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	skb_copy_datagram_iovec() can die	2014-12-09 16:29:11 -05:00
dev_addr_lists.c	net: fix spelling for synchronized	2014-11-18 15:26:32 -05:00
dev_ioctl.c	dev_ioctl: use sizeof(x) instead of sizeof x	2014-11-18 15:27:32 -05:00
dev.c	net: reject creation of netdev names with colons	2015-02-21 21:45:25 -05:00
drop_monitor.c	net: Replace get_cpu_var through this_cpu_ptr	2014-08-26 13:45:47 -04:00
dst.c	dst: no need to take reference on DST_NOCACHE dsts	2014-12-09 16:08:17 -05:00
ethtool.c	ethtool: Add hw-switch-offload to netdev_features_strings.	2015-02-20 16:36:43 -05:00
fib_rules.c	netlink: make nlmsg_end() and genlmsg_end() void	2015-01-18 01:03:45 -05:00
filter.c	net: spelling fixes	2015-02-14 20:36:08 -08:00
flow_dissector.c	xps: fix xps for stacked devices	2015-02-04 13:02:54 -08:00
flow.c	flowcache: Fix kernel panic in flow_cache_flush_task	2015-02-05 14:38:53 -08:00
gen_estimator.c	net: sched: make bstats per cpu and estimator RCU safe	2014-09-30 01:02:26 -04:00
gen_stats.c	gen_stats.c: Duplicate xstats buffer for later use	2015-02-19 15:45:53 -05:00
link_watch.c	net/core: include linux/types.h instead of asm/types.h	2014-11-18 15:26:32 -05:00
Makefile	net: bury net/core/iovec.c - nothing in there is used anymore	2015-02-04 01:34:15 -05:00
neighbour.c	netlink: Fix bugs in nlmsg_end() conversions.	2015-01-18 23:36:08 -05:00
net_namespace.c	Last round of updates for net-next:	2015-02-04 14:57:45 -08:00
net-procfs.c	rps: selective flow shedding during softnet overflow	2013-05-20 13:48:04 -07:00
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: netdev_kobject_init: annotate with __init	2014-01-05 20:27:54 -05:00
net-traces.c	net: Add export.h for EXPORT_SYMBOL/THIS_MODULE to non-modules	2011-10-31 19:30:30 -04:00
netclassid_cgroup.c	cgroup: rename cgroup_subsys->base_cftypes to ->legacy_cftypes	2014-07-15 11:05:09 -04:00
netevent.c	net: Add export.h for EXPORT_SYMBOL/THIS_MODULE to non-modules	2011-10-31 19:30:30 -04:00
netpoll.c	net: rename vlan_tx_* helpers since "tx" is misleading there	2015-01-13 17:51:08 -05:00
netprio_cgroup.c	cgroup: rename cgroup_subsys->base_cftypes to ->legacy_cftypes	2014-07-15 11:05:09 -04:00
pktgen.c	net: pktgen: disable xmit_clone on virtual devices	2015-02-22 22:43:20 -05:00
ptp_classifier.c	net: filter: split 'struct sk_filter' into socket and bpf parts	2014-08-02 15:03:58 -07:00
request_sock.c	inet: reduce TLB pressure for listeners	2014-06-25 16:37:24 -07:00
rtnetlink.c	net: do not use rcu in rtnl_dump_ifinfo()	2015-03-01 00:07:00 -05:00
scm.c	net: introduce helper macro for_each_cmsghdr	2014-12-10 22:41:55 -05:00
secure_seq.c	net: use ktime_get_ns() and ktime_get_real_ns() helpers	2014-08-22 19:57:23 -07:00
skbuff.c	sock: sock_dequeue_err_skb() needs hard irq safety	2015-02-20 15:52:21 -05:00
sock_diag.c	net: filter: split 'struct sk_filter' into socket and bpf parts	2014-08-02 15:03:58 -07:00
sock.c	net-timestamp: no-payload only sysctl	2015-02-02 18:46:51 -08:00
stream.c	net: replace macros net_random and net_srandom with direct calls to prandom	2014-01-14 15:15:25 -08:00
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	net-timestamp: Make the clone operation stand-alone from phy timestamping	2014-09-05 17:43:45 -07:00
tso.c	net: tso: fix unaligned access to crafted TCP header in helper API	2014-10-22 12:52:55 -04:00
utils.c	net: Convert LIMIT_NETDEBUG to net_dbg_ratelimited	2014-11-11 14:10:31 -05:00