syzbot


INFO: task hung in vhost_task_stop

Status: auto-obsoleted due to no activity on 2025/04/06 23:10
Subsystems: kernel
[Documentation on labels]
First crash: 277d, last: 236d
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in vhost_task_stop (2) kernel 1 4 95d 118d 0/29 auto-obsoleted due to no activity on 2025/08/25 04:17

Sample crash report:
INFO: task syz.8.843:11046 blocked for more than 143 seconds.
      Not tainted 6.13.0-rc6-syzkaller-00006-g5428dc1906dd #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.8.843       state:D
 stack:23840 pid:11046 tgid:11046 ppid:7235   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5369 [inline]
 __schedule+0x1850/0x4c30 kernel/sched/core.c:6756
 __schedule_loop kernel/sched/core.c:6833 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6848
 schedule_timeout+0xb0/0x290 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x355/0x620 kernel/sched/completion.c:148
 vhost_task_stop+0xc1/0xe0 kernel/vhost_task.c:102
 kvm_destroy_vm virt/kvm/kvm_main.c:1271 [inline]
 kvm_put_kvm+0x372/0xf60 virt/kvm/kvm_main.c:1340
 kvm_vm_release+0x43/0x50 virt/kvm/kvm_main.c:1363
 __fput+0x23c/0xa50 fs/file_table.c:450
 task_work_run+0x24f/0x310 kernel/task_work.c:239
 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:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x13f/0x340 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f71cbd85d29
RSP: 002b:00007f71cc09fb88 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f71cbf77ba0 RCX: 00007f71cbd85d29
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f71cbf77ba0 R08: 00000000000011a4 R09: 00007f71cc09fe7f
R10: 00007f71cbf77ac0 R11: 0000000000000246 R12: 0000000000051ec2
R13: 00007f71cc09fc90 R14: 0000000000000032 R15: ffffffffffffffff
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/30:
 #0: ffffffff8e937ae0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #0: ffffffff8e937ae0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e937ae0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6744
2 locks held by getty/5593:
 #0: ffff888031c410a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900033332f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x6a6/0x1e00 drivers/tty/n_tty.c:2211
1 lock held by syz-executor/12295:
 #0: ffffffff8e93cff8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:329 [inline]
 #0: ffffffff8e93cff8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x451/0x830 kernel/rcu/tree_exp.h:976
2 locks held by syz-executor/12550:
2 locks held by syz-executor/13177:
 #0: ffff8880496d8d80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close net/bluetooth/hci_core.c:480 [inline]
 #0: ffff8880496d8d80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_unregister_dev+0x203/0x510 net/bluetooth/hci_core.c:2697
 #1: ffff8880496d8078 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x5c8/0x11c0 net/bluetooth/hci_sync.c:5200
1 lock held by syz-executor/13206:
 #0: ffffffff8e93cff8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:297 [inline]
 #0: ffffffff8e93cff8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x381/0x830 kernel/rcu/tree_exp.h:976

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.13.0-rc6-syzkaller-00006-g5428dc1906dd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:234 [inline]
 watchdog+0xff6/0x1040 kernel/hung_task.c:397
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/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: 5194 Comm: klogd Not tainted 6.13.0-rc6-syzkaller-00006-g5428dc1906dd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:lock_acquire+0x9e/0x550 kernel/locking/lockdep.c:5817
Code: ec 03 48 b8 f1 f1 f1 f1 00 f2 f2 f2 4b 89 04 2c 43 c7 44 2c 09 f2 f2 f2 00 43 c7 44 2c 11 f3 f3 f3 f3 66 43 c7 44 2c 15 f3 f3 <43> c6 44 2c 17 f3 0f 1f 44 00 00 65 8b 05 ec 16 89 7e 83 f8 08 0f
RSP: 0018:ffffc9000fbe77c0 EFLAGS: 00000a06
RAX: f2f2f200f1f1f1f1 RBX: ffffffff8e813320 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8e813388
RBP: ffffc9000fbe7908 R08: 0000000000000001 R09: 0000000000000000
R10: ffffc9000fbe7a00 R11: fffff52001f7cf45 R12: 1ffff92001f7cf00
R13: dffffc0000000000 R14: 0000000000000000 R15: dffffc0000000000
FS:  00007f95b89e1380(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055cdaa221f50 CR3: 000000007ec20000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 __mutex_lock_common kernel/locking/mutex.c:585 [inline]
 __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
 syslog_print+0x7d9/0x9c0 kernel/printk/printk.c:1685
 do_syslog+0x3c2/0x820 kernel/printk/printk.c:1785
 __do_sys_syslog kernel/printk/printk.c:1877 [inline]
 __se_sys_syslog kernel/printk/printk.c:1875 [inline]
 __x64_sys_syslog+0x7c/0x90 kernel/printk/printk.c:1875
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f95b8b42fa7
Code: 73 01 c3 48 8b 0d 81 ce 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 67 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 51 ce 0c 00 f7 d8 64 89 01 48
RSP: 002b:00007ffec2cf5ff8 EFLAGS: 00000206 ORIG_RAX: 0000000000000067
RAX: ffffffffffffffda RBX: 00007f95b8ce14a0 RCX: 00007f95b8b42fa7
RDX: 00000000000003ff RSI: 00007f95b8ce14a0 RDI: 0000000000000002
RBP: 0000000000000000 R08: 0000000000000007 R09: 115ec6d6946061e3
R10: 0000000000004000 R11: 0000000000000206 R12: 00007f95b8ce14a0
R13: 00007f95b8cd1212 R14: 00007f95b8ce16e3 R15: 00007f95b8ce16e3
 </TASK>

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/01/06 23:04 upstream 5428dc1906dd f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in vhost_task_stop
2024/12/18 09:38 upstream aef25be35d23 a0626d3a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in vhost_task_stop
2024/12/15 23:56 upstream 2d8308bf5b67 7cbfbb3a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in vhost_task_stop
2024/11/26 16:49 upstream 2c22dc1ee3a1 11dbc254 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in vhost_task_stop
2024/11/26 04:58 upstream 2c22dc1ee3a1 a84878fc .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in vhost_task_stop
2024/11/26 04:56 upstream 2c22dc1ee3a1 a84878fc .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in vhost_task_stop
2024/12/23 01:26 upstream bcde95ce32b6 b4fbdbd4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 INFO: task hung in vhost_task_stop
2024/12/19 16:59 linux-next 8503810115fb 1d58202c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in vhost_task_stop
* Struck through repros no longer work on HEAD.