* [syzbot] [acpi?] possible deadlock in cpu_device_down
@ 2026-10-28 5:57 syzbot
0 siblings, 0 replies; only message in thread
From: syzbot @ 2026-10-28 5:57 UTC (permalink / raw)
To: lenb, linux-acpi, linux-kernel, rafael, syzkaller-bugs
Hello,
syzbot found the following issue on:
HEAD commit: 4da9dedf3fc5 Merge tag 'iommu-updates-v7.4' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13058459580000
kernel config: https://syzkaller.appspot.com/x/.config?x=cd00d0b501e8d973
dashboard link: https://syzkaller.appspot.com/bug?extid=cea7285bc17b76ffe39f
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/86361da34cc2/disk-4da9dedf.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8afe65c41dcc/vmlinux-4da9dedf.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ef091f7d9636/bzImage-4da9dedf.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cea7285bc17b76ffe39f@syzkaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G L
------------------------------------------------------
kworker/u8:4/62 is trying to acquire lock:
ffffffff8fe7a7a0 (cpu_add_remove_lock){+.+.}-{4:4}, at: cpu_maps_update_begin kernel/cpu.c:468 [inline]
ffffffff8fe7a7a0 (cpu_add_remove_lock){+.+.}-{4:4}, at: cpu_down kernel/cpu.c:1490 [inline]
ffffffff8fe7a7a0 (cpu_add_remove_lock){+.+.}-{4:4}, at: cpu_device_down+0x46/0xc0 kernel/cpu.c:1508
but task is already holding lock:
ffff88802528c760 (&device->physical_node_lock){+.+.}-{4:4}, at: acpi_bus_offline+0x156/0x550 drivers/acpi/scan.c:152
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #5 (&device->physical_node_lock){+.+.}-{4:4}:
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x19f/0x1c10 kernel/locking/mutex.c:821
class_mutex_constructor include/linux/mutex.h:253 [inline]
acpi_primary_dev_companion drivers/acpi/bus.c:817 [inline]
acpi_companion_match+0xc0/0x180 drivers/acpi/bus.c:873
acpi_device_uevent_modalias+0x19/0x30 drivers/acpi/device_sysfs.c:280
platform_uevent+0x51/0xc0 drivers/base/platform.c:1474
dev_uevent+0x1de/0x870 drivers/base/core.c:2766
kobject_uevent_env+0x6eb/0x18b0 lib/kobject_uevent.c:576
kobject_synth_uevent+0x679/0x7d0 lib/kobject_uevent.c:207
uevent_store+0x24/0x50 drivers/base/core.c:2847
dev_attr_store+0x58/0x80 drivers/base/core.c:2509
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+0x6af/0x1050 fs/read_write.c:687
ksys_write+0x12a/0x250 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #4 (kn->active#5){++++}-{0:0}:
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
kernfs_drain+0x4eb/0x600 fs/kernfs/dir.c:534
__kernfs_remove+0x34c/0xbc0 fs/kernfs/dir.c:1578
kernfs_remove_by_name_ns+0x7c/0x120 fs/kernfs/dir.c:1796
sysfs_remove_file include/linux/sysfs.h:780 [inline]
device_remove_file drivers/base/core.c:3146 [inline]
device_remove_file drivers/base/core.c:3142 [inline]
device_del+0x361/0x9b0 drivers/base/core.c:3963
device_unregister+0x1d/0xe0 drivers/base/core.c:4006
kref_put include/linux/kref.h:65 [inline]
device_link_put_kref drivers/base/core.c:1022 [inline]
device_link_put_kref+0x156/0x1b0 drivers/base/core.c:1019
device_link_remove+0xbb/0x110 drivers/base/core.c:1065
destroy_regulator+0x417/0x510 drivers/regulator/core.c:2650
_regulator_put+0xf2/0x1b0 drivers/regulator/core.c:2682
regulator_put+0x23/0x30 drivers/regulator/core.c:2699
release_nodes+0xa5/0x120 drivers/base/devres.c:546
devres_release_group+0x1c2/0x2d0 drivers/base/devres.c:739
