linux-kernel - Re: [PATCH] drm/mediatek: Correctly free sg

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Date:   Mon, 2 Oct 2023 12:40:26 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Chen-Yu Tsai <wenst@...omium.org>,
        Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     dri-devel@...ts.freedesktop.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, stable@...r.kernel.org
Subject: Re: [PATCH] drm/mediatek: Correctly free sg_table in gem prime vmap

Il 02/10/23 11:20, Chen-Yu Tsai ha scritto:
> The MediaTek DRM driver implements GEM PRIME vmap by fetching the
> sg_table for the object, iterating through the pages, and then
> vmapping them. In essence, unlike the GEM DMA helpers which vmap
> when the object is first created or imported, the MediaTek version
> does it on request.
> 
> Unfortunately, the code never correctly frees the sg_table contents.
> This results in a kernel memory leak. On a Hayato device with a text
> console on the internal display, this results in the system running
> out of memory in a few days from all the console screen cursor updates.
> 
> Add sg_free_table() to correctly free the contents of the sg_table. This
> was missing despite explicitly required by mtk_gem_prime_get_sg_table().
> 
> Fixes: 3df64d7b0a4f ("drm/mediatek: Implement gem prime vmap/vunmap function")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Chen-Yu Tsai <wenst@...omium.org>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>