syzbot

================================
WARNING: inconsistent lock state
syzkaller #0 Tainted: G             L     
--------------------------------
inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.
dhcpcd/5482 [HC1[1]:SC0[0]:HE0:SE1] takes:
ffff888032187868 (&dev->spinlock){?...}-{3:3}, at: spin_lock include/linux/spinlock.h:341 [inline]
ffff888032187868 (&dev->spinlock){?...}-{3:3}, at: das16m1_interrupt+0x68/0x120 drivers/comedi/drivers/das16m1.c:460
{HARDIRQ-ON-W} state was registered at:
  lock_acquire kernel/locking/lockdep.c:5868 [inline]
  lock_acquire+0x1cf/0x380 kernel/locking/lockdep.c:5825
  __raw_spin_lock_bh include/linux/spinlock_api_smp.h:150 [inline]
  _raw_spin_lock_bh+0x33/0x40 kernel/locking/spinlock.c:178
  spin_lock_bh include/linux/spinlock.h:347 [inline]
  waveform_ao_cancel+0x96/0x150 drivers/comedi/drivers/comedi_test.c:628
  do_cancel+0xf4/0x180 drivers/comedi/comedi_fops.c:818
  comedi_close+0x2f6/0x470 drivers/comedi/comedi_fops.c:3036
  __fput+0x3ff/0xb40 fs/file_table.c:469
  task_work_run+0x150/0x240 kernel/task_work.c:233
  resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
  __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
  exit_to_user_mode_loop+0x100/0x4a0 kernel/entry/common.c:98
  __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
  syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
  syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
  do_syscall_64+0x67c/0xf80 arch/x86/entry/syscall_64.c:100
  entry_SYSCALL_64_after_hwframe+0x77/0x7f
irq event stamp: 235036
hardirqs last  enabled at (235035): [<ffffffff826504f1>] seqcount_lockdep_reader_access include/linux/seqlock.h:75 [inline]
hardirqs last  enabled at (235035): [<ffffffff826504f1>] read_seqbegin include/linux/seqlock.h:838 [inline]
hardirqs last  enabled at (235035): [<ffffffff826504f1>] zone_span_seqbegin include/linux/memory_hotplug.h:87 [inline]
hardirqs last  enabled at (235035): [<ffffffff826504f1>] page_outside_zone_boundaries mm/page_alloc.c:612 [inline]
hardirqs last  enabled at (235035): [<ffffffff826504f1>] bad_range+0x261/0x400 mm/page_alloc.c:631
hardirqs last disabled at (235036): [<ffffffff8b8f5dc9>] common_interrupt+0x19/0xe0 arch/x86/kernel/irq.c:326
softirqs last  enabled at (235032): [<ffffffff89593477>] local_bh_disable include/linux/bottom_half.h:20 [inline]
softirqs last  enabled at (235032): [<ffffffff89593477>] __alloc_skb+0x5b7/0x710 net/core/skbuff.c:695
softirqs last disabled at (235030): [<ffffffff89593477>] local_bh_disable include/linux/bottom_half.h:20 [inline]
softirqs last disabled at (235030): [<ffffffff89593477>] __alloc_skb+0x5b7/0x710 net/core/skbuff.c:695

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

       CPU0
       ----
  lock(&dev->spinlock);
  <Interrupt>
    lock(&dev->spinlock);

 *** DEADLOCK ***

3 locks held by dhcpcd/5482:
 #0: ffff888020ba86f0 (nlk_cb_mutex-ROUTE){+.+.}-{4:4}, at: __netlink_dump_start+0x150/0x990 net/netlink/af_netlink.c:2404
 #1: ffffffff8e7e7920 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #1: ffffffff8e7e7920 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #1: ffffffff8e7e7920 (rcu_read_lock){....}-{1:3}, at: inet_dump_fib+0x12f/0x990 net/ipv4/fib_frontend.c:1033
 #2: ffffffff8e7e7920 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #2: ffffffff8e7e7920 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #2: ffffffff8e7e7920 (rcu_read_lock){....}-{1:3}, at: fib_dump_info_fnhe+0x24b/0x12e0 net/ipv4/route.c:3145

