[ Upstream commit d39ca2590d10712f412add7a88e1dd467a7246f4 ]

This reverts commit 0d4a6608.

Willem reported that after commit 0d4a6608 ("udp: do rmem bulk
free even if the rx sk queue is empty") the memory allocated by
an almost idle system with many UDP sockets can grow a lot.

For stable kernel keep the solution as simple as possible and revert
the offending commit.
Reported-by: NWillem de Bruijn <willemdebruijn.kernel@gmail.com>
Diagnosed-by: NEric Dumazet <eric.dumazet@gmail.com>
Fixes: 0d4a6608 ("udp: do rmem bulk free even if the rx sk queue is empty")
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Acked-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>