syzbot

INFO: task syz.3.7923:24373 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.3.7923      state:D stack:26224 pid:24373 tgid:24372 ppid:5628   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x17b4/0x5680 kernel/sched/core.c:7189
 __schedule_loop kernel/sched/core.c:7268 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7283
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7340
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0x7f7/0x1550 kernel/locking/mutex.c:820
 nfsd_nl_rpc_status_get_dumpit+0xdc/0x1410 fs/nfsd/nfsctl.c:1494
 genl_dumpit+0x10b/0x1b0 net/netlink/genetlink.c:1026
 netlink_dump+0x702/0xe10 net/netlink/af_netlink.c:2325
 __netlink_dump_start+0x5cb/0x7e0 net/netlink/af_netlink.c:2440
 genl_family_rcv_msg_dumpit+0x213/0x310 net/netlink/genetlink.c:1075
 genl_family_rcv_msg net/netlink/genetlink.c:1191 [inline]
 genl_rcv_msg+0x5e8/0x7a0 net/netlink/genetlink.c:1209
 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:787 [inline]
 __sock_sendmsg net/socket.c:802 [inline]
 ____sys_sendmsg+0x972/0x9f0 net/socket.c:2698
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
 __sys_sendmsg net/socket.c:2784 [inline]
 __do_sys_sendmsg net/socket.c:2789 [inline]
 __se_sys_sendmsg net/socket.c:2787 [inline]
 __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2787
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fac4459cdd9
RSP: 002b:00007fac453ee028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fac44815fa0 RCX: 00007fac4459cdd9
RDX: 0000000000000800 RSI: 0000200000000180 RDI: 0000000000000003
RBP: 00007fac44632d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fac44816038 R14: 00007fac44815fa0 R15: 00007ffef1d9d0a8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e95cd60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8e95cd60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #0: ffffffff8e95cd60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
3 locks held by kworker/1:2/801:
 #0: ffff8880b873aea0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x31/0x150 kernel/sched/core.c:652
 #1: ffff8880b8724588 (psi_seq){-.-.}-{0:0}, at: psi_task_switch+0x53/0x880 kernel/sched/psi.c:933
 #2: ffff88801e6800c0 (&ACCESS_PRIVATE(ssp->srcu_sup, lock)){-...}-{2:2}, at: srcu_reschedule+0x44/0x1d0 kernel/rcu/srcutree.c:1944
2 locks held by getty/5373:
 #0: ffff888032a000a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000322b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13a0 drivers/tty/n_tty.c:2211
2 locks held by kworker/u8:3/17147:
 #0: ffff88813fe7c940 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3277 [inline]
 #0: ffff88813fe7c940 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860 kernel/workqueue.c:3385
 #1: ffffc90005bf7c40 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3278 [inline]
 #1: ffffc90005bf7c40 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860 kernel/workqueue.c:3385
2 locks held by syz.0.5454/18392:
 #0: ffffffff8fe3ed48 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8ec8ac60 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x141/0x1670 fs/nfsd/nfsctl.c:1938
3 locks held by syz.3.7923/24373:
 #0: ffffffff8fe3ed48 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffff88802b73e6e8 (nlk_cb_mutex-GENERIC){+.+.}-{4:4}, at: __netlink_dump_start+0xfe/0x7e0 net/netlink/af_netlink.c:2404
 #2: ffffffff8ec8ac60 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_rpc_status_get_dumpit+0xdc/0x1410 fs/nfsd/nfsctl.c:1494
1 lock held by syz-executor/24935:
2 locks held by syz.4.8528/25975:
 #0: ffff888052b640d8 (&type->s_umount_key#116){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff888052b640d8 (&type->s_umount_key#116){++++}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
 #0: ffff888052b640d8 (&type->s_umount_key#116){++++}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:508
 #1: ffffffff8ec8ac60 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x4e/0xd0 fs/nfsd/nfssvc.c:576
2 locks held by syz.0.9440/30735:
 #0: ffffffff8fe3ed48 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8ec8ac60 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_get_doit+0x1c0/0x790 fs/nfsd/nfsctl.c:1728
1 lock held by syz.8.9715/31998:
 #0: ffff888052b640d8 (&type->s_umount_key#116){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff888052b640d8 (&type->s_umount_key#116){++++}-{4:4}, at: super_lock+0x2d6/0x3d0 fs/super.c:122
1 lock held by syz-executor/32416:
7 locks held by syz-executor/641:
 #0: ffff888036676410 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2724 [inline]
 #0: ffff888036676410 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x227/0xb90 fs/read_write.c:684
 #1: ffff888038c81c80 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1de/0x540 fs/kernfs/file.c:343
 #2: ffff888029ed1968 (kn->active#52){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
 #2: ffff888029ed1968 (kn->active#52){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x231/0x540 fs/kernfs/file.c:344
 #3: ffffffff8f64ecc0 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: del_device_store+0xd7/0x370 drivers/net/netdevsim/bus.c:234
 #4: ffff888056429128 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1040 [inline]
 #4: ffff888056429128 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1174 [inline]
 #4: ffff888056429128 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb6/0x870 drivers/base/dd.c:1372
 #5: ffff88805642e258 (&devlink->lock_key#6){+.+.}-{4:4}, at: nsim_drv_remove+0x50/0x170 drivers/net/netdevsim/dev.c:1799
 #6: ffffffff8e962f38 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
4 locks held by dhcpcd-run-hook/1324:
 #0: ffff8880b873aea0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x31/0x150 kernel/sched/core.c:652
 #1: ffffffff9a48a588 (&____s->seqcount#2){----}-{0:0}, at: ktime_get_real_ts64+0xa9/0x3e0 kernel/time/timekeeping.c:943
 #2: ffff888045043d98 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:342 [inline]
 #2: ffff888045043d98 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: pte_offset_map_lock+0x13d/0x210 mm/pgtable-generic.c:404
 #3: ffffffff8e95cd60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #3: ffffffff8e95cd60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #3: ffffffff8e95cd60 (rcu_read_lock){....}-{1:3}, at: page_table_check_set+0x126/0x510 mm/page_table_check.c:112
4 locks held by sed/1329:

