Merge Linux 4.4.174 kernel

Changes in 4.4.174: (35 commits)
        inet: frags: change inet_frags_init_net() return value
        inet: frags: add a pointer to struct netns_frags
        inet: frags: refactor ipfrag_init()
        inet: frags: refactor ipv6_frag_init()
        inet: frags: refactor lowpan_net_frag_init()
        rhashtable: add rhashtable_lookup_get_insert_key()
        rhashtable: Add rhashtable_lookup()
        rhashtable: add schedule points
        inet: frags: use rhashtables for reassembly units
        net: ieee802154: 6lowpan: fix frag reassembly
        ipfrag: really prevent allocation on netns exit
        inet: frags: remove some helpers
        inet: frags: get rif of inet_frag_evicting()
        inet: frags: remove inet_frag_maybe_warn_overflow()
        inet: frags: break the 2GB limit for frags storage
        inet: frags: do not clone skb in ip_expire()
        ipv6: frags: rewrite ip6_expire_frag_queue()
        rhashtable: reorganize struct rhashtable layout
        inet: frags: reorganize struct netns_frags
        inet: frags: get rid of ipfrag_skb_cb/FRAG_CB
        inet: frags: fix ip6frag_low_thresh boundary
        ip: discard IPv4 datagrams with overlapping segments.
        net: modify skb_rbtree_purge to return the truesize of all purged skbs.
        ipv6: defrag: drop non-last frags smaller than min mtu
        net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends
        ip: use rb trees for IP frag queue.
        ip: add helpers to process in-order fragments faster.
        ip: process in-order fragments efficiently
        ip: frags: fix crash in ip_do_fragment()
        ipv4: frags: precedence bug in ip_expire()
        inet: frags: better deal with smp races
        net: fix pskb_trim_rcsum_slow() with odd trim offset
        net: ipv4: do not handle duplicate fragments as overlapping
        rcu: Force boolean subscript for expedited stall warnings
        Linux 4.4.174