syzbot

 sign-in | mailing list | source | docs
🐞 Open [1410]
≡ Subsystems
🐞 Fixed [6987]
🐞 Invalid [18213]
⬇ Missing Backports [223]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap Subsystems Heatmap
✨ AI
💬 Send us feedback

possible deadlock in kernfs_unlink_sibling (2)

Status: upstream: reported on 2025/11/06 02:54
Subsystems: kernfs
[Documentation on labels]
Reported-by: syzbot+a0ec0dbf8642550c291a@syzkaller.appspotmail.com
First crash: 132d, last: 2d15h
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
33ce6309-d3f7-462a-ac35-6b3c7dc86145 repro ❓ possible deadlock in kernfs_unlink_sibling (2) 2026/03/06 07:57 2026/03/06 07:57 2026/03/06 08:06 31e9c887f7dc24e04b3ca70d0d54fc34141844b0
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [kernfs?] possible deadlock in kernfs_unlink_sibling (2) 0 (1) 2025/11/06 02:54
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in kernfs_unlink_sibling kernfs 4 26 159d 191d 29/29 fixed on 2025/10/29 21:02

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.0.4615/25977 is trying to acquire lock:
ffff88801cac8220 (&root->kernfs_iattr_rwsem){++++}-{4:4}, at: kernfs_unlink_sibling+0xa3/0x320 fs/kernfs/dir.c:424

but task is already holding lock:
ffff88801cac8188 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x3d/0xf0 fs/kernfs/dir.c:1717

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #10 (&root->kernfs_rwsem){++++}-{4:4}:
       down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1590
       kernfs_add_one+0x38/0x850 fs/kernfs/dir.c:796
       kernfs_create_dir_ns+0xfc/0x1a0 fs/kernfs/dir.c:1098
       internal_create_group+0x36f/0xf40 fs/sysfs/group.c:176
       cpuhp_invoke_callback+0x3ab/0x9a0 kernel/cpu.c:194
       cpuhp_issue_call+0x1b8/0x970 kernel/cpu.c:2354
       __cpuhp_setup_state_cpuslocked+0x431/0x880 kernel/cpu.c:2507
       __cpuhp_setup_state+0xf4/0x300 kernel/cpu.c:2536
       do_one_initcall+0x11d/0x760 init/main.c:1382
       do_initcall_level init/main.c:1444 [inline]
       do_initcalls init/main.c:1460 [inline]
       do_basic_setup init/main.c:1479 [inline]
       kernel_init_freeable+0x6e5/0x7a0 init/main.c:1692
       kernel_init+0x1f/0x1e0 init/main.c:1582
       ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #9 (cpuhp_state_mutex){+.+.}-{4:4}:

