syzbot

INFO: task syz.3.540:8132 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.3.540       state:D stack:25720 pid:8132  tgid:8128  ppid:5823   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x1139/0x6150 kernel/sched/core.c:6863
 __schedule_loop kernel/sched/core.c:6945 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6960
 io_schedule+0xbf/0x130 kernel/sched/core.c:7789
 folio_wait_bit_common+0x3d5/0x9e0 mm/filemap.c:1323
 folio_lock include/linux/pagemap.h:1159 [inline]
 migrate_folio_unmap mm/migrate.c:1249 [inline]
 migrate_pages_batch+0x1487/0x3bb0 mm/migrate.c:1890
 migrate_pages_sync+0x4c5/0x8a0 mm/migrate.c:2034
 migrate_pages+0x1b0b/0x2350 mm/migrate.c:2116
 compact_zone+0x1e78/0x4540 mm/compaction.c:2647
 compact_node+0x1a3/0x2c0 mm/compaction.c:2916
 compact_nodes mm/compaction.c:2938 [inline]
 sysctl_compaction_handler mm/compaction.c:2989 [inline]
 sysctl_compaction_handler+0x141/0x210 mm/compaction.c:2976
 proc_sys_call_handler+0x493/0x5b0 fs/proc/proc_sysctl.c:600
 iter_file_splice_write+0xa24/0x12b0 fs/splice.c:738
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x192/0x6c0 fs/splice.c:1161
 splice_direct_to_actor+0x345/0xa30 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0x174/0x240 fs/splice.c:1230
 do_sendfile+0xb06/0xe50 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1425 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x154/0x220 fs/read_write.c:1417
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6863b8f749
RSP: 002b:00007f686499a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f6863de6180 RCX: 00007f6863b8f749
RDX: 00002000000000c0 RSI: 0000000000000009 RDI: 000000000000000a
RBP: 00007f6863c13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6863de6218 R14: 00007f6863de6180 R15: 00007ffdd0153968
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e3c96a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e3c96a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8e3c96a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
5 locks held by kworker/u8:8/2021:
 #0: ffff88801badc948 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232
 #1: ffffc900054a7c90 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233
 #2: ffffffff9012b3d0 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xad/0x830 net/core/net_namespace.c:670
 #3: ffffffff90141ba8 (rtnl_mutex){+.+.}-{4:4}, at: ops_exit_rtnl_list net/core/net_namespace.c:173 [inline]
 #3: ffffffff90141ba8 (rtnl_mutex){+.+.}-{4:4}, at: ops_undo_list+0x7e9/0xab0 net/core/net_namespace.c:248
 #4: ffffffff8e3d4df8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x284/0x3c0 kernel/rcu/tree_exp.h:311
2 locks held by getty/5579:
 #0: ffff8880316950a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x1510 drivers/tty/n_tty.c:2211
4 locks held by kworker/0:7/5923:
 #0: ffff88801fefe948 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232
 #1: ffffc90002f47c90 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233
 #2: ffff888143746198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #2: ffff888143746198 (&dev->mutex){....}-{4:4}, at: hub_event+0x1c0/0x52f0 drivers/usb/core/hub.c:5899
 #3: ffff88807c4bb198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #3: ffff88807c4bb198 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4e0 drivers/base/dd.c:1006
1 lock held by udevd/6219:
 #0: ffff888025d88358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe40 block/bdev.c:962
3 locks held by kworker/u8:19/6331:
1 lock held by syz.3.540/8132:
 #0: ffff8880254d6420 (sb_writers#3){.+.+}-{0:0}, at: splice_direct_to_actor+0x345/0xa30 fs/splice.c:1105
6 locks held by kworker/1:14/9523:
 #0: ffff88801fefe948 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232
 #1: ffffc90003f6fc90 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233
 #2: ffff88802974e198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #2: ffff88802974e198 (&dev->mutex){....}-{4:4}, at: hub_event+0x1c0/0x52f0 drivers/usb/core/hub.c:5899
 #3: ffff888029821518 (&port_dev->status_lock){+.+.}-{4:4}, at: usb_lock_port drivers/usb/core/hub.c:3252 [inline]
 #3: ffff888029821518 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_port_connect drivers/usb/core/hub.c:5464 [inline]
 #3: ffff888029821518 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
 #3: ffff888029821518 (&port_dev->status_lock){+.+.}-{4:4}, at: port_event drivers/usb/core/hub.c:5871 [inline]
 #3: ffff888029821518 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_event+0x2b87/0x52f0 drivers/usb/core/hub.c:5953
 #4: ffff88802966f268 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_port_connect drivers/usb/core/hub.c:5465 [inline]
 #4: ffff88802966f268 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
 #4: ffff88802966f268 (hcd->address0_mutex){+.+.}-{4:4}, at: port_event drivers/usb/core/hub.c:5871 [inline]
 #4: ffff88802966f268 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_event+0x2bb0/0x52f0 drivers/usb/core/hub.c:5953
 #5: ffffffff8f6fe630 (ehci_cf_port_reset_rwsem){.+.+}-{4:4}, at: hub_port_reset+0x1a1/0x1d50 drivers/usb/core/hub.c:3067

