INFO: task kworker/u8:2:36 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:2    state:D stack:20800 pid:36    tgid:36    ppid:2      task_flags:0x4208160 flags:0x00004000
Workqueue: events_unbound netfs_write_collection_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 netfs_wait_for_in_progress_stream+0x260/0x4b0 fs/netfs/misc.c:370
 netfs_retry_writes+0xf9/0x1680 fs/netfs/write_retry.c:214
 netfs_collect_write_results fs/netfs/write_collect.c:349 [inline]
 netfs_write_collection+0x1ed6/0x2b60 fs/netfs/write_collect.c:365
 netfs_write_collection_worker+0x5b/0xa0 fs/netfs/write_collect.c:448
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Showing all locks held in the system:
1 lock held by pool_workqueue_/3:
1 lock held by khungtaskd/31:
 #0: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by kworker/u8:2/36:
 #0: ffff88801a481148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline]
 #0: ffff88801a481148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3319
 #1: ffffc90000ac7bc0 ((work_completion)(&rreq->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline]
 #1: ffffc90000ac7bc0 ((work_completion)(&rreq->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3319
3 locks held by kworker/1:2/1204:
 #0: ffff888143ac2d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline]
 #0: ffff888143ac2d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3319
 #1: ffffc90003effbc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline]
 #1: ffffc90003effbc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3319
 #2: ffff888027bb0198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:911 [inline]
 #2: ffff888027bb0198 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4a20 drivers/usb/core/hub.c:5898
2 locks held by getty/5617:
 #0: ffff888033e0b0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900036bb2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
1 lock held by syz.7.2071/15570:
 #0: ffff88804c229850 (&ctx->wb_lock){+.+.}-{4:4}, at: netfs_writepages+0xa9/0x900 fs/netfs/write_issue.c:559
1 lock held by syz.0.2390/16865:
3 locks held by syz.3.2420/16984:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:328 [inline]
 watchdog+0xf93/0xfe0 kernel/hung_task.c:491
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 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: 16984 Comm: syz.3.2420 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2025
RIP: 0010:deref_stack_reg+0x1cf/0x230 arch/x86/kernel/unwind_orc.c:408
Code: 24 18 48 89 d8 48 c1 e8 03 42 80 3c 38 00 74 08 48 89 df e8 33 38 b0 00 4c 89 33 b0 01 eb 02 31 c0 48 83 c4 20 5b 41 5c 41 5d <41> 5e 41 5f 5d e9 32 58 9d ff cc 44 89 f9 80 e1 07 80 c1 03 38 c1
RSP: 0018:ffffc90004b26018 EFLAGS: 00000286
RAX: 1ffff92000964c01 RBX: ffffffff903e2e8e RCX: 0000000000000001
RDX: ffffc90004b26148 RSI: dffffc0000000000 RDI: ffffc90004b26b10
RBP: 1ffff92000964c21 R08: ffffc90004b26b10 R09: ffffc90004b26158
R10: dffffc0000000000 R11: fffff52000964c2d R12: ffffc90004b26b10
R13: ffffc90004b26158 R14: ffffc90004b26c58 R15: dffffc0000000000
FS:  00007f13481cd6c0(0000) GS:ffff888125d15000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe304ebff0 CR3: 000000005700a000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 unwind_next_frame+0x17c4/0x2390 arch/x86/kernel/unwind_orc.c:-1
 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 save_stack+0xf5/0x1f0 mm/page_owner.c:156
 __set_page_owner+0x8d/0x4a0 mm/page_owner.c:329
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 folio_alloc_mpol_noprof+0x39/0x70 mm/mempolicy.c:2435
 shmem_alloc_folio mm/shmem.c:1908 [inline]
 shmem_alloc_and_add_folio+0x447/0xf60 mm/shmem.c:1947
 shmem_get_folio_gfp+0x59d/0x1660 mm/shmem.c:2597
 shmem_get_folio mm/shmem.c:2703 [inline]
 shmem_write_begin+0xf7/0x2b0 mm/shmem.c:3353
 generic_perform_write+0x2c5/0x900 mm/filemap.c:4175
 shmem_file_write_iter+0xf8/0x120 mm/shmem.c:3528
 __kernel_write_iter+0x428/0x910 fs/read_write.c:619
 dump_emit_page fs/coredump.c:1296 [inline]
 dump_user_range+0x8a0/0xc90 fs/coredump.c:1370
 elf_core_dump+0x337b/0x3990 fs/binfmt_elf.c:2085
 coredump_write+0x1169/0x1900 fs/coredump.c:1049
 vfs_coredump+0x1daa/0x2a50 fs/coredump.c:1168
 get_signal+0x1109/0x1340 kernel/signal.c:3019
 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:40 [inline]
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 irqentry_exit_to_user_mode+0x81/0x120 kernel/entry/common.c:73
 exc_page_fault+0x9f/0xf0 arch/x86/mm/fault.c:1535
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
RIP: 0033:0x7f134738ebe9
Code: Unable to access opcode bytes at 0x7f134738ebbf.
RSP: 002b:00007f13481ccfe8 EFLAGS: 00010206
RAX: 0000000000000000 RBX: 00007f13475c5fa0 RCX: 00007f134738ebe9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000c800400
RBP: 00007f1347411e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f13475c6038 R14: 00007f13475c5fa0 R15: 00007ffc3a6e7828
 </TASK>