-> #8 (cpu_hotplug_lock){++++}-{0:0}:
       percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline]
       percpu_down_read include/linux/percpu-rwsem.h:77 [inline]
       cpus_read_lock+0x42/0x170 kernel/cpu.c:490
       static_key_disable+0x12/0x20 kernel/jump_label.c:247
       __inet_hash_connect+0x1378/0x1e40 net/ipv4/inet_hashtables.c:1074
       tcp_v4_connect+0xeb0/0x1b40 net/ipv4/tcp_ipv4.c:307
       __inet_stream_connect+0x208/0xfa0 net/ipv4/af_inet.c:679
       inet_stream_connect+0x57/0xa0 net/ipv4/af_inet.c:750
       __sys_connect_file+0x141/0x1a0 net/socket.c:2089
       __sys_connect+0x141/0x170 net/socket.c:2108
       __do_sys_connect net/socket.c:2114 [inline]
       __se_sys_connect net/socket.c:2111 [inline]
       __x64_sys_connect+0x72/0xb0 net/socket.c:2111
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #7 (sk_lock-AF_INET){+.+.}-{0:0}:
       lock_sock_nested+0x41/0xf0 net/core/sock.c:3780
       lock_sock include/net/sock.h:1709 [inline]
       inet_shutdown+0x67/0x410 net/ipv4/af_inet.c:913
       nbd_mark_nsock_dead+0xae/0x5c0 drivers/block/nbd.c:318
       sock_shutdown+0x16b/0x200 drivers/block/nbd.c:411
       nbd_clear_sock drivers/block/nbd.c:1427 [inline]
       nbd_clear_sock_ioctl drivers/block/nbd.c:1575 [inline]
       __nbd_ioctl drivers/block/nbd.c:1603 [inline]
       nbd_ioctl+0x25e/0xd30 drivers/block/nbd.c:1663
       blkdev_ioctl+0x5ad/0x6f0 block/ioctl.c:804
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:597 [inline]
       __se_sys_ioctl fs/ioctl.c:583 [inline]
       __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #6 (&nsock->tx_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776
       nbd_handle_cmd drivers/block/nbd.c:1143 [inline]
       nbd_queue_rq+0x428/0x1080 drivers/block/nbd.c:1207
       blk_mq_dispatch_rq_list+0x422/0x1e70 block/blk-mq.c:2148
       __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
       blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
       __blk_mq_sched_dispatch_requests+0xcea/0x1620 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329
       blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2386
       blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2949
       blk_mq_flush_plug_list block/blk-mq.c:2997 [inline]
       blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2969
       __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1230
       blk_finish_plug block/blk-core.c:1257 [inline]
       __submit_bio+0x584/0x6c0 block/blk-core.c:649
       __submit_bio_noacct_mq block/blk-core.c:722 [inline]
       submit_bio_noacct_nocheck+0x562/0xc10 block/blk-core.c:753
       submit_bio_noacct+0xd17/0x2010 block/blk-core.c:884
       blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline]
       submit_bh_wbc+0x59c/0x770 fs/buffer.c:2821
       submit_bh fs/buffer.c:2826 [inline]
       block_read_full_folio+0x264/0x8e0 fs/buffer.c:2444
       filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2501
       do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4101
       read_mapping_folio include/linux/pagemap.h:1028 [inline]
       read_part_sector+0xd1/0x370 block/partitions/core.c:723
       adfspart_check_ICS+0x93/0x910 block/partitions/acorn.c:360
       check_partition block/partitions/core.c:142 [inline]
       blk_add_partitions block/partitions/core.c:590 [inline]
       bdev_disk_changed+0x7f8/0xc80 block/partitions/core.c:694
       blkdev_get_whole+0x187/0x290 block/bdev.c:764
       bdev_open+0x2c7/0xe40 block/bdev.c:973
       blkdev_open+0x34e/0x4f0 block/fops.c:697
       do_dentry_open+0x6d8/0x1660 fs/open.c:949
       vfs_open+0x82/0x3f0 fs/open.c:1081
       do_open fs/namei.c:4671 [inline]
       path_openat+0x208c/0x31a0 fs/namei.c:4830
       do_file_open+0x20e/0x430 fs/namei.c:4859
       do_sys_openat2+0x10d/0x1e0 fs/open.c:1366
       do_sys_open fs/open.c:1372 [inline]
       __do_sys_openat fs/open.c:1388 [inline]
       __se_sys_openat fs/open.c:1383 [inline]
       __x64_sys_openat+0x12d/0x210 fs/open.c:1383
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #5 (&cmd->lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776
       nbd_queue_rq+0xba/0x1080 drivers/block/nbd.c:1199
       blk_mq_dispatch_rq_list+0x422/0x1e70 block/blk-mq.c:2148
