On Tue, Jan 17, 2017 at 8:35 PM, Eric Dumazet <eric.duma...@gmail.com> wrote:
> On Tue, 2017-01-17 at 20:21 -0800, Eric Dumazet wrote:
>> On Wed, 2017-01-18 at 03:12 +0000, Ashizuka, Yuusuke wrote:
>>
>> > indeed.
>> >
>> > In the case of TSO with i.MX6 system (highmem enabled) with 2GB memory,
>> > "this_frag->page.p" did not become highmem area.
>> > (We confirmed by transferring about 100MB of files)
>> >
>> > However, in the case of non-tso on an i.MX6 system with 2GB of memory,
>> > "this_frag->page.p" may become a highmem area.
>> > (Occurred with approximately 2MB of file transfer)
>> >
>> > For non-tso only, I do not know the reason why "this_frag-> page.p"
>> > in this driver shows highmem area.
>>
>> This worries me, since this driver does not set NETIF_F_HIGHDMA in its
>> features.
>>
>> No packet should be given to this driver with a highmem fragment
>>
>> Check is done in illegal_highdma() in net/core/dev.c
>
> This used to work.
>
> I suspect commit ec5f061564238892005257c83565a0b58ec79295
> ("net: Kill link between CSUM and SG features.")
>
> added this bug.
>
> Can you try this hot fix :
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index
> ad5959e561166f445bdd9d7260652a338f74cfea..073b832b945257dba9ed47f4bf875605225effc9
> 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -2773,9 +2773,9 @@ static netdev_features_t harmonize_features(struct
> sk_buff *skb,
> if (skb->ip_summed != CHECKSUM_NONE &&
> !can_checksum_protocol(features, type)) {
> features &= ~(NETIF_F_CSUM_MASK | NETIF_F_GSO_MASK);
> - } else if (illegal_highdma(skb->dev, skb)) {
> - features &= ~NETIF_F_SG;
> }
> + if (illegal_highdma(skb->dev, skb))
> + features &= ~NETIF_F_SG;
>
> return features;
> }
Right, this high mem check should be decoupled from csum check.
Thanks,
Pravin.
