INFO: task syz.0.16:6696 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.16 state:D stack:28984 pid:6696 tgid:6686 ppid:6590 task_flags:0x400040 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5260 [inline]
__schedule+0x1472/0x4fe0 kernel/sched/core.c:6867
__schedule_loop kernel/sched/core.c:6949 [inline]
rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7245
rt_mutex_slowlock_block+0x508/0x680 kernel/locking/rtmutex.c:1647
__rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
__rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline]
rt_mutex_slowlock+0x2dc/0x710 kernel/locking/rtmutex.c:1800
__rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
__mutex_lock_common kernel/locking/rtmutex_api.c:534 [inline]
mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:552
fdget_pos+0x252/0x320 fs/file.c:1255
class_fd_pos_constructor include/linux/file.h:85 [inline]
ksys_read+0x79/0x270 fs/read_write.c:706
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7faed883a079
RSP: 002b:00007faed7a75028 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007faed8a66080 RCX: 00007faed883a079
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 00007faed88cca4c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007faed8a66080 R15: 00007ffd151a6ab8
Showing all locks held in the system:
1 lock held by khungtaskd/38:
#0: ffffffff8dbc77c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8dbc77c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#0: ffffffff8dbc77c0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
4 locks held by kworker/u8:5/1290:
2 locks held by getty/5553:
#0: ffff88814f3410a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000421b2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13c0 drivers/tty/n_tty.c:2211
2 locks held by syz.0.16/6688:
1 lock held by syz.0.16/6696:
#0: ffff8880347db328 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1255
2 locks held by syz.1.17/6758:
1 lock held by syz.1.17/6760:
#0: ffff88803317e928 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1255
4 locks held by syz.2.18/6788:
1 lock held by syz.2.18/6790:
#0: ffff8880351afd28 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1255
2 locks held by syz.3.19/6813:
1 lock held by syz.3.19/6815:
#0: ffff8880354dc528 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1255
2 locks held by syz.4.20/6845:
1 lock held by syz.4.20/6847:
#0: ffff888029721d28 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1255
2 locks held by syz.5.21/6884:
1 lock held by syz.5.21/6886:
#0: ffff888030558128 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1255
2 locks held by syz.6.22/6916:
1 lock held by syz.6.22/6918:
#0: ffff888011255f28 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1255
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x135/0x170 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
watchdog+0xf90/0xfe0 kernel/hung_task.c:515
kthread+0x726/0x8b0 kernel/kthread.c:463
ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6813 Comm: syz.3.19 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:mark_lock+0x95/0x190 kernel/locking/lockdep.c:4731
Code: 83 3d 12 c8 a8 0d 00 75 13 48 8d 3d 45 d3 ab 0d 48 c7 c6 e0 cc 44 8d 67 48 0f b9 3a 90 31 c9 4c 89 fe 4c 89 f7 b8 01 00 00 00 <85> 69 60 74 10 5b 41 5c 41 5d 41 5e 41 5f 5d e9 07 0e 72 09 cc 49
RSP: 0018:ffffc90004147880 EFLAGS: 00000006
RAX: 0000000000000001 RBX: 0000000000000002 RCX: ffffffff92d4d150
RDX: 0000000000000002 RSI: ffff8880382c8bb8 RDI: ffff8880382c8000
RBP: 0000000000000004 R08: ffffffff8f47e477 R09: 1ffffffff1e8fc8e
R10: dffffc0000000000 R11: fffffbfff1e8fc8f R12: ffff8880382c8bb8
R13: 0000000000000000 R14: ffff8880382c8b90 R15: 0000000000000001
FS: 00007fc5c6a466c0(0000) GS:ffff8881265c9000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001000 CR3: 0000000024160000 CR4: 00000000003526f0
Call Trace:
mark_held_locks kernel/locking/lockdep.c:4325 [inline]
__trace_hardirqs_on_caller kernel/locking/lockdep.c:4343 [inline]
lockdep_hardirqs_on_prepare+0x110/0x260 kernel/locking/lockdep.c:4410
trace_hardirqs_on+0x28/0x40 kernel/trace/trace_preemptirq.c:78
irqentry_exit+0x59c/0x620 kernel/entry/common.c:219
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0010:rep_movs_alternative+0x4a/0x90 arch/x86/lib/copy_user_64.S:74
Code: cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 8b 06 48 89 07 48 83 c6 08 48 83 c7 08 83 e9 08 74 db 83 f9 08 73 e8 eb c5 a4 c3 cc cc cc cc 48 8b 06 48 89 07 48 8d 47 08 48 83 e0 f8 48
RSP: 0018:ffffc900041479f8 EFLAGS: 00050202
RAX: ffffffff848e0601 RBX: ffff8880398c2000 RCX: 0000000000000036
RDX: 0000000000000000 RSI: ffff8880398c2e80 RDI: 0000200000001000
RBP: ffffc90004147b78 R08: ffff8880398c2eb5 R09: 1ffff110073185d6
R10: dffffc0000000000 R11: ffffed10073185d7 R12: 1ffff92000828faf
R13: 0000200000000180 R14: ffffc90004147d88 R15: 0000000000000eb6
copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline]
raw_copy_to_user arch/x86/include/asm/uaccess_64.h:147 [inline]
copy_to_user_iter lib/iov_iter.c:25 [inline]
iterate_ubuf include/linux/iov_iter.h:30 [inline]
iterate_and_advance2 include/linux/iov_iter.h:302 [inline]
iterate_and_advance include/linux/iov_iter.h:330 [inline]
_copy_to_iter+0x255/0x17d0 lib/iov_iter.c:197
copy_to_iter include/linux/uio.h:220 [inline]
seq_read_iter+0xbf6/0xe20 fs/seq_file.c:281
proc_reg_read_iter+0x1bf/0x290 fs/proc/inode.c:299
new_sync_read fs/read_write.c:491 [inline]
vfs_read+0x58b/0xa70 fs/read_write.c:572
ksys_read+0x156/0x270 fs/read_write.c:715
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc5c77ea079
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc5c6a46028 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007fc5c7a15fa0 RCX: 00007fc5c77ea079
RDX: 0000000000002024 RSI: 0000200000000180 RDI: 0000000000000005
RBP: 00007fc5c787ca4c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fc5c7a15fa0 R15: 00007ffff4610b78