INFO: task syz.2.2013:11288 blocked for more than 144 seconds.
Tainted: G L syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.2013 state:D stack:27672 pid:11288 tgid:11286 ppid:5599 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5510 [inline]
__schedule+0x16dc/0x5500 kernel/sched/core.c:7234
__schedule_loop kernel/sched/core.c:7311 [inline]
rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7607
rt_mutex_slowlock_block+0x55c/0x680 kernel/locking/rtmutex.c:1670
__rt_mutex_slowlock kernel/locking/rtmutex.c:1747 [inline]
__rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1787 [inline]
rt_mutex_slowlock+0x2d4/0x780 kernel/locking/rtmutex.c:1827
__rt_mutex_lock kernel/locking/rtmutex.c:1842 [inline]
__mutex_lock_common kernel/locking/rtmutex_api.c:560 [inline]
mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:578
write_threads+0x3a0/0x5a0 fs/nfsd/nfsctl.c:432
nfsctl_transaction_write+0x112/0x160 fs/nfsd/nfsctl.c:112
vfs_write+0x29f/0xbb0 fs/read_write.c:685
ksys_write+0x156/0x270 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc87648de99
RSP: 002b:00007fc8746e6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fc876715fa0 RCX: 00007fc87648de99
RDX: 0000000000000002 RSI: 0000200000000740 RDI: 0000000000000003
RBP: 00007fc876523eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc876716038 R14: 00007fc876715fa0 R15: 00007ffd273610f8
Showing all locks held in the system:
6 locks held by kworker/u8:1/13:
3 locks held by ktimers/0/16:
1 lock held by khungtaskd/38:
#0: ffffffff8e1c3000 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffffffff8e1c3000 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
#0: ffffffff8e1c3000 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
5 locks held by kworker/u8:12/3399:
2 locks held by getty/5349:
#0: ffff888035cdb0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc90003cc62e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x460/0x1360 drivers/tty/n_tty.c:2211
10 locks held by syz-executor/5595:
8 locks held by kworker/u8:13/5808:
3 locks held by syz.2.2013/11288:
#0: ffff888034479328 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1259
#1: ffff888062b1c500 (sb_writers#18){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2733 [inline]
#1: ffff888062b1c500 (sb_writers#18){.+.+}-{0:0}, at: vfs_write+0x231/0xbb0 fs/read_write.c:683
#2: ffffffff8e4e9538 (nfsd_mutex){+.+.}-{4:4}, at: write_threads+0x3a0/0x5a0 fs/nfsd/nfsctl.c:432
3 locks held by syz.2.2013/11290:
#0: ffff88802c3bd928 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1259
#1: ffff888062b1c500 (sb_writers#18){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2733 [inline]
#1: ffff888062b1c500 (sb_writers#18){.+.+}-{0:0}, at: vfs_write+0x231/0xbb0 fs/read_write.c:683
#2: ffffffff8e4e9538 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd20 fs/nfsd/nfsctl.c:860
1 lock held by udevd/11457:
4 locks held by syz.0.2355/12415:
4 locks held by syz.5.2354/12416:
#0: ffff88805d987158 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
#0: ffff88805d987158 (sk_lock-AF_INET){+.+.}-{0:0}, at: sctp_bind+0x23/0x130 net/sctp/socket.c:314
#1: ffffffff8e059220 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
#2: ffffffff8e1c3000 (rcu_read_lock){....}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
#3: ffff88805d9870a0 (slock-AF_INET#2){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock_rt.h:90 [inline]
#3: ffff88805d9870a0 (slock-AF_INET#2){+...}-{3:3}, at: release_sock+0x45/0x290 net/core/sock.c:3857
6 locks held by syz.5.2354/12419:
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 38 Comm: khungtaskd Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:122
nmi_trigger_cpumask_backtrace+0x17a/0x380 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+0x135/0x170 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
watchdog+0xfd7/0x1030 kernel/hung_task.c:561
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 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: 16 Comm: ktimers/0 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:in_softirq_really kernel/kcov.c:171 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:246 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x32/0xa0 kernel/kcov.c:314
Code: 65 48 8b 0d 58 20 d8 10 65 44 8b 05 78 20 d8 10 41 81 e0 00 00 ff 00 ba 00 01 00 00 23 91 f4 0b 00 00 41 89 d1 45 09 c1 74 12 <45> 85 c0 75 5f 85 d2 74 5b 83 b9 0c 17 00 00 00 74 52 8b 91 e0 16
RSP: 0018:ffffc90000157098 EFLAGS: 00000206
RAX: ffffffff891fc406 RBX: 0000000000000000 RCX: ffff88801caa8000
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000100
R10: ffffc90000157240 R11: fffff5200002ae4a R12: 0000000000000003
R13: ffff88805f79f8c8 R14: dffffc0000000000 R15: 0000000000000001
FS: 0000000000000000(0000) GS:ffff888125c41000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f396df956b8 CR3: 000000003a55c000 CR4: 00000000003526f0
Call Trace:
lockdep_rtnl_is_held+0x26/0x40 net/core/rtnetlink.c:182
__in6_dev_get include/net/addrconf.h:348 [inline]
ip6_ignore_linkdown+0x4f/0x140 include/net/addrconf.h:457
find_match+0x9c/0xb80 net/ipv6/route.c:783
__find_rr_leaf+0x243/0x740 net/ipv6/route.c:872
find_rr_leaf net/ipv6/route.c:893 [inline]
rt6_select net/ipv6/route.c:937 [inline]
fib6_table_lookup+0x3cb/0xb00 net/ipv6/route.c:2255
ip6_pol_route+0x229/0x14d0 net/ipv6/route.c:2292
pol_lookup_func include/net/ip6_fib.h:669 [inline]
fib6_rule_lookup+0x556/0x730 net/ipv6/fib6_rules.c:123
ip6_route_input_lookup net/ipv6/route.c:2363 [inline]
ip6_route_input+0x78d/0xb20 net/ipv6/route.c:2666
ip6_rcv_finish+0x141/0x280 net/ipv6/ip6_input.c:117
NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:318
__netif_receive_skb_one_core net/core/dev.c:6212 [inline]
__netif_receive_skb net/core/dev.c:6325 [inline]
process_backlog+0x3bf/0xc50 net/core/dev.c:6676
__napi_poll+0xae/0x550 net/core/dev.c:7735
napi_poll net/core/dev.c:7798 [inline]
net_rx_action+0x621/0xd70 net/core/dev.c:7955
handle_softirqs+0x1d9/0x6c0 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
run_ktimerd+0x69/0x100 kernel/softirq.c:1151
smpboot_thread_fn+0x57c/0xa80 kernel/smpboot.c:160
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245