Re: [BUG] from x86: Support kmap_local() forced debugging

[Linus Torvalds]

On Wed, Jan 6, 2021 at 8:45 PM Willem de Bruijn <willemb@xxxxxxxxxx> wrote:
>
> But there are three other kmap_atomic callers under net/ that do not
> loop at all, so assume non-compound pages. In esp_output_head,
> esp6_output_head and skb_seq_read. The first two directly use
> skb_page_frag_refill, which can allocate compound (but not
> __GFP_HIGHMEM) pages, and the third can be inserted with
> netfilter xt_string in the path of tcp transmit skbs, which can also
> have compound pages. I think that these could similarly access
> data beyond the end of the kmap_atomic mapped page. I'll take
> a closer look.

Thanks.

Note that I have flushed my random one-liner patch from my system, and
expect to get a proper fix through the normal networking pulls.

And _if_ the networking people feel that my one-liner was the proper
fix, you can use it and add my sign-off if you want to, but it really
was more of a "this is the quick ugly fix for testing" rather than
anything else.

          Linus