From: David Ahern <d...@cumulusnetworks.com>
Date: Sat, 22 Apr 2017 09:33:16 -0700
> systemd-sysctl is triggering a suspicious RCU usage message when
> net.ipv4.tcp_early_demux or net.ipv4.udp_early_demux is changed via
> a sysctl config file:
>
> [ 33.896184] ===============================
> [ 33.899558] [ ERR: suspicious RCU usage. ]
> [ 33.900624] 4.11.0-rc7+ #104 Not tainted
> [ 33.901698] -------------------------------
> [ 33.903059] /home/dsa/kernel-2.git/net/ipv4/sysctl_net_ipv4.c:305
> suspicious rcu_dereference_check() usage!
> [ 33.905724]
> other info that might help us debug this:
>
> [ 33.907656]
> rcu_scheduler_active = 2, debug_locks = 0
> [ 33.909288] 1 lock held by systemd-sysctl/143:
> [ 33.910373] #0: (sb_writers#5){.+.+.+}, at: [<ffffffff8123a370>]
> file_start_write+0x45/0x48
> [ 33.912407]
> stack backtrace:
> [ 33.914018] CPU: 0 PID: 143 Comm: systemd-sysctl Not tainted 4.11.0-rc7+
> #104
> [ 33.915631] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> 1.7.5-20140531_083030-gandalf 04/01/2014
> [ 33.917870] Call Trace:
> [ 33.918431] dump_stack+0x81/0xb6
> [ 33.919241] lockdep_rcu_suspicious+0x10f/0x118
> [ 33.920263] proc_configure_early_demux+0x65/0x10a
> [ 33.921391] proc_udp_early_demux+0x3a/0x41
>
> add rcu locking to proc_configure_early_demux.
>
> Fixes: dddb64bcb3461 ("net: Add sysctl to toggle early demux for tcp and udp")
> Signed-off-by: David Ahern <d...@cumulusnetworks.com>
Applied, thanks David.
