INFO: task kworker/u4:1:144 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u4:1 state:D stack:22880 pid: 144 ppid: 2 flags:0x00004000 Workqueue: writeback wb_workfn (flush-7:0) Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11c3/0x4350 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 rwsem_down_write_slowpath+0xe63/0