=============================================================================
======================================================
WARNING: possible circular locking dependency detected
6.16.0-rc4-next-20250702-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor/5829 is trying to acquire lock:
ffffffff8e130220 (console_owner){-.-.}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:2048 [inline]
ffffffff8e130220 (console_owner){-.-.}-{0:0}, at: vprintk_emit+0x444/0x7a0 kernel/printk/printk.c:2449

but task is already holding lock:
ffff888031e7ca98 (&n->list_lock){-.-.}-{3:3}, at: spin_lock_irq include/linux/spinlock.h:376 [inline]
ffff888031e7ca98 (&n->list_lock){-.-.}-{3:3}, at: free_partial mm/slub.c:5897 [inline]
ffff888031e7ca98 (&n->list_lock){-.-.}-{3:3}, at: __kmem_cache_shutdown+0xa9/0x250 mm/slub.c:5934

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&n->list_lock){-.-.}-{3:3}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
       get_partial_node+0x37/0x390 mm/slub.c:2899
       get_partial mm/slub.c:3013 [inline]
       ___slab_alloc+0xb3f/0x1410 mm/slub.c:3871
       __slab_alloc mm/slub.c:3981 [inline]
       __slab_alloc_node mm/slub.c:4056 [inline]
       slab_alloc_node mm/slub.c:4217 [inline]
       __do_kmalloc_node mm/slub.c:4364 [inline]
       __kmalloc_noprof+0x305/0x4f0 mm/slub.c:4377
       kmalloc_noprof include/linux/slab.h:909 [inline]
       tty_buffer_alloc drivers/tty/tty_buffer.c:180 [inline]
       __tty_buffer_request_room+0x1c8/0x520 drivers/tty/tty_buffer.c:273
       __tty_insert_flip_string_flags+0xb8/0x430 drivers/tty/tty_buffer.c:309
       tty_insert_flip_string_fixed_flag include/linux/tty_flip.h:35 [inline]
       tty_insert_flip_string include/linux/tty_flip.h:83 [inline]
       tty_insert_flip_string_and_push_buffer+0xa3/0x1f0 drivers/tty/tty_buffer.c:559
       pty_write+0xa7/0xe0 drivers/tty/pty.c:118
       tty_put_char+0x111/0x160 drivers/tty/tty_io.c:3154
       __process_echoes+0x193/0xa20 drivers/tty/n_tty.c:708
       flush_echoes drivers/tty/n_tty.c:791 [inline]
       __receive_buf drivers/tty/n_tty.c:1626 [inline]
       n_tty_receive_buf_common+0xc29/0x12f0 drivers/tty/n_tty.c:1723
       tty_port_default_receive_buf+0x6e/0xa0 drivers/tty/tty_port.c:37
       receive_buf drivers/tty/tty_buffer.c:445 [inline]
       flush_to_ldisc+0x24a/0x720 drivers/tty/tty_buffer.c:495
       process_one_work kernel/workqueue.c:3239 [inline]
       process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3322
       worker_thread+0x8a0/0xda0 kernel/workqueue.c:3403
       kthread+0x70e/0x8a0 kernel/kthread.c:463
       ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #2 (&port->lock#2){-.-.}-{3:3}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
       tty_port_tty_get drivers/tty/tty_port.c:307 [inline]
       tty_port_default_wakeup+0x21/0xf0 drivers/tty/tty_port.c:66
       serial8250_tx_chars+0x72e/0x970 drivers/tty/serial/8250/8250_port.c:1728
       serial8250_handle_irq+0x633/0xbb0 drivers/tty/serial/8250/8250_port.c:1836
       serial8250_default_handle_irq+0xbf/0x1e0 drivers/tty/serial/8250/8250_port.c:1856
       serial8250_interrupt+0x8d/0x160 drivers/tty/serial/8250/8250_core.c:82
       __handle_irq_event_percpu+0x28c/0x980 kernel/irq/handle.c:158
       handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
       handle_irq_event+0x8b/0x1e0 kernel/irq/handle.c:210
       handle_edge_irq+0x267/0x9c0 kernel/irq/chip.c:797
       generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
       handle_irq arch/x86/kernel/irq.c:254 [inline]
       call_irq_handler arch/x86/kernel/irq.c:266 [inline]
       __common_interrupt+0x140/0x250 arch/x86/kernel/irq.c:292
       common_interrupt+0xb6/0xe0 arch/x86/kernel/irq.c:285
       asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
       __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
       _raw_spin_unlock_irqrestore+0xa8/0x110 kernel/locking/spinlock.c:194
       spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
       uart_port_unlock_irqrestore include/linux/serial_core.h:788 [inline]
       uart_port_unlock_deref+0x111/0x2f0 drivers/tty/serial/serial_core.c:91
       uart_write+0xe8/0x130 drivers/tty/serial/serial_core.c:637
       process_output_block drivers/tty/n_tty.c:561 [inline]
       n_tty_write+0xd35/0x11d0 drivers/tty/n_tty.c:2377
       iterate_tty_write drivers/tty/tty_io.c:1006 [inline]
       file_tty_write+0x500/0x990 drivers/tty/tty_io.c:1081
       new_sync_write fs/read_write.c:593 [inline]
       vfs_write+0x54b/0xa90 fs/read_write.c:686
       ksys_write+0x145/0x250 fs/read_write.c:738
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&port_lock_key){-.-.}-{3:3}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
       uart_port_lock_irqsave include/linux/serial_core.h:717 [inline]
       serial8250_console_write+0x17e/0x1ba0 drivers/tty/serial/8250/8250_port.c:3355
       console_emit_next_record kernel/printk/printk.c:3138 [inline]
       console_flush_all+0x728/0xc40 kernel/printk/printk.c:3226
       __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
       console_unlock+0xc4/0x270 kernel/printk/printk.c:3325
       vprintk_emit+0x5b7/0x7a0 kernel/printk/printk.c:2450
       _printk+0xcf/0x120 kernel/printk/printk.c:2475
       register_console+0xa8b/0xf90 kernel/printk/printk.c:4126
       univ8250_console_init+0x52/0x90 drivers/tty/serial/8250/8250_core.c:516
       console_init+0x1a1/0x670 kernel/printk/printk.c:4325
       start_kernel+0x2cc/0x500 init/main.c:1035
       x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:307
       x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:288
       common_startup_64+0x13e/0x147

