=============================================================================
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.1.1989/12909 is trying to acquire lock:
ffffffff8eaf4160 (console_owner){-.-.}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:2026 [inline]
ffffffff8eaf4160 (console_owner){-.-.}-{0:0}, at: vprintk_emit+0x4c0/0x6b0 kernel/printk/printk.c:2478

but task is already holding lock:
ffff888036d56318 (&n->list_lock){-.-.}-{3:3}, at: spin_lock_irq include/linux/spinlock.h:372 [inline]
ffff888036d56318 (&n->list_lock){-.-.}-{3:3}, at: free_partial mm/slub.c:8009 [inline]
ffff888036d56318 (&n->list_lock){-.-.}-{3:3}, at: __kmem_cache_shutdown+0x10c/0x330 mm/slub.c:8058

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&n->list_lock){-.-.}-{3:3}:
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
       _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:166
       get_partial_node_bulk mm/slub.c:3744 [inline]
       __refill_objects_node+0x120/0xaa0 mm/slub.c:7169
       refill_objects+0x58/0x410 mm/slub.c:7297
       refill_sheaf mm/slub.c:2804 [inline]
       __pcs_replace_empty_main+0x376/0x680 mm/slub.c:4675
       alloc_from_pcs mm/slub.c:4773 [inline]
       slab_alloc_node mm/slub.c:4905 [inline]
       __do_kmalloc_node mm/slub.c:5333 [inline]
       __kmalloc_noprof+0x66d/0x820 mm/slub.c:5359
       _kmalloc_noprof include/linux/slab.h:992 [inline]
       tty_buffer_alloc+0x29f/0x320 drivers/tty/tty_buffer.c:187
       __tty_buffer_request_room+0x129/0x2c0 drivers/tty/tty_buffer.c:280
       __tty_insert_flip_string_flags+0xdb/0x3f0 drivers/tty/tty_buffer.c:316
       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+0x9c/0x230 drivers/tty/tty_buffer.c:565
       pty_write+0xd2/0x100 drivers/tty/pty.c:116
       n_tty_write+0xa9e/0x1160 drivers/tty/n_tty.c:2388
       iterate_tty_write drivers/tty/tty_io.c:1006 [inline]
       file_tty_write.isra.0+0x4d2/0x890 drivers/tty/tty_io.c:1081
       new_sync_write fs/read_write.c:595 [inline]
       vfs_write+0x6ac/0x1050 fs/read_write.c:687
       ksys_write+0x12a/0x250 fs/read_write.c:739
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&port->lock#2){-...}-{3:3}:
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
       _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:166
       class_spinlock_irqsave_constructor include/linux/spinlock.h:619 [inline]
       tty_port_tty_get+0x21/0x100 drivers/tty/tty_port.c:322
       class_tty_port_tty_constructor include/linux/tty_port.h:293 [inline]
       tty_port_default_wakeup+0x15/0x60 drivers/tty/tty_port.c:66
       serial8250_tx_chars+0x68f/0x860 drivers/tty/serial/8250/8250_port.c:1723
       serial8250_handle_irq_locked+0x770/0x9a0 drivers/tty/serial/8250/8250_port.c:1837
       serial8250_handle_irq.part.0+0xb4/0x530 drivers/tty/serial/8250/8250_port.c:1853
       serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1849 [inline]
       serial8250_default_handle_irq+0xc2/0x280 drivers/tty/serial/8250/8250_port.c:1867
       serial8250_interrupt+0xf8/0x1b0 drivers/tty/serial/8250/8250_core.c:86
       __handle_irq_event_percpu+0x232/0x880 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+0x34c/0x950 kernel/irq/chip.c:859
       generic_handle_irq_desc include/linux/irqdesc.h:188 [inline]
       handle_irq arch/x86/kernel/irq.c:209 [inline]
       call_irq_handler arch/x86/kernel/irq.c:265 [inline]
       __common_interrupt+0xd8/0x2f0 arch/x86/kernel/irq.c:280
       common_interrupt+0xb9/0xe0 arch/x86/kernel/irq.c:273
       asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:665
       __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline]
       _raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:198
       spin_unlock_irqrestore include/linux/spinlock.h:408 [inline]
       uart_port_unlock_irqrestore include/linux/serial_core.h:790 [inline]
       uart_port_unlock_deref drivers/tty/serial/serial_core.c:91 [inline]
       uart_port_unlock_deref drivers/tty/serial/serial_core.c:88 [inline]
       uart_write+0x29d/0xb20 drivers/tty/serial/serial_core.c:630
       process_output_block drivers/tty/n_tty.c:557 [inline]
       n_tty_write+0x431/0x1160 drivers/tty/n_tty.c:2366
       iterate_tty_write drivers/tty/tty_io.c:1006 [inline]
       file_tty_write.isra.0+0x4d2/0x890 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+0xd4/0x120 drivers/tty/tty_io.c:1105
       new_sync_write fs/read_write.c:595 [inline]
       vfs_write+0x6ac/0x1050 fs/read_write.c:687
       ksys_write+0x12a/0x250 fs/read_write.c:739
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&port_lock_key){-.-.}-{3:3}:
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
       _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:166
       uart_port_lock_irqsave include/linux/serial_core.h:719 [inline]
       serial8250_console_write+0x177/0x1a50 drivers/tty/serial/8250/8250_port.c:3344
       console_emit_next_record kernel/printk/printk.c:3183 [inline]
       console_flush_one_record+0x790/0xe50 kernel/printk/printk.c:3269
       console_flush_all kernel/printk/printk.c:3343 [inline]
       __console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
       console_unlock+0x103/0x260 kernel/printk/printk.c:3413
       vprintk_emit+0x407/0x6b0 kernel/printk/printk.c:2479
       _printk+0xcf/0x110 kernel/printk/printk.c:2504
       register_console.cold+0xc0/0x248 kernel/printk/printk.c:4208
       univ8250_console_init+0x6f/0x80 drivers/tty/serial/8250/8250_core.c:515
       console_init+0x3d5/0x5b0 kernel/printk/printk.c:4407
       start_kernel+0x314/0x490 init/main.c:1112
       x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x12b/0x130 arch/x86/kernel/head64.c:291
       common_startup_64+0x13e/0x158