stack backtrace:
CPU: 0 UID: 101 PID: 5482 Comm: dhcpcd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_usage_bug.part.0+0x257/0x340 kernel/locking/lockdep.c:4042
 print_usage_bug kernel/locking/lockdep.c:4010 [inline]
 valid_state kernel/locking/lockdep.c:4056 [inline]
 mark_lock_irq kernel/locking/lockdep.c:4267 [inline]
 mark_lock+0x74a/0xa20 kernel/locking/lockdep.c:4753
 mark_usage kernel/locking/lockdep.c:4639 [inline]
 __lock_acquire+0x10ff/0x2630 kernel/locking/lockdep.c:5191
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x1cf/0x380 kernel/locking/lockdep.c:5825
 __raw_spin_lock include/linux/spinlock_api_smp.h:158 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:341 [inline]
 das16m1_interrupt+0x68/0x120 drivers/comedi/drivers/das16m1.c:460
 __handle_irq_event_percpu+0x232/0x8e0 kernel/irq/handle.c:209
 handle_irq_event_percpu kernel/irq/handle.c:246 [inline]
 handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:263
 handle_edge_irq+0x375/0x970 kernel/irq/chip.c:855
 generic_handle_irq_desc include/linux/irqdesc.h:186 [inline]
 handle_irq arch/x86/kernel/irq.c:262 [inline]
 call_irq_handler arch/x86/kernel/irq.c:318 [inline]
 __common_interrupt+0xd8/0x2f0 arch/x86/kernel/irq.c:333
 common_interrupt+0xb9/0xe0 arch/x86/kernel/irq.c:326
 </IRQ>
 <TASK>
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:688
RIP: 0010:debug_lockdep_rcu_enabled+0x0/0x40 kernel/rcu/update.c:319
Code: 00 00 8b 44 24 04 eb b2 89 44 24 04 e8 a9 fa ff ff 8b 44 24 04 eb aa 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 8b 05 82 5b 4a 05 85 c0 74 20 8b 05 60 8e 4a 05 85 c0
RSP: 0018:ffffc900030f7118 EFLAGS: 00000286
RAX: 0000000000000000 RBX: ffff88801eb23c80 RCX: 0000000000000002
RDX: 0000000000000000 RSI: ffffffff8de5e4ed RDI: ffffffff8c1b1a20
RBP: 0000000000000000 R08: 00000000992858fd R09: 0000000000000007
R10: 0000000000000200 R11: 0000000000000000 R12: ffff88801eb23c00
R13: 0000000000000000 R14: ffffc900030f72f8 R15: dffffc0000000000
 rcu_read_lock include/linux/rcupdate.h:851 [inline]
 fib_dump_info_fnhe+0x261/0x12e0 net/ipv4/route.c:3145
 fn_trie_dump_leaf net/ipv4/fib_trie.c:2309 [inline]
 fib_table_dump+0x658/0xd40 net/ipv4/fib_trie.c:2349
 inet_dump_fib+0x394/0x990 net/ipv4/fib_frontend.c:1075
 rtnl_dumpit+0x97/0x1f0 net/core/rtnetlink.c:6849
 netlink_dump+0x539/0xd30 net/netlink/af_netlink.c:2325
 __netlink_dump_start+0x6d6/0x990 net/netlink/af_netlink.c:2440
 netlink_dump_start include/linux/netlink.h:341 [inline]
 rtnetlink_dump_start net/core/rtnetlink.c:6878 [inline]
 rtnetlink_rcv_msg+0xb3e/0xe90 net/core/rtnetlink.c:6945
 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 ____sys_sendmsg+0x9e1/0xb70 net/socket.c:2592
 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2646
 __sys_sendmsg+0x170/0x220 net/socket.c:2678
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7c931c6407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffe900520f0 EFLAGS: 00000202 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f7c9313c780 RCX: 00007f7c931c6407
RDX: 0000000000000000 RSI: 00007ffe90052170 RDI: 000000000000000c
RBP: 00007ffe90056390 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000055963c91ac60
R13: 000000000000000c R14: 00007ffe90056350 R15: 00007ffe90056390
 </TASK>
comedi comedi3: fifo overflow
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	8b 44 24 04          	mov    0x4(%rsp),%eax
   6:	eb b2                	jmp    0xffffffba
   8:	89 44 24 04          	mov    %eax,0x4(%rsp)
   c:	e8 a9 fa ff ff       	call   0xfffffaba
  11:	8b 44 24 04          	mov    0x4(%rsp),%eax
  15:	eb aa                	jmp    0xffffffc1
  17:	0f 1f 00             	nopl   (%rax)
  1a:	90                   	nop
  1b:	90                   	nop
  1c:	90                   	nop
  1d:	90                   	nop
  1e:	90                   	nop
  1f:	90                   	nop
  20:	90                   	nop
  21:	90                   	nop
  22:	90                   	nop
  23:	90                   	nop
  24:	90                   	nop
  25:	90                   	nop
  26:	90                   	nop
  27:	90                   	nop
  28:	90                   	nop
  29:	90                   	nop
* 2a:	f3 0f 1e fa          	endbr64 <-- trapping instruction
  2e:	8b 05 82 5b 4a 05    	mov    0x54a5b82(%rip),%eax        # 0x54a5bb6
  34:	85 c0                	test   %eax,%eax
  36:	74 20                	je     0x58
  38:	8b 05 60 8e 4a 05    	mov    0x54a8e60(%rip),%eax        # 0x54a8e9e
  3e:	85 c0                	test   %eax,%eax