INFO: task kworker/u4:30:5482 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:30   state:D stack:23744 pid:5482  ppid:2      flags:0x00004000
Workqueue: writeback wb_workfn
 (flush-7:3)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 rwsem_down_write_slowpath+0xbed/0x1090 kernel/locking/rwsem.c:1189
 f2fs_down_write fs/f2fs/f2fs.h:2177 [inline]
 f2fs_balance_fs+0x4a7/0x680 fs/f2fs/segment.c:428
 f2fs_write_inode+0x531/0x760 fs/f2fs/inode.c:744
 write_inode fs/fs-writeback.c:1460 [inline]
 __writeback_single_inode+0x75b/0x1160 fs/fs-writeback.c:1677
 writeback_sb_inodes+0xad8/0x17d0 fs/fs-writeback.c:1903
 __writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:1974
 wb_writeback+0x47a/0xd00 fs/fs-writeback.c:2079
 wb_check_old_data_flush fs/fs-writeback.c:2179 [inline]
 wb_do_writeback fs/fs-writeback.c:2232 [inline]
 wb_workfn+0xb66/0xec0 fs/fs-writeback.c:2260
 process_one_work+0x898/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8cb2b570 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8cb2bd90 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/27:
 #0: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6513
2 locks held by udevd/3638:
2 locks held by getty/4028:
 #0: ffff88814d00e098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000327e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41b/0x1380 drivers/tty/n_tty.c:2198
4 locks held by kworker/u4:30/5482:
 #0: ffff888142af1938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #1: ffffc900033f7d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #2: ffff8880555200e0 (&type->s_umount_key#64){++++}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:415
 #3: ffff88807ab491e8 (&sbi->gc_lock){+.+.}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2177 [inline]
 #3: ffff88807ab491e8 (&sbi->gc_lock){+.+.}-{3:3}, at: f2fs_balance_fs+0x4a7/0x680 fs/f2fs/segment.c:428
6 locks held by syz.3.483/6054:

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3f4/0x470 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xeee/0xf30 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5671 Comm: kworker/u4:48 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:set_canary_byte mm/kfence/core.c:305 [inline]
RIP: 0010:for_each_canary mm/kfence/core.c:345 [inline]
RIP: 0010:kfence_guarded_alloc+0x685/0xcf0 mm/kfence/core.c:439
Code: ff ff 4d 8b 75 00 4c 89 f3 48 81 e3 00 f0 ff ff 48 89 df 4c 89 f6 e8 fa b0 af ff 4c 39 f3 75 07 e8 10 af af ff eb 5a 49 89 de <4c> 89 f0 48 c1 e8 03 42 0f b6 04 20 84 c0 75 2e 44 89 f0 24 07 34
RSP: 0018:ffffc900048af6a0 EFLAGS: 00000293
RAX: ffffffff81d12021 RBX: ffff88823bd08000 RCX: ffff88804f5e0000
RDX: 0000000000000000 RSI: ffff88823bd08f00 RDI: ffff88823bd08000
RBP: ffffc900048af7b0 R08: dffffc0000000000 R09: fffff940011de841
R10: fffff940011de841 R11: 1ffffd40011de840 R12: dffffc0000000000
R13: ffffffff96c75e40 R14: ffff88823bd08788 R15: ffff8881401f0000
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055e5c221f950 CR3: 0000000030740000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __kfence_alloc+0x369/0x3a0 mm/kfence/core.c:1050
 kfence_alloc include/linux/kfence.h:128 [inline]
 slab_alloc_node mm/slub.c:3283 [inline]
 kmem_cache_alloc_node+0x2b5/0x320 mm/slub.c:3404
 __alloc_skb+0xfc/0x7e0 net/core/skbuff.c:505
 alloc_skb include/linux/skbuff.h:1271 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:748 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:805 [inline]
 nsim_dev_trap_report_work+0x28f/0xaf0 drivers/net/netdevsim/dev.c:851
 process_one_work+0x898/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>