[PATCH 6.1 348/482] net: add netdev_lockdep_set_classes() to virtual drivers

26 Aug 2025

6.1-stable review patch.  If anyone has any objections, please let me know.
------------------
From: Eric Dumazet edumazet@google.com
commit 0bef512012b1cd8820f0c9ec80e5f8ceb43fdd59 upstream.
Based on a syzbot report, it appears many virtual
drivers do not yet use netdev_lockdep_set_classes(),
triggerring lockdep false positives.
WARNING: possible recursive locking detected
6.8.0-rc4-next-20240212-syzkaller #0 Not tainted
syz-executor.0/19016 is trying to acquire lock:
 ffff8880162cb298 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
 ffff8880162cb298 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4452 [inline]
 ffff8880162cb298 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x1c4/0x5f0 net/sched/sch_generic.c:340
but task is already holding lock:
 ffff8880223db4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
 ffff8880223db4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4452 [inline]
 ffff8880223db4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x1c4/0x5f0 net/sched/sch_generic.c:340
other info that might help us debug this:
 Possible unsafe locking scenario:
CPU0
  lock(_xmit_ETHER#2);
  lock(_xmit_ETHER#2);
*** DEADLOCK ***
May be due to missing lock nesting notation
9 locks held by syz-executor.0/19016:
  #0: ffffffff8f385208 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:79 [inline]
  #0: ffffffff8f385208 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x82c/0x1040 net/core/rtnetlink.c:6603
  #1: ffffc90000a08c00 ((&in_dev->mr_ifc_timer)){+.-.}-{0:0}, at: call_timer_fn+0xc0/0x600 kernel/time/timer.c:1697
  #2: ffffffff8e131520 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
  #2: ffffffff8e131520 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
  #2: ffffffff8e131520 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x45f/0x1360 net/ipv4/ip_output.c:228
  #3: ffffffff8e131580 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
  #3: ffffffff8e131580 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:802 [inline]
  #3: ffffffff8e131580 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2c4/0x3b10 net/core/dev.c:4284
  #4: ffff8880416e3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline]
  #4: ffff8880416e3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline]
  #4: ffff8880416e3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3771 [inline]
  #4: ffff8880416e3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x1262/0x3b10 net/core/dev.c:4325
  #5: ffff8880223db4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
  #5: ffff8880223db4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4452 [inline]
  #5: ffff8880223db4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x1c4/0x5f0 net/sched/sch_generic.c:340
  #6: ffffffff8e131520 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
  #6: ffffffff8e131520 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
  #6: ffffffff8e131520 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x45f/0x1360 net/ipv4/ip_output.c:228
  #7: ffffffff8e131580 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
  #7: ffffffff8e131580 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:802 [inline]
  #7: ffffffff8e131580 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2c4/0x3b10 net/core/dev.c:4284
  #8: ffff888014d9d258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline]
  #8: ffff888014d9d258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline]
  #8: ffff888014d9d258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3771 [inline]
  #8: ffff888014d9d258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x1262/0x3b10 net/core/dev.c:4325
stack backtrace:
CPU: 1 PID: 19016 Comm: syz-executor.0 Not tainted 6.8.0-rc4-next-20240212-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
Call Trace:
 <IRQ>
  __dump_stack lib/dump_stack.c:88 [inline]
  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
  check_deadlock kernel/locking/lockdep.c:3062 [inline]
  validate_chain+0x15c1/0x58e0 kernel/locking/lockdep.c:3856
  __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
  lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
  __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
  _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
  spin_lock include/linux/spinlock.h:351 [inline]
  __netif_tx_lock include/linux/netdevice.h:4452 [inline]
  sch_direct_xmit+0x1c4/0x5f0 net/sched/sch_generic.c:340
  __dev_xmit_skb net/core/dev.c:3784 [inline]
  __dev_queue_xmit+0x1912/0x3b10 net/core/dev.c:4325
  neigh_output include/net/neighbour.h:542 [inline]
  ip_finish_output2+0xe66/0x1360 net/ipv4/ip_output.c:235