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

NMI backtrace for cpu 0
CPU: 0 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 04/18/2026
Call Trace:
 <TASK>
 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: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+0xfd3/0x1030 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
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 4970 Comm: syslogd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:should_resched arch/x86/include/asm/preempt.h:104 [inline]
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x53/0x80 kernel/locking/spinlock.c:198
Code: 74 05 e8 80 f8 22 f6 9c 58 a9 00 02 00 00 75 27 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 e8 54 e7 e8 f5 65 8b 05 ed 20 8e 07 <85> c0 74 18 5b 41 5e e9 bc 61 65 f5 cc e8 cb 55 fd ff f7 c3 00 02
RSP: 0018:ffffc900044f7898 EFLAGS: 00000297
RAX: 0000000080000000 RBX: 0000000000000292 RCX: 0000000000000000
RDX: 0000000000000006 RSI: ffffffff8dfa5a7b RDI: 00000000ffffffff
RBP: 0000000000000000 R08: ffffffff9030a7f7 R09: 1ffffffff20614fe
R10: dffffc0000000000 R11: fffffbfff20614ff R12: ffff88802f6f0870
R13: ffff88802f6f0780 R14: ffffffff9a64aeb0 R15: 0000000000000001
FS:  00007fd2effc3c80(0000) GS:ffff888125390000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005606f4440950 CR3: 0000000032fbf000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 __debug_check_no_obj_freed lib/debugobjects.c:1125 [inline]
 debug_check_no_obj_freed+0x52e/0x550 lib/debugobjects.c:1146
 slab_free_hook mm/slub.c:2620 [inline]
 slab_free mm/slub.c:6250 [inline]
 kmem_cache_free+0xfd/0x650 mm/slub.c:6377
 __unix_dgram_recvmsg+0x9df/0xd60 net/unix/af_unix.c:2669
 sock_recvmsg_nosec net/socket.c:1137 [inline]
 sock_recvmsg+0x172/0x1b0 net/socket.c:1159
 sock_read_iter+0x251/0x320 net/socket.c:1229
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x582/0xa70 fs/read_write.c:574
 ksys_read+0x150/0x270 fs/read_write.c:717
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd2f0113407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffd865ad150 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007fd2effc3c80 RCX: 00007fd2f0113407
RDX: 00000000000000ff RSI: 000055ca6a6b2950 RDI: 0000000000000000
RBP: 000055ca6a6b2910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000055ca6a6b299a
R13: 0000000000000000 R14: 000055ca6a6b2950 R15: 000055ca52508d98
 </TASK>