======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
cpuhp/1/18 is trying to acquire lock:
ffff88802a8d3008 (kn->active#32){++++}-{0:0}, at: kernfs_remove_by_name_ns+0x91/0x100 fs/kernfs/dir.c:1566

but task is already holding lock:
ffffffff8c1bd860 (cpuhp_state-down){+.+.}-{0:0}, at: cpuhp_lock_acquire+0x8/0x40 kernel/cpu.c:99

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (cpuhp_state-down){+.+.}-{0:0}:
       cpuhp_lock_acquire+0x3a/0x40 kernel/cpu.c:100
       cpuhp_kick_ap_work+0x7f/0x1b0 kernel/cpu.c:901
       _cpu_down+0x35b/0xbb0 kernel/cpu.c:1170
       cpu_down_maps_locked kernel/cpu.c:1217 [inline]
       cpu_down kernel/cpu.c:1225 [inline]
       cpu_device_down+0x69/0xa0 kernel/cpu.c:1242
       device_offline+0x259/0x3a0 drivers/base/core.c:3948
       acpi_bus_offline+0x23e/0x400 drivers/acpi/scan.c:163
       acpi_scan_try_to_offline drivers/acpi/scan.c:226 [inline]
       acpi_scan_hot_remove drivers/acpi/scan.c:258 [inline]
       acpi_generic_hotplug_event drivers/acpi/scan.c:374 [inline]
       acpi_device_hotplug+0x56c/0xc60 drivers/acpi/scan.c:398
       acpi_hotplug_work_fn+0x8f/0xc0 drivers/acpi/osl.c:1160
       process_one_work+0x867/0xff0 kernel/workqueue.c:2310
       worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
       kthread+0x42e/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #3 (cpu_hotplug_lock){++++}-{0:0}:
       percpu_down_write+0x52/0x2f0 kernel/locking/percpu-rwsem.c:217
       cpus_write_lock kernel/cpu.c:327 [inline]
       _cpu_up+0x77/0x810 kernel/cpu.c:1354
       cpu_up+0x16d/0x1a0 kernel/cpu.c:1436
       bringup_nonboot_cpus+0x100/0x1a0 kernel/cpu.c:1502
       smp_init+0x3a/0x150 kernel/smp.c:1091
       kernel_init_freeable+0x3bc/0x560 init/main.c:1581
       kernel_init+0x19/0x1b0 init/main.c:1480
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #2 (cpu_add_remove_lock){+.+.}-{3:3}:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       cpu_maps_update_begin kernel/cpu.c:289 [inline]
       cpu_down kernel/cpu.c:1224 [inline]
       cpu_device_down+0x3a/0xa0 kernel/cpu.c:1242
       device_offline+0x259/0x3a0 drivers/base/core.c:3948
       acpi_bus_offline+0x23e/0x400 drivers/acpi/scan.c:163
       acpi_scan_try_to_offline drivers/acpi/scan.c:226 [inline]
       acpi_scan_hot_remove drivers/acpi/scan.c:258 [inline]
       acpi_generic_hotplug_event drivers/acpi/scan.c:374 [inline]
       acpi_device_hotplug+0x56c/0xc60 drivers/acpi/scan.c:398
       acpi_hotplug_work_fn+0x8f/0xc0 drivers/acpi/osl.c:1160
       process_one_work+0x867/0xff0 kernel/workqueue.c:2310
       worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
       kthread+0x42e/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #1 (&device->physical_node_lock){+.+.}-{3:3}:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       acpi_get_first_physical_node drivers/acpi/bus.c:644 [inline]
       acpi_primary_dev_companion drivers/acpi/bus.c:663 [inline]
       acpi_companion_match+0x86/0x110 drivers/acpi/bus.c:717
       acpi_device_uevent_modalias+0x16/0x30 drivers/acpi/device_sysfs.c:283
       platform_uevent+0x38/0xb0 drivers/base/platform.c:1357
       dev_uevent+0x3a5/0x740 drivers/base/core.c:2344
       kobject_uevent_env+0x465/0x890 lib/kobject_uevent.c:572
       kobject_synth_uevent+0x457/0x940 lib/kobject_uevent.c:208
       uevent_store+0x22/0x60 drivers/base/core.c:2428
       kernfs_fop_write_iter+0x3a8/0x500 fs/kernfs/file.c:296
       call_write_iter include/linux/fs.h:2179 [inline]
       new_sync_write fs/read_write.c:507 [inline]
       vfs_write+0x748/0xd70 fs/read_write.c:594
       ksys_write+0x153/0x260 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (kn->active#32){++++}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
       lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5625
       kernfs_drain fs/kernfs/dir.c:478 [inline]
       __kernfs_remove+0x5da/0xcb0 fs/kernfs/dir.c:1372
       kernfs_remove_by_name_ns+0x91/0x100 fs/kernfs/dir.c:1566
       sysfs_remove_file include/linux/sysfs.h:613 [inline]
       device_remove_file drivers/base/core.c:2796 [inline]
       device_del+0x62f/0xa80 drivers/base/core.c:3613
       device_unregister+0x1c/0xc0 drivers/base/core.c:3660
       mce_device_remove arch/x86/kernel/cpu/mce/core.c:2575 [inline]
       mce_cpu_pre_down+0x33f/0x540 arch/x86/kernel/cpu/mce/core.c:2638
       cpuhp_invoke_callback+0x423/0x7e0 kernel/cpu.c:191
       cpuhp_thread_fun+0x3b2/0x7f0 kernel/cpu.c:822
       smpboot_thread_fn+0x520/0x990 kernel/smpboot.c:164
       kthread+0x42e/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

other info that might help us debug this:

Chain exists of:
  kn->active#32 --> cpu_hotplug_lock --> cpuhp_state-down

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(cpuhp_state-down);
                               lock(cpu_hotplug_lock);
                               lock(cpuhp_state-down);
  lock(kn->active#32);

 *** DEADLOCK ***

2 locks held by cpuhp/1/18:
 #0: ffffffff8c1bd6f0 (cpu_hotplug_lock){++++}-{0:0}, at: lockdep_acquire_cpus_lock+0x5/0x30 kernel/cpu.c:357
 #1: ffffffff8c1bd860 (cpuhp_state-down){+.+.}-{0:0}, at: cpuhp_lock_acquire+0x8/0x40 kernel/cpu.c:99

stack backtrace:
CPU: 1 PID: 18 Comm: cpuhp/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5625
 kernfs_drain fs/kernfs/dir.c:478 [inline]
 __kernfs_remove+0x5da/0xcb0 fs/kernfs/dir.c:1372
 kernfs_remove_by_name_ns+0x91/0x100 fs/kernfs/dir.c:1566
 sysfs_remove_file include/linux/sysfs.h:613 [inline]
 device_remove_file drivers/base/core.c:2796 [inline]
 device_del+0x62f/0xa80 drivers/base/core.c:3613
 device_unregister+0x1c/0xc0 drivers/base/core.c:3660
 mce_device_remove arch/x86/kernel/cpu/mce/core.c:2575 [inline]
 mce_cpu_pre_down+0x33f/0x540 arch/x86/kernel/cpu/mce/core.c:2638
 cpuhp_invoke_callback+0x423/0x7e0 kernel/cpu.c:191
 cpuhp_thread_fun+0x3b2/0x7f0 kernel/cpu.c:822
 smpboot_thread_fn+0x520/0x990 kernel/smpboot.c:164
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>