syzbot


INFO: task hung in nsim_bus_dev_del

Status: upstream: reported C repro on 2026/05/16 00:11
Subsystems: kernel
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+1cf303af03cf30b1275a@syzkaller.appspotmail.com
First crash: 21d, last: 17h33m
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
2733131a-a7f7-40ff-8c79-5ef52a500aec assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ INFO: task hung in nsim_bus_dev_del 2026/05/12 00:22 2026/05/12 00:22 2026/05/12 01:24 d168f2605715ec7b7ab6840d636f69c758e424d9
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [kernel?] INFO: task hung in nsim_bus_dev_del 1 (4) 2026/05/18 06:58
Last patch testing requests (3)
Created Duration User Patch Repo Result
2026/05/26 06:35 34m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2026/05/18 06:58 26m yun.zhou@windriver.com patch git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2026/05/16 11:04 27m hdanton@sina.com patch git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci error

Sample crash report:
INFO: task syz-executor:4825 blocked for more than 145 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:0     pid:4825  tgid:4825  ppid:4824   task_flags:0x400140 flags:0x00800010
Call trace:
 __switch_to+0x2b0/0x6e0 arch/arm64/kernel/process.c:810 (T)
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1bec/0x2dcc kernel/sched/core.c:7189
 __schedule_loop kernel/sched/core.c:7268 [inline]
 schedule+0x140/0x218 kernel/sched/core.c:7283
 schedule_preempt_disabled+0x18/0x2c kernel/sched/core.c:7340
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0x4e4/0xef8 kernel/locking/mutex.c:820
 mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:873
 device_lock include/linux/device.h:1040 [inline]
 device_del+0xa0/0x710 drivers/base/core.c:3857
 device_unregister+0x2c/0xf0 drivers/base/core.c:3936
 nsim_bus_dev_del+0x60/0x88 drivers/net/netdevsim/bus.c:491
 del_device_store+0x248/0x2d0 drivers/net/netdevsim/bus.c:244
 bus_attr_store+0x80/0xa4 drivers/base/bus.c:172
 sysfs_kf_write+0xe0/0x108 fs/sysfs/file.c:142
 kernfs_fop_write_iter+0x264/0x3c0 fs/kernfs/file.c:352
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x52c/0xa14 fs/read_write.c:688
 ksys_write+0x12c/0x224 fs/read_write.c:740
 __do_sys_write fs/read_write.c:751 [inline]
 __se_sys_write fs/read_write.c:748 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:748
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:140
 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:740
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:759
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594
INFO: task syz-executor:4836 blocked for more than 146 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:0     pid:4836  tgid:4836  ppid:4828   task_flags:0x400140 flags:0x00800000
Call trace:
 __switch_to+0x2b0/0x6e0 arch/arm64/kernel/process.c:810 (T)
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1bec/0x2dcc kernel/sched/core.c:7189
 __schedule_loop kernel/sched/core.c:7268 [inline]
 schedule+0x140/0x218 kernel/sched/core.c:7283
 schedule_preempt_disabled+0x18/0x2c kernel/sched/core.c:7340
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0x4e4/0xef8 kernel/locking/mutex.c:820
 mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:873
 del_device_store+0xd8/0x2d0 drivers/net/netdevsim/bus.c:234
 bus_attr_store+0x80/0xa4 drivers/base/bus.c:172
 sysfs_kf_write+0xe0/0x108 fs/sysfs/file.c:142
 kernfs_fop_write_iter+0x264/0x3c0 fs/kernfs/file.c:352
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x52c/0xa14 fs/read_write.c:688
 ksys_write+0x12c/0x224 fs/read_write.c:740
 __do_sys_write fs/read_write.c:751 [inline]
 __se_sys_write fs/read_write.c:748 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:748
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:140
 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:740
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:759
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594
INFO: task syz-executor:4837 blocked for more than 147 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:0     pid:4837  tgid:4837  ppid:4831   task_flags:0x400140 flags:0x00800000
Call trace:
 __switch_to+0x2b0/0x6e0 arch/arm64/kernel/process.c:810 (T)
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1bec/0x2dcc kernel/sched/core.c:7189
 __schedule_loop kernel/sched/core.c:7268 [inline]
 schedule+0x140/0x218 kernel/sched/core.c:7283
 schedule_preempt_disabled+0x18/0x2c kernel/sched/core.c:7340
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0x4e4/0xef8 kernel/locking/mutex.c:820
 mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:873
 del_device_store+0xd8/0x2d0 drivers/net/netdevsim/bus.c:234
 bus_attr_store+0x80/0xa4 drivers/base/bus.c:172
 sysfs_kf_write+0xe0/0x108 fs/sysfs/file.c:142
 kernfs_fop_write_iter+0x264/0x3c0 fs/kernfs/file.c:352
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x52c/0xa14 fs/read_write.c:688
 ksys_write+0x12c/0x224 fs/read_write.c:740
 __do_sys_write fs/read_write.c:751 [inline]
 __se_sys_write fs/read_write.c:748 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:748
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:140
 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:740
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:759
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594
INFO: task syz-executor:4843 blocked for more than 148 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:0     pid:4843  tgid:4843  ppid:4832   task_flags:0x400140 flags:0x00800000
Call trace:
 __switch_to+0x2b0/0x6e0 arch/arm64/kernel/process.c:810 (T)
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1bec/0x2dcc kernel/sched/core.c:7189
 __schedule_loop kernel/sched/core.c:7268 [inline]
 schedule+0x140/0x218 kernel/sched/core.c:7283
 schedule_preempt_disabled+0x18/0x2c kernel/sched/core.c:7340
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0x4e4/0xef8 kernel/locking/mutex.c:820
 mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:873
 del_device_store+0xd8/0x2d0 drivers/net/netdevsim/bus.c:234
 bus_attr_store+0x80/0xa4 drivers/base/bus.c:172
 sysfs_kf_write+0xe0/0x108 fs/sysfs/file.c:142
 kernfs_fop_write_iter+0x264/0x3c0 fs/kernfs/file.c:352
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x52c/0xa14 fs/read_write.c:688
 ksys_write+0x12c/0x224 fs/read_write.c:740
 __do_sys_write fs/read_write.c:751 [inline]
 __se_sys_write fs/read_write.c:748 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:748
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:140
 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:740
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:759
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594

