Increase LOCKDEP_CIRCULAR_QUEUE_BITS to avoid this warning: ------------[ cut here ]------------ lockdep bfs error:-1 WARNING: kernel/locking/lockdep.c:2059 at print_bfs_bug+0x24/0x40 kernel/locking/lockdep.c:2059, CPU#3: syz-executor.1/5867 Modules linked in: CPU: 3 UID: 0 PID: 5867 Comm: syz-executor.1 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:print_bfs_bug+0x26/0x40 kernel/locking/lockdep.c:2059 Code: 90 90 90 90 55 53 89 fb e8 97 ea 11 03 89 c5 e8 20 ff ff ff 85 ed 74 17 83 fb ff 0f 84 e8 ee 3d ff 48 8d 3d 0c 02 f7 0e 89 de <67> 48 0f b9 3a 5b 5d c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 RSP: 0018:ffffc900045c7388 EFLAGS: 00010086 RAX: 000000000000003b RBX: 00000000ffffffff RCX: 0000000000000000 RDX: 000000000000003b RSI: 00000000ffffffff RDI: ffffffff90db0ac0 RBP: 0000000000000001 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000002 R11: 6573616572636e49 R12: ffffc900045c7400 R13: ffff888025d4d608 R14: ffffc900045c7440 R15: ffff888025d4ca00 FS: 000055556c8094c0(0000) GS:ffff8880d6673000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000056421e554340 CR3: 0000000023552000 CR4: 0000000000352ef0 Call Trace: check_irq_usage+0x332/0x810 kernel/locking/lockdep.c:2816 check_prev_add kernel/locking/lockdep.c:3169 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x14cf/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b1/0x370 kernel/locking/lockdep.c:5825 seqcount_lockdep_reader_access include/linux/seqlock.h:73 [inline] ktime_expiry_to_cycles+0x9b/0x2c0 kernel/time/timekeeping.c:904 clockevent_set_next_coupled kernel/time/clockevents.c:314 [inline] clockevents_program_event+0x1bf/0x820 kernel/time/clockevents.c:360 tick_program_event+0xa9/0x140 kernel/time/tick-oneshot.c:48 hrtimer_rearm_event kernel/time/hrtimer.c:707 [inline] hrtimer_rearm kernel/time/hrtimer.c:2039 [inline] __hrtimer_rearm_deferred+0x237/0x740 kernel/time/hrtimer.c:2059 hrtimer_rearm_deferred_tif include/linux/hrtimer_rearm.h:53 [inline] hrtimer_rearm_deferred include/linux/hrtimer_rearm.h:62 [inline] irqentry_exit_to_kernel_mode_after_preempt include/linux/irq-entry-common.h:513 [inline] irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:550 [inline] irqentry_exit+0x502/0x790 kernel/entry/common.c:164 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:preempt_schedule_irq+0x4b/0x90 kernel/sched/core.c:7513 Code: 00 00 00 fc ff df 48 89 eb 48 c1 eb 03 48 01 d3 f6 c4 02 75 47 bf 01 00 00 00 e8 e0 68 49 f6 e8 bb 42 85 f6 fb bf 01 00 00 00 e0 8f ff ff 9c 58 fa f6 c4 02 75 1e bf 01 00 00 00 e8 0e 07 49 RSP: 0018:ffffc900045c78a8 EFLAGS: 00000206 RAX: 00000000006aff47 RBX: ffffed1004ba9940 RCX: 0000000000000040 RDX: 0000000000000000 RSI: ffffffff8df20a62 RDI: 0000000000000001 RBP: ffff888025d4ca00 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:476 [inline] irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline] irqentry_exit+0x1fe/0x790 kernel/entry/common.c:164 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:lock_acquire+0x5e/0x370 kernel/locking/lockdep.c:5872 Code: 05 bb 5d 26 12 83 f8 07 0f 87 d9 02 00 00 48 0f a3 05 c6 30 f3 0e 0f 82 a4 02 00 00 8b 35 4e 64 f3 0e 85 f6 0f 85 bf 00 00 00 <48> 8b 44 24 30 65 48 2b 05 5d 5d 26 12 0f 85 ed 02 00 00 48 83 c4 RSP: 0018:ffffc900045c79a8 EFLAGS: 00000206 RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000001 RDX: 0000000000000000 RSI: ffffffff8defb538 RDI: ffffffff8c1c3600 RBP: ffff88802e065140 R08: 00000000002c32d8 R09: ffffffff96f01770 R10: 0000000000000200 R11: 0000000000000001 R12: 0000000000000000 R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000 touch_wq_lockdep_map+0xad/0x1c0 kernel/workqueue.c:4017 __flush_workqueue+0x131/0x1200 kernel/workqueue.c:4059 close_ctree+0x43b/0xfe2 fs/btrfs/disk-io.c:4349 generic_shutdown_super+0x167/0x360 fs/super.c:646 kill_anon_super+0x3a/0x60 fs/super.c:1292 btrfs_kill_super+0x3b/0x50 fs/btrfs/super.c:2127 deactivate_locked_super+0xc1/0x1b0 fs/super.c:476 deactivate_super fs/super.c:509 [inline] deactivate_super+0xe7/0x110 fs/super.c:505 cleanup_mnt+0x21f/0x450 fs/namespace.c:1312 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:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] do_syscall_64+0x706/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7efcf046ea17 Code: a2 c7 05 e8 94 11 00 00 00 00 00 eb 96 e8 f1 09 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 d0 ff ff ff f7 d8 64 89 02 b8 RSP: 002b:00007fffa5253068 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 00007efcf04ce3ef RCX: 00007efcf046ea17 RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fffa5253120 RBP: 00007fffa5253120 R08: 00007fffa5254120 R09: 00000000ffffffff R10: 0000000000000000 R11: 0000000000000246 R12: 00007fffa52541e0 R13: 00007efcf04ce3ef R14: 000000000005323d R15: 0000000000000003 ---------------- Code disassembly (best guess): 0: 90 nop 1: 90 nop 2: 90 nop 3: 90 nop 4: 55 push %rbp 5: 53 push %rbx 6: 89 fb mov %edi,%ebx 8: e8 97 ea 11 03 call 0x311eaa4 d: 89 c5 mov %eax,%ebp f: e8 20 ff ff ff call 0xffffff34 14: 85 ed test %ebp,%ebp 16: 74 17 je 0x2f 18: 83 fb ff cmp $0xffffffff,%ebx 1b: 0f 84 e8 ee 3d ff je 0xff3def09 21: 48 8d 3d 0c 02 f7 0e lea 0xef7020c(%rip),%rdi # 0xef70234 28: 89 de mov %ebx,%esi * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: 5b pop %rbx 30: 5d pop %rbp 31: c3 ret 32: cc int3 33: cc int3 34: cc int3 35: cc int3 36: 66 data16 37: 66 data16 38: 2e cs 39: 0f .byte 0xf 3a: 1f (bad) 3b: 84 00 test %al,(%rax) 3d: 00 00 add %al,(%rax)