Merge branch 'tcp-mmap-rework-zerocopy-receive'

Merge branch 'tcp-mmap-rework-zerocopy-receive'

Eric Dumazet says:

====================
tcp: mmap: rework zerocopy receive

syzbot reported a lockdep issue caused by tcp mmap() support.

I implemented Andy Lutomirski nice suggestions to resolve the
issue and increase scalability as well.

First patch is adding a new getsockopt() operation and changes mmap()
behavior.

Second patch changes tcp_mmap reference program.

v4: tcp mmap() support depends on CONFIG_MMU, as kbuild bot told us.

v3: change TCP_ZEROCOPY_RECEIVE to be a getsockopt() option
    instead of setsockopt(), feedback from Ka-Cheon Poon

v2: Added a missing page align of zc->length in tcp_zerocopy_receive()
    Properly clear zc->recv_skip_hint in case user request was completed.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>