| Message ID | 20231010091323.195451-1-jiri@resnulli.us (mailing list archive) |
|---|---|
| Headers | show |
| Series | devlink: don't take instance lock for nested handle put | expand |
On Tue, 10 Oct 2023 11:13:20 +0200 Jiri Pirko wrote: > From: Jiri Pirko <jiri@nvidia.com> > > Lockdep reports following issue: Weren't you complaining about people posting stuff before discussion is over in the past? :)
Tue, Oct 10, 2023 at 09:10:15PM CEST, kuba@kernel.org wrote: >On Tue, 10 Oct 2023 11:13:20 +0200 Jiri Pirko wrote: >> From: Jiri Pirko <jiri@nvidia.com> >> >> Lockdep reports following issue: > >Weren't you complaining about people posting stuff before discussion >is over in the past? :) Sure, but it isn't? I believe that this fix is needed regardless of the A->B objects lifetime. If I'm missing something, sorry about that.
From: Jiri Pirko <jiri@nvidia.com> Lockdep reports following issue: WARNING: possible circular locking dependency detected ------------------------------------------------------ devlink/8191 is trying to acquire lock: ffff88813f32c250 (&devlink->lock_key#14){+.+.}-{3:3}, at: devlink_rel_devlink_handle_put+0x11e/0x2d0 but task is already holding lock: ffffffff8511eca8 (rtnl_mutex){+.+.}-{3:3}, at: unregister_netdev+0xe/0x20 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (rtnl_mutex){+.+.}-{3:3}: lock_acquire+0x1c3/0x500 __mutex_lock+0x14c/0x1b20 register_netdevice_notifier_net+0x13/0x30 mlx5_lag_add_mdev+0x51c/0xa00 [mlx5_core] mlx5_load+0x222/0xc70 [mlx5_core] mlx5_init_one_devl_locked+0x4a0/0x1310 [mlx5_core] mlx5_init_one+0x3b/0x60 [mlx5_core] probe_one+0x786/0xd00 [mlx5_core] local_pci_probe+0xd7/0x180 pci_device_probe+0x231/0x720 really_probe+0x1e4/0xb60 __driver_probe_device+0x261/0x470 driver_probe_device+0x49/0x130 __driver_attach+0x215/0x4c0 bus_for_each_dev+0xf0/0x170 bus_add_driver+0x21d/0x590 driver_register+0x133/0x460 vdpa_match_remove+0x89/0xc0 [vdpa] do_one_initcall+0xc4/0x360 do_init_module+0x22d/0x760 load_module+0x51d7/0x6750 init_module_from_file+0xd2/0x130 idempotent_init_module+0x326/0x5a0 __x64_sys_finit_module+0xc1/0x130 do_syscall_64+0x3d/0x90 entry_SYSCALL_64_after_hwframe+0x46/0xb0 -> #2 (mlx5_intf_mutex){+.+.}-{3:3}: lock_acquire+0x1c3/0x500 __mutex_lock+0x14c/0x1b20 mlx5_register_device+0x3e/0xd0 [mlx5_core] mlx5_init_one_devl_locked+0x8fa/0x1310 [mlx5_core] mlx5_devlink_reload_up+0x147/0x170 [mlx5_core] devlink_reload+0x203/0x380 devlink_nl_cmd_reload+0xb84/0x10e0 genl_family_rcv_msg_doit+0x1cc/0x2a0 genl_rcv_msg+0x3c9/0x670 netlink_rcv_skb+0x12c/0x360 genl_rcv+0x24/0x40 netlink_unicast+0x435/0x6f0 netlink_sendmsg+0x7a0/0xc70 sock_sendmsg+0xc5/0x190 __sys_sendto+0x1c8/0x290 __x64_sys_sendto+0xdc/0x1b0 do_syscall_64+0x3d/0x90 entry_SYSCALL_64_after_hwframe+0x46/0xb0 -> #1 (&dev->lock_key#8){+.+.