syzbot

ODEBUG: object ffffc90002e77a98 is on stack ffffc90002e70000, but NOT annotated.
======================================================
WARNING: possible circular locking dependency detected
6.16.0-rc1-syzkaller-00004-gaef17cb3d3c4 #0 Not tainted
------------------------------------------------------
bch-copygc/loop/5851 is trying to acquire lock:
ffffffff8e4d1dc0 (console_owner){....}-{0:0}, at: console_lock_spinning_enable+0x9f/0xd0 kernel/printk/printk.c:1924

but task is already holding lock:
ffffffff9af9fc28 (&obj_hash[i].lock){-.-.}-{2:2}, at: __debug_object_init+0xec/0x3d0 lib/debugobjects.c:741

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (&obj_hash[i].lock){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
       debug_object_activate+0x14c/0x4c0 lib/debugobjects.c:818
       debug_work_activate kernel/workqueue.c:664 [inline]
       insert_work+0x2e/0x230 kernel/workqueue.c:2180
       __queue_work+0x97e/0x10f0 kernel/workqueue.c:2341
       queue_work_on+0x15f/0x1f0 kernel/workqueue.c:2392
       queue_work include/linux/workqueue.h:662 [inline]
       start_poll_synchronize_rcu_expedited+0x113/0x190 kernel/rcu/tree_exp.h:1075
       rcu_init+0xe95/0x1630 kernel/rcu/tree.c:4854
       start_kernel+0x1df/0x4d0 init/main.c:991
       x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:307
       x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:288
       common_startup_64+0x13e/0x148

-> #3 (&pool->lock){-.-.}-{2:2}:
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
       __queue_work+0x26b/0x10f0 kernel/workqueue.c:2301
       queue_work_on+0x15f/0x1f0 kernel/workqueue.c:2392
       queue_work include/linux/workqueue.h:662 [inline]
       rpm_suspend+0xeba/0x11d0 drivers/base/power/runtime.c:673
       rpm_idle+0x5b4/0x730 drivers/base/power/runtime.c:547
       __pm_runtime_idle+0xba/0x1a0 drivers/base/power/runtime.c:1112
       pm_runtime_put include/linux/pm_runtime.h:470 [inline]
       __device_attach+0x37e/0x4b0 drivers/base/dd.c:1047
       bus_probe_device+0x17f/0x1c0 drivers/base/bus.c:537
       device_add+0x1148/0x1a70 drivers/base/core.c:3692
       serial_base_port_add+0x357/0x4b0 drivers/tty/serial/serial_base_bus.c:179
       serial_core_port_device_add drivers/tty/serial/serial_core.c:3341 [inline]
       serial_core_register_port+0x13c/0x2570 drivers/tty/serial/serial_core.c:3380
       serial8250_register_8250_port+0x159b/0x23c0 drivers/tty/serial/8250/8250_core.c:822
       serial_pnp_probe+0x431/0x910 drivers/tty/serial/8250/8250_pnp.c:480
       pnp_device_probe+0x2a8/0x4d0 drivers/pnp/driver.c:111
       call_driver_probe drivers/base/dd.c:579 [inline]
       really_probe+0x241/0xa90 drivers/base/dd.c:657
       __driver_probe_device+0x1de/0x440 drivers/base/dd.c:799
       driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:829
       __driver_attach+0x283/0x580 drivers/base/dd.c:1215
       bus_for_each_dev+0x13e/0x1d0 drivers/base/bus.c:370
       bus_add_driver+0x2e9/0x690 drivers/base/bus.c:678
       driver_register+0x15c/0x4b0 drivers/base/driver.c:249
       serial8250_init+0xc9/0x1e0 drivers/tty/serial/8250/8250_platform.c:315
       do_one_initcall+0x123/0x6e0 init/main.c:1273
       do_initcall_level init/main.c:1335 [inline]
       do_initcalls init/main.c:1351 [inline]
       do_basic_setup init/main.c:1370 [inline]
       kernel_init_freeable+0x5c2/0x900 init/main.c:1583
       kernel_init+0x1c/0x2b0 init/main.c:1473
       ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #2 (&dev->power.lock){-...}-{3:3}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
       __pm_runtime_resume+0xa9/0x170 drivers/base/power/runtime.c:1179
       pm_runtime_get include/linux/pm_runtime.h:418 [inline]
       __uart_start+0x1b0/0x4c0 drivers/tty/serial/serial_core.c:149
       uart_write+0x218/0xb30 drivers/tty/serial/serial_core.c:636
       process_output_block drivers/tty/n_tty.c:561 [inline]
       n_tty_write+0x412/0x1160 drivers/tty/n_tty.c:2377
       iterate_tty_write drivers/tty/tty_io.c:1006 [inline]
       file_tty_write.constprop.0+0x504/0x9b0 drivers/tty/tty_io.c:1081
       tty_write drivers/tty/tty_io.c:1102 [inline]
       redirected_tty_write drivers/tty/tty_io.c:1125 [inline]
       redirected_tty_write+0xd4/0x150 drivers/tty/tty_io.c:1105
       new_sync_write fs/read_write.c:593 [inline]
       vfs_write+0x6c7/0x1150 fs/read_write.c:686
       ksys_write+0x12a/0x250 fs/read_write.c:738
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&port_lock_key){-...}-{3:3}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
       uart_port_lock_irqsave include/linux/serial_core.h:717 [inline]
       serial8250_console_write+0x181/0x1890 drivers/tty/serial/8250/8250_port.c:3415
       console_emit_next_record kernel/printk/printk.c:3138 [inline]
       console_flush_all+0x801/0xc60 kernel/printk/printk.c:3226
       __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
       console_unlock+0xd8/0x210 kernel/printk/printk.c:3325
       vprintk_emit+0x418/0x6d0 kernel/printk/printk.c:2450
       _printk+0xc7/0x100 kernel/printk/printk.c:2475
       register_console+0xc2d/0x11b0 kernel/printk/printk.c:4125
       univ8250_console_init+0x5f/0x90 drivers/tty/serial/8250/8250_core.c:513
       console_init+0x14f/0x680 kernel/printk/printk.c:4323
       start_kernel+0x29f/0x4d0 init/main.c:1035
       x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:307
       x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:288
       common_startup_64+0x13e/0x148

