From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6E35734CF5; Mon, 7 Apr 2025 11:01:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744023663; cv=none; b=qWxgCDJHIeyG2xtXFXbO+T/f9G9BZPGYD3S+vM8BoDeqt0qFC+PISonOaAOuCZhYI5VvUC1tpGHy+U7wAVmvllFlH7+y+730TVzn2EQJzou2VUFqVM4zNef3hkySKHAbikCmzhfvT8piS0/M/IEIHngo+yu9joXLHWAELKa8LTE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744023663; c=relaxed/simple; bh=Nnk6OYZfIvOhCMybpmmi5TH57BIjPZ5Rw8wESi+FkRQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=SCd952t9RXcv6Cv+X6ocG0r0u9vYexs27CpbbPREvaqlrn5Z6VuT8Z7sbH1XUrTknRF/Ml1f35JnxtV2WqeV6dzdVGydj8WKBCmIOqubEcIjXK68yJZ321lMKPrTjT+msTXktClZaoCRPyCiVNnm8rerJ6RspfhTsSAEnbAl9jA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pxD/VeJm; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="pxD/VeJm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D21BCC4CEDD; Mon, 7 Apr 2025 11:01:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744023662; bh=Nnk6OYZfIvOhCMybpmmi5TH57BIjPZ5Rw8wESi+FkRQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=pxD/VeJmyzVnZkvWivxjW3rhgeLKbsYyTo4UIbrkvrHjLWSCOCNci6uuBa5loCfCj H1IP1nqqij3Qa7QgAdgMMIhtjY4tLWjTvyx6/ZLiV5w0H3DapcEpB1mOYibhUR/WBA EXuZqbJOK6SeEVvc+N3mpOMA5WoZUSC8eeBVSUpdKH+istCNxoQ2NGOl6obhdkpb8l AKKvnfFGgLYGWbwXfmLk9c/+sENUCtNd95rRkNsYtRK/l9kBHj0LVvnEIDIw3unyvP vS918NvwMS7fLQYcG5vPFK34jJl/0W7GXw+SGj4o8IHIxSO1NzgL8P5mJ/2OaY2U45 B4gVDbGGGw0zA== Received: from johan by xi.lan with local (Exim 4.97.1) (envelope-from ) id 1u1kE1-000000001N5-1Qxr; Mon, 07 Apr 2025 13:01:09 +0200 Date: Mon, 7 Apr 2025 13:01:09 +0200 From: Johan Hovold To: Bryan O'Donoghue Cc: Robert Foss , Todor Tomov , Vladimir Zapolskiy , linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: camss NULL-deref on power on with 6.12-rc2 Message-ID: References: <778e2cd0-5371-424f-809d-20f7c3ae5343@linaro.org> Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Apr 07, 2025 at 12:38:56PM +0200, Johan Hovold wrote: > On Mon, Apr 07, 2025 at 10:58:52AM +0100, Bryan O'Donoghue wrote: > > On 07/04/2025 10:12, Johan Hovold wrote: > > > [ 5.740833] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000030 > > > > [ 5.744704] Call trace: > > > [ 5.744706] camss_find_sensor_pad+0x20/0x74 [qcom_camss] (P) > > > [ 5.744711] camss_get_pixel_clock+0x18/0x64 [qcom_camss] > > > [ 5.744716] vfe_get+0xb8/0x504 [qcom_camss] > > > [ 5.744724] vfe_set_power+0x30/0x58 [qcom_camss] > > > [ 5.744731] pipeline_pm_power_one+0x13c/0x150 [videodev] > > > [ 5.744745] pipeline_pm_power.part.0+0x58/0xf4 [videodev] > > > [ 5.744754] v4l2_pipeline_pm_use+0x58/0x94 [videodev] > > > [ 5.744762] v4l2_pipeline_pm_get+0x14/0x20 [videodev] > > > [ 5.744771] video_open+0x78/0xf4 [qcom_camss] > > > [ 5.744776] v4l2_open+0x80/0x120 [videodev] > I've only seen it twice myself (that I've noticed, at least this time it > prevented the display from probing so I knew something was wrong). Just hit this again with 6.15-rc1 after the third reboot so timing has likely changed slightly which now makes it easier to hit this. > Since it's obviously a race condition I think you'll need to analyse the > code to try to figure out where the bug is. With an hypothesis you may > be able to instrument a reliable reproducer (e.g. by adding appropriate > delays to extend the race window). It's apparently udev which powers up the camera when running v4l_id: [ 5.859741] CPU: 4 UID: 0 PID: 420 Comm: v4l_id Not tainted 6.15.0-rc1 #106 PREEMPT So this looks like the classic bug of drivers registering their devices before they have been fully set up. > The fact that the sensor driver is probe deferring may also be relevant > here. Johan