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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2477FC433EF for ; Thu, 9 Jun 2022 12:27:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236811AbiFIM1c (ORCPT ); Thu, 9 Jun 2022 08:27:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54968 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229637AbiFIM13 (ORCPT ); Thu, 9 Jun 2022 08:27:29 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AD99D13EAF for ; Thu, 9 Jun 2022 05:27:24 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 2F7D4B82D31 for ; Thu, 9 Jun 2022 12:27:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 43A28C34114; Thu, 9 Jun 2022 12:27:20 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="cL/t578z" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1654777638; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=jmAyfJLi9ZPxrr5XglUuWLKXwd2sQ5F4418QWy98e5Q=; b=cL/t578zwy2SyTTjrlTP22f5QIRFvmgvvl9HuxtD+7WAkfIJY5OTtDsziFj4ML1n+HfiW8 W3wiYocFp64vZeE7bjSyNLOazgsL+zYQ+VlLYMb6/H6u2vajPcU9DTyCO1x8eLin2OR6q9 T6JGHso3VsxHLGkcRD/jFuzU5W2+hFg= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 969d3aeb (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Thu, 9 Jun 2022 12:27:18 +0000 (UTC) Date: Thu, 9 Jun 2022 14:27:11 +0200 From: "Jason A. Donenfeld" To: Dmitry Vyukov Cc: John Ogness , Geert Uytterhoeven , Marek Szyprowski , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , Linux Kernel Mailing List , Greg Kroah-Hartman , "open list:ARM/Amlogic Meson..." , Theodore Ts'o , Alexander Potapenko , Marco Elver , kasan-dev@googlegroups.com, bigeasy@linutronix.de Subject: Re: [PATCH printk v5 1/1] printk: extend console_lock for per-console locking Message-ID: References: <87fslyv6y3.fsf@jogness.linutronix.de> <51dfc4a0-f6cf-092f-109f-a04eeb240655@samsung.com> <87k0b6blz2.fsf@jogness.linutronix.de> <32bba8f8-dec7-78aa-f2e5-f62928412eda@samsung.com> <87y1zkkrjy.fsf@jogness.linutronix.de> <87fske3wzw.fsf@jogness.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Dmitry, On Thu, Jun 09, 2022 at 02:18:19PM +0200, Dmitry Vyukov wrote: > > AFAIK, CONFIG_PROVE_RAW_LOCK_NESTING is useful for teasing out cases > > where RT's raw spinlocks will nest wrong with RT's sleeping spinlocks. > > But nobody who wants an RT kernel will be using KFENCE. So this seems > > like a non-issue? Maybe just add a `depends on !KFENCE` to > > PROVE_RAW_LOCK_NESTING? > > Don't know if there are other good solutions (of similar simplicity). Fortunately, I found one that solves things without needing to compromise on anything: https://lore.kernel.org/lkml/20220609121709.12939-1-Jason@zx2c4.com/ > Btw, should this new CONFIG_PROVE_RAW_LOCK_NESTING be generally > enabled on testing systems? We don't have it enabled on syzbot. Last time I spoke with RT people about this, the goal was eventually to *always* enable it when lock proving is enabled, but there are too many bugs and cases now to do that, so it's an opt-in. I might be misremembering, though, so CC'ing Sebastian in case he wants to chime in. Jason