  iptunnel_xmit+0x540/0x9b0 net/ipv4/ip_tunnel_core.c:82
  ip_tunnel_xmit+0x20ee/0x2960 net/ipv4/ip_tunnel.c:831
  erspan_xmit+0x9de/0x1460 net/ipv4/ip_gre.c:720
  __netdev_start_xmit include/linux/netdevice.h:4989 [inline]
  netdev_start_xmit include/linux/netdevice.h:5003 [inline]
  xmit_one net/core/dev.c:3555 [inline]
  dev_hard_start_xmit+0x242/0x770 net/core/dev.c:3571
  sch_direct_xmit+0x2b6/0x5f0 net/sched/sch_generic.c:342
  __dev_xmit_skb net/core/dev.c:3784 [inline]
  __dev_queue_xmit+0x1912/0x3b10 net/core/dev.c:4325
  neigh_output include/net/neighbour.h:542 [inline]
  ip_finish_output2+0xe66/0x1360 net/ipv4/ip_output.c:235
  igmpv3_send_cr net/ipv4/igmp.c:723 [inline]
  igmp_ifc_timer_expire+0xb71/0xd90 net/ipv4/igmp.c:813
  call_timer_fn+0x17e/0x600 kernel/time/timer.c:1700
  expire_timers kernel/time/timer.c:1751 [inline]
  __run_timers+0x621/0x830 kernel/time/timer.c:2038
  run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2051
  __do_softirq+0x2bc/0x943 kernel/softirq.c:554
  invoke_softirq kernel/softirq.c:428 [inline]
  __irq_exit_rcu+0xf2/0x1c0 kernel/softirq.c:633
  irq_exit_rcu+0x9/0x30 kernel/softirq.c:645
  instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1076 [inline]
  sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1076
 </IRQ>
 <TASK>
  asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
 RIP: 0010:resched_offsets_ok kernel/sched/core.c:10127 [inline]
 RIP: 0010:__might_resched+0x16f/0x780 kernel/sched/core.c:10142
Code: 00 4c 89 e8 48 c1 e8 03 48 ba 00 00 00 00 00 fc ff df 48 89 44 24 38 0f b6 04 10 84 c0 0f 85 87 04 00 00 41 8b 45 00 c1 e0 08 <01> d8 44 39 e0 0f 85 d6 00 00 00 44 89 64 24 1c 48 8d bc 24 a0 00
RSP: 0018:ffffc9000ee069e0 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff8880296a9e00
RDX: dffffc0000000000 RSI: ffff8880296a9e00 RDI: ffffffff8bfe8fa0
RBP: ffffc9000ee06b00 R08: ffffffff82326877 R09: 1ffff11002b5ad1b
R10: dffffc0000000000 R11: ffffed1002b5ad1c R12: 0000000000000000
R13: ffff8880296aa23c R14: 000000000000062a R15: 1ffff92001dc0d44
  down_write+0x19/0x50 kernel/locking/rwsem.c:1578
  kernfs_activate fs/kernfs/dir.c:1403 [inline]
  kernfs_add_one+0x4af/0x8b0 fs/kernfs/dir.c:819
  __kernfs_create_file+0x22e/0x2e0 fs/kernfs/file.c:1056
  sysfs_add_file_mode_ns+0x24a/0x310 fs/sysfs/file.c:307
  create_files fs/sysfs/group.c:64 [inline]
  internal_create_group+0x4f4/0xf20 fs/sysfs/group.c:152
  internal_create_groups fs/sysfs/group.c:192 [inline]
  sysfs_create_groups+0x56/0x120 fs/sysfs/group.c:218
  create_dir lib/kobject.c:78 [inline]
  kobject_add_internal+0x472/0x8d0 lib/kobject.c:240
  kobject_add_varg lib/kobject.c:374 [inline]
  kobject_init_and_add+0x124/0x190 lib/kobject.c:457
  netdev_queue_add_kobject net/core/net-sysfs.c:1706 [inline]
  netdev_queue_update_kobjects+0x1f3/0x480 net/core/net-sysfs.c:1758
  register_queue_kobjects net/core/net-sysfs.c:1819 [inline]
  netdev_register_kobject+0x265/0x310 net/core/net-sysfs.c:2059
  register_netdevice+0x1191/0x19c0 net/core/dev.c:10298
  bond_newlink+0x3b/0x90 drivers/net/bonding/bond_netlink.c:576
  rtnl_newlink_create net/core/rtnetlink.c:3506 [inline]
  __rtnl_newlink net/core/rtnetlink.c:3726 [inline]
  rtnl_newlink+0x158f/0x20a0 net/core/rtnetlink.c:3739
  rtnetlink_rcv_msg+0x885/0x1040 net/core/rtnetlink.c:6606
  netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2543
  netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline]
  netlink_unicast+0x7ea/0x980 net/netlink/af_netlink.c:1367
  netlink_sendmsg+0xa3c/0xd70 net/netlink/af_netlink.c:1908
  sock_sendmsg_nosec net/socket.c:730 [inline]
  __sock_sendmsg+0x221/0x270 net/socket.c:745
  __sys_sendto+0x3a4/0x4f0 net/socket.c:2191
  __do_sys_sendto net/socket.c:2203 [inline]
  __se_sys_sendto net/socket.c:2199 [inline]
  __x64_sys_sendto+0xde/0x100 net/socket.c:2199
 do_syscall_64+0xfb/0x240
 entry_SYSCALL_64_after_hwframe+0x6d/0x75
RIP: 0033:0x7fc3fa87fa9c
Reported-by: syzbot syzkaller@googlegroups.com
Signed-off-by: Eric Dumazet edumazet@google.com
Link: https://lore.kernel.org/r/20240212140700.2795436-4-edumazet@google.com
Signed-off-by: Jakub Kicinski kuba@kernel.org
Signed-off-by: Sumanth Gavini sumanth.gavini@yahoo.com
Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
---
 drivers/net/dummy.c            |    1 +
 drivers/net/geneve.c           |    1 +
 drivers/net/loopback.c         |    1 +
 drivers/net/veth.c             |    1 +
 drivers/net/vxlan/vxlan_core.c |    1 +
 net/ipv4/ip_tunnel.c           |    1 +
 net/ipv6/ip6_gre.c             |    2 ++
 net/ipv6/ip6_tunnel.c          |    1 +
 net/ipv6/ip6_vti.c             |    1 +
 net/ipv6/sit.c                 |    1 +
 10 files changed, 11 insertions(+)

