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 E017FC6FD1D for ; Tue, 14 Mar 2023 12:02:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231769AbjCNMCy (ORCPT ); Tue, 14 Mar 2023 08:02:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59700 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231520AbjCNMCs (ORCPT ); Tue, 14 Mar 2023 08:02:48 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E854351F96 for ; Tue, 14 Mar 2023 05:02:05 -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 BA21FB81900 for ; Tue, 14 Mar 2023 12:01:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7E625C4339B for ; Tue, 14 Mar 2023 12:01:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1678795300; bh=cC+3opRtfomBdQkbY8l2F4/DwaxVUxed3uEOtpSCVGY=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=sy1iAENpbiVb+hSBkxUpo5wbLmjVSm6C/zZm2Qzdm8FzgNcHycuDI1rnh2KjRrUu/ gg20wOoTC2AqbE7A8ye4m6ewNPd5B11Y7ogZ2B/hL6xrKdI1ZdIp3R9o0jk3qAq5lZ RiIAiepGpoyvVsExQyD7vybCtMEwKor4nyxMYAoZT3DTwR/maxSm5vszhTmOjtZH8S Wr2qmnhXAu6RJw/qtB5fcTQfqVoCPBlrBDofGyuqjmNXiABi7++GkxIvHvO3UcW6yv DnZNTglgvoLkl9u5lT1TnPBkKcPleLJfVI63XsE/QCNFyVCWYGKsparXc46md9CD6x okSwKxA0Exmlg== Received: by mail-lf1-f47.google.com with SMTP id br6so1506034lfb.11 for ; Tue, 14 Mar 2023 05:01:40 -0700 (PDT) X-Gm-Message-State: AO0yUKWI7GOkvOaHGQ9rd6ar576kN4S3fuI9Z2rwBjhj+885M2SsfZY9 RM9hJXMXopGA00qvbGN8EQEZ6A8nDXGNxB0Ji4g= X-Google-Smtp-Source: AK7set9YaucDyYslwqHf47x5ktQpZKUm6qYScAZY2ls9L2X7/10DPF1gWXiPE3QiaNyuToFznb2DzIc2s5L23xjGsBQ= X-Received: by 2002:ac2:5591:0:b0:4dd:98c6:ee3 with SMTP id v17-20020ac25591000000b004dd98c60ee3mr655779lfg.4.1678795298502; Tue, 14 Mar 2023 05:01:38 -0700 (PDT) MIME-Version: 1.0 References: <20230314114018.GF1845660@hirez.programming.kicks-ass.net> In-Reply-To: <20230314114018.GF1845660@hirez.programming.kicks-ass.net> From: Ard Biesheuvel Date: Tue, 14 Mar 2023 13:01:27 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: Linux 6.3-rc2 To: Peter Zijlstra Cc: Frederic Weisbecker , Guenter Roeck , Linus Torvalds , "Paul E. McKenney" , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 14 Mar 2023 at 12:40, Peter Zijlstra wrote: > > On Tue, Mar 14, 2023 at 12:18:33PM +0100, Frederic Weisbecker wrote: > > How does the following look like as a culprit? > > > > 62b95a7b44d1 (ARM: 9282/1: vfp: Manipulate task VFP state with softirqs disabled) > > Ooh yeah, that asm implementation of local_bh_{dis,en}able completely > miss out on the lockdep state tracking. Also I think it breaks RCU, note > how __local_bh_disable_ip() explicitly does rcu_read_lock() for the > first bh-disable. > Thanks a lot for the diagnosis, doctor :-) I may need some hand holding getting this fixed - probably better to run the C implementations wherever feasible, right?