-> #0 (console_owner){-.-.}-{0:0}:
       check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
       console_trylock_spinning kernel/printk/printk.c:2026 [inline]
       vprintk_emit+0x4d1/0x6b0 kernel/printk/printk.c:2478
       _printk+0xcf/0x110 kernel/printk/printk.c:2504
       __slab_bug+0x4f/0xb0 mm/slub.c:1144
       slab_bug+0x5d/0x80 mm/slub.c:1155
       list_slab_objects mm/slub.c:7978 [inline]
       free_partial mm/slub.c:8015 [inline]
       __kmem_cache_shutdown.cold+0x39/0x177 mm/slub.c:8058
       kmem_cache_destroy mm/slab_common.c:569 [inline]
       kmem_cache_destroy+0x73/0x190 mm/slab_common.c:527
       virtio_gpu_free_vbufs+0x38/0x80 drivers/gpu/drm/virtio/virtgpu_vq.c:86
       virtio_gpu_release+0x5c/0x1c0 drivers/gpu/drm/virtio/virtgpu_kms.c:312
       drm_dev_release drivers/gpu/drm/drm_drv.c:912 [inline]
       kref_put include/linux/kref.h:65 [inline]
       drm_dev_put.part.0+0xbd/0x140 drivers/gpu/drm/drm_drv.c:948
       drm_dev_put drivers/gpu/drm/drm_drv.c:947 [inline]
       drm_minor_release+0x3e/0x50 drivers/gpu/drm/drm_drv.c:262
       drm_release+0x238/0x360 drivers/gpu/drm/drm_file.c:446
       __fput+0x3ff/0xb50 fs/file_table.c:512
       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:70 [inline]
       exit_to_user_mode_loop+0x1d8/0x6f0 kernel/entry/common.c:101
       __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:230 [inline]
       syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
       do_syscall_64+0x666/0x870 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 ***

3 locks held by syz.1.1989/12909:
 #0: ffffffff8ea7a230 (cpu_hotplug_lock){++++}-{0:0}, at: kmem_cache_destroy mm/slab_common.c:556 [inline]
 #0: ffffffff8ea7a230 (cpu_hotplug_lock){++++}-{0:0}, at: kmem_cache_destroy+0x4b/0x190 mm/slab_common.c:527
 #1: ffffffff8ed88280 (slab_mutex){+.+.}-{4:4}, at: kmem_cache_destroy mm/slab_common.c:557 [inline]
 #1: ffffffff8ed88280 (slab_mutex){+.+.}-{4:4}, at: kmem_cache_destroy+0x59/0x190 mm/slab_common.c:527
 #2: ffff888036d56318 (&n->list_lock){-.-.}-{3:3}, at: spin_lock_irq include/linux/spinlock.h:372 [inline]
 #2: ffff888036d56318 (&n->list_lock){-.-.}-{3:3}, at: free_partial mm/slub.c:8009 [inline]
 #2: ffff888036d56318 (&n->list_lock){-.-.}-{3:3}, at: __kmem_cache_shutdown+0x10c/0x330 mm/slub.c:8058