--- a/drivers/net/dummy.c
+++ b/drivers/net/dummy.c
@@ -71,6 +71,7 @@ static int dummy_dev_init(struct net_dev
    if (!dev->lstats)
    	return -ENOMEM;
+	netdev_lockdep_set_classes(dev);
    return 0;
 }
--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -349,6 +349,7 @@ static int geneve_init(struct net_device
    	gro_cells_destroy(&geneve->gro_cells);
    	return err;
    }
+	netdev_lockdep_set_classes(dev);
    return 0;
 }
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -144,6 +144,7 @@ static int loopback_dev_init(struct net_
    dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
    if (!dev->lstats)
    	return -ENOMEM;
+	netdev_lockdep_set_classes(dev);
    return 0;
 }
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -1373,6 +1373,7 @@ static void veth_free_queues(struct net_
static int veth_dev_init(struct net_device *dev)
 {
+	netdev_lockdep_set_classes(dev);
    return veth_alloc_queues(dev);
 }
--- a/drivers/net/vxlan/vxlan_core.c
+++ b/drivers/net/vxlan/vxlan_core.c
@@ -2998,6 +2998,7 @@ static int vxlan_init(struct net_device
    if (err)
    	goto err_free_percpu;
+	netdev_lockdep_set_classes(dev);
    return 0;
err_free_percpu:
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -1298,6 +1298,7 @@ int ip_tunnel_init(struct net_device *de
if (tunnel->collect_md)
    	netif_keep_dst(dev);
+	netdev_lockdep_set_classes(dev);
    return 0;
 }
 EXPORT_SYMBOL_GPL(ip_tunnel_init);
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -1537,6 +1537,7 @@ static int ip6gre_tunnel_init_common(str
    ip6gre_tnl_init_features(dev);
netdev_hold(dev, &tunnel->dev_tracker, GFP_KERNEL);
+	netdev_lockdep_set_classes(dev);
    return 0;
cleanup_dst_cache_init:
@@ -1929,6 +1930,7 @@ static int ip6erspan_tap_init(struct net
    ip6erspan_tnl_link_config(tunnel, 1);
netdev_hold(dev, &tunnel->dev_tracker, GFP_KERNEL);
+	netdev_lockdep_set_classes(dev);
    return 0;
cleanup_dst_cache_init:
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -1902,6 +1902,7 @@ ip6_tnl_dev_init_gen(struct net_device *
    dev->max_mtu = IP6_MAX_MTU - dev->hard_header_len - t_hlen;
netdev_hold(dev, &t->dev_tracker, GFP_KERNEL);
+	netdev_lockdep_set_classes(dev);
    return 0;
destroy_dst:
--- a/net/ipv6/ip6_vti.c
+++ b/net/ipv6/ip6_vti.c
@@ -937,6 +937,7 @@ static inline int vti6_dev_init_gen(stru
    if (!dev->tstats)
    	return -ENOMEM;
    netdev_hold(dev, &t->dev_tracker, GFP_KERNEL);
+	netdev_lockdep_set_classes(dev);
    return 0;
 }
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -1460,6 +1460,7 @@ static int ipip6_tunnel_init(struct net_
    	return err;
    }
    netdev_hold(dev, &tunnel->dev_tracker, GFP_KERNEL);
+	netdev_lockdep_set_classes(dev);
    return 0;
 }

    

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[PATCH 6.1 348/482] net: add netdev_lockdep_set_classes() to virtual drivers