lkml.org 
[lkml]   [2021]   [Jan]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [BUG] from x86: Support kmap_local() forced debugging
On Wed, 6 Jan 2021 17:03:48 -0800 Linus Torvalds wrote:
> I wonder whether there is other code that "knows" about kmap() only
> affecting PageHighmem() pages thing that is no longer true.
>
> Looking at some other code, skb_gro_reset_offset() looks suspiciously
> like it also thinks highmem pages are special.
>
> Adding the networking people involved in this area to the cc too.

Thanks for the detailed analysis! skb_gro_reset_offset() checks if
kernel can read data in the fragments directly as an optimization,
in case the entire header is in a fragment.

IIUC DEBUG_KMAP_LOCAL_FORCE_MAP only affects the mappings from
explicit kmap calls, which GRO won't make - it will fall back to
pulling the header out of the fragment and end up in skb_copy_bits(),
i.e. the loop you fixed. So GRO should be good. I think..

\
 
 \ /
  Last update: 2021-01-07 02:50    [W:0.557 / U:0.088 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site