linux/net
William Tu d265929930 netfilter: nf_conncount: reduce unnecessary GC
Currently nf_conncount can trigger garbage collection (GC)
at multiple places. Each GC process takes a spin_lock_bh
to traverse the nf_conncount_list. We found that when testing
port scanning use two parallel nmap, because the number of
connection increase fast, the nf_conncount_count and its
subsequent call to __nf_conncount_add take too much time,
causing several CPU lockup. This happens when user set the
conntrack limit to +20,000, because the larger the limit,
the longer the list that GC has to traverse.

The patch mitigate the performance issue by avoiding unnecessary
GC with a timestamp. Whenever nf_conncount has done a GC,
a timestamp is updated, and beforce the next time GC is
triggered, we make sure it's more than a jiffies.
By doin this we can greatly reduce the CPU cycles and
avoid the softirq lockup.

To reproduce it in OVS,
$ ovs-appctl dpctl/ct-set-limits zone=1,limit=20000
$ ovs-appctl dpctl/ct-get-limits

At another machine, runs two nmap
$ nmap -p1- <IP>
$ nmap -p1- <IP>

Signed-off-by: William Tu <u9012063@gmail.com>
Co-authored-by: Yifeng Sun <pkusunyifeng@gmail.com>
Reported-by: Greg Rose <gvrose8192@gmail.com>
Suggested-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2022-05-16 13:05:40 +02:00
..
6lowpan net: don't include ndisc.h from ipv6.h 2022-02-04 14:15:11 -08:00
9p xen/grant-table: remove readonly parameter from functions 2022-03-15 20:34:40 -05:00
802
8021q net: add netif_inherit_tso_max() 2022-05-06 12:07:56 +01:00
appletalk net: remove noblock parameter from skb_recv_datagram() 2022-04-06 13:45:26 +01:00
atm net: SO_RCVMARK socket option for SO_MARK with recvmsg() 2022-04-28 13:08:15 -07:00
ax25 net: remove noblock parameter from skb_recv_datagram() 2022-04-06 13:45:26 +01:00
batman-adv Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-12 16:15:30 -07:00
bluetooth Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-12 16:15:30 -07:00
bpf Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-04-28 13:02:01 -07:00
bpfilter uaccess: remove CONFIG_SET_FS 2022-02-25 09:36:06 +01:00
bridge rtnetlink: add extack support in fdb del handlers 2022-05-09 11:58:20 +01:00
caif net: remove noblock parameter from skb_recv_datagram() 2022-04-06 13:45:26 +01:00
can Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-05 13:03:18 -07:00
ceph libceph: disambiguate cluster/pool full log message 2022-04-25 10:45:15 +02:00
core net: page_pool: add page allocation stats for two fast page allocate path 2022-05-13 11:28:55 +01:00
dcb net: dcb: disable softirqs in dcbnl_flush_dev() 2022-03-03 08:01:55 -08:00
dccp net: inet: Retire port only listening_hash 2022-05-12 16:52:18 -07:00
decnet decnet: Use container_of() for struct dn_neigh casts 2022-05-10 12:21:51 +02:00
dns_resolver
dsa net: dsa: remove port argument from ->change_tag_protocol() 2022-05-12 16:38:55 -07:00
ethernet net: ethernet: set default assignment identifier to NET_NAME_ENUM 2022-04-07 21:04:03 -07:00
ethtool ethtool: Add 10base-T1L link mode entry 2022-05-01 17:45:35 +01:00
hsr net: add per-cpu storage and net->core_stats 2022-03-11 23:17:24 -08:00
ieee802154 net: SO_RCVMARK socket option for SO_MARK with recvmsg() 2022-04-28 13:08:15 -07:00
ife
ipv4 netfilter: Use l3mdev flow key when re-routing mangled packets 2022-05-16 13:03:29 +02:00
ipv6 netfilter: Use l3mdev flow key when re-routing mangled packets 2022-05-16 13:03:29 +02:00
iucv net: remove noblock parameter from skb_recv_datagram() 2022-04-06 13:45:26 +01:00
