net: Revert "net: optimize the sockptr_t for unified kernel/user address spaces"

net: Revert "net: optimize the sockptr_t for unified kernel/user address spaces"

This reverts commits 073369af28ce37693900f39eb6111eaada5459c3 and
aac6d22d4167727c1107a0b7a856eedb2db30f76.

It turns out the idea to share a single pointer for both kernel and user
space address causes various kinds of problems.  So use the slightly less
optimal version that uses an extra bit, but which is guaranteed to be safe
everywhere.

Fixes: 073369af28ce ("net: optimize the sockptr_t for unified kernel/user address spaces")
Reported-by: Eric Dumazet <edumazet@google.com>
Reported-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>