Re: [PATCH] dma-buf: Make DMABUF_DEBUG default to y on DEBUG_KERNEL kernels

From: "Diederik de Haas" <diederik@cknow-tech.com>
To: <linux-rockchip@lists.infradead.org>
Subject: Re: [PATCH] dma-buf: Make DMABUF_DEBUG default to y on DEBUG_KERNEL kernels
Date: Mon, 05 Oct 2026 11:05:32 +0200	[thread overview]
Message-ID: <DLWS9II64U19.2RE8CUG71USY4@cknow-tech.com> (raw)
In-Reply-To: <DLR74W1U9YPC.375IK0HOYHDIG@cknow-tech.com>

On Mon Sep 28, 2026 at 9:28 PM CEST, Diederik de Haas wrote:
> On Mon Sep 7, 2026 at 4:00 AM CEST, Karl Mehltretter wrote:
>> Commit 646013f513f3 ("dma-buf: enable DMABUF_DEBUG by default on DEBUG
>> kernels") changed the default of DMABUF_DEBUG to "y if DEBUG", but no
>> Kconfig symbol DEBUG exists, so the option has had no default since.
>>
>> Use DEBUG_KERNEL, the Kconfig symbol for a debug kernel.
>
> I wondered why since 7.3-rc4 when playing videos I got a WHOLE lot of the
> following error messages, which weren't there with 7.3-rc3:
>
>   [drm:rockchip_gem_iommu_map [rockchipdrm]] *ERROR* failed to map buffer: size=0 request_size=3956736
>   [drm:rockchip_gem_prime_import_sg_table [rockchipdrm]] *ERROR* failed to import sg table: -12
>
> Both come from ``drivers/gpu/drm/rockchip/rockchip_drm_gem.c``.
>
> ...
>
> When I explicitly disable ``DMABUF_DEBUG``, I no longer see those errors.
>
> Whether that fixes or just hides a problem, I'll leave that for others to
> decide.

It seems it hides the problem. Follow up with more context/links:
https://lore.kernel.org/all/20261005064133.7305-1-kmehltretter@gmail.com/

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