linux-kernel - Re: [PATCH] memory: mtk-smi: Fix NULL pointer dereference in config

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Message-ID: <13d96b3c-4db6-48f5-b1bb-68171ffa6bc0@kernel.org>
Date: Fri, 14 Nov 2025 08:21:29 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Jian Hui Lee <jianhui.lee@...onical.com>
Cc: Yong Wu <yong.wu@...iatek.com>, Matthias Brugger
 <matthias.bgg@...il.com>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
 Joerg Roedel <jroedel@...e.de>, linux-mediatek@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] memory: mtk-smi: Fix NULL pointer dereference in
 config_port

On 14/11/2025 04:03, Jian Hui Lee wrote:
> On Wed, Nov 12, 2025 at 11:51 PM Krzysztof Kozlowski <krzk@...nel.org> wrote:
>>
>> Please trim the traces from all irrelevant information.
>>
>>>
>>> Fixes: e6dec92308628 ("iommu/mediatek: Add mt2712 IOMMU support")
>>
>> Add Cc stable.
>>
>>> Signed-off-by: Jian Hui Lee <jianhui.lee@...onical.com>
>>
>>> ---
>>>  drivers/memory/mtk-smi.c | 4 ++++
>>>  1 file changed, 4 insertions(+)
>>>
>>> diff --git a/drivers/memory/mtk-smi.c b/drivers/memory/mtk-smi.c
>>> index 733e22f695ab..8eb043ff8280 100644
>>> --- a/drivers/memory/mtk-smi.c
>>> +++ b/drivers/memory/mtk-smi.c
>>> @@ -244,6 +244,10 @@ static int mtk_smi_larb_config_port_gen2_general(struct device *dev)
>>>       struct arm_smccc_res res;
>>>       int i;
>>>
>>> +     /* larb->mmu and larb->bank are set in bind(), may not be ready yet */
>>
>> And how do you synchronize this between CPUs? IOW, what certainty you
>> have that this CPU sees correct data and the checks below have any sense?
> 
> Thank you for the review and for pointing this out. Moving
> pm_runtime_enable/disable to component bind/unbind should ensure that
> the synchronization happens correctly. I will send a v2 to address
> those you mentioned.

Runtime PM synchronizes nothing in this matter, so I don't understand
what you want to achieve with it.

Best regards,
Krzysztof