i2c_device_probe+0x70c/0xd10 drivers/i2c/i2c-core-base.c:612
call_driver_probe drivers/base/dd.c:628 [inline]
really_probe+0x241/0xa60 drivers/base/dd.c:706
__driver_probe_device+0x210/0x460 drivers/base/dd.c:868
driver_probe_device+0x4a/0x140 drivers/base/dd.c:898
__device_attach_driver+0x1df/0x320 drivers/base/dd.c:1026
bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:503
__device_attach+0x1e4/0x4d0 drivers/base/dd.c:1098
device_initial_probe+0xaf/0xd0 drivers/base/dd.c:1153
bus_probe_device+0x64/0x160 drivers/base/bus.c:623
device_add+0x121d/0x1970 drivers/base/core.c:3776
i2c_new_client_device+0x660/0xd30 drivers/i2c/i2c-core-base.c:1020
new_device_store+0x20f/0x420 drivers/i2c/i2c-core-base.c:1308
dev_attr_store+0x58/0x80 drivers/base/core.c:2509
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+0x6af/0x1050 fs/read_write.c:687
ksys_write+0x12a/0x250 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #3 (device_links_lock){+.+.}-{4:4}:
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x19f/0x1c10 kernel/locking/mutex.c:821
device_links_write_lock drivers/base/core.c:322 [inline]
device_links_purge drivers/base/core.c:1704 [inline]
device_del+0x3d7/0x9b0 drivers/base/core.c:3969
device_unregister+0x1d/0xe0 drivers/base/core.c:4006
mce_device_remove arch/x86/kernel/cpu/mce/core.c:2715 [inline]
mce_cpu_pre_down+0x325/0x620 arch/x86/kernel/cpu/mce/core.c:2776
cpuhp_invoke_callback+0x3b4/0x9a0 kernel/cpu.c:194
cpuhp_thread_fun+0x3e9/0x7c0 kernel/cpu.c:1109
smpboot_thread_fn+0x41f/0xb90 kernel/smpboot.c:162
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #2 (cpuhp_state-down){+.+.}-{0:0}:
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
cpuhp_lock_acquire kernel/cpu.c:103 [inline]
cpuhp_kick_ap_work+0xa4/0xbd0 kernel/cpu.c:1188
_cpu_down+0x47d/0x1020 kernel/cpu.c:1436
cpu_down_maps_locked kernel/cpu.c:1483 [inline]
cpu_down kernel/cpu.c:1491 [inline]
cpu_device_down+0x82/0xc0 kernel/cpu.c:1508
device_offline drivers/base/core.c:4283 [inline]
device_offline+0x2f4/0x400 drivers/base/core.c:4267
online_store+0xd1/0x180 drivers/base/core.c:2883
dev_attr_store+0x58/0x80 drivers/base/core.c:2509
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+0x6af/0x1050 fs/read_write.c:687
ksys_write+0x12a/0x250 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #1 (cpu_hotplug_lock){++++}-{0:0}:
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
percpu_down_write+0x4e/0x3d0 kernel/locking/percpu-rwsem.c:232
cpus_write_lock kernel/cpu.c:508 [inline]
_cpu_up+0x68/0x960 kernel/cpu.c:1622
cpu_up+0x1ba/0x230 kernel/cpu.c:1706
cpuhp_bringup_mask+0xf8/0x180 kernel/cpu.c:1772
cpuhp_bringup_cpus_parallel kernel/cpu.c:1850 [inline]
bringup_nonboot_cpus+0xd9/0x1b0 kernel/cpu.c:1876
smp_init+0x32/0x150 kernel/smp.c:1151
kernel_init_freeable+0x44b/0x7b0 init/main.c:1728
kernel_init+0x21/0x1e0 init/main.c:1626
ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #0 (cpu_add_remove_lock){+.+.}-{4:4}:
check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209
check_prevs_add kernel/locking/lockdep.c:3328 [inline]
validate_chain kernel/locking/lockdep.c:3952 [inline]
__lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x19f/0x1c10 kernel/locking/mutex.c:821
cpu_maps_update_begin kernel/cpu.c:468 [inline]
cpu_down kernel/cpu.c:1490 [inline]
cpu_device_down+0x46/0xc0 kernel/cpu.c:1508
device_offline drivers/base/core.c:4283 [inline]
device_offline+0x2f4/0x400 drivers/base/core.c:4267
