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Date:   Wed, 17 May 2023 00:34:57 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Xiaoming Ding <xiaoming.ding@mediatek.com>
Cc:     Jens Wiklander <jens.wiklander@linaro.org>,
        Sumit Garg <sumit.garg@linaro.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        op-tee@lists.trustedfirmware.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, fei.xu@mediatek.com,
        srv_heupstream@mediatek.com, linux-mm@kvack.org
Subject: Re: [PATCH] tee: add FOLL_LONGTERM for CMA case when alloc shm
Message-ID: <ZGSDoVKKVqCkbaCB@infradead.org>
References: <20230517031856.19660-1-xiaoming.ding@mediatek.com>
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> +	u32 page_flag = FOLL_WRITE;
>  
>  	if (!tee_device_get(teedev))
>  		return ERR_PTR(-EINVAL);
> @@ -255,9 +256,11 @@ register_shm_helper(struct tee_context *ctx, unsigned long addr,
>  		ret = ERR_PTR(-ENOMEM);
>  		goto err_free_shm;
>  	}
> -
> +#if IS_ENABLED(CONFIG_CMA)
> +	page_flag |= FOLL_LONGTERM;
> +#endif
>  	if (flags & TEE_SHM_USER_MAPPED)

If this mapping is long live it should always use FOLL_LONGTERM.

The ifdef does not make sense.