INFO: task kworker/u8:3:57 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u8:3 state:D stack:20584 pid:57 tgid:57 ppid:2 task_flags:0x4208160 flags:0x00004000 Workqueue: writeback wb_workfn (flush-7:0) Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x16f3/0x4c20 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] rt_mutex_schedule+0x77/0xf0 kernel/sched/core.c:7339 rt_mutex_slowlock_block kernel/locking/rtmutex.c:1647 [inline] __rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline] __rt_mutex_slowlock_locked+0x1e04/0x25e0 kernel/locking/rtmutex.c:1760 rt_mutex_slowlock+0xb5/0x160 kernel/locking/rtmutex.c:1800 __rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline] rwbase_write_lock+0x14f/0x750 kernel/locking/rwbase_rt.c:244 f2fs_down_write fs/f2fs/f2fs.h:2234 [inline] f2fs_balance_fs+0x5af/0x7f0 fs/f2fs/segment.c:464 f2fs_write_inode+0x3fb/0x5f0 fs/f2fs/inode.c:820 write_inode fs/fs-writeback.c:1525 [inline] __writeback_single_inode+0x6f1/0x1000 fs/fs-writeback.c:1745 writeback_sb_inodes+0x6b7/0xf60 fs/fs-writeback.c:1976 __writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:2047 wb_writeback+0x44f/0xaf0 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+0xaf4/0xf00 fs/fs-writeback.c:2343 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Showing all locks held in the system: 1 lock held by khungtaskd/38: #0: ffffffff8d9a8d80 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8d9a8d80 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #0: ffffffff8d9a8d80 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775 4 locks held by kworker/u8:3/57: #0: ffff8881404ba938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline] #0: ffff8881404ba938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3319 #1: ffffc9000123fbc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline] #1: ffffc9000123fbc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3319 #2: ffff8880357060d0 (&type->s_umount_key#54){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0 fs/super.c:563 #3: ffff888027c2d990 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_down_write fs/f2fs/f2fs.h:2234 [inline] #3: ffff888027c2d990 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_balance_fs+0x5af/0x7f0 fs/f2fs/segment.c:464 4 locks held by kworker/u8:4/67: #0: ffff8881404ba938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline] #0: ffff8881404ba938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3319 #1: ffffc9000152fbc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline] #1: ffffc9000152fbc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3319 #2: ffff88805531a0d0 (&type->s_umount_key#54){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0 fs/super.c:563 #3: ffff88803d469990 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_down_write fs/f2fs/f2fs.h:2234 [inline] #3: ffff88803d469990 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_balance_fs+0x5af/0x7f0 fs/f2fs/segment.c:464 4 locks held by kworker/u8:5/152: #0: ffff8881404ba938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline] #0: ffff8881404ba938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3319 #1: ffffc90003a5fbc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline] #1: ffffc90003a5fbc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3319 #2: ffff88803e36c0d0 (&type->s_umount_key#54){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0 fs/super.c:563 #3: ffff888033c4d990 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_down_write fs/f2fs/f2fs.h:2234 [inline] #3: ffff888033c4d990 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_balance_fs+0x5af/0x7f0 fs/f2fs/segment.c:464 4 locks held by kworker/u8:6/1167: #0: ffff8881404ba938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline] #0: ffff8881404ba938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3319 #1: ffffc900048c7bc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline] #1: ffffc900048c7bc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3319 #2: ffff88803146a0d0 (&type->s_umount_key#54){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0 fs/super.c:563 #3: ffff888036299990 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_down_write fs/f2fs/f2fs.h:2234 [inline] #3: ffff888036299990 