Eric Dumazet cac5e65e8a net: do not use rcu in rtnl_dump_ifinfo() ... We did a failed attempt in the past to only use rcu in rtnl dump operations (commit e67f88dd12 "net: dont hold rtnl mutex during netlink dump callbacks") Now that dumps are holding RTNL anyway, there is no need to also use rcu locking, as it forbids any scheduling ability, like GFP_KERNEL allocations that controlling path should use instead of GFP_ATOMIC whenever possible. This should fix following splat Cong Wang reported : [ INFO: suspicious RCU usage. ] 3.19.0+ #805 Tainted: G W include/linux/rcupdate.h:538 Illegal context switch in RCU read-side critical section! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 0 2 locks held by ip/771: #0: (rtnl_mutex){+.+.+.}, at: [<ffffffff8182b8f4>] netlink_dump+0x21/0x26c #1: (rcu_read_lock){......}, at: [<ffffffff817d785b>] rcu_read_lock+0x0/0x6e stack backtrace: CPU: 3 PID: 771 Comm: ip Tainted: G W 3.19.0+ #805 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 0000000000000001 ffff8800d51e7718 ffffffff81a27457 0000000029e729e6 ffff8800d6108000 ffff8800d51e7748 ffffffff810b539b ffffffff820013dd 00000000000001c8 0000000000000000 ffff8800d7448088 ffff8800d51e7758 Call Trace: [<ffffffff81a27457>] dump_stack+0x4c/0x65 [<ffffffff810b539b>] lockdep_rcu_suspicious+0x107/0x110 [<ffffffff8109796f>] rcu_preempt_sleep_check+0x45/0x47 [<ffffffff8109e457>] ___might_sleep+0x1d/0x1cb [<ffffffff8109e67d>] __might_sleep+0x78/0x80 [<ffffffff814b9b1f>] idr_alloc+0x45/0xd1 [<ffffffff810cb7ab>] ? rcu_read_lock_held+0x3b/0x3d [<ffffffff814b9f9d>] ? idr_for_each+0x53/0x101 [<ffffffff817c1383>] alloc_netid+0x61/0x69 [<ffffffff817c14c3>] __peernet2id+0x79/0x8d [<ffffffff817c1ab7>] peernet2id+0x13/0x1f [<ffffffff817d8673>] rtnl_fill_ifinfo+0xa8d/0xc20 [<ffffffff810b17d9>] ? __lock_is_held+0x39/0x52 [<ffffffff817d894f>] rtnl_dump_ifinfo+0x149/0x213 [<ffffffff8182b9c2>] netlink_dump+0xef/0x26c [<ffffffff8182bcba>] netlink_recvmsg+0x17b/0x2c5 [<ffffffff817b0adc>] __sock_recvmsg+0x4e/0x59 [<ffffffff817b1b40>] sock_recvmsg+0x3f/0x51 [<ffffffff817b1f9a>] ___sys_recvmsg+0xf6/0x1d9 [<ffffffff8115dc67>] ? handle_pte_fault+0x6e1/0xd3d [<ffffffff8100a3a0>] ? native_sched_clock+0x35/0x37 [<ffffffff8109f45b>] ? sched_clock_local+0x12/0x72 [<ffffffff8109f6ac>] ? sched_clock_cpu+0x9e/0xb7 [<ffffffff810cb7ab>] ? rcu_read_lock_held+0x3b/0x3d [<ffffffff811abde8>] ? __fcheck_files+0x4c/0x58 [<ffffffff811ac556>] ? __fget_light+0x2d/0x52 [<ffffffff817b376f>] __sys_recvmsg+0x42/0x60 [<ffffffff817b379f>] SyS_recvmsg+0x12/0x1c Signed-off-by: Eric Dumazet <edumazet@google.com> Fixes: 0c7aecd4bd ("netns: add rtnl cmd to add and get peer netns ids") Cc: Nicolas Dichtel <nicolas.dichtel@6wind.com> Reported-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2015-03-01 00:07:00 -05:00
..
datagram.c
dev_addr_lists.c
dev_ioctl.c
dev.c	net: reject creation of netdev names with colons	2015-02-21 21:45:25 -05:00
drop_monitor.c
dst.c
ethtool.c	ethtool: Add hw-switch-offload to netdev_features_strings.	2015-02-20 16:36:43 -05:00
fib_rules.c
filter.c	net: spelling fixes	2015-02-14 20:36:08 -08:00
flow_dissector.c
flow.c
gen_estimator.c
gen_stats.c	gen_stats.c: Duplicate xstats buffer for later use	2015-02-19 15:45:53 -05:00
link_watch.c
Makefile
neighbour.c
net_namespace.c
net-procfs.c
net-sysfs.c	net: use %*pb[l] to print bitmaps including cpumasks and nodemasks	2015-02-13 21:21:38 -08:00
net-sysfs.h
net-traces.c
netclassid_cgroup.c
netevent.c
netpoll.c
netprio_cgroup.c
pktgen.c	net: pktgen: disable xmit_clone on virtual devices	2015-02-22 22:43:20 -05:00
ptp_classifier.c
request_sock.c
rtnetlink.c	net: do not use rcu in rtnl_dump_ifinfo()	2015-03-01 00:07:00 -05:00
scm.c
secure_seq.c
skbuff.c	sock: sock_dequeue_err_skb() needs hard irq safety	2015-02-20 15:52:21 -05:00
sock_diag.c
sock.c
stream.c
sysctl_net_core.c	net: use %*pb[l] to print bitmaps including cpumasks and nodemasks	2015-02-13 21:21:38 -08:00
timestamping.c
tso.c
utils.c