| Message ID | 1492878796-31328-1-git-send-email-dsa@cumulusnetworks.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: David Ahern <dsa@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 <dsa@cumulusnetworks.com> Applied, thanks David.
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index 6fb25693c00b..ddac9e64b702 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -302,6 +302,8 @@ static void proc_configure_early_demux(int enabled, int protocol) struct inet6_protocol *ip6prot; #endif + rcu_read_lock(); + ipprot = rcu_dereference(inet_protos[protocol]); if (ipprot) ipprot->early_demux = enabled ? ipprot->early_demux_handler : @@ -313,6 +315,7 @@ static void proc_configure_early_demux(int enabled, int protocol) ip6prot->early_demux = enabled ? ip6prot->early_demux_handler : NULL; #endif + rcu_read_unlock(); } static int proc_tcp_early_demux(struct ctl_table *table, int write,
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 <dsa@cumulusnetworks.com> --- net/ipv4/sysctl_net_ipv4.c | 3 +++ 1 file changed, 3 insertions(+)