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

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 10/25/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x133/0x180 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xe66/0x1180 kernel/hung_task.c:515
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 9523 Comm: kworker/1:14 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: usb_hub_wq hub_event
RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:228 [inline]
RIP: 0010:unwind_next_frame+0x1f6/0x20b0 arch/x86/kernel/unwind_orc.c:510
Code: 89 c3 39 d0 0f 83 17 16 00 00 48 ba 00 00 00 00 00 fc ff df 89 c1 48 8d 3c 8d 2c 9c dc 91 49 89 f8 49 c1 e8 03 45 0f b6 04 10 <48> 89 fa 83 e2 07 83 c2 03 44 38 c2 7c 2f 45 84 c0 74 2a 48 89 4c
RSP: 0018:ffffc90000a087d0 EFLAGS: 00000802
RAX: 000000000000a963 RBX: 0000000000000002 RCX: 000000000000a963
RDX: dffffc0000000000 RSI: 00000000000a7c15 RDI: ffffffff91df41b8
RBP: ffffc90000a08888 R08: 0000000000000000 R09: 00000000ba9d4ab2
R10: 0000000000000002 R11: 000000000000a963 R12: ffffc90000a08890
R13: ffffc90000a08840 R14: ffffc90000a08875 R15: ffffffff81a9635d
FS:  0000000000000000(0000) GS:ffff8881249f5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f91781b7198 CR3: 0000000073b9e000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:556
 insert_work+0x36/0x230 kernel/workqueue.c:2180
 __queue_work+0x94f/0x10e0 kernel/workqueue.c:2335
 call_timer_fn+0x19a/0x5a0 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1794 [inline]
 __run_timers+0x569/0xae0 kernel/time/timer.c:2373
 __run_timer_base kernel/time/timer.c:2385 [inline]
 __run_timer_base kernel/time/timer.c:2377 [inline]
 run_timer_base+0x114/0x190 kernel/time/timer.c:2394
 run_timer_softirq+0x1a/0x40 kernel/time/timer.c:2404
 handle_softirqs+0x219/0x950 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x109/0x170 kernel/softirq.c:723
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1056
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:console_trylock_spinning kernel/printk/printk.c:2037 [inline]
RIP: 0010:vprintk_emit+0x556/0x6b0 kernel/printk/printk.c:2425
Code: 00 4d 85 ed 0f 85 19 01 00 00 e8 b5 d7 21 00 9c 5d 81 e5 00 02 00 00 31 ff 48 89 ee e8 73 d2 21 00 48 85 ed 0f 85 25 01 00 00 <e8> 95 d7 21 00 45 31 c9 41 b8 01 00 00 00 31 c9 48 8d 05 00 00 00
RSP: 0018:ffffc90003f6f5c8 EFLAGS: 00000287
RAX: 0000000000097560 RBX: 000000000000003c RCX: ffffc9001af97000
RDX: 0000000000100000 RSI: ffffffff819d0ff5 RDI: 0000000000000007
RBP: 0000000000000000 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: ffff88802a25d4b0 R12: 1ffff920007edebb
R13: 0000000000000200 R14: ffff88801ea9a4c0 R15: ffffc90003f6f690
 dev_vprintk_emit drivers/base/core.c:4914 [inline]
 dev_printk_emit+0xfa/0x140 drivers/base/core.c:4925
 __dev_printk+0xf5/0x270 drivers/base/core.c:4937
 _dev_info+0xe4/0x120 drivers/base/core.c:4983
 hub_port_init+0x11ac/0x3a90 drivers/usb/core/hub.c:4996
 hub_port_connect drivers/usb/core/hub.c:5496 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
 port_event drivers/usb/core/hub.c:5871 [inline]
 hub_event+0x2ee7/0x52f0 drivers/usb/core/hub.c:5953
 process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257
 process_scheduled_works kernel/workqueue.c:3340 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>