[syzbot] [kernel?] INFO: task hung in vmci_qp_broker_detach

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7fa4d8dc380f Add linux-next specific files for 20250821
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17a3ca62580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ae76068823a236b3
dashboard link: https://syzkaller.appspot.com/bug?extid=68c586d577defab7485e
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14975262580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/63178c6ef3f8/disk-7fa4d8dc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c5c27b0841e0/vmlinux-7fa4d8dc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9a8832715cca/bzImage-7fa4d8dc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+68c586...@syzkaller.appspotmail.com

INFO: task syz.1.8150:15216 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.8150 state:D stack:27448 pid:15216 tgid:15216 ppid:13883 task_flags:0x400040 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5357 [inline]
__schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
__schedule_loop kernel/sched/core.c:7043 [inline]
schedule+0x165/0x360 kernel/sched/core.c:7058
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115
__mutex_lock_common kernel/locking/mutex.c:676 [inline]
__mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760
vmci_qp_broker_detach+0x113/0xf10 drivers/misc/vmw_vmci/vmci_queue_pair.c:2095
ctx_free_ctx drivers/misc/vmw_vmci/vmci_context.c:424 [inline]
kref_put include/linux/kref.h:65 [inline]
vmci_ctx_put+0x603/0xbf0 drivers/misc/vmw_vmci/vmci_context.c:477
vmci_ctx_enqueue_datagram+0x3ab/0x420 drivers/misc/vmw_vmci/vmci_context.c:340
dg_dispatch_as_host drivers/misc/vmw_vmci/vmci_datagram.c:276 [inline]
vmci_datagram_dispatch+0x43f/0xc10 drivers/misc/vmw_vmci/vmci_datagram.c:340
qp_notify_peer drivers/misc/vmw_vmci/vmci_queue_pair.c:1481 [inline]
vmci_qp_broker_detach+0x8c8/0xf10 drivers/misc/vmw_vmci/vmci_queue_pair.c:2188
ctx_free_ctx drivers/misc/vmw_vmci/vmci_context.c:424 [inline]
kref_put include/linux/kref.h:65 [inline]
vmci_ctx_put+0x603/0xbf0 drivers/misc/vmw_vmci/vmci_context.c:477
vmci_host_close+0x98/0x160 drivers/misc/vmw_vmci/vmci_host.c:143
__fput+0x449/0xa70 fs/file_table.c:468
task_work_run+0x1d4/0x260 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xec/0x130 kernel/entry/common.c:43
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f68c378ebe9
RSP: 002b:00007ffe9f27e238 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 000000000008c3bc RCX: 00007f68c378ebe9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000001 R09: 000000099f27e52f
R10: 0000001b2f520000 R11: 0000000000000246 R12: 00007f68c39c5fac
R13: 00007f68c39c5fa0 R14: ffffffffffffffff R15: 0000000000000003
</TASK>
INFO: task syz.2.8151:15217 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.8151 state:D stack:28360 pid:15217 tgid:15217 ppid:14709 task_flags:0x400040 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5357 [inline]
__schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
__schedule_loop kernel/sched/core.c:7043 [inline]
schedule+0x165/0x360 kernel/sched/core.c:7058
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115
__mutex_lock_common kernel/locking/mutex.c:676 [inline]
__mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760
qp_broker_alloc+0x1a2/0x2330 drivers/misc/vmw_vmci/vmci_queue_pair.c:1731
vmci_qp_broker_alloc+0x92/0xc0 drivers/misc/vmw_vmci/vmci_queue_pair.c:1942
vmci_host_do_alloc_queuepair drivers/misc/vmw_vmci/vmci_host.c:470 [inline]
vmci_host_unlocked_ioctl+0x1262/0x2650 drivers/misc/vmw_vmci/vmci_host.c:934
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:598 [inline]
__se_sys_ioctl+0xf9/0x170 fs/ioctl.c:584
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f34e798ebe9
RSP: 002b:00007ffcb7deb748 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f34e7bc5fa0 RCX: 00007f34e798ebe9
RDX: 0000200000000540 RSI: 00000000000007a8 RDI: 0000000000000005
RBP: 00007f34e7a11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f34e7bc5fa0 R14: 00007f34e7bc5fa0 R15: 0000000000000003
</TASK>
