syzbot

============================================
WARNING: possible recursive locking detected
6.1.133-syzkaller #0 Not tainted
--------------------------------------------
dhcpcd-run-hook/8875 is trying to acquire lock:
ffff888056e80218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff888056e80218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3925 [inline]
ffff888056e80218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x22db/0x3d50 net/core/dev.c:4300

but task is already holding lock:
ffff888063d07258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline]
ffff888063d07258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline]
ffff888063d07258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3882 [inline]
ffff888063d07258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x12c7/0x3d50 net/core/dev.c:4300

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
  lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

11 locks held by dhcpcd-run-hook/8875:
 #0: ffff888076a597d8 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
 #0: ffff888076a597d8 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0x175/0x2d0 mm/util.c:518
 #1: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #1: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #1: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: mt_validate+0x1be/0x5ad0 lib/maple_tree.c:7219
 #2: ffffc90000007bc0 ((&ndev->rs_timer)){+.-.}-{0:0}, at: call_timer_fn+0xc2/0x6b0 kernel/time/timer.c:1501
 #3: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #3: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #3: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: ndisc_send_skb+0x1f0/0x15f0 net/ipv6/ndisc.c:484
 #4: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #4: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #4: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: ip6_finish_output2+0x6a0/0x1700 net/ipv6/ip6_output.c:123
 #5: ffffffff8d32e7a0 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
 #5: ffffffff8d32e7a0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:843 [inline]
 #5: ffffffff8d32e7a0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2d6/0x3d50 net/core/dev.c:4257
 #6: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #6: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #6: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: bond_start_xmit+0x128/0x1d50 drivers/net/bonding/bond_main.c:5523
 #7: ffffffff8d32e7a0 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
 #7: ffffffff8d32e7a0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:843 [inline]
 #7: ffffffff8d32e7a0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2d6/0x3d50 net/core/dev.c:4257
 #8: ffff888063d07258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline]
 #8: ffff888063d07258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline]
 #8: ffff888063d07258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3882 [inline]
 #8: ffff888063d07258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x12c7/0x3d50 net/core/dev.c:4300
 #9: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #9: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #9: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x3ee/0x1270 net/ipv4/ip_output.c:221
 #10: ffffffff8d32e7a0 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
 #10: ffffffff8d32e7a0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:843 [inline]
 #10: ffffffff8d32e7a0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2d6/0x3d50 net/core/dev.c:4257