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_balance_fs+0x5af/0x7f0 fs/f2fs/segment.c:464 4 locks held by kworker/u8:10/1472: #0: ffff8881404ba938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline] #0: ffff8881404ba938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3319 #1: ffffc900054b7bc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline] #1: ffffc900054b7bc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3319 #2: ffff8880378980d0 (&type->s_umount_key#54){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0 fs/super.c:563 #3: ffff88803a339990 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_down_write fs/f2fs/f2fs.h:2234 [inline] #3: ffff88803a339990 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_balance_fs+0x5af/0x7f0 fs/f2fs/segment.c:464 2 locks held by kworker/u8:12/1540: 2 locks held by getty/5598: #0: ffff88823bf380a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc90003e832e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x444/0x1410 drivers/tty/n_tty.c:2222 6 locks held by syz.0.17/6051: 5 locks held by syz.1.18/6075: 5 locks held by syz.2.19/6106: 6 locks held by syz.3.20/6136: 5 locks held by syz.4.21/6169: 4 locks held by kworker/u8:0/6179: #0: ffff8881404ba938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline] #0: ffff8881404ba938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3319 #1: ffffc90004977bc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline] #1: ffffc90004977bc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3319 #2: ffff88805bb7c0d0 (&type->s_umount_key#54){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0 fs/super.c:563 #3: ffff888031f6d990 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_down_write fs/f2fs/f2fs.h:2234 [inline] #3: ffff888031f6d990 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_balance_fs+0x5af/0x7f0 fs/f2fs/segment.c:464 4 locks held by syz.5.22/6210: 5 locks held by syz.6.25/6258: ============================================= NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Call Trace: 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+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 6258 Comm: syz.6.25 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 RIP: 0010:check_kcov_mode kernel/kcov.c:185 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x40/0x80 kernel/kcov.c:217 Code: 37 10 81 e6 00 00 ff 00 ba 00 01 00 00 23 91 0c 0b 00 00 89 d7 09 f7 74 11 85 f6 75 39 85 d2 74 35 83 b9 d4 15 00 00 00 74 2c <8b> 91 b0 15 00 00 83 fa 02 75 21 48 8b 91 b8 15 00 00 48 8b 32 48 RSP: 0018:ffffc90004bc6728 EFLAGS: 00000246 RAX: ffffffff8af50983 RBX: ffff88805f94e680 RCX: ffff8880311f1dc0 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff88805f94e680 R08: 0000000000000000 R09: 0000000000000000 R10: ffffc90004bc6800 R11: fffff52000978d03 R12: ffffc90004bc67f2 R13: dffffc0000000000 R14: ffffea0001600ec0 R15: 0000000000000000 FS: 0000555565395500(0000) GS:ffff8881269bc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005555653b05c8 CR3: 000000003732a000 CR4: 00000000003526f0 Call Trace: xas_load+0x593/0x5b0 lib/xarray.c:-1 filemap_get_entry+0x168/0x2f0 mm/filemap.c:1871 __filemap_get_folio+0x37/0xa40 mm/filemap.c:1916 f2fs_grab_cache_folio+0x2b/0x380 fs/f2fs/f2fs.h:2872 f2fs_ra_meta_pages+0x615/0x970 fs/f2fs/checkpoint.c:303 gc_data_segment fs/f2fs/gc.c:1568 [inline] do_garbage_collect+0x20f1/0x6410 fs/f2fs/gc.c:1826 f2fs_gc+0xca9/0x2580 fs/f2fs/gc.c:1931 f2fs_balance_fs+0x5fb/0x7f0 fs/f2fs/segment.c:466 f2fs_map_blocks+0x345f/0x4130 fs/f2fs/data.c:1792 f2fs_expand_inode_data+0x5b1/0xa60 fs/f2fs/file.c:1923 f2fs_fallocate+0x4f8/0x990 fs/f2fs/file.c:2026 vfs_fallocate+0x672/0x7f0 fs/open.c:342 ioctl_preallocate fs/ioctl.c:290 [inline] file_ioctl+0x61d/0x780 fs/ioctl.c:-1 do_vfs_ioctl+0xb36/0x1440 fs/ioctl.c:577 __do_sys_ioctl fs/ioctl.c:596 [inline] __se_sys_ioctl+0x82/0x170 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb6ad16eec9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffd7acf8de8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fb6ad3c5fa0 RCX: 00007fb6ad16eec9 RDX: 00002000000000c0 RSI: 0000000040305828 RDI: 0000000000000004 RBP: 00007fb6ad1f1f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fb6ad3c5fa0 R14: 00007fb6ad3c5fa0 R15: 0000000000000003