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INFO: task hung in nmi_cpu_backtrace (3)

Status: auto-obsoleted due to no activity on 2024/11/17 17:25
Subsystems: block serial
[Documentation on labels]
First crash: 529d, last: 514d
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in nmi_cpu_backtrace fs 1 7 2752d 2750d 0/29 auto-closed as invalid on 2019/02/22 10:26
android-49 INFO: task hung in nmi_cpu_backtrace 1 3 2720d 2896d 0/3 auto-closed as invalid on 2019/02/22 13:59
upstream INFO: task hung in nmi_cpu_backtrace (2) serial 1 1 829d 829d 0/29 auto-obsoleted due to no activity on 2024/01/08 02:36
upstream INFO: task hung in nmi_cpu_backtrace (5) kernfs 1 1 138d 138d 0/29 auto-obsoleted due to no activity on 2025/11/29 08:08
upstream INFO: task hung in nmi_cpu_backtrace (4) nfs 1 5 264d 369d 0/29 auto-obsoleted due to no activity on 2025/07/25 14:14
linux-4.14 INFO: task hung in nmi_cpu_backtrace 1 1 2205d 2205d 0/1 auto-closed as invalid on 2020/05/02 01:19
android-6-12 INFO: task hung in nmi_cpu_backtrace 1 3 77d 172d 0/1 premoderation: reported on 2025/07/28 05:35

Sample crash report:
INFO: task syz.3.2102:18851 blocked for more than 143 seconds.
      Not tainted 6.11.0-rc4-syzkaller #0
Showing all locks held in the system:

=============================================

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.11.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:119
 nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:223 [inline]
 watchdog+0xf0c/0x1240 kernel/hung_task.c:379
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 21554 Comm: syz.3.3010 Not tainted 6.11.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
RIP: 0010:remove_class_from_lock_chain kernel/locking/lockdep.c:6084 [inline]
RIP: 0010:remove_class_from_lock_chains kernel/locking/lockdep.c:6123 [inline]
RIP: 0010:zap_class+0x247/0x9a0 kernel/locking/lockdep.c:6165
Code: 00 0f 85 f6 06 00 00 49 8b 2c 24 48 85 ed 0f 84 c2 00 00 00 48 83 ed 08 0f 84 b8 00 00 00 48 89 e8 48 c1 e8 03 42 0f b6 04 38 <84> c0 74 08 3c 03 0f 8e 94 05 00 00 0f b6 45 00 44 8b 6d 00 c0 e8
RSP: 0018:ffffc900047f7990 EFLAGS: 00000806
RAX: 0000000000000000 RBX: ffffffff94622698 RCX: ffffffff8167a3d5
RDX: 0000000000000ce9 RSI: 000000000000002c RDI: 0000000000000000
RBP: ffffffff935976c0 R08: ffffffff932bc5aa R09: 000000000002d115
R10: ffffffff9462a85f R11: 0000000000000000 R12: ffffffff9451b250
R13: 000000000002d10d R14: ffffffff93623428 R15: dffffc0000000000
FS:  000055555b467500(0000) GS:ffff8880b9200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff7100e8178 CR3: 0000000024860000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 __lockdep_free_key_range+0x56/0x110 kernel/locking/lockdep.c:6284
 lockdep_unregister_key+0x18c/0x280 kernel/locking/lockdep.c:6480
 __qdisc_destroy+0x11a/0x4a0 net/sched/sch_generic.c:1079
 qdisc_put+0xab/0xe0 net/sched/sch_generic.c:1105
 shutdown_scheduler_queue+0xa5/0x160 net/sched/sch_generic.c:1158
 netdev_for_each_tx_queue include/linux/netdevice.h:2513 [inline]
 dev_shutdown+0xac/0x430 net/sched/sch_generic.c:1490
 unregister_netdevice_many_notify+0x620/0x1e40 net/core/dev.c:11342
 unregister_netdevice_many net/core/dev.c:11414 [inline]
 unregister_netdevice_queue+0x307/0x3f0 net/core/dev.c:11289
 unregister_netdevice include/linux/netdevice.h:3129 [inline]
 __tun_detach+0x11cc/0x14a0 drivers/net/tun.c:685
 tun_detach drivers/net/tun.c:701 [inline]
 tun_chr_close+0xc8/0x230 drivers/net/tun.c:3510
 __fput+0x408/0xbb0 fs/file_table.c:422
 task_work_run+0x14e/0x250 kernel/task_work.c:228
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x27b/0x2a0 kernel/entry/common.c:218
 do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcb04979e79
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe1c9ab2a8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fcb04b17a80 RCX: 00007fcb04979e79
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007fcb04b17a80 R08: 00007fcb04b02000 R09: 00007ffe1c9ab58f
R10: 00000000003ffd40 R11: 0000000000000246 R12: 00000000001d8db3
R13: 00007ffe1c9ab3a0 R14: 00007ffe1c9ab3c0 R15: ffffffffffffffff
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/08/19 17:18 upstream 47ac09b91bef 9f0ab3fb .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in nmi_cpu_backtrace
2024/08/04 20:58 upstream a5dbd76a8942 1786a2a8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in nmi_cpu_backtrace
2024/08/04 16:07 upstream defaf1a2113a 1786a2a8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in nmi_cpu_backtrace
* Struck through repros no longer work on HEAD.