INFO: task syz.3.8152:15218 blocked for more than 144 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.8152 state:D stack:27176 pid:15218 tgid:15218 ppid:14309 task_flags:0x400040 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5357 [inline]
__schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
__schedule_loop kernel/sched/core.c:7043 [inline]
schedule+0x165/0x360 kernel/sched/core.c:7058
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115
__mutex_lock_common kernel/locking/mutex.c:676 [inline]
__mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760
qp_broker_alloc+0x1a2/0x2330 drivers/misc/vmw_vmci/vmci_queue_pair.c:1731
vmci_qp_broker_alloc+0x92/0xc0 drivers/misc/vmw_vmci/vmci_queue_pair.c:1942
vmci_host_do_alloc_queuepair drivers/misc/vmw_vmci/vmci_host.c:470 [inline]
vmci_host_unlocked_ioctl+0x1262/0x2650 drivers/misc/vmw_vmci/vmci_host.c:934
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:598 [inline]
__se_sys_ioctl+0xf9/0x170 fs/ioctl.c:584
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd21db8ebe9
RSP: 002b:00007ffef05a1128 EFLAGS: 00000246
ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fd21ddc5fa0 RCX: 00007fd21db8ebe9
RDX: 0000200000000540 RSI: 00000000000007a8 RDI: 0000000000000003
RBP: 00007fd21dc11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd21ddc5fa0 R14: 00007fd21ddc5fa0 R15: 0000000000000003
</TASK>
INFO: task syz.0.8114:15287 blocked for more than 144 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.8114 state:D stack:27336 pid:15287 tgid:15287 ppid:15178 task_flags:0x400040 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5357 [inline]
__schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
__schedule_loop kernel/sched/core.c:7043 [inline]
schedule+0x165/0x360 kernel/sched/core.c:7058
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115
__mutex_lock_common kernel/locking/mutex.c:676 [inline]
__mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760
qp_broker_alloc+0x1a2/0x2330 drivers/misc/vmw_vmci/vmci_queue_pair.c:1731
vmci_qp_broker_alloc+0x92/0xc0 drivers/misc/vmw_vmci/vmci_queue_pair.c:1942
vmci_host_do_alloc_queuepair drivers/misc/vmw_vmci/vmci_host.c:470 [inline]
vmci_host_unlocked_ioctl+0x1262/0x2650 drivers/misc/vmw_vmci/vmci_host.c:934
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:598 [inline]
__se_sys_ioctl+0xf9/0x170 fs/ioctl.c:584
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f874118ebe9
RSP: 002b:00007ffc65512958 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f87413c5fa0 RCX: 00007f874118ebe9
RDX: 0000200000000540 RSI: 00000000000007a8 RDI: 0000000000000003
RBP: 00007f8741211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f87413c5fa0 R14: 00007f87413c5fa0 R15: 0000000000000003
</TASK>
INFO: lockdep is turned off.
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline]
watchdog+0xf60/0xfa0 kernel/hung_task.c:495
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x47c/0x820 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82
Code: cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 83 0f 22 00 f3 0f 1e fa fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffffff8e207d80 EFLAGS: 000002c2
RAX: 2609b6a075c24000 RBX: ffffffff8197ac78 RCX: 2609b6a075c24000
RDX: 0000000000000001 RSI: ffffffff8c04e5e0 RDI: ffffffff8197ac78
RBP: ffffffff8e207ea8 R08: ffff8880b8632f9b R09: 1ffff110170c65f3
R10: dffffc0000000000 R11: ffffed10170c65f4 R12: ffffffff8fe52d30
R13: 0000000000000000 R14: 0000000000000000 R15: 1ffffffff1c52a38
FS: 0000000000000000(0000) GS:ffff8881257c4000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbef4cf7d60 CR3: 000000000e338000 CR4: 00000000003526f0
Call Trace:
<TASK>
arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
default_idle+0x13/0x20 arch/x86/kernel/process.c:757
default_idle_call+0x74/0xb0 kernel/sched/idle.c:122
cpuidle_idle_call kernel/sched/idle.c:190 [inline]
do_idle+0x1e8/0x510 kernel/sched/idle.c:330
cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:428
rest_init+0x2de/0x300 init/main.c:756
start_kernel+0x3a9/0x410 init/main.c:1109
x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:307
x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:288
common_startup_64+0x13e/0x147
</TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup