=============================================================================
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.2.827/9062 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:
ffff888027533618 (&n->list_lock){-.-.}-{3:3}, at: spin_lock_irq include/linux/spinlock.h:372 [inline]
ffff888027533618 (&n->list_lock){-.-.}-{3:3}, at: free_partial mm/slub.c:8009 [inline]
ffff888027533618 (&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
       native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
       pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63
       arch_safe_halt arch/x86/include/asm/paravirt.h:62 [inline]
       default_idle+0x9/0x10 arch/x86/kernel/process.c:768
       default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122
       cpuidle_idle_call kernel/sched/idle.c:199 [inline]
       do_idle+0x3a7/0x5b0 kernel/sched/idle.c:355
       cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:454
       rest_init+0x251/0x260 init/main.c:717
       start_kernel+0x48e/0x490 init/main.c:1175
       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

-> #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+0x1f/0x30 drivers/gpu/drm/drm_drv.c:947
       virtio_dev_remove+0xb8/0x170 drivers/virtio/virtio.c:375
       device_remove+0xcb/0x180 drivers/base/dd.c:616
       __device_release_driver drivers/base/dd.c:1349 [inline]
       device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372
       bus_remove_device+0x2bc/0x560 drivers/base/bus.c:664
       device_del+0x376/0x9b0 drivers/base/core.c:3961
       device_unregister+0x1d/0xe0 drivers/base/core.c:4002
       unregister_virtio_device+0x39/0x60 drivers/virtio/virtio.c:594
       virtio_pci_remove+0x7c/0x110 drivers/virtio/virtio_pci_common.c:758
       pci_device_remove+0xb2/0x1d0 drivers/pci/pci-driver.c:512
       device_remove+0xcb/0x180 drivers/base/dd.c:616
       __device_release_driver drivers/base/dd.c:1349 [inline]
       device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372
       unbind_store+0xf8/0x110 drivers/base/bus.c:244
       drv_attr_store+0x74/0xb0 drivers/base/bus.c:125
       sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145
       kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345
       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

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 ***

8 locks held by syz.2.827/9062:
 #0: ffff88802b8900f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259
 #1: ffff88802c2e0450 (sb_writers#8){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
 #2: ffff8880574eac80 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:336
 #3: ffff88801d3161f8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #3: ffff88801d3161f8 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1171 [inline]
 #3: ffff88801d3161f8 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb2/0x620 drivers/base/dd.c:1369
 #4: ffff888022d0e1b0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline]
 #4: ffff888022d0e1b0 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1171 [inline]
 #4: ffff888022d0e1b0 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb2/0x620 drivers/base/dd.c:1369
 #5: ffffffff8ea7a230 (cpu_hotplug_lock){++++}-{0:0}, at: kmem_cache_destroy mm/slab_common.c:556 [inline]
 #5: ffffffff8ea7a230 (cpu_hotplug_lock){++++}-{0:0}, at: kmem_cache_destroy+0x4b/0x190 mm/slab_common.c:527
 #6: ffffffff8ed88280 (slab_mutex){+.+.}-{4:4}, at: kmem_cache_destroy mm/slab_common.c:557 [inline]
 #6: ffffffff8ed88280 (slab_mutex){+.+.}-{4:4}, at: kmem_cache_destroy+0x59/0x190 mm/slab_common.c:527
 #7: ffff888027533618 (&n->list_lock){-.-.}-{3:3}, at: spin_lock_irq include/linux/spinlock.h:372 [inline]
 #7: ffff888027533618 (&n->list_lock){-.-.}-{3:3}, at: free_partial mm/slub.c:8009 [inline]
 #7: ffff888027533618 (&n->list_lock){-.-.}-{3:3}, at: __kmem_cache_shutdown+0x10c/0x330 mm/slub.c:8058

stack backtrace:
CPU: 2 UID: 0 PID: 9062 Comm: syz.2.827 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+0x1f/0x30 drivers/gpu/drm/drm_drv.c:947
 virtio_dev_remove+0xb8/0x170 drivers/virtio/virtio.c:375
 device_remove+0xcb/0x180 drivers/base/dd.c:616
 __device_release_driver drivers/base/dd.c:1349 [inline]
 device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372
 bus_remove_device+0x2bc/0x560 drivers/base/bus.c:664
 device_del+0x376/0x9b0 drivers/base/core.c:3961
 device_unregister+0x1d/0xe0 drivers/base/core.c:4002
 unregister_virtio_device+0x39/0x60 drivers/virtio/virtio.c:594
 virtio_pci_remove+0x7c/0x110 drivers/virtio/virtio_pci_common.c:758
 pci_device_remove+0xb2/0x1d0 drivers/pci/pci-driver.c:512
 device_remove+0xcb/0x180 drivers/base/dd.c:616
 __device_release_driver drivers/base/dd.c:1349 [inline]
 device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372
 unbind_store+0xf8/0x110 drivers/base/bus.c:244
 drv_attr_store+0x74/0xb0 drivers/base/bus.c:125
 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345
 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
RIP: 0033:0x7fd06dd9e019
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:00007fd06ebe3028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fd06e026090 RCX: 00007fd06dd9e019
RDX: 000000000000000c RSI: 00002000000001c0 RDI: 0000000000000006
RBP: 00007fd06de3500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd06e026128 R14: 00007fd06e026090 R15: 00007ffd15fb5f98
 </TASK>
BUG virtio-gpu-vbufs (Tainted: G             L     ): Objects remaining on __kmem_cache_shutdown()
-----------------------------------------------------------------------------

Object 0xffff88803d4cd928 @offset=6440
Object 0xffff88803d4cda40 @offset=6720
Object 0xffff88803d4cdb58 @offset=7000
Object 0xffff88803d4cdc70 @offset=7280
Slab 0xffffea0000f53300 objects=29 used=4 fp=0xffff88803d4cc000 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#2: syz.2.827/9062
Modules linked in:
CPU: 2 UID: 0 PID: 9062 Comm: syz.2.827 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:ffffc90003847800 EFLAGS: 00010093

RAX: 0000000000000000 RBX: ffffc90003847850 RCX: ffffffff81c709af
RDX: ffff888025b28000 RSI: ffffffff81c709bd RDI: ffff888025b28000
RBP: ffff888027533618 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 3038383866666666 R12: 0000000000001ea0
R13: ffff88803d4cdfb8 R14: ffff888027533600 R15: ffffea0000f53300
FS:  00007fd06ebe36c0(0000) GS:ffff8880d5fd8000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc4fcbd0840 CR3: 000000003e040000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000001800
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
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+0x1f/0x30 drivers/gpu/drm/drm_drv.c:947
 virtio_dev_remove+0xb8/0x170 drivers/virtio/virtio.c:375
 device_remove+0xcb/0x180 drivers/base/dd.c:616
 __device_release_driver drivers/base/dd.c:1349 [inline]
 device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372
 bus_remove_device+0x2bc/0x560 drivers/base/bus.c:664
 device_del+0x376/0x9b0 drivers/base/core.c:3961
 device_unregister+0x1d/0xe0 drivers/base/core.c:4002
 unregister_virtio_device+0x39/0x60 drivers/virtio/virtio.c:594
 virtio_pci_remove+0x7c/0x110 drivers/virtio/virtio_pci_common.c:758
 pci_device_remove+0xb2/0x1d0 drivers/pci/pci-driver.c:512
 device_remove+0xcb/0x180 drivers/base/dd.c:616
 __device_release_driver drivers/base/dd.c:1349 [inline]
 device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372
 unbind_store+0xf8/0x110 drivers/base/bus.c:244
 drv_attr_store+0x74/0xb0 drivers/base/bus.c:125
 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345
 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
RIP: 0033:0x7fd06dd9e019
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:00007fd06ebe3028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fd06e026090 RCX: 00007fd06dd9e019
RDX: 000000000000000c RSI: 00002000000001c0 RDI: 0000000000000006
RBP: 00007fd06de3500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd06e026128 R14: 00007fd06e026090 R15: 00007ffd15fb5f98
 </TASK>