* [PATCH net-next] net: Fix suspicious RCU usage in fib_rebalance
@ 2015-10-14 23:44 David Ahern
2015-10-15 15:36 ` Peter Nørlund
2015-10-16 8:03 ` David Miller
0 siblings, 2 replies; 3+ messages in thread
From: David Ahern @ 2015-10-14 23:44 UTC (permalink / raw)
To: netdev; +Cc: pch, David Ahern
This command:
ip route add 192.168.1.0/24 nexthop via 10.2.1.5 dev eth1 nexthop via 10.2.2.5 dev eth2
generated this suspicious RCU usage message:
[ 63.249262]
[ 63.249939] ===============================
[ 63.251571] [ INFO: suspicious RCU usage. ]
[ 63.253250] 4.3.0-rc3+ #298 Not tainted
[ 63.254724] -------------------------------
[ 63.256401] ../include/linux/inetdevice.h:205 suspicious rcu_dereference_check() usage!
[ 63.259450]
[ 63.259450] other info that might help us debug this:
[ 63.259450]
[ 63.262297]
[ 63.262297] rcu_scheduler_active = 1, debug_locks = 1
[ 63.264647] 1 lock held by ip/2870:
[ 63.265896] #0: (rtnl_mutex){+.+.+.}, at: [<ffffffff813ebfb7>] rtnl_lock+0x12/0x14
[ 63.268858]
[ 63.268858] stack backtrace:
[ 63.270409] CPU: 4 PID: 2870 Comm: ip Not tainted 4.3.0-rc3+ #298
[ 63.272478] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
[ 63.275745] 0000000000000001 ffff8800b8c9f8b8 ffffffff8125f73c ffff88013afcf301
[ 63.278185] ffff8800bab7a380 ffff8800b8c9f8e8 ffffffff8107bf30 ffff8800bb728000
[ 63.280634] ffff880139fe9a60 0000000000000000 ffff880139fe9a00 ffff8800b8c9f908
[ 63.283177] Call Trace:
[ 63.283959] [<ffffffff8125f73c>] dump_stack+0x4c/0x68
[ 63.285593] [<ffffffff8107bf30>] lockdep_rcu_suspicious+0xfa/0x103
[ 63.287500] [<ffffffff8144d752>] __in_dev_get_rcu+0x48/0x4f
[ 63.289169] [<ffffffff8144d797>] fib_rebalance+0x3e/0x127
[ 63.290753] [<ffffffff8144d986>] ? rcu_read_unlock+0x3e/0x5f
[ 63.292442] [<ffffffff8144ea45>] fib_create_info+0xaf9/0xdcc
[ 63.294093] [<ffffffff8106c12f>] ? sched_clock_local+0x12/0x75
[ 63.295791] [<ffffffff8145236a>] fib_table_insert+0x8c/0x451
[ 63.297493] [<ffffffff8144bf9c>] ? fib_get_table+0x36/0x43
[ 63.299109] [<ffffffff8144c3ca>] inet_rtm_newroute+0x43/0x51
[ 63.300709] [<ffffffff813ef684>] rtnetlink_rcv_msg+0x182/0x195
[ 63.302334] [<ffffffff8107d04c>] ? trace_hardirqs_on+0xd/0xf
[ 63.303888] [<ffffffff813ebfb7>] ? rtnl_lock+0x12/0x14
[ 63.305346] [<ffffffff813ef502>] ? __rtnl_unlock+0x12/0x12
[ 63.306878] [<ffffffff81407c4c>] netlink_rcv_skb+0x3d/0x90
[ 63.308437] [<ffffffff813ec00e>] rtnetlink_rcv+0x21/0x28
[ 63.309916] [<ffffffff81407742>] netlink_unicast+0xfa/0x17f
[ 63.311447] [<ffffffff81407a5e>] netlink_sendmsg+0x297/0x2dc
[ 63.313029] [<ffffffff813c6cd4>] sock_sendmsg_nosec+0x12/0x1d
[ 63.314597] [<ffffffff813c835b>] ___sys_sendmsg+0x196/0x21b
[ 63.316125] [<ffffffff8100bf9f>] ? native_sched_clock+0x1f/0x3c
[ 63.317671] [<ffffffff8106c12f>] ? sched_clock_local+0x12/0x75
[ 63.319185] [<ffffffff8106c397>] ? sched_clock_cpu+0x9d/0xb6
[ 63.320693] [<ffffffff8107e2d7>] ? __lock_is_held+0x32/0x54
[ 63.322145] [<ffffffff81159fcb>] ? __fget_light+0x4b/0x77
[ 63.323541] [<ffffffff813c8726>] __sys_sendmsg+0x3d/0x5b
[ 63.324947] [<ffffffff813c8751>] SyS_sendmsg+0xd/0x19
[ 63.326274] [<ffffffff814c8f57>] entry_SYSCALL_64_fastpath+0x12/0x6f
It looks like all of the code paths to fib_rebalance are under rtnl.
