| Message ID | 20241022063822.462057-1-idosch@nvidia.com (mailing list archive) |
|---|---|
| State | New |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] ipv4: ip_tunnel: Fix suspicious RCU usage warning in ip_tunnel_init_flow() | expand |
On 10/22/24 12:38 AM, Ido Schimmel wrote: > There are code paths from which the function is called without holding > the RCU read lock, resulting in a suspicious RCU usage warning [1]. > > Fix by using l3mdev_master_upper_ifindex_by_index() which will acquire > the RCU read lock before calling > l3mdev_master_upper_ifindex_by_index_rcu(). > > [1] > WARNING: suspicious RCU usage > 6.12.0-rc3-custom-gac8f72681cf2 #141 Not tainted > ----------------------------- > net/core/dev.c:876 RCU-list traversed in non-reader section!! > > other info that might help us debug this: > > rcu_scheduler_active = 2, debug_locks = 1 > 1 lock held by ip/361: > #0: ffffffff86fc7cb0 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x377/0xf60 > > stack backtrace: > CPU: 3 UID: 0 PID: 361 Comm: ip Not tainted 6.12.0-rc3-custom-gac8f72681cf2 #141 > Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 > Call Trace: > <TASK> > dump_stack_lvl+0xba/0x110 > lockdep_rcu_suspicious.cold+0x4f/0xd6 > dev_get_by_index_rcu+0x1d3/0x210 > l3mdev_master_upper_ifindex_by_index_rcu+0x2b/0xf0 > ip_tunnel_bind_dev+0x72f/0xa00 > ip_tunnel_newlink+0x368/0x7a0 > ipgre_newlink+0x14c/0x170 > __rtnl_newlink+0x1173/0x19c0 > rtnl_newlink+0x6c/0xa0 > rtnetlink_rcv_msg+0x3cc/0xf60 > netlink_rcv_skb+0x171/0x450 > netlink_unicast+0x539/0x7f0 > netlink_sendmsg+0x8c1/0xd80 > ____sys_sendmsg+0x8f9/0xc20 > ___sys_sendmsg+0x197/0x1e0 > __sys_sendmsg+0x122/0x1f0 > do_syscall_64+0xbb/0x1d0 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > Fixes: db53cd3d88dc ("net: Handle l3mdev in ip_tunnel_init_flow") > Signed-off-by: Ido Schimmel <idosch@nvidia.com> > --- > include/net/ip_tunnels.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > Reviewed-by: David Ahern <dsahern@kernel.org>
diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h index 6194fbb564c6..6a070478254d 100644 --- a/include/net/ip_tunnels.h +++ b/include/net/ip_tunnels.h @@ -354,7 +354,7 @@ static inline void ip_tunnel_init_flow(struct flowi4 *fl4, memset(fl4, 0, sizeof(*fl4)); if (oif) { - fl4->flowi4_l3mdev = l3mdev_master_upper_ifindex_by_index_rcu(net, oif); + fl4->flowi4_l3mdev = l3mdev_master_upper_ifindex_by_index(net, oif); /* Legacy VRF/l3mdev use case */ fl4->flowi4_oif = fl4->flowi4_l3mdev ? 0 : oif; }
There are code paths from which the function is called without holding the RCU read lock, resulting in a suspicious RCU usage warning [1]. Fix by using l3mdev_master_upper_ifindex_by_index() which will acquire the RCU read lock before calling l3mdev_master_upper_ifindex_by_index_rcu(). [1] WARNING: suspicious RCU usage 6.12.0-rc3-custom-gac8f72681cf2 #141 Not tainted ----------------------------- net/core/dev.c:876 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by ip/361: #0: ffffffff86fc7cb0 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x377/0xf60 stack backtrace: CPU: 3 UID: 0 PID: 361 Comm: ip Not tainted 6.12.0-rc3-custom-gac8f72681cf2 #141 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 Call Trace: <TASK> dump_stack_lvl+0xba/0x110 lockdep_rcu_suspicious.cold+0x4f/0xd6 dev_get_by_index_rcu+0x1d3/0x210 l3mdev_master_upper_ifindex_by_index_rcu+0x2b/0xf0 ip_tunnel_bind_dev+0x72f/0xa00 ip_tunnel_newlink+0x368/0x7a0 ipgre_newlink+0x14c/0x170 __rtnl_newlink+0x1173/0x19c0 rtnl_newlink+0x6c/0xa0 rtnetlink_rcv_msg+0x3cc/0xf60 netlink_rcv_skb+0x171/0x450 netlink_unicast+0x539/0x7f0 netlink_sendmsg+0x8c1/0xd80 ____sys_sendmsg+0x8f9/0xc20 ___sys_sendmsg+0x197/0x1e0 __sys_sendmsg+0x122/0x1f0 do_syscall_64+0xbb/0x1d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fixes: db53cd3d88dc ("net: Handle l3mdev in ip_tunnel_init_flow") Signed-off-by: Ido Schimmel <idosch@nvidia.com> --- include/net/ip_tunnels.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)