Showing all locks held in the system:
1 lock held by kthreadd/2:
3 locks held by kworker/u8:0/12:
4 locks held by kworker/u8:1/15:
 #0: ffff0000c004b940 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3289 [inline]
 #0: ffff0000c004b940 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_scheduled_works+0x748/0x1098 kernel/workqueue.c:3397
 #1: ffff80008eae7c40 ((reg_check_chans).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3289 [inline]
 #1: ffff80008eae7c40 ((reg_check_chans).work){+.+.}-{0:0}, at: process_scheduled_works+0x750/0x1098 kernel/workqueue.c:3397
 #2: ffff800089c3bb80 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock+0x20/0x2c net/core/rtnetlink.c:80
 #3: ffff0000df1f0780 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6645 [inline]
 #3: ffff0000df1f0780 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: reg_leave_invalid_chans net/wireless/reg.c:2454 [inline]
 #3: ffff0000df1f0780 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: reg_check_chans_work+0x14c/0x112c net/wireless/reg.c:2469
1 lock held by khungtaskd/31:

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/01 19:56 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 4b4362973b6f 8d8eeb3a .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 INFO: task hung in nsim_bus_dev_del
2026/05/12 00:07 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 5cbb61bf4168 d168f260 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 INFO: task hung in nsim_bus_dev_del
2026/06/01 12:38 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 4b4362973b6f 8d8eeb3a .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 INFO: task hung in nsim_bus_dev_del
2026/05/31 21:26 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 4b4362973b6f 6b4a8443 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 INFO: task hung in nsim_bus_dev_del
* Struck through repros no longer work on HEAD.