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SubjectRe: [PATCH v2] net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag
On Fri, 3 Jun 2022 10:25:16 -0700 Eric Dumazet wrote:
> > goto release_desc;
> > @@ -1914,7 +1923,16 @@ static int mtk_rx_alloc(struct mtk_eth *eth, int ring_no, int rx_flag)
> > return -ENOMEM;
> >
> > for (i = 0; i < rx_dma_size; i++) {
> > - ring->data[i] = netdev_alloc_frag(ring->frag_size);
>
> Note aside, calling netdev_alloc_frag() in a loop like that is adding
> GFP_ATOMIC pressure.
>
> mtk_rx_alloc() being in process context, using GFP_KERNEL allocations
> would be less aggressive and
> have more chances to succeed.
>
> We probably should offer a generic helper. This could be used from
> driver/net/tun.c and others.

Do cases where netdev_alloc_frag() is not run from a process context
from to your mind? My feeling is that the prevailing pattern is what
this driver does, which is netdev_alloc_frag() at startup / open and
napi_alloc_frag() from the datapath. So maybe we can even spare the
detail in the API and have napi_alloc_frag() assume GFP_KERNEL by
default?

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