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From:   Sumit Semwal <sumit.semwal@linaro.org>
Date:   Wed, 1 Dec 2021 15:39:17 +0530
Message-ID: <CAO_48GHxanR=-mN232ANwxQEiBo9zb3WjvO-6WmP6eFYWA1M5A@mail.gmail.com>
Subject: Re: [PATCH v4] dma-buf: system_heap: Use 'for_each_sgtable_sg' in
 pages free flow
To:     John Stultz <john.stultz@linaro.org>
Cc:     guangming.cao@mediatek.com, greg@kroah.com, brian.starkey@arm.com,
        benjamin.gaignard@linaro.org, christian.koenig@amd.com,
        dri-devel@lists.freedesktop.org, labbott@redhat.com,
        linaro-mm-sig@lists.linaro.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-media@vger.kernel.org, linux-mediatek@lists.infradead.org,
        lmark@codeaurora.org, matthias.bgg@gmail.com, robin.murphy@arm.com,
        stable@vger.kernel.org, wsd_upstream@mediatek.com,
        kuan-ying.lee@mediatek.com
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Hello Guangming,

On Mon, 29 Nov 2021 at 23:35, John Stultz <john.stultz@linaro.org> wrote:
>
> On Thu, Nov 25, 2021 at 11:48 PM <guangming.cao@mediatek.com> wrote:
> >
> > From: Guangming <Guangming.Cao@mediatek.com>
> >
> > For previous version, it uses 'sg_table.nent's to traverse sg_table in =
pages
> > free flow.
> > However, 'sg_table.nents' is reassigned in 'dma_map_sg', it means the n=
umber of
> > created entries in the DMA adderess space.
> > So, use 'sg_table.nents' in pages free flow will case some pages can't =
be freed.
> >
> > Here we should use sg_table.orig_nents to free pages memory, but use th=
e
> > sgtable helper 'for each_sgtable_sg'(, instead of the previous rather c=
ommon
> > helper 'for_each_sg' which maybe cause memory leak) is much better.

Thanks for catching this and the patch; applied to drm-misc-fixes.
> >
> > Fixes: d963ab0f15fb0 ("dma-buf: system_heap: Allocate higher order page=
s if available")
> > Signed-off-by: Guangming <Guangming.Cao@mediatek.com>
> > Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> > Cc: <stable@vger.kernel.org> # 5.11.*
>
> Thanks so much for catching this and sending in all the revisions!
>
> Reviewed-by: John Stultz <john.stultz@linaro.org>


Best,
Sumit.

--=20
Thanks and regards,

Sumit Semwal (he / him)
Tech Lead - LCG, Vertical Technologies
Linaro.org =E2=94=82 Open source software for ARM SoCs