-> #0 (console_owner){....}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3168 [inline]
       check_prevs_add kernel/locking/lockdep.c:3287 [inline]
       validate_chain kernel/locking/lockdep.c:3911 [inline]
       __lock_acquire+0x126f/0x1c90 kernel/locking/lockdep.c:5240
       lock_acquire kernel/locking/lockdep.c:5871 [inline]
       lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5828
       console_lock_spinning_enable+0xb0/0xd0 kernel/printk/printk.c:1924
       console_emit_next_record kernel/printk/printk.c:3132 [inline]
       console_flush_all+0x7aa/0xc60 kernel/printk/printk.c:3226
       __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
       console_unlock+0xd8/0x210 kernel/printk/printk.c:3325
       vprintk_emit+0x418/0x6d0 kernel/printk/printk.c:2450
       _printk+0xc7/0x100 kernel/printk/printk.c:2475
       debug_object_is_on_stack lib/debugobjects.c:649 [inline]
       lookup_object_or_alloc.part.0+0x3d7/0x590 lib/debugobjects.c:688
       lookup_object_or_alloc lib/debugobjects.c:665 [inline]
       __debug_object_init+0x2a9/0x3d0 lib/debugobjects.c:743
       __init_work+0x4c/0x60 kernel/workqueue.c:677
       rhashtable_init_noprof+0x49f/0x7e0 lib/rhashtable.c:1085
       bch2_copygc_thread+0xf6/0xdd0 fs/bcachefs/movinggc.c:353
       kthread+0x3c5/0x780 kernel/kthread.c:464
       ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

other info that might help us debug this:

Chain exists of:
  console_owner --> &pool->lock --> &obj_hash[i].lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&obj_hash[i].lock);
                               lock(&pool->lock);
                               lock(&obj_hash[i].lock);
  lock(console_owner);

