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 3CEB0C4332F for ; Fri, 11 Nov 2022 08:55:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233408AbiKKIz5 (ORCPT ); Fri, 11 Nov 2022 03:55:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43386 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233397AbiKKIzz (ORCPT ); Fri, 11 Nov 2022 03:55:55 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6B3DADFD4; Fri, 11 Nov 2022 00:55:54 -0800 (PST) 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 1EB34B82473; Fri, 11 Nov 2022 08:55:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C0DD5C433B5; Fri, 11 Nov 2022 08:55:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1668156951; bh=UwnQcW+DIbVM73qHx8GWpyYkzIMHZcKiFWqIze2hyRY=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=Pp8507HrWf8Jk/myn9ejt1xfHquBLgI59QDipZgTtByCB/o28TTut85Pagtx3u60V JOhfsDu6b94aCjSsfi1sJePKXyQ+ud8Sw8HaGwi7yIdBnUc/t8AB5AmwLDcXqyBieN 8tudYmIWSvpEoXKy9AmGvadVsi1h8Kf9rMNGzpG+O8qPHKlUOMpDWMawYQRLbHY4Tw zHttHHSU0WgPicCgn8rGaPLFi7cqXrKy5QQFFd30wFikAL7aESo33dfkd8STTqzi6Q aaNpVp040u4v57UmfvkxkXyryVFd+mUPaGdKrhj704NgKv9sxZX8oIlo+QpUBQxbYe ybzpFJeKvXNIQ== Received: by mail-lf1-f53.google.com with SMTP id r12so7424847lfp.1; Fri, 11 Nov 2022 00:55:51 -0800 (PST) X-Gm-Message-State: ANoB5pkiL3EZ9Wa2lxgCXqnMCkCrDsLra8X9U46Pvr4qFlhJXhwxnXdK 3iFV14MLFcYlPkBl03o6ONjO6wvIlxiDTZNIjk4= X-Google-Smtp-Source: AA0mqf71xb+rTQ+RGjWOJjElNP/NJKbcHQEHO8Ea095YIB/Wp9FjUpaCoK/GGsmuVGM90XxvuvECKhKDmA5HUhyn68o= X-Received: by 2002:a05:6512:3ca8:b0:4a2:bfd2:b218 with SMTP id h40-20020a0565123ca800b004a2bfd2b218mr433243lfv.228.1668156949779; Fri, 11 Nov 2022 00:55:49 -0800 (PST) MIME-Version: 1.0 References: <29824864-f076-401f-bfb4-bc105bb2d38f@app.fastmail.com> <96a99291-7caa-429c-9bbd-29721a2b5637@app.fastmail.com> <89a8e93c-f667-4de1-972f-3d2d051bd789@app.fastmail.com> In-Reply-To: <89a8e93c-f667-4de1-972f-3d2d051bd789@app.fastmail.com> From: Ard Biesheuvel Date: Fri, 11 Nov 2022 09:55:38 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: arm: TI BeagleBoard X15 : Unable to handle kernel NULL pointer dereference at virtual address 00000369 - Internal error: Oops: 5 [#1] SMP ARM To: Arnd Bergmann Cc: Naresh Kamboju , linux-stable , open list , Linux ARM , lkft-triage@lists.linaro.org, Greg Kroah-Hartman , Sasha Levin , Linus Walleij , Mark Brown , Liam Girdwood Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 11 Nov 2022 at 09:45, Arnd Bergmann wrote: > > On Fri, Nov 11, 2022, at 07:28, Naresh Kamboju wrote: > > On Thu, 10 Nov 2022 at 03:33, Arnd Bergmann wrote: > >> > >> One more idea I had is the unwinder: since this kernel is built > >> with the frame-pointer unwinder, I think the stack usage per > >> function is going to be slightly larger than with the arm unwinder. > >> > >> Naresh, how hard is it to reproduce this bug intentionally? > >> Can you try if it still happens if you change the .config to > >> use these:? > >> > >> # CONFIG_FUNCTION_GRAPH_TRACER is not set > >> # CONFIG_UNWINDER_FRAME_POINTER is not set > >> CONFIG_UNWINDER_ARM=y > > > > I have done this experiment and reported crash not reproduced > > after eight rounds of testing [1]. > > > > https://lkft.validation.linaro.org/scheduler/job/5835922#L1993 > > Ok, good to hear. In this case, I see three possible ways forward > to prevent this from coming back on your system: > > a) use asynchronous probing for one or more of the drivers as > Dmitry suggested. This means fixing it upstream first and then > backporting the fix to all stable kernels. We should probably > do this anyway, but this will need more testing on your side. > > b) Change your kernel config permanently with the options above, > if LKFT does not actually rely on CONFIG_FUNCTION_GRAPH_TRACER. > I don't know if it does. > > c) backport commit 41918ec82eb6 ("ARM: ftrace: enable the graph > tracer with the EABI unwinder") from 5.17. This was part of > a longer series from Ard, and while the patch itself looks > simple enough to be backported, I suspect we'd have to > backport the entire series, which is probably not going to > be realistic. Ard, any comments on this? > It at least needs the preceding patch, which tracks the location of LR on the stack when using CONFIG_UNWINDER_ARM. But I'd take the whole series for good measure.