INFO: task syz.6.5944:28967 blocked for more than 143 seconds.
Tainted: G L syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.5944 state:D stack:28856 pid:28967 tgid:28961 ppid:24674 task_flags:0x400040 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5510 [inline]
__schedule+0x125c/0x6730 kernel/sched/core.c:7234
__schedule_loop kernel/sched/core.c:7311 [inline]
schedule+0xdd/0x2c0 kernel/sched/core.c:7326
cgroup_lock_and_drain_offline+0x383/0x800 kernel/cgroup/cgroup.c:3275
cgroup_kn_lock_live+0x188/0x520 kernel/cgroup/cgroup.c:1715
cgroup_subtree_control_write+0x3dd/0xe90 kernel/cgroup/cgroup.c:3577
cgroup_file_write+0x1e6/0x8a0 kernel/cgroup/cgroup.c:4337
kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x6ac/0x1050 fs/read_write.c:687
ksys_write+0x12a/0x250 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdf6b59e0d9
RSP: 002b:00007fdf6c4ef028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fdf6b826270 RCX: 00007fdf6b59e0d9
RDX: 000000000000000b RSI: 0000200000000180 RDI: 000000000000000b
RBP: 00007fdf6b635024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdf6b826308 R14: 00007fdf6b826270 R15: 00007ffc93dc7518
INFO: task syz.3.5958:29026 blocked for more than 143 seconds.
Tainted: G L syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.5958 state:D stack:26664 pid:29026 tgid:29021 ppid:17227 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5510 [inline]
__schedule+0x125c/0x6730 kernel/sched/core.c:7234
__schedule_loop kernel/sched/core.c:7311 [inline]
schedule+0xdd/0x2c0 kernel/sched/core.c:7326
cgroup_lock_and_drain_offline+0x383/0x800 kernel/cgroup/cgroup.c:3275
cgroup_kn_lock_live+0x188/0x520 kernel/cgroup/cgroup.c:1715
cgroup_subtree_control_write+0x3dd/0xe90 kernel/cgroup/cgroup.c:3577
cgroup_file_write+0x1e6/0x8a0 kernel/cgroup/cgroup.c:4337
kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x6ac/0x1050 fs/read_write.c:687
ksys_write+0x12a/0x250 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff48979e0d9
RSP: 002b:00007ff48a695028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007ff489a26180 RCX: 00007ff48979e0d9
RDX: 0000000000000005 RSI: 0000200000000300 RDI: 000000000000000b
RBP: 00007ff489835024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff489a26218 R14: 00007ff489a26180 R15: 00007fff2336fd68
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8ebe8200 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffffffff8ebe8200 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
#0: ffffffff8ebe8200 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
2 locks held by getty/20171:
#0: ffff8880380970a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1: ffffc90002fe22e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x14e0 drivers/tty/n_tty.c:2211
3 locks held by syz.6.5944/28967:
#0: ffff888026292b70 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259
#1: ffff88807ce5a450 (sb_writers#10){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
#2: ffff8880670a9080 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:336
3 locks held by syz.3.5958/29026:
#0: ffff88807625cb70 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259
#1: ffff88807ce5a450 (sb_writers#10){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
#2: ffff888052c7f880 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:336
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:122
nmi_trigger_cpumask_backtrace+0x21c/0x2a0 lib/nmi_backtrace.c:65
trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x141/0x190 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
watchdog+0xcb1/0x1030 kernel/hung_task.c:561
kthread+0x370/0x450 kernel/kthread.c:436
ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 4318 Comm: kworker/u8:10 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Workqueue: 0x0 (events_unbound)
RIP: 0010:variable_test_bit arch/x86/include/asm/bitops.h:222 [inline]
RIP: 0010:arch_test_bit arch/x86/include/asm/bitops.h:233 [inline]
RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
RIP: 0010:cpumask_test_cpu include/linux/cpumask.h:651 [inline]
RIP: 0010:cpu_online include/linux/cpumask.h:1233 [inline]
RIP: 0010:trace_lock_release include/trace/events/lock.h:68 [inline]
RIP: 0010:lock_release+0x38/0x310 kernel/locking/lockdep.c:5879
Code: fb 48 83 ec 18 65 48 8b 2d 3d 86 7e 12 48 89 6c 24 10 48 89 f5 0f 1f 44 00 00 65 8b 05 55 86 7e 12 83 f8 07 0f 87 07 02 00 00 <48> 0f a3 05 e0 8c 3c 0f 0f 82 02 02 00 00 44 8b 05 a7 c0 3c 0f 45
RSP: 0018:ffffc9001008fa00 EFLAGS: 00000097
RAX: 0000000000000000 RBX: ffff8880b843b520 RCX: 0000000000000001
RDX: 1ffff1101708780d RSI: ffffffff81dd0643 RDI: ffff8880b843b520
RBP: ffffffff81dd0643 R08: ffff8880b843b718 R09: ffff8880b843c1c0
R10: ffff8880b843c028 R11: ffff8880b843b4c0 R12: ffff8880b843c128
R13: ffff88801cecc800 R14: ffff8880b843b4c0 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff888123dd8000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000556bc781f0c8 CR3: 000000000e994000 CR4: 00000000003526f0
Call Trace:
__raw_spin_unlock include/linux/spinlock_api_smp.h:167 [inline]
_raw_spin_unlock+0x16/0x50 kernel/locking/spinlock.c:190
raw_spin_rq_unlock kernel/sched/sched.h:1659 [inline]
sched_balance_newidle kernel/sched/fair.c:14405 [inline]
pick_task_fair+0x6a3/0x1bf0 kernel/sched/fair.c:9948
__pick_next_task+0x105/0x710 kernel/sched/core.c:6144
pick_next_task kernel/sched/core.c:6242 [inline]
__schedule+0x587/0x6730 kernel/sched/core.c:7149
__schedule_loop kernel/sched/core.c:7311 [inline]
schedule+0xdd/0x2c0 kernel/sched/core.c:7326
worker_thread+0x53b/0xe50 kernel/workqueue.c:3501
kthread+0x370/0x450 kernel/kthread.c:436
ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245