       __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
       blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
       __blk_mq_sched_dispatch_requests+0xcea/0x1620 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329
       blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2386
       blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2949
       blk_mq_flush_plug_list block/blk-mq.c:2997 [inline]
       blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2969
       __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1230
       blk_finish_plug block/blk-core.c:1257 [inline]
       __submit_bio+0x584/0x6c0 block/blk-core.c:649
       __submit_bio_noacct_mq block/blk-core.c:722 [inline]
       submit_bio_noacct_nocheck+0x562/0xc10 block/blk-core.c:753
       submit_bio_noacct+0xd17/0x2010 block/blk-core.c:884
       blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline]
       submit_bh_wbc+0x59c/0x770 fs/buffer.c:2821
       submit_bh fs/buffer.c:2826 [inline]
       block_read_full_folio+0x264/0x8e0 fs/buffer.c:2444
       filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2501
       do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4101
       read_mapping_folio include/linux/pagemap.h:1028 [inline]
       read_part_sector+0xd1/0x370 block/partitions/core.c:723
       adfspart_check_ICS+0x93/0x910 block/partitions/acorn.c:360
       check_partition block/partitions/core.c:142 [inline]
       blk_add_partitions block/partitions/core.c:590 [inline]
       bdev_disk_changed+0x7f8/0xc80 block/partitions/core.c:694
       blkdev_get_whole+0x187/0x290 block/bdev.c:764
       bdev_open+0x2c7/0xe40 block/bdev.c:973
       blkdev_open+0x34e/0x4f0 block/fops.c:697
       do_dentry_open+0x6d8/0x1660 fs/open.c:949
       vfs_open+0x82/0x3f0 fs/open.c:1081
       do_open fs/namei.c:4671 [inline]
       path_openat+0x208c/0x31a0 fs/namei.c:4830
       do_file_open+0x20e/0x430 fs/namei.c:4859
       do_sys_openat2+0x10d/0x1e0 fs/open.c:1366
       do_sys_open fs/open.c:1372 [inline]
       __do_sys_openat fs/open.c:1388 [inline]
       __se_sys_openat fs/open.c:1383 [inline]
       __x64_sys_openat+0x12d/0x210 fs/open.c:1383
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #4 (set->srcu){.+.+}-{0:0}:
       srcu_lock_sync include/linux/srcu.h:199 [inline]
       __synchronize_srcu+0xa1/0x2a0 kernel/rcu/srcutree.c:1505
       blk_mq_wait_quiesce_done block/blk-mq.c:284 [inline]
       blk_mq_wait_quiesce_done block/blk-mq.c:281 [inline]
       blk_mq_quiesce_queue block/blk-mq.c:304 [inline]
       blk_mq_quiesce_queue+0x149/0x1c0 block/blk-mq.c:299
       elevator_switch+0x17b/0x7e0 block/elevator.c:576
       elevator_change+0x352/0x530 block/elevator.c:681
       elevator_set_default+0x29e/0x360 block/elevator.c:754
       blk_register_queue+0x412/0x590 block/blk-sysfs.c:946
       __add_disk+0x73f/0xe40 block/genhd.c:528
       add_disk_fwnode+0x118/0x5c0 block/genhd.c:597
       add_disk include/linux/blkdev.h:785 [inline]
       nbd_dev_add+0x77a/0xb10 drivers/block/nbd.c:1984
       nbd_init+0x291/0x2b0 drivers/block/nbd.c:2692
       do_one_initcall+0x11d/0x760 init/main.c:1382
       do_initcall_level init/main.c:1444 [inline]
       do_initcalls init/main.c:1460 [inline]
       do_basic_setup init/main.c:1479 [inline]
       kernel_init_freeable+0x6e5/0x7a0 init/main.c:1692
       kernel_init+0x1f/0x1e0 init/main.c:1582
       ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #3 (&q->elevator_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776
       elevator_change+0x1bc/0x530 block/elevator.c:679
       elevator_set_none+0x92/0xf0 block/elevator.c:769
       blk_mq_elv_switch_none block/blk-mq.c:5110 [inline]
       __blk_mq_update_nr_hw_queues block/blk-mq.c:5155 [inline]
       blk_mq_update_nr_hw_queues+0x4c1/0x15f0 block/blk-mq.c:5220
       nbd_start_device+0x1a6/0xbd0 drivers/block/nbd.c:1489
       nbd_start_device_ioctl drivers/block/nbd.c:1548 [inline]
       __nbd_ioctl drivers/block/nbd.c:1623 [inline]
       nbd_ioctl+0x4a6/0xd30 drivers/block/nbd.c:1663
       blkdev_ioctl+0x5ad/0x6f0 block/ioctl.c:804
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:597 [inline]
       __se_sys_ioctl fs/ioctl.c:583 [inline]
       __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&q->q_usage_counter(io)#58){++++}-{0:0}:
       blk_alloc_queue+0x610/0x790 block/blk-core.c:461
       blk_mq_alloc_queue+0x174/0x290 block/blk-mq.c:4429
       __blk_mq_alloc_disk+0x29/0x120 block/blk-mq.c:4476
       nbd_dev_add+0x492/0xb10 drivers/block/nbd.c:1954
       nbd_init+0x291/0x2b0 drivers/block/nbd.c:2692
       do_one_initcall+0x11d/0x760 init/main.c:1382
       do_initcall_level init/main.c:1444 [inline]
       do_initcalls init/main.c:1460 [inline]
       do_basic_setup init/main.c:1479 [inline]
       kernel_init_freeable+0x6e5/0x7a0 init/main.c:1692
       kernel_init+0x1f/0x1e0 init/main.c:1582
       ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #1 (fs_reclaim){+.+.}-{0:0}:
       __fs_reclaim_acquire mm/page_alloc.c:4348 [inline]
       fs_reclaim_acquire+0xc4/0x100 mm/page_alloc.c:4362
       might_alloc include/linux/sched/mm.h:317 [inline]
       slab_pre_alloc_hook mm/slub.c:4493 [inline]
       slab_alloc_node mm/slub.c:4846 [inline]
       kmem_cache_alloc_noprof+0x4c/0x6e0 mm/slub.c:4876
       __kernfs_iattrs+0x126/0x400 fs/kernfs/inode.c:36
       kernfs_iattrs fs/kernfs/inode.c:61 [inline]
       __kernfs_setattr+0x4d/0x3c0 fs/kernfs/inode.c:74
       kernfs_iop_setattr+0xda/0x130 fs/kernfs/inode.c:128
       notify_change+0xb25/0x1330 fs/attr.c:556
       do_truncate+0x1df/0x240 fs/open.c:68
       handle_truncate fs/namei.c:4279 [inline]
       do_open fs/namei.c:4675 [inline]
       path_openat+0x2a55/0x31a0 fs/namei.c:4830
       do_file_open+0x20e/0x430 fs/namei.c:4859
       do_sys_openat2+0x10d/0x1e0 fs/open.c:1366
       do_sys_open fs/open.c:1372 [inline]
       __do_sys_openat fs/open.c:1388 [inline]
       __se_sys_openat fs/open.c:1383 [inline]
       __x64_sys_openat+0x12d/0x210 fs/open.c:1383
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&root->kernfs_iattr_rwsem){++++}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x14b8/0x2630 kernel/locking/lockdep.c:5237
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x1cf/0x380 kernel/locking/lockdep.c:5825
       down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1590
       kernfs_unlink_sibling+0xa3/0x320 fs/kernfs/dir.c:424
       __kernfs_remove+0x308/0x910 fs/kernfs/dir.c:1519
       kernfs_remove_by_name_ns+0x68/0xf0 fs/kernfs/dir.c:1722
       kernfs_remove_by_name include/linux/kernfs.h:633 [inline]
       remove_files+0x96/0x1c0 fs/sysfs/group.c:28
       sysfs_remove_group+0x8b/0x1b0 fs/sysfs/group.c:328
       sysfs_remove_groups fs/sysfs/group.c:352 [inline]
       sysfs_remove_groups+0x60/0xb0 fs/sysfs/group.c:344
       net_rx_queue_update_kobjects+0x53c/0x760 net/core/net-sysfs.c:1337
       remove_queue_kobjects net/core/net-sysfs.c:2169 [inline]
       netdev_unregister_kobject+0x154/0x540 net/core/net-sysfs.c:2325
       unregister_netdevice_many_notify+0x1817/0x2580 net/core/dev.c:12449
       unregister_netdevice_many net/core/dev.c:12477 [inline]
       unregister_netdevice_queue net/core/dev.c:12291 [inline]
       unregister_netdevice_queue+0x30b/0x3c0 net/core/dev.c:12281
       unregister_netdevice include/linux/netdevice.h:3408 [inline]
       unregister_netdev+0x1f/0x60 net/core/dev.c:12495
       slip_close+0x16a/0x1d0 drivers/net/slip/slip.c:906
       tty_ldisc_close+0x114/0x1a0 drivers/tty/tty_ldisc.c:455
       tty_ldisc_kill+0x8e/0x150 drivers/tty/tty_ldisc.c:613
       tty_ldisc_release+0x21c/0x2f0 drivers/tty/tty_ldisc.c:781
       tty_release_struct+0x23/0xe0 drivers/tty/tty_io.c:1681
       tty_release+0xd7a/0x1300 drivers/tty/tty_io.c:1852
       __fput+0x3ff/0xb40 fs/file_table.c:469
       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:67 [inline]
       exit_to_user_mode_loop+0x100/0x4a0 kernel/entry/common.c:98
       __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
       syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
       syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
       do_syscall_64+0x67c/0xf80 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:
  &root->kernfs_iattr_rwsem --> cpuhp_state_mutex --> &root->kernfs_rwsem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&root->kernfs_rwsem);
                               lock(cpuhp_state_mutex);
                               lock(&root->kernfs_rwsem);
  lock(&root->kernfs_iattr_rwsem);