Fixes: 0e884c78ee19 ("ipv4: L3 hash-based multipath")
Cc: Peter Nørlund <pch@ordbogen.com>
Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
---
net/ipv4/fib_semantics.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index af77298c8b4f..42778d9d71e5 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -545,7 +545,7 @@ static void fib_rebalance(struct fib_info *fi)
if (nh->nh_flags & RTNH_F_DEAD)
continue;
- in_dev = __in_dev_get_rcu(nh->nh_dev);
+ in_dev = __in_dev_get_rtnl(nh->nh_dev);
if (in_dev &&
IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
@@ -559,7 +559,7 @@ static void fib_rebalance(struct fib_info *fi)
change_nexthops(fi) {
int upper_bound;
- in_dev = __in_dev_get_rcu(nexthop_nh->nh_dev);
+ in_dev = __in_dev_get_rtnl(nexthop_nh->nh_dev);
if (nexthop_nh->nh_flags & RTNH_F_DEAD) {
upper_bound = -1;
--
1.9.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH net-next] net: Fix suspicious RCU usage in fib_rebalance
2015-10-14 23:44 [PATCH net-next] net: Fix suspicious RCU usage in fib_rebalance David Ahern
@ 2015-10-15 15:36 ` Peter Nørlund
2015-10-16 8:03 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: Peter Nørlund @ 2015-10-15 15:36 UTC (permalink / raw)
To: David Ahern; +Cc: netdev
On Wed, 14 Oct 2015 16:44:00 -0700
David Ahern <dsa@cumulusnetworks.com> wrote:
> This command:
> ip route add 192.168.1.0/24 nexthop via 10.2.1.5 dev eth1 nexthop
> via 10.2.2.5 dev eth2
>
> generated this suspicious RCU usage message:
>
> [ 63.249262]
> [ 63.249939] ===============================
> [ 63.251571] [ INFO: suspicious RCU usage. ]
> [ 63.253250] 4.3.0-rc3+ #298 Not tainted
> [ 63.254724] -------------------------------
> [ 63.256401] ../include/linux/inetdevice.h:205 suspicious
> rcu_dereference_check() usage! [ 63.259450]
> [ 63.259450] other info that might help us debug this:
> [ 63.259450]
> [ 63.262297]
> [ 63.262297] rcu_scheduler_active = 1, debug_locks = 1
> [ 63.264647] 1 lock held by ip/2870:
> [ 63.265896] #0: (rtnl_mutex){+.+.+.}, at: [<ffffffff813ebfb7>]
> rtnl_lock+0x12/0x14 [ 63.268858]
> [ 63.268858] stack backtrace:
> [ 63.270409] CPU: 4 PID: 2870 Comm: ip Not tainted 4.3.0-rc3+ #298
> [ 63.272478] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
> BIOS 1.7.5-20140531_083030-gandalf 04/01/2014 [ 63.275745]
> 0000000000000001 ffff8800b8c9f8b8 ffffffff8125f73c ffff88013afcf301
> [ 63.278185] ffff8800bab7a380 ffff8800b8c9f8e8 ffffffff8107bf30
> ffff8800bb728000 [ 63.280634] ffff880139fe9a60 0000000000000000
> ffff880139fe9a00 ffff8800b8c9f908 [ 63.283177] Call Trace:
> [ 63.283959] [<ffffffff8125f73c>] dump_stack+0x4c/0x68 [ 63.285593]
> [<ffffffff8107bf30>] lockdep_rcu_suspicious+0xfa/0x103 [ 63.287500]
> [<ffffffff8144d752>] __in_dev_get_rcu+0x48/0x4f [ 63.289169]
> [<ffffffff8144d797>] fib_rebalance+0x3e/0x127 [ 63.290753]
> [<ffffffff8144d986>] ? rcu_read_unlock+0x3e/0x5f [ 63.292442]
> [<ffffffff8144ea45>] fib_create_info+0xaf9/0xdcc [ 63.294093]
> [<ffffffff8106c12f>] ? sched_clock_local+0x12/0x75 [ 63.295791]
> [<ffffffff8145236a>] fib_table_insert+0x8c/0x451 [ 63.297493]
> [<ffffffff8144bf9c>] ? fib_get_table+0x36/0x43 [ 63.299109]
> [<ffffffff8144c3ca>] inet_rtm_newroute+0x43/0x51 [ 63.300709]
> [<ffffffff813ef684>] rtnetlink_rcv_msg+0x182/0x195 [ 63.302334]
> [<ffffffff8107d04c>] ? trace_hardirqs_on+0xd/0xf [ 63.303888]
> [<ffffffff813ebfb7>] ? rtnl_lock+0x12/0x14 [ 63.305346]
> [<ffffffff813ef502>] ? __rtnl_unlock+0x12/0x12 [ 63.306878]
> [<ffffffff81407c4c>] netlink_rcv_skb+0x3d/0x90 [ 63.308437]
> [<ffffffff813ec00e>] rtnetlink_rcv+0x21/0x28 [ 63.309916]
> [<ffffffff81407742>] netlink_unicast+0xfa/0x17f [ 63.311447]
> [<ffffffff81407a5e>] netlink_sendmsg+0x297/0x2dc [ 63.313029]
> [<ffffffff813c6cd4>] sock_sendmsg_nosec+0x12/0x1d [ 63.314597]
> [<ffffffff813c835b>] ___sys_sendmsg+0x196/0x21b [ 63.316125]
> [<ffffffff8100bf9f>] ? native_sched_clock+0x1f/0x3c [ 63.317671]
> [<ffffffff8106c12f>] ? sched_clock_local+0x12/0x75 [ 63.319185]
> [<ffffffff8106c397>] ? sched_clock_cpu+0x9d/0xb6 [ 63.320693]
> [<ffffffff8107e2d7>] ? __lock_is_held+0x32/0x54 [ 63.322145]
> [<ffffffff81159fcb>] ? __fget_light+0x4b/0x77 [ 63.323541]
> [<ffffffff813c8726>] __sys_sendmsg+0x3d/0x5b [ 63.324947]
> [<ffffffff813c8751>] SyS_sendmsg+0xd/0x19 [ 63.326274]
> [<ffffffff814c8f57>] entry_SYSCALL_64_fastpath+0x12/0x6f
>
> It looks like all of the code paths to fib_rebalance are under rtnl.
>
> Fixes: 0e884c78ee19 ("ipv4: L3 hash-based multipath")
> Cc: Peter Nørlund <pch@ordbogen.com>
> Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
> ---
> net/ipv4/fib_semantics.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
> index af77298c8b4f..42778d9d71e5 100644
> --- a/net/ipv4/fib_semantics.c
> +++ b/net/ipv4/fib_semantics.c
> @@ -545,7 +545,7 @@ static void fib_rebalance(struct fib_info *fi)
> if (nh->nh_flags & RTNH_F_DEAD)
> continue;
>
> - in_dev = __in_dev_get_rcu(nh->nh_dev);
> + in_dev = __in_dev_get_rtnl(nh->nh_dev);
>
> if (in_dev &&
> IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
> @@ -559,7 +559,7 @@ static void fib_rebalance(struct fib_info *fi)
> change_nexthops(fi) {
> int upper_bound;
>
> - in_dev = __in_dev_get_rcu(nexthop_nh->nh_dev);
> + in_dev = __in_dev_get_rtnl(nexthop_nh->nh_dev);
>
> if (nexthop_nh->nh_flags & RTNH_F_DEAD) {
> upper_bound = -1;
Totally missed that. You are right. All paths to fib_rebalance have a
rtnl_lock or ASSERT_RTNL. Besides, fib_rebalance would have a race
without the lock.
Best Regards
Peter Nørlund
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH net-next] net: Fix suspicious RCU usage in fib_rebalance
2015-10-14 23:44 [PATCH net-next] net: Fix suspicious RCU usage in fib_rebalance David Ahern
2015-10-15 15:36 ` Peter Nørlund
@ 2015-10-16 8:03 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: David Miller @ 2015-10-16 8:03 UTC (permalink / raw)
To: dsa; +Cc: netdev, pch
From: David Ahern <dsa@cumulusnetworks.com>
Date: Wed, 14 Oct 2015 16:44:00 -0700
> This command:
> ip route add 192.168.1.0/24 nexthop via 10.2.1.5 dev eth1 nexthop via 10.2.2.5 dev eth2
>
> generated this suspicious RCU usage message:
...
> It looks like all of the code paths to fib_rebalance are under rtnl.
>
> Fixes: 0e884c78ee19 ("ipv4: L3 hash-based multipath")
> Cc: Peter Nørlund <pch@ordbogen.com>
> Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Applied.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2015-10-16 7:46 UTC | newest]
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2015-10-14 23:44 [PATCH net-next] net: Fix suspicious RCU usage in fib_rebalance David Ahern
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2015-10-16 8:03 ` David Miller
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