 *** DEADLOCK ***

3 locks held by bch-copygc/loop/5851:
 #0: ffffffff9af9fc28 (&obj_hash[i].lock){-.-.}-{2:2}, at: __debug_object_init+0xec/0x3d0 lib/debugobjects.c:741
 #1: ffffffff8e5b2200 (console_lock){+.+.}-{0:0}, at: _printk+0xc7/0x100 kernel/printk/printk.c:2475
 #2: ffffffff8e5b2270 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:336 [inline]
 #2: ffffffff8e5b2270 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:346 [inline]
 #2: ffffffff8e5b2270 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:288 [inline]
 #2: ffffffff8e5b2270 (console_srcu){....}-{0:0}, at: console_flush_all+0x158/0xc60 kernel/printk/printk.c:3203

stack backtrace:
CPU: 1 UID: 0 PID: 5851 Comm: bch-copygc/loop Not tainted 6.16.0-rc1-syzkaller-00004-gaef17cb3d3c4 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2046
 check_noncircular+0x14c/0x170 kernel/locking/lockdep.c:2178
 check_prev_add kernel/locking/lockdep.c:3168 [inline]
 check_prevs_add kernel/locking/lockdep.c:3287 [inline]
 validate_chain kernel/locking/lockdep.c:3911 [inline]
 __lock_acquire+0x126f/0x1c90 kernel/locking/lockdep.c:5240
 lock_acquire kernel/locking/lockdep.c:5871 [inline]
 lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5828
 console_lock_spinning_enable+0xb0/0xd0 kernel/printk/printk.c:1924
 console_emit_next_record kernel/printk/printk.c:3132 [inline]
 console_flush_all+0x7aa/0xc60 kernel/printk/printk.c:3226
 __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
 console_unlock+0xd8/0x210 kernel/printk/printk.c:3325
 vprintk_emit+0x418/0x6d0 kernel/printk/printk.c:2450
 _printk+0xc7/0x100 kernel/printk/printk.c:2475
 debug_object_is_on_stack lib/debugobjects.c:649 [inline]
 lookup_object_or_alloc.part.0+0x3d7/0x590 lib/debugobjects.c:688
 lookup_object_or_alloc lib/debugobjects.c:665 [inline]
 __debug_object_init+0x2a9/0x3d0 lib/debugobjects.c:743
 __init_work+0x4c/0x60 kernel/workqueue.c:677
 rhashtable_init_noprof+0x49f/0x7e0 lib/rhashtable.c:1085
 bch2_copygc_thread+0xf6/0xdd0 fs/bcachefs/movinggc.c:353
 kthread+0x3c5/0x780 kernel/kthread.c:464
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
------------[ cut here ]------------
WARNING: CPU: 1 PID: 5851 at lib/debugobjects.c:655 debug_object_is_on_stack lib/debugobjects.c:655 [inline]
WARNING: CPU: 1 PID: 5851 at lib/debugobjects.c:655 lookup_object_or_alloc.part.0+0x2b1/0x590 lib/debugobjects.c:688
Modules linked in:
CPU: 1 UID: 0 PID: 5851 Comm: bch-copygc/loop Not tainted 6.16.0-rc1-syzkaller-00004-gaef17cb3d3c4 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:debug_object_is_on_stack lib/debugobjects.c:655 [inline]
RIP: 0010:lookup_object_or_alloc.part.0+0x2b1/0x590 lib/debugobjects.c:688
Code: 0e 48 8d 7d 20 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 58 02 00 00 48 8b 55 20 4c 89 e6 48 c7 c7 60 67 15 8c e8 a0 ea bb fc 90 <0f> 0b 90 48 83 c4 18 48 89 d8 5b 5d 41 5c 41 5d 41 5e 41 5f e9 d1
RSP: 0018:ffffc90002e777b0 EFLAGS: 00010086
RAX: 0000000000000050 RBX: ffff888030d385e8 RCX: ffffffff819b01d9
RDX: 0000000000000000 RSI: ffffffff819b8066 RDI: 0000000000000005
RBP: ffff888034213c00 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000001 R11: 0000000035383554 R12: ffffc90002e77a98
R13: ffff888034213c00 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88812485b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000562552374450 CR3: 0000000075e5a000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 lookup_object_or_alloc lib/debugobjects.c:665 [inline]
 __debug_object_init+0x2a9/0x3d0 lib/debugobjects.c:743
 __init_work+0x4c/0x60 kernel/workqueue.c:677
 rhashtable_init_noprof+0x49f/0x7e0 lib/rhashtable.c:1085
 bch2_copygc_thread+0xf6/0xdd0 fs/bcachefs/movinggc.c:353
 kthread+0x3c5/0x780 kernel/kthread.c:464
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>