INFO: task kworker/u8:8:1325 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:8    state:D stack:22520 pid:1325  tgid:1325  ppid:2      task_flags:0x4248060 flags:0x00004000
Workqueue: writeback wb_workfn (flush-8:0)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7058
 io_schedule+0xbf/0x130 kernel/sched/core.c:7903
 rq_qos_wait+0x22f/0x340 block/blk-rq-qos.c:307
 __wbt_wait block/blk-wbt.c:596 [inline]
 wbt_wait+0x1af/0x390 block/blk-wbt.c:656
 __rq_qos_throttle+0x56/0xa0 block/blk-rq-qos.c:66
 rq_qos_throttle block/blk-rq-qos.h:168 [inline]
 rq_qos_throttle block/blk-rq-qos.h:163 [inline]
 blk_mq_get_new_requests block/blk-mq.c:3033 [inline]
 blk_mq_submit_bio+0x2174/0x2a10 block/blk-mq.c:3183
 __submit_bio+0x3cf/0x690 block/blk-core.c:635
 __submit_bio_noacct_mq block/blk-core.c:722 [inline]
 submit_bio_noacct_nocheck+0x660/0xd30 block/blk-core.c:751
 submit_bio_noacct+0xc20/0x1ed0 block/blk-core.c:874
 ext4_io_submit fs/ext4/page-io.c:404 [inline]
 io_submit_add_bh fs/ext4/page-io.c:445 [inline]
 ext4_bio_write_folio+0x756/0x1dc0 fs/ext4/page-io.c:589
 mpage_process_page_bufs+0x47c/0x8d0 fs/ext4/inode.c:2191
 mpage_prepare_extent_to_map+0x79f/0x14d0 fs/ext4/inode.c:2736
 ext4_do_writepages+0xa11/0x3cf0 fs/ext4/inode.c:2877
 ext4_writepages+0x37a/0x7d0 fs/ext4/inode.c:3025
 do_writepages+0x27a/0x600 mm/page-writeback.c:2634
 __writeback_single_inode+0x160/0xfb0 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x60d/0xfa0 fs/fs-writeback.c:1976
 __writeback_inodes_wb+0xf8/0x2d0 fs/fs-writeback.c:2047
 wb_writeback+0x7f3/0xb70 fs/fs-writeback.c:2158
 wb_check_old_data_flush fs/fs-writeback.c:2262 [inline]
 wb_do_writeback fs/fs-writeback.c:2315 [inline]
 wb_workfn+0x8ca/0xbe0 fs/fs-writeback.c:2343
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 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:
2 locks held by ksoftirqd/1/23:
2 locks held by kworker/1:0/24:
 #0: ffff8880b853a458 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x29/0x130 kernel/sched/core.c:636
 #1: ffff8880b8524088 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:220 [inline]
 #1: ffff8880b8524088 (psi_seq){-.-.}-{0:0}, at: __schedule+0x1861/0x5de0 kernel/sched/core.c:6955
1 lock held by khungtaskd/31:
 #0: ffffffff8e5c10e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e5c10e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e5c10e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
4 locks held by kworker/u8:8/1325:
 #0: ffff8880222c0148 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc900041ffd10 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
 #2: ffff88814d6560e0 (&type->s_umount_key#31){++++}-{4:4}, at: super_trylock_shared+0x1e/0xf0 fs/super.c:563
 #3: ffff88814d660b98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: do_writepages+0x27a/0x600 mm/page-writeback.c:2634
2 locks held by getty/5625:
 #0: ffff88814c92d0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc900036bb2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222
3 locks held by syz.0.225/6884:
 #0: ffff888062807448 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x11b/0x530 mm/mmap_lock.c:147
 #1: ffff88814d656520 (sb_pagefaults){.+.+}-{0:0}, at: do_page_mkwrite+0x174/0x380 mm/memory.c:3361
 #2: ffff88814d662950 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x5e4/0x1410 fs/jbd2/transaction.c:444
3 locks held by syz-executor/6886:
 #0: ffff88814d656428 (sb_writers#4){.+.+}-{0:0}, at: filename_create+0x10e/0x4a0 fs/namei.c:4132
 #1: ffff8880125eed10 (&type->i_mutex_dir_key#3/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:915 [inline]
 #1: ffff8880125eed10 (&type->i_mutex_dir_key#3/1){+.+.}-{4:4}, at: filename_create+0x1bb/0x4a0 fs/namei.c:4139
 #2: ffff88814d662950 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x5e4/0x1410 fs/jbd2/transaction.c:444

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

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 08/18/2025
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]
 check_hung_uninterruptible_tasks kernel/hung_task.c:328 [inline]
 watchdog+0xf0e/0x1260 kernel/hung_task.c:491
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 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: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82
Code: 8c 64 02 c3 cc cc cc cc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d e3 d1 18 00 fb f4 <e9> 7c 09 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffc90000197df8 EFLAGS: 000002c6
RAX: 00000000000c907b RBX: 0000000000000001 RCX: ffffffff8b913bf9
RDX: 0000000000000000 RSI: ffffffff8de4eb89 RDI: ffffffff8c163180
RBP: ffffed1003c56b40 R08: 0000000000000001 R09: ffffed10170a6655
R10: ffff8880b85332ab R11: 0000000000000000 R12: 0000000000000001
R13: ffff88801e2b5a00 R14: ffffffff90aba290 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881247bd000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055d208602608 CR3: 000000000e380000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:757
 default_idle_call+0x6d/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:190 [inline]
 do_idle+0x391/0x510 kernel/sched/idle.c:330
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:428
 start_secondary+0x21d/0x2b0 arch/x86/kernel/smpboot.c:315
 common_startup_64+0x13e/0x148
 </TASK>