On 8/27/19 1:42 PM, Shmulik Ladkani wrote:
[...]

- Another thing that puzzles me is that we hit the BUG_ON rather rarely
   and cannot yet reproduce synthetically. If skb_segment's handling of
   skbs with a frag_list (that have gso_size mangled) is broken, I'd expect
   to hit this more often... Any ideas?

- Suppose going for a rewrite, care to elaborate what's exactly missing
   in skb_segment's logic?
   I must admit I do not fully understand all the different code flows in
   this function, it seems to support many different input skbs - any
   assistance is highly appreciated.

Given first point above wrt hitting rarely, it would be good to first get a
better understanding for writing a reproducer. Back then Yonghong added one
to the BPF kernel test suite [0], so it would be desirable to extend it for
the case you're hitting. Given NAT64 use-case is needed and used by multiple
parties, we should try to (fully) fix it generically.

Thanks,
Daniel

   [0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=76db8087c4c991dcd17f5ea8ac0eafd0696ab450

Shmulik