syzbot


INFO: task hung in nmi_cpu_backtrace (2)

Status: auto-obsoleted due to no activity on 2024/01/08 02:36
Subsystems: serial
[Documentation on labels]
First crash: 561d, last: 561d
Similar bugs (4)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in nmi_cpu_backtrace fs 7 2484d 2483d 0/28 auto-closed as invalid on 2019/02/22 10:26
upstream INFO: task hung in nmi_cpu_backtrace (3) block serial 3 247d 262d 0/28 auto-obsoleted due to no activity on 2024/11/17 17:25
android-49 INFO: task hung in nmi_cpu_backtrace 3 2452d 2629d 0/3 auto-closed as invalid on 2019/02/22 13:59
linux-4.14 INFO: task hung in nmi_cpu_backtrace 1 1937d 1937d 0/1 auto-closed as invalid on 2020/05/02 01:19

Sample crash report:
INFO: task syz-executor.0:11211 blocked for more than 143 seconds.
      Not tainted 6.6.0-rc4-syzkaller-01097-g19537e125cc7 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8cbab360 (rcu_read_lock
){....}-{1:2}
, at: rcu_lock_acquire include/linux/rcupdate.h:303 [inline]
, at: rcu_read_lock include/linux/rcupdate.h:749 [inline]
, at: debug_show_all_locks+0x75/0x340 kernel/locking/lockdep.c:6613
2 locks held by getty/4795:
 #0: ffff888025f510a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002f062f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xfc5/0x1480 drivers/tty/n_tty.c:2206
2 locks held by syz-fuzzer/5070:
2 locks held by kworker/0:0/31736:
 #0: ffff888012c72938 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x787/0x15c0 kernel/workqueue.c:2605
 #1: ffffc90016c47d80 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7e9/0x15c0 kernel/workqueue.c:2606
4 locks held by syz-executor.4/11248:
 #0: ffff8880777c90b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x26/0x90 net/bluetooth/hci_core.c:552
 #1: ffff8880777c8078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_close_sync+0x345/0x1160 net/bluetooth/hci_sync.c:5008
 #2: ffffffff8e85fce8 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1947 [inline]
 #2: ffffffff8e85fce8 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xc4/0x260 net/bluetooth/hci_conn.c:2558
 #3: ffffffff8cbb6c38 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:325 [inline]
 #3: ffffffff8cbb6c38 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x404/0x7e0 kernel/rcu/tree_exp.h:992
2 locks held by kworker/u4:40/11282:
1 lock held by syz-executor.2/11300:
 #0: ffffffff8cbb6c38 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:325 [inline]
 #0: ffffffff8cbb6c38 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x404/0x7e0 kernel/rcu/tree_exp.h:992
1 lock held by dhcpcd/11356:
 #0: ffff8880ad0e5c10 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:802 [inline]
 #0: ffff8880ad0e5c10 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: __sock_release+0x86/0x260 net/socket.c:658
1 lock held by dhcpcd/11357:
 #0: ffff8880ad0e6e10 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:802 [inline]
 #0: ffff8880ad0e6e10 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: __sock_release+0x86/0x260 net/socket.c:658
1 lock held by dhcpcd/11358:
 #0: ffff8880ad0e3810 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:802 [inline]
 #0: ffff8880ad0e3810 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: __sock_release+0x86/0x260 net/socket.c:658

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

NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted 6.6.0-rc4-syzkaller-01097-g19537e125cc7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x277/0x380 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x299/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xf87/0x1210 kernel/hung_task.c:379
 kthread+0x33c/0x440 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 5070 Comm: syz-fuzzer Not tainted 6.6.0-rc4-syzkaller-01097-g19537e125cc7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
RIP: 0033:0x41f5b0
Code: 81 fe 00 00 40 00 0f 83 38 02 00 00 48 8b 14 f2 48 89 c6 48 c1 e8 0d 25 ff 1f 00 00 48 8b bc c2 00 40 10 00 84 02 48 8b 57 68 <48> 85 d2 0f 84 00 02 00 00 44 0f b6 47 62 66 90 41 f6 c0 01 0f 85
RSP: 002b:000000c000aa9e88 EFLAGS: 00000246
RAX: 0000000000000799 RBX: 000000c000045238 RCX: 000000c000f328a0
RDX: 0000000000000030 RSI: 000000c000f328a0 RDI: 00007f886a593b40
RBP: 000000c000aa9f08 R08: 0000000000011838 R09: 000000c002707000
R10: 000000000000008f R11: 000000000000008e R12: 000000c000aa9f08
R13: 0000000000000001 R14: 000000c0027a49c0 R15: 000000000113d000
FS:  000000c00ef6c890 GS:  0000000000000000

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/10/10 02:27 net-next 19537e125cc7 3c53c7d9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: task hung in nmi_cpu_backtrace
* Struck through repros no longer work on HEAD.