acpi_bus_offline+0x3c7/0x550 drivers/acpi/scan.c:164
acpi_scan_try_to_offline drivers/acpi/scan.c:227 [inline]
acpi_scan_hot_remove drivers/acpi/scan.c:329 [inline]
acpi_generic_hotplug_event drivers/acpi/scan.c:432 [inline]
acpi_device_hotplug+0x627/0xbe0 drivers/acpi/scan.c:456
acpi_hotplug_work_fn+0x5e/0x90 drivers/acpi/osl.c:1194
process_one_work+0xac7/0x1b10 kernel/workqueue.c:3495
process_scheduled_works kernel/workqueue.c:3578 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3659
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
other info that might help us debug this:
Chain exists of:
cpu_add_remove_lock --> kn->active#5 --> &device->physical_node_lock
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&device->physical_node_lock);
lock(kn->active#5);
lock(&device->physical_node_lock);
lock(cpu_add_remove_lock);
*** DEADLOCK ***
locks held by kworker/u8:4/62: 6, last CPU#1:
#0: ffff8880226a5148 ((wq_completion)kacpi_hotplug){+.+.}-{0:0}, at: process_one_work+0x1461/0x1b10 kernel/workqueue.c:3470
#1: ffffc9000203fd08 ((work_completion)(&hpw->work)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3471
#2: ffffffff910363e0 (device_hotplug_lock){+.+.}-{4:4}, at: acpi_device_hotplug+0x7e/0xbe0 drivers/acpi/scan.c:442
#3: ffffffff90d09b40 (acpi_scan_lock){+.+.}-{4:4}, at: acpi_device_hotplug+0x8c/0xbe0 drivers/acpi/scan.c:443
#4: ffff88802528c760 (&device->physical_node_lock){+.+.}-{4:4}, at: acpi_bus_offline+0x156/0x550 drivers/acpi/scan.c:152
#5: ffff8880b8138650 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#5: ffff8880b8138650 (&dev->mutex){....}-{4:4}, at: device_offline drivers/base/core.c:4278 [inline]
#5: ffff8880b8138650 (&dev->mutex){....}-{4:4}, at: device_offline+0x1c5/0x400 drivers/base/core.c:4267
stack backtrace:
CPU: 1 UID: 0 PID: 62 Comm: kworker/u8:4 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/15/2026
Workqueue: kacpi_hotplug acpi_hotplug_work_fn
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+0x178/0x1be kernel/locking/lockdep.c:2087
check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2219
check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209
check_prevs_add kernel/locking/lockdep.c:3328 [inline]
validate_chain kernel/locking/lockdep.c:3952 [inline]
__lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x19f/0x1c10 kernel/locking/mutex.c:821
cpu_maps_update_begin kernel/cpu.c:468 [inline]
cpu_down kernel/cpu.c:1490 [inline]
cpu_device_down+0x46/0xc0 kernel/cpu.c:1508
device_offline drivers/base/core.c:4283 [inline]
device_offline+0x2f4/0x400 drivers/base/core.c:4267
acpi_bus_offline+0x3c7/0x550 drivers/acpi/scan.c:164
acpi_scan_try_to_offline drivers/acpi/scan.c:227 [inline]
acpi_scan_hot_remove drivers/acpi/scan.c:329 [inline]
acpi_generic_hotplug_event drivers/acpi/scan.c:432 [inline]
acpi_device_hotplug+0x627/0xbe0 drivers/acpi/scan.c:456
acpi_hotplug_work_fn+0x5e/0x90 drivers/acpi/osl.c:1194
process_one_work+0xac7/0x1b10 kernel/workqueue.c:3495
process_scheduled_works kernel/workqueue.c:3578 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3659
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
smpboot: CPU 1 is now offline
ACPI: \_SB_.CP01: Eject incomplete - status 0xf
---
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2026-10-28 5:57 [syzbot] [acpi?] possible deadlock in cpu_device_down syzbot
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