 *** DEADLOCK ***

3 locks held by syz.0.4615/25977:
 #0: ffff88805a29b0a0 (&tty->ldisc_sem){++++}-{0:0}, at: __tty_ldisc_lock drivers/tty/tty_ldisc.c:289 [inline]
 #0: ffff88805a29b0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_lock_pair_timeout drivers/tty/tty_ldisc.c:352 [inline]
 #0: ffff88805a29b0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_lock_pair drivers/tty/tty_ldisc.c:366 [inline]
 #0: ffff88805a29b0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_release+0x256/0x2f0 drivers/tty/tty_ldisc.c:780
 #1: ffffffff90610828 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #1: ffffffff90610828 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_dev_lock+0x146/0x360 net/core/dev.c:2162
 #2: ffff88801cac8188 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x3d/0xf0 fs/kernfs/dir.c:1717

stack backtrace:
CPU: 1 UID: 0 PID: 25977 Comm: syz.0.4615 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/27/2026
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 kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x14b8/0x2630 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x1cf/0x380 kernel/locking/lockdep.c:5825
 down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1590
 kernfs_unlink_sibling+0xa3/0x320 fs/kernfs/dir.c:424
 __kernfs_remove+0x308/0x910 fs/kernfs/dir.c:1519
 kernfs_remove_by_name_ns+0x68/0xf0 fs/kernfs/dir.c:1722
 kernfs_remove_by_name include/linux/kernfs.h:633 [inline]
 remove_files+0x96/0x1c0 fs/sysfs/group.c:28
 sysfs_remove_group+0x8b/0x1b0 fs/sysfs/group.c:328
 sysfs_remove_groups fs/sysfs/group.c:352 [inline]
 sysfs_remove_groups+0x60/0xb0 fs/sysfs/group.c:344
 net_rx_queue_update_kobjects+0x53c/0x760 net/core/net-sysfs.c:1337
 remove_queue_kobjects net/core/net-sysfs.c:2169 [inline]
 netdev_unregister_kobject+0x154/0x540 net/core/net-sysfs.c:2325
 unregister_netdevice_many_notify+0x1817/0x2580 net/core/dev.c:12449
 unregister_netdevice_many net/core/dev.c:12477 [inline]
 unregister_netdevice_queue net/core/dev.c:12291 [inline]
 unregister_netdevice_queue+0x30b/0x3c0 net/core/dev.c:12281
 unregister_netdevice include/linux/netdevice.h:3408 [inline]
 unregister_netdev+0x1f/0x60 net/core/dev.c:12495
 slip_close+0x16a/0x1d0 drivers/net/slip/slip.c:906
 tty_ldisc_close+0x114/0x1a0 drivers/tty/tty_ldisc.c:455
 tty_ldisc_kill+0x8e/0x150 drivers/tty/tty_ldisc.c:613
 tty_ldisc_release+0x21c/0x2f0 drivers/tty/tty_ldisc.c:781
 tty_release_struct+0x23/0xe0 drivers/tty/tty_io.c:1681
 tty_release+0xd7a/0x1300 drivers/tty/tty_io.c:1852
 __fput+0x3ff/0xb40 fs/file_table.c:469
 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:67 [inline]
 exit_to_user_mode_loop+0x100/0x4a0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x67c/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1dc1d9c799
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:00007fff0bf09e48 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fff0bf09f30 RCX: 00007f1dc1d9c799
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00000000001d7640 R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b2db20000 R11: 0000000000000246 R12: 00007fff0bf09f70
R13: 00007f1dc201609c R14: 00000000001d76e2 R15: 00007f1dc2016090
 </TASK>

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/11 21:07 upstream b29fb8829bff 2d88ab01 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in kernfs_unlink_sibling
2025/11/22 10:53 upstream 2eba5e05d9bc 4fb8ef37 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto possible deadlock in kernfs_unlink_sibling
2025/11/02 02:41 upstream 691d401c7e0e 2c50b6a9 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto possible deadlock in kernfs_unlink_sibling
2026/03/10 20:37 upstream 1f318b96cc84 4683d576 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in kernfs_unlink_sibling
2025/12/28 21:43 linux-next cc3aa43b44bd d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce possible deadlock in kernfs_unlink_sibling
* Struck through repros no longer work on HEAD.