-> #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+0xb9b/0x2140 kernel/locking/lockdep.c:3911
       __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
       console_trylock_spinning kernel/printk/printk.c:2048 [inline]
       vprintk_emit+0x460/0x7a0 kernel/printk/printk.c:2449
       _printk+0xcf/0x120 kernel/printk/printk.c:2475
       __slab_bug+0x6e/0xd0 mm/slub.c:1065
       slab_bug+0x57/0x80 mm/slub.c:1076
       list_slab_objects+0x35/0x1c0 mm/slub.c:5866
       free_partial mm/slub.c:5903 [inline]
       __kmem_cache_shutdown+0xd4/0x250 mm/slub.c:5934
       kmem_cache_destroy+0x76/0x160 mm/slab_common.c:523
       bio_put_slab block/bio.c:155 [inline]
       bioset_exit+0x583/0x690 block/bio.c:1764
       bch2_fs_io_read_exit+0x67/0x80 fs/bcachefs/io_read.c:1513
       __bch2_fs_free fs/bcachefs/super.c:607 [inline]
       bch2_fs_release+0x24c/0x830 fs/bcachefs/super.c:667
       kobject_cleanup lib/kobject.c:689 [inline]
       kobject_release lib/kobject.c:720 [inline]
       kref_put include/linux/kref.h:65 [inline]
       kobject_put+0x22b/0x480 lib/kobject.c:737
       deactivate_locked_super+0xb9/0x130 fs/super.c:474
       cleanup_mnt+0x425/0x4c0 fs/namespace.c:1417
       task_work_run+0x1d1/0x260 kernel/task_work.c:227
       resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
       exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:43
       exit_to_user_mode_prepare include/linux/irq-entry-common.h:208 [inline]
       syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
       syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
       do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  console_owner --> &port->lock#2 --> &n->list_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&n->list_lock);
                               lock(&port->lock#2);
                               lock(&n->list_lock);
  lock(console_owner);

 *** DEADLOCK ***

4 locks held by syz-executor/5829:
 #0: ffffffff8e890948 (bio_slab_lock){+.+.}-{4:4}, at: bio_put_slab block/bio.c:140 [inline]
 #0: ffffffff8e890948 (bio_slab_lock){+.+.}-{4:4}, at: bioset_exit+0x44a/0x690 block/bio.c:1764
 #1: ffffffff8dfd41f0 (cpu_hotplug_lock){++++}-{0:0}, at: kmem_cache_destroy+0x3e/0x160 mm/slab_common.c:510
 #2: ffffffff8e22bc30 (slab_mutex){+.+.}-{4:4}, at: kmem_cache_destroy+0x4c/0x160 mm/slab_common.c:511
 #3: ffff888031e7ca98 (&n->list_lock){-.-.}-{3:3}, at: spin_lock_irq include/linux/spinlock.h:376 [inline]
 #3: ffff888031e7ca98 (&n->list_lock){-.-.}-{3:3}, at: free_partial mm/slub.c:5897 [inline]
 #3: ffff888031e7ca98 (&n->list_lock){-.-.}-{3:3}, at: __kmem_cache_shutdown+0xa9/0x250 mm/slub.c:5934

