Thaw then does the reverse, frobs lockdep > > Yes, in particular it does > > lockdep_sb_freeze_acquire() > percpu_rwsem_acquire() > sem->rw_sem.owner = current; > Oh ARGGH, I missed that. This is horrible :-(