[PATCH v2 net-next 00/12] inet: frags: bring rhashtables to IP defrag

[Eric Dumazet <edumazet@google.com>]

IP defrag processing is one of the remaining problematic layer in linux.

It uses static hash tables of 1024 buckets, and up to 128 items per bucket.

A work queue is supposed to garbage collect items when host is under memory
pressure, and doing a hash rebuild, changing seed used in hash computations.

This work queue blocks softirqs for up to 25 ms when doing a hash rebuild,
occurring every 5 seconds if host is under fire.

Then there is the problem of sharing this hash table for all netns.

It is time to switch to rhashtables, and allocate one of them per netns
to speedup netns dismantle, since this is a critical metric these days.

Lookup is now using RCU, and 64bit hosts can now provision whatever amount
of memory needed to handle the expected workloads.

v2: Addressed Herbert and Kirill feedbacks

Eric Dumazet (12):
  ipv6: frag: remove unused field
  inet: frags: change inet_frags_init_net() return value
  inet: frags: add a pointer to struct netns_frags
  inet: frags: refactor ipv6_frag_init()
  inet: frags: refactor lowpan_net_frag_init()
  inet: frags: refactor ipfrag_init()
  rhashtable: add schedule points
  inet: frags: use rhashtables for reassembly units
  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

 Documentation/networking/ip-sysctl.txt  |  11 +-
 include/net/inet_frag.h                 | 123 ++++----
 include/net/ip.h                        |   1 -
 include/net/ipv6.h                      |  27 +-
 lib/rhashtable.c                        |   2 +
 net/ieee802154/6lowpan/6lowpan_i.h      |  26 +-
 net/ieee802154/6lowpan/reassembly.c     | 150 +++++-----
 net/ipv4/inet_fragment.c                | 362 +++++-------------------
 net/ipv4/ip_fragment.c                  | 214 +++++++-------
 net/ipv4/proc.c                         |   6 +-
 net/ipv6/netfilter/nf_conntrack_reasm.c |  90 +++---
 net/ipv6/proc.c                         |   5 +-
 net/ipv6/reassembly.c                   | 181 ++++++------
 13 files changed, 441 insertions(+), 757 deletions(-)

-- 
2.17.0.rc1.321.gba9d0f2565-goog