stack backtrace:
CPU: 3 UID: 0 PID: 12909 Comm: syz.1.1989 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043
 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2175
 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
 console_trylock_spinning kernel/printk/printk.c:2026 [inline]
 vprintk_emit+0x4d1/0x6b0 kernel/printk/printk.c:2478
 _printk+0xcf/0x110 kernel/printk/printk.c:2504
 __slab_bug+0x4f/0xb0 mm/slub.c:1144
 slab_bug+0x5d/0x80 mm/slub.c:1155
 list_slab_objects mm/slub.c:7978 [inline]
 free_partial mm/slub.c:8015 [inline]
 __kmem_cache_shutdown.cold+0x39/0x177 mm/slub.c:8058
 kmem_cache_destroy mm/slab_common.c:569 [inline]
 kmem_cache_destroy+0x73/0x190 mm/slab_common.c:527
 virtio_gpu_free_vbufs+0x38/0x80 drivers/gpu/drm/virtio/virtgpu_vq.c:86
 virtio_gpu_release+0x5c/0x1c0 drivers/gpu/drm/virtio/virtgpu_kms.c:312
 drm_dev_release drivers/gpu/drm/drm_drv.c:912 [inline]
 kref_put include/linux/kref.h:65 [inline]
 drm_dev_put.part.0+0xbd/0x140 drivers/gpu/drm/drm_drv.c:948
 drm_dev_put drivers/gpu/drm/drm_drv.c:947 [inline]
 drm_minor_release+0x3e/0x50 drivers/gpu/drm/drm_drv.c:262
 drm_release+0x238/0x360 drivers/gpu/drm/drm_file.c:446
 __fput+0x3ff/0xb50 fs/file_table.c:512
 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:70 [inline]
 exit_to_user_mode_loop+0x1d8/0x6f0 kernel/entry/common.c:101
 __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:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x666/0x870 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f11d5b9e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe44a381d8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f11d5e27da0 RCX: 00007f11d5b9e0d9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f11d5e27da0 R08: 0000000000000006 R09: 0000000000000000
R10: 00007f11d5e27cb0 R11: 0000000000000246 R12: 0000000000037fc9
R13: 00007f11d5e25fac R14: 0000000000037cc2 R15: 00007ffe44a382e0
 </TASK>
BUG virtio-gpu-vbufs (Tainted: G             L     ): Objects remaining on __kmem_cache_shutdown()
-----------------------------------------------------------------------------

Object 0xffff888034d2d3b0 @offset=5040
Object 0xffff888034d2d4c8 @offset=5320
Object 0xffff888034d2d5e0 @offset=5600
Object 0xffff888034d2d6f8 @offset=5880
Object 0xffff888034d2d810 @offset=6160
Object 0xffff888034d2d928 @offset=6440
Object 0xffff888034d2da40 @offset=6720
Slab 0xffffea0000d34b00 objects=29 used=7 fp=0xffff888034d2c000 flags=0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
------------[ cut here ]------------
1
WARNING: mm/slub.c:1244 at __slab_err+0x15/0x20 mm/slub.c:1244, CPU#3: syz.1.1989/12909
Modules linked in:
CPU: 3 UID: 0 PID: 12909 Comm: syz.1.1989 Tainted: G    B        L      syzkaller #0 PREEMPT(full) 
Tainted: [B]=BAD_PAGE, [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:__slab_err+0x15/0x20 mm/slub.c:1244
Code: 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 e8 5b fd ff ff be 01 00 00 00 bf 05 00 00 00 e8 dc ba a2 00 90 <0f> 0b 90 c3 cc cc cc cc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90003b27c30 EFLAGS: 00010093
RAX: 0000000000000000 RBX: ffffc90003b27c80 RCX: ffffffff81c709af
RDX: ffff888029830000 RSI: ffffffff81c709bd RDI: ffff888029830000
RBP: ffff888036d56318 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000001ea0
R13: ffff888034d2dfb8 R14: ffff888036d56300 R15: ffffea0000d34b00
FS:  0000555591aee500(0000) GS:ffff8880d60d8000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1f84d556c8 CR3: 00000000357a2000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 list_slab_objects mm/slub.c:7994 [inline]
 free_partial mm/slub.c:8015 [inline]
 __kmem_cache_shutdown.cold+0x16e/0x177 mm/slub.c:8058
 kmem_cache_destroy mm/slab_common.c:569 [inline]
 kmem_cache_destroy+0x73/0x190 mm/slab_common.c:527
 virtio_gpu_free_vbufs+0x38/0x80 drivers/gpu/drm/virtio/virtgpu_vq.c:86
 virtio_gpu_release+0x5c/0x1c0 drivers/gpu/drm/virtio/virtgpu_kms.c:312
 drm_dev_release drivers/gpu/drm/drm_drv.c:912 [inline]
 kref_put include/linux/kref.h:65 [inline]
 drm_dev_put.part.0+0xbd/0x140 drivers/gpu/drm/drm_drv.c:948
 drm_dev_put drivers/gpu/drm/drm_drv.c:947 [inline]
 drm_minor_release+0x3e/0x50 drivers/gpu/drm/drm_drv.c:262
 drm_release+0x238/0x360 drivers/gpu/drm/drm_file.c:446
 __fput+0x3ff/0xb50 fs/file_table.c:512
 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:70 [inline]
 exit_to_user_mode_loop+0x1d8/0x6f0 kernel/entry/common.c:101
 __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:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x666/0x870 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f11d5b9e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe44a381d8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f11d5e27da0 RCX: 00007f11d5b9e0d9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f11d5e27da0 R08: 0000000000000006 R09: 0000000000000000
R10: 00007f11d5e27cb0 R11: 0000000000000246 R12: 0000000000037fc9
R13: 00007f11d5e25fac R14: 0000000000037cc2 R15: 00007ffe44a382e0
 </TASK>