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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 76AFDC43387 for ; Thu, 10 Jan 2019 19:47:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 46EFD20879 for ; Thu, 10 Jan 2019 19:47:16 +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="nBsMHABf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728930AbfAJTrP (ORCPT ); Thu, 10 Jan 2019 14:47:15 -0500 Received: from merlin.infradead.org ([205.233.59.134]:51148 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728073AbfAJTrM (ORCPT ); Thu, 10 Jan 2019 14:47:12 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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=us2vqTukos5xrP0a48X02kFzcYNH72RHcMba+8KaRv4=; b=nBsMHABfB4uOhR66sDZK0hnS/ bGxGMEXpzGM0Ex+BAHjoZlYAGuJ//kchYd7xvR38SpRCw2IiFrsnUzINcwDJjd8IS0wNrUqbXlbQ8 JNVqlb76H/9Zy+ldxvtIjJM4/4kj5zOgPukYVoiuIt0Ds208kDsNlyca8DqAmNtNiyzUUrb8hOxK9 ivms9tQFU7cabpcN28xpL+WUqlohj82QSf//1EzaKZmyMLJm6lXPggIR9hWBuFtLR9leYrFtsdMCb viE6MBVom+Itn+XkgU3mtI29K8xMRMegPZxDNWQIaFdM3wyQYlxd10Md3sGgzYd2aDGfjMfuTFGjz k0fsdZwjg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1ghgIE-0006q0-1o; Thu, 10 Jan 2019 19:47:06 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id BE0A49844AF; Thu, 10 Jan 2019 20:47:03 +0100 (CET) Date: Thu, 10 Jan 2019 20:47:03 +0100 From: Peter Zijlstra To: Bart Van Assche Cc: mingo@redhat.com, tj@kernel.org, longman@redhat.com, johannes.berg@intel.com, linux-kernel@vger.kernel.org, Johannes Berg Subject: Re: [PATCH v5 07/15] locking/lockdep: Free lock classes that are no longer in use Message-ID: <20190110194703.GE2861@worktop.programming.kicks-ass.net> References: <20181217213002.73776-1-bvanassche@acm.org> <20181217213002.73776-8-bvanassche@acm.org> <20190110152804.GH30894@hirez.programming.kicks-ass.net> <1547148671.83374.54.camel@acm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1547148671.83374.54.camel@acm.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 10, 2019 at 11:31:11AM -0800, Bart Van Assche wrote: > On Thu, 2019-01-10 at 16:28 +0100, Peter Zijlstra wrote: > > On Mon, Dec 17, 2018 at 01:29:54PM -0800, Bart Van Assche wrote: > > > +static bool inside_selftest(void) > > > +{ > > > + return current == lockdep_selftest_task_struct; > > > +} > > > +void lockdep_free_key_range(void *start, unsigned long size) > > > +{ > > > + init_data_structures_once(); > > > + > > > + if (inside_selftest()) > > > + lockdep_free_key_range_imm(start, size); > > > + else > > > + lockdep_free_key_range_reg(start, size); > > > } > > > > That is .... unfortunate. The whole reason that whole immediate thing > > works at all is because there is no concurrency what so ever that early, > > right? > > > > Should we maybe key off of: 'system_state == SYSTEM_BOOTING' instead? > > Hi Peter, > > I agree that it is unfortunate that the selftests require a different code > path. I have not been able to find any way to avoid this. Using the test > system_state == SYSTEM_BOOTING should work and will allow to remove the > lockdep_selftest_task_struct variable. Do you want me to make that change? I can do it; another approach is simply using the _imm (maybe renamed to _selftest) functions directly, and getting rid of this dynamic choice. I'm undecided as of yet.