}-{3:3}: lock_acquire+0x1c3/0x500 __mutex_lock+0x14c/0x1b20 mlx5_init_one_devl_locked+0x45/0x1310 [mlx5_core] mlx5_devlink_reload_up+0x147/0x170 [mlx5_core] devlink_reload+0x203/0x380 devlink_nl_cmd_reload+0xb84/0x10e0 genl_family_rcv_msg_doit+0x1cc/0x2a0 genl_rcv_msg+0x3c9/0x670 netlink_rcv_skb+0x12c/0x360 genl_rcv+0x24/0x40 netlink_unicast+0x435/0x6f0 netlink_sendmsg+0x7a0/0xc70 sock_sendmsg+0xc5/0x190 __sys_sendto+0x1c8/0x290 __x64_sys_sendto+0xdc/0x1b0 do_syscall_64+0x3d/0x90 entry_SYSCALL_64_after_hwframe+0x46/0xb0 -> #0 (&devlink->lock_key#14){+.+.}-{3:3}: check_prev_add+0x1af/0x2300 __lock_acquire+0x31d7/0x4eb0 lock_acquire+0x1c3/0x500 __mutex_lock+0x14c/0x1b20 devlink_rel_devlink_handle_put+0x11e/0x2d0 devlink_nl_port_fill+0xddf/0x1b00 devlink_port_notify+0xb5/0x220 __devlink_port_type_set+0x151/0x510 devlink_port_netdevice_event+0x17c/0x220 notifier_call_chain+0x97/0x240 unregister_netdevice_many_notify+0x876/0x1790 unregister_netdevice_queue+0x274/0x350 unregister_netdev+0x18/0x20 mlx5e_vport_rep_unload+0xc5/0x1c0 [mlx5_core] __esw_offloads_unload_rep+0xd8/0x130 [mlx5_core] mlx5_esw_offloads_rep_unload+0x52/0x70 [mlx5_core] mlx5_esw_offloads_unload_rep+0x85/0xc0 [mlx5_core] mlx5_eswitch_unload_sf_vport+0x41/0x90 [mlx5_core] mlx5_devlink_sf_port_del+0x120/0x280 [mlx5_core] genl_family_rcv_msg_doit+0x1cc/0x2a0 genl_rcv_msg+0x3c9/0x670 netlink_rcv_skb+0x12c/0x360 genl_rcv+0x24/0x40 netlink_unicast+0x435/0x6f0 netlink_sendmsg+0x7a0/0xc70 sock_sendmsg+0xc5/0x190 __sys_sendto+0x1c8/0x290 __x64_sys_sendto+0xdc/0x1b0 do_syscall_64+0x3d/0x90 entry_SYSCALL_64_after_hwframe+0x46/0xb0 other info that might help us debug this: Chain exists of: &devlink->lock_key#14 --> mlx5_intf_mutex --> rtnl_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(rtnl_mutex); lock(mlx5_intf_mutex); lock(rtnl_mutex); lock(&devlink->lock_key#14); Problem is taking the devlink instance lock of nested instance when RTNL is already held. To fix this, don't take the devlink instance lock when putting nested handle. Instead, rely on devlink reference to access relevant pointers within devlink structure. Also, make sure that the device does not disappear by taking a reference in devlink_alloc_ns(). Patch #1 is dependency of patch #2. Patch #2 converts the peernet2id_alloc() call so it could called without devlink instance lock and prepares for the lock taking removal done in patch #3. Jiri Pirko (3): net: treat possible_net_t net pointer as an RCU one and add read_pnet_rcu() devlink: call peernet2id_alloc() with net pointer under RCU read lock devlink: don't take instance lock for nested handle put include/net/net_namespace.h | 15 ++++++++++++--- net/devlink/core.c | 20 +++++--------------- net/devlink/netlink.c | 12 +++++++++--- 3 files changed, 26 insertions(+), 21 deletions(-)