Re: [PATCH] bus: mhi: ep: Do not allocate memory for MHI objects from DMA zone

[Mayank Rana]

On 6/3/2024 9:43 AM, Manivannan Sadhasivam wrote:
> MHI endpoint stack accidentally started allocating memory for objects from
> DMA zone since commit 62210a26cd4f ("bus: mhi: ep: Use slab allocator
Going through mentioned commit it seems that it was intended purpose to 
use GFP_DMA/SLAB
> where applicable"). But there is no real need to allocate memory from this
> naturally limited DMA zone. This also causes the MHI endpoint stack to run
> out of memory while doing high bandwidth transfers.
>
> So let's switch over to normal memory.
>
> Cc: stable@xxxxxxxxxxxxxxx # 6.8
> Fixes: 62210a26cd4f ("bus: mhi: ep: Use slab allocator where applicable")
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> ---
>   drivers/bus/mhi/ep/main.c | 14 +++++++-------
>   1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
> index f8f674adf1d4..4acfac73ca9a 100644
> --- a/drivers/bus/mhi/ep/main.c
> +++ b/drivers/bus/mhi/ep/main.c
> @@ -90,7 +90,7 @@ static int mhi_ep_send_completion_event(struct mhi_ep_cntrl *mhi_cntrl, struct m
>   	struct mhi_ring_element *event;
>   	int ret;
>   
> -	event = kmem_cache_zalloc(mhi_cntrl->ev_ring_el_cache, GFP_KERNEL | GFP_DMA);
> +	event = kmem_cache_zalloc(mhi_cntrl->ev_ring_el_cache, GFP_KERNEL);
>   	if (!event)
>   		return -ENOMEM;
>   
> @@ -109,7 +109,7 @@ int mhi_ep_send_state_change_event(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_stat
>   	struct mhi_ring_element *event;
>   	int ret;
>   
> -	event = kmem_cache_zalloc(mhi_cntrl->ev_ring_el_cache, GFP_KERNEL | GFP_DMA);
> +	event = kmem_cache_zalloc(mhi_cntrl->ev_ring_el_cache, GFP_KERNEL);
>   	if (!event)
>   		return -ENOMEM;
>   
> @@ -127,7 +127,7 @@ int mhi_ep_send_ee_event(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_ee_type exec_e
>   	struct mhi_ring_element *event;
>   	int ret;
>   
> -	event = kmem_cache_zalloc(mhi_cntrl->ev_ring_el_cache, GFP_KERNEL | GFP_DMA);
> +	event = kmem_cache_zalloc(mhi_cntrl->ev_ring_el_cache, GFP_KERNEL);
>   	if (!event)
>   		return -ENOMEM;
>   
> @@ -146,7 +146,7 @@ static int mhi_ep_send_cmd_comp_event(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_e
>   	struct mhi_ring_element *event;
>   	int ret;
>   
> -	event = kmem_cache_zalloc(mhi_cntrl->ev_ring_el_cache, GFP_KERNEL | GFP_DMA);
> +	event = kmem_cache_zalloc(mhi_cntrl->ev_ring_el_cache, GFP_KERNEL);
>   	if (!event)
>   		return -ENOMEM;
>   
> @@ -438,7 +438,7 @@ static int mhi_ep_read_channel(struct mhi_ep_cntrl *mhi_cntrl,
>   		read_offset = mhi_chan->tre_size - mhi_chan->tre_bytes_left;
>   		write_offset = len - buf_left;
>   
> -		buf_addr = kmem_cache_zalloc(mhi_cntrl->tre_buf_cache, GFP_KERNEL | GFP_DMA);
> +		buf_addr = kmem_cache_zalloc(mhi_cntrl->tre_buf_cache, GFP_KERNEL);
>   		if (!buf_addr)
>   			return -ENOMEM;
>   
> @@ -1481,14 +1481,14 @@ int mhi_ep_register_controller(struct mhi_ep_cntrl *mhi_cntrl,
>   
>   	mhi_cntrl->ev_ring_el_cache = kmem_cache_create("mhi_ep_event_ring_el",
>   							sizeof(struct mhi_ring_element), 0,
> -							SLAB_CACHE_DMA, NULL);
> +							0, NULL);
>   	if (!mhi_cntrl->ev_ring_el_cache) {
>   		ret = -ENOMEM;
>   		goto err_free_cmd;
>   	}
>   
>   	mhi_cntrl->tre_buf_cache = kmem_cache_create("mhi_ep_tre_buf", MHI_EP_DEFAULT_MTU, 0,
> -						      SLAB_CACHE_DMA, NULL);
> +						      0, NULL);
>   	if (!mhi_cntrl->tre_buf_cache) {
>   		ret = -ENOMEM;
>   		goto err_destroy_ev_ring_el_cache;
Reviewed-by: Mayank Rana <quic_mrana@xxxxxxxxxxx>