INFO: task kworker/u4:2:154 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:2    state:D stack:24912 pid:  154 ppid:     2 flags:0x00004000
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 rwsem_down_write_slowpath+0xc87/0x1260 kernel/locking/rwsem.c:1165
 f2fs_balance_fs+0x47e/0x650 fs/f2fs/segment.c:528
 f2fs_write_inode+0x531/0x760 fs/f2fs/inode.c:745
 write_inode fs/fs-writeback.c:1505 [inline]
 __writeback_single_inode+0x6c3/0xda0 fs/fs-writeback.c:1715
 writeback_sb_inodes+0xa4e/0x1680 fs/fs-writeback.c:1940
 __writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:2011
 wb_writeback+0x46f/0xbe0 fs/fs-writeback.c:2116
 wb_check_background_flush fs/fs-writeback.c:2182 [inline]
 wb_do_writeback fs/fs-writeback.c:2270 [inline]
 wb_workfn+0xbd6/0xf20 fs/fs-writeback.c:2298
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Showing all locks held in the system:
4 locks held by kworker/u4:0/9:
 #0: ffff888141d88138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90000ce7d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffff888024a680e0 (&type->s_umount_key#54){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: ffff8880608b11b0 (&sbi->gc_lock){+.+.}-{3:3}, at: f2fs_balance_fs+0x47e/0x650 fs/f2fs/segment.c:528
1 lock held by khungtaskd/27:
 #0: ffffffff8c31eaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
4 locks held by kworker/u4:2/154:
 #0: ffff888141d88138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90002027d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffff8880206fe0e0 (&type->s_umount_key#54){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: ffff8880796251b0 (&sbi->gc_lock){+.+.}-{3:3}, at: f2fs_balance_fs+0x47e/0x650 fs/f2fs/segment.c:528
4 locks held by kworker/u4:3/155:
 #0: ffff888141d88138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90002037d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffff88801a3e80e0 (&type->s_umount_key#54){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: ffff88802adcd1b0 (&sbi->gc_lock){+.+.}-{3:3}, at: f2fs_balance_fs+0x47e/0x650 fs/f2fs/segment.c:528
4 locks held by kworker/u4:4/1281:
 #0: ffff888141d88138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90004dc7d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffff88805fc4a0e0 (&type->s_umount_key#54){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: ffff8880779e51b0 (&sbi->gc_lock){+.+.}-{3:3}, at: f2fs_balance_fs+0x47e/0x650 fs/f2fs/segment.c:528
4 locks held by kworker/u4:5/1459:
 #0: ffff888141d88138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90005457d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffff88801fe760e0 (&type->s_umount_key#54){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: ffff88801eebd1b0 (&sbi->gc_lock){+.+.}-{3:3}, at: f2fs_balance_fs+0x47e/0x650 fs/f2fs/segment.c:528
2 locks held by getty/3951:
 #0: ffff88814cb4f098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc900025e62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5df/0x1a70 drivers/tty/n_tty.c:2158
3 locks held by kworker/0:12/4378:
4 locks held by syz.0.16/5189:
4 locks held by syz.1.17/5249:
4 locks held by kworker/u4:6/5267:
 #0: ffff888141d88138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc9000347fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffff8880258cc0e0 (&type->s_umount_key#54){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: ffff88807ab991b0 (&sbi->gc_lock){+.+.}-{3:3}, at: f2fs_balance_fs+0x47e/0x650 fs/f2fs/segment.c:528
6 locks held by syz.2.18/5277:
4 locks held by kworker/u4:7/5304:
 #0: ffff888141d88138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc900035dfd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffff88807e44c0e0 (&type->s_umount_key#54){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: ffff88805d45d1b0 (&sbi->gc_lock){+.+.}-{3:3}, at: f2fs_balance_fs+0x47e/0x650 fs/f2fs/segment.c:528
6 locks held by syz.3.19/5310:
4 locks held by syz.4.20/5344:
4 locks held by syz.5.21/5378:
5 locks held by syz.6.22/5418:
7 locks held by syz.7.23/5449:
2 locks held by syz.7.23/5453:
 #0: ffff88807df28460 (sb_writers#13){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:3043 [inline]
 #0: ffff88807df28460 (sb_writers#13){.+.+}-{0:0}, at: vfs_fallocate+0x4f4/0x6f0 fs/open.c:307
 #1: ffff88806e0cc3d0 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
 #1: ffff88806e0cc3d0 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}, at: f2fs_fallocate+0x20a/0x8c0 fs/f2fs/file.c:1784

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

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 01/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe0f/0xe50 kernel/hung_task.c:369
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5310 Comm: syz.3.19 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:mark_usage kernel/locking/lockdep.c:4464 [inline]
RIP: 0010:__lock_acquire+0xb7a/0x7d10 kernel/locking/lockdep.c:4966
Code: df 85 c0 74 25 48 c7 c0 c8 0e 8a 8d 48 c1 e8 03 42 0f b6 04 00 84 c0 0f 85 57 62 00 00 83 3d 14 fd 2c 0c 00 0f 84 95 0f 00 00 <83> 7c 24 68 00 0f 84 d4 01 00 00 48 8b 44 24 58 42 0f b6 04 00 84
RSP: 0018:ffffc9000363ea00 EFLAGS: 00000046
RAX: 0000000000000004 RBX: 0000000000000004 RCX: 0000000000000003
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff901d2200
RBP: ffffc9000363ec50 R08: dffffc0000000000 R09: 1ffffffff203a440
R10: dffffc0000000000 R11: fffffbfff203a441 R12: ffff8880288c2970
R13: ffff8880288c1dc0 R14: ffffffff8fbd39b8 R15: ffff8880288c2950
FS:  00007fe15ffa46c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6e3ac9e000 CR3: 000000002a0b6000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
 down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
 check_valid_map fs/f2fs/gc.c:881 [inline]
 gc_data_segment fs/f2fs/gc.c:1451 [inline]
 do_garbage_collect+0x1d02/0x6300 fs/f2fs/gc.c:1671
 f2fs_gc+0x8da/0x1950 fs/f2fs/gc.c:1765
 f2fs_balance_fs+0x492/0x650 fs/f2fs/segment.c:529
 f2fs_map_blocks+0x2972/0x3300 fs/f2fs/data.c:1746
 expand_inode_data+0x4bf/0x700 fs/f2fs/file.c:1717
 f2fs_fallocate+0x423/0x8c0 fs/f2fs/file.c:1819
 vfs_fallocate+0x587/0x6f0 fs/open.c:308
 ioctl_preallocate fs/ioctl.c:294 [inline]
 file_ioctl fs/ioctl.c:334 [inline]
 do_vfs_ioctl+0x1b52/0x1ef0 fs/ioctl.c:853
 __do_sys_ioctl fs/ioctl.c:872 [inline]
 __se_sys_ioctl+0x83/0x170 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fe160d5f8f9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe15ffa4028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fe160f8d080 RCX: 00007fe160d5f8f9
RDX: 00002000000000c0 RSI: 0000000040305828 RDI: 0000000000000004
RBP: 00007fe160df2984 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007fe160f8d080 R15: 00007fff4d297d88
 </TASK>