stack backtrace:
CPU: 1 UID: 0 PID: 5829 Comm: syz-executor Not tainted 6.16.0-rc4-next-20250702-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2046
 check_noncircular+0x134/0x160 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+0xb9b/0x2140 kernel/locking/lockdep.c:3911
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
 console_trylock_spinning kernel/printk/printk.c:2048 [inline]
 vprintk_emit+0x460/0x7a0 kernel/printk/printk.c:2449
 _printk+0xcf/0x120 kernel/printk/printk.c:2475
 __slab_bug+0x6e/0xd0 mm/slub.c:1065
 slab_bug+0x57/0x80 mm/slub.c:1076
 list_slab_objects+0x35/0x1c0 mm/slub.c:5866
 free_partial mm/slub.c:5903 [inline]
 __kmem_cache_shutdown+0xd4/0x250 mm/slub.c:5934
 kmem_cache_destroy+0x76/0x160 mm/slab_common.c:523
 bio_put_slab block/bio.c:155 [inline]
 bioset_exit+0x583/0x690 block/bio.c:1764
 bch2_fs_io_read_exit+0x67/0x80 fs/bcachefs/io_read.c:1513
 __bch2_fs_free fs/bcachefs/super.c:607 [inline]
 bch2_fs_release+0x24c/0x830 fs/bcachefs/super.c:667
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x22b/0x480 lib/kobject.c:737
 deactivate_locked_super+0xb9/0x130 fs/super.c:474
 cleanup_mnt+0x425/0x4c0 fs/namespace.c:1417
 task_work_run+0x1d1/0x260 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:208 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd1da98fc57
Code: a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 44 00 00 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 a8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007fffad2fdc88 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007fd1daa10925 RCX: 00007fd1da98fc57
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fffad2fdd40
RBP: 00007fffad2fdd40 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007fffad2fedd0
R13: 00007fd1daa10925 R14: 00000000000519af R15: 00007fffad2fee10
 </TASK>
BUG bio-488 (Not tainted): Objects remaining on __kmem_cache_shutdown()
-----------------------------------------------------------------------------

Object 0xffff888079362000 @offset=0
Object 0xffff888079362280 @offset=640
Slab 0xffffea0001e4d880 objects=12 used=2 fp=0xffff888079362500 flags=0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
------------[ cut here ]------------
WARNING: mm/slub.c:1171 at __slab_err+0x15/0x20 mm/slub.c:1171, CPU#1: syz-executor/5829
Modules linked in:
CPU: 1 UID: 0 PID: 5829 Comm: syz-executor Tainted: G    B               6.16.0-rc4-next-20250702-syzkaller #0 PREEMPT(full) 
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:__slab_err+0x15/0x20 mm/slub.c:1171
Code: 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 e8 bb ff ff ff bf 05 00 00 00 be 01 00 00 00 e8 0c 6c 5b 00 90 <0f> 0b 90 e9 03 38 4a 0a cc 66 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000404fba8 EFLAGS: 00010093
RAX: ffffffff81836dfa RBX: ffff8880610763c0 RCX: ffff888026ac9e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffff92a69fc7 R09: 1ffffffff254d3f8
R10: dffffc0000000000 R11: fffffbfff254d3f9 R12: ffff888031e7cac8
R13: ffffea0001e4d880 R14: ffffea0001b20a10 R15: ffff888031e7ca80
FS:  000055555575d500(0000) GS:ffff888125d1d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff8d2bb3000 CR3: 0000000078e02000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 free_partial mm/slub.c:5903 [inline]
 __kmem_cache_shutdown+0xd4/0x250 mm/slub.c:5934
 kmem_cache_destroy+0x76/0x160 mm/slab_common.c:523
 bio_put_slab block/bio.c:155 [inline]
 bioset_exit+0x583/0x690 block/bio.c:1764
 bch2_fs_io_read_exit+0x67/0x80 fs/bcachefs/io_read.c:1513
 __bch2_fs_free fs/bcachefs/super.c:607 [inline]
 bch2_fs_release+0x24c/0x830 fs/bcachefs/super.c:667
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x22b/0x480 lib/kobject.c:737
 deactivate_locked_super+0xb9/0x130 fs/super.c:474
 cleanup_mnt+0x425/0x4c0 fs/namespace.c:1417
 task_work_run+0x1d1/0x260 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:208 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd1da98fc57
Code: a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 44 00 00 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 a8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007fffad2fdc88 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007fd1daa10925 RCX: 00007fd1da98fc57
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fffad2fdd40
RBP: 00007fffad2fdd40 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007fffad2fedd0
R13: 00007fd1daa10925 R14: 00000000000519af R15: 00007fffad2fee10
 </TASK>