kcm net: Don't include filter.h from net/sock.h 2021-12-29 08:48:14 -08:00
key net: SO_RCVMARK socket option for SO_MARK with recvmsg() 2022-04-28 13:08:15 -07:00
l2tp net: remove noblock parameter from recvmsg() entities 2022-04-12 15:00:25 +02:00
l3mdev l3mdev: l3mdev_master_upper_ifindex_by_index_rcu should be using netdev_master_upper_dev_get_rcu 2022-04-15 14:27:24 -07:00
lapb
llc llc: only change llc->dev when bind() succeeds 2022-03-25 16:55:41 -07:00
mac80211 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-12 16:15:30 -07:00
mac802154 net: mac802154: Fix symbol durations 2022-04-30 20:29:47 +02:00
mctp net: SO_RCVMARK socket option for SO_MARK with recvmsg() 2022-04-28 13:08:15 -07:00
mpls net: mpls: fix memdup.cocci warning 2022-04-07 21:06:41 -07:00
mptcp net: inet: Retire port only listening_hash 2022-05-12 16:52:18 -07:00
ncsi all: replace find_next{,_zero}_bit with find_first{,_zero}_bit where appropriate 2022-01-15 08:47:31 -08:00
netfilter netfilter: nf_conncount: reduce unnecessary GC 2022-05-16 13:05:40 +02:00
netlabel netlabel: fix out-of-bounds memory accesses 2022-03-21 10:59:11 +00:00
netlink Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-12 16:15:30 -07:00
netrom net: remove noblock parameter from skb_recv_datagram() 2022-04-06 13:45:26 +01:00
nfc Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-05 13:03:18 -07:00
nsh
openvswitch openvswitch: fix OOB access in reserve_sfa_size() 2022-04-15 11:50:02 +01:00
packet net: SO_RCVMARK socket option for SO_MARK with recvmsg() 2022-04-28 13:08:15 -07:00
phonet net: remove noblock parameter from recvmsg() entities 2022-04-12 15:00:25 +02:00
psample
qrtr net: remove noblock parameter from skb_recv_datagram() 2022-04-06 13:45:26 +01:00
rds net: rds: use maybe_get_net() when acquiring refcount on TCP sockets 2022-05-05 16:44:49 -07:00
rfkill rfkill: make new event layout opt-in 2022-03-18 13:09:17 +02:00
rose ROSE: Remove unused code and clean up some inconsistent indenting 2022-05-09 17:19:27 -07:00
rxrpc rxrpc: Enable IPv6 checksums on transport socket 2022-04-30 13:59:34 +01:00
sched Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-12 16:15:30 -07:00
sctp net: SO_RCVMARK socket option for SO_MARK with recvmsg() 2022-04-28 13:08:15 -07:00
smc net/smc: non blocking recvmsg() return -EAGAIN when no data and signal_pending 2022-05-12 10:01:36 -07:00
strparser
sunrpc Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-12 16:15:30 -07:00
switchdev net: switchdev: remove lag_mod_cb from switchdev_handle_fdb_event_to_device 2022-02-24 21:31:43 -08:00
tipc Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-03-23 10:53:49 -07:00
tls Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-12 16:15:30 -07:00
unix net: remove noblock parameter from recvmsg() entities 2022-04-12 15:00:25 +02:00
vmw_vsock vsock/virtio: add support for device suspend/resume 2022-05-02 16:04:34 -07:00
wireless Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-05-12 16:15:30 -07:00
x25 x25: remove redundant pointer dev 2022-05-10 11:59:22 +02:00
xdp Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-04-28 13:02:01 -07:00
xfrm xfrm: drop not needed flags variable in XFRM offload struct 2022-05-06 08:35:46 +02:00
compat.c
devres.c
Kconfig page_pool: Add allocation stats 2022-03-03 09:55:28 +00:00
Kconfig.debug net: add CONFIG_DEBUG_NET 2022-05-11 12:43:10 +01:00
Makefile
socket.c ptp: Support late timestamp determination 2022-05-10 09:48:08 +02:00
sysctl_net.c