stack backtrace:
CPU: 0 PID: 8875 Comm: dhcpcd-run-hook Not tainted 6.1.133-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 print_deadlock_bug kernel/locking/lockdep.c:2983 [inline]
 check_deadlock kernel/locking/lockdep.c:3026 [inline]
 validate_chain+0x4711/0x5950 kernel/locking/lockdep.c:3812
 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:351 [inline]
 __dev_xmit_skb net/core/dev.c:3925 [inline]
 __dev_queue_xmit+0x22db/0x3d50 net/core/dev.c:4300
 dev_queue_xmit include/linux/netdevice.h:3051 [inline]
 neigh_hh_output include/net/neighbour.h:528 [inline]
 neigh_output include/net/neighbour.h:542 [inline]
 ip_finish_output2+0xd6e/0x1270 net/ipv4/ip_output.c:228
 iptunnel_xmit+0x51a/0x920 net/ipv4/ip_tunnel_core.c:82
 ip_tunnel_xmit+0x1b52/0x2550 net/ipv4/ip_tunnel.c:858
 __gre_xmit net/ipv4/ip_gre.c:474 [inline]
 gre_tap_xmit+0x4eb/0x6e0 net/ipv4/ip_gre.c:751
 __netdev_start_xmit include/linux/netdevice.h:4896 [inline]
 netdev_start_xmit include/linux/netdevice.h:4910 [inline]
 xmit_one net/core/dev.c:3658 [inline]
 dev_hard_start_xmit+0x261/0x8c0 net/core/dev.c:3674
 sch_direct_xmit+0x2b2/0x5e0 net/sched/sch_generic.c:342
 __dev_xmit_skb net/core/dev.c:3895 [inline]
 __dev_queue_xmit+0x1a7a/0x3d50 net/core/dev.c:4300
 dev_queue_xmit include/linux/netdevice.h:3051 [inline]
 bond_dev_queue_xmit+0x143/0x240 drivers/net/bonding/bond_main.c:307
 __bond_start_xmit drivers/net/bonding/bond_main.c:5503 [inline]
 bond_start_xmit+0xdb5/0x1d50 drivers/net/bonding/bond_main.c:5525
 __netdev_start_xmit include/linux/netdevice.h:4896 [inline]
 netdev_start_xmit include/linux/netdevice.h:4910 [inline]
 xmit_one net/core/dev.c:3658 [inline]
 dev_hard_start_xmit+0x261/0x8c0 net/core/dev.c:3674
 __dev_queue_xmit+0x1b5d/0x3d50 net/core/dev.c:4334
 dev_queue_xmit include/linux/netdevice.h:3051 [inline]
 neigh_hh_output include/net/neighbour.h:528 [inline]
 neigh_output include/net/neighbour.h:542 [inline]
 ip6_finish_output2+0xfa5/0x1700 net/ipv6/ip6_output.c:138
 __ip6_finish_output net/ipv6/ip6_output.c:205 [inline]
 ip6_finish_output+0x6a0/0xa80 net/ipv6/ip6_output.c:216
 dst_output include/net/dst.h:453 [inline]
 NF_HOOK include/linux/netfilter.h:302 [inline]
 ndisc_send_skb+0xbf6/0x15f0 net/ipv6/ndisc.c:513
 addrconf_rs_timer+0x357/0x610 net/ipv6/addrconf.c:3982
 call_timer_fn+0x1ad/0x6b0 kernel/time/timer.c:1504
 expire_timers kernel/time/timer.c:1549 [inline]
 __run_timers+0x67c/0x890 kernel/time/timer.c:1820
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1833
 handle_softirqs+0x2ee/0xa40 kernel/softirq.c:578
 __do_softirq kernel/softirq.c:612 [inline]
 invoke_softirq kernel/softirq.c:452 [inline]
 __irq_exit_rcu+0x157/0x240 kernel/softirq.c:661
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:673
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:mas_dfs_postorder lib/maple_tree.c:6779 [inline]
RIP: 0010:mt_validate+0x4487/0x5ad0 lib/maple_tree.c:7242
Code: 00 00 00 00 fc ff df 48 8b 8c 24 88 00 00 00 80 3c 01 00 74 0d 48 8b bc 24 80 00 00 00 e8 41 7b 39 f7 4c 89 bc 24 60 01 00 00 <4c> 8b 3c 24 eb 25 e8 6e 19 e2 f6 48 8b 44 24 10 42 80 3c 30 00 4c
RSP: 0018:ffffc90003ad7600 EFLAGS: 00000246
RAX: dffffc0000000000 RBX: 0000000000000009 RCX: 1ffff9200075aeec
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90003ad77f0 R08: ffffffff8aaa617a R09: 0000000000000003
R10: ffffffffffffffff R11: dffffc0000000001 R12: ffffffffffffffff
R13: 0000000000000002 R14: ffff88807834921c R15: 0000000000000000
 validate_mm_mt+0x165/0x670 mm/mmap.c:294
 validate_mm+0x16e/0x380 mm/mmap.c:331
 mmap_region+0x1556/0x2660 mm/mmap.c:2910
 do_mmap+0x8c5/0xf60 mm/mmap.c:1424
 vm_mmap_pgoff+0x1ca/0x2d0 mm/util.c:520
 ksys_mmap_pgoff+0x4f5/0x6d0 mm/mmap.c:1470
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb7b2789b74
Code: 63 08 44 89 e8 5b 41 5c 41 5d c3 41 89 ca 41 f7 c1 ff 0f 00 00 74 0c c7 05 f5 46 01 00 16 00 00 00 eb 17 b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 0c f7 d8 89 05 dc 46 01 00 48 83 c8 ff c3 0f
RSP: 002b:00007ffc7f791e68 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00000fff8fef23ce RCX: 00007fb7b2789b74
RDX: 0000000000000001 RSI: 0000000000054188 RDI: 0000000000000000
RBP: 00007ffc7f792200 R08: 0000000000000003 R09: 0000000000000000
R10: 0000000000000802 R11: 0000000000000246 R12: 00007fb7b276d570
R13: 00007ffc7f792288 R14: fffffffffffff000 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess), 7 bytes skipped:
   0:	48 8b 8c 24 88 00 00 	mov    0x88(%rsp),%rcx
   7:	00
   8:	80 3c 01 00          	cmpb   $0x0,(%rcx,%rax,1)
   c:	74 0d                	je     0x1b
   e:	48 8b bc 24 80 00 00 	mov    0x80(%rsp),%rdi
  15:	00
  16:	e8 41 7b 39 f7       	call   0xf7397b5c
  1b:	4c 89 bc 24 60 01 00 	mov    %r15,0x160(%rsp)
  22:	00
* 23:	4c 8b 3c 24          	mov    (%rsp),%r15 <-- trapping instruction
  27:	eb 25                	jmp    0x4e
  29:	e8 6e 19 e2 f6       	call   0xf6e2199c
  2e:	48 8b 44 24 10       	mov    0x10(%rsp),%rax
  33:	42 80 3c 30 00       	cmpb   $0x0,(%rax,%r14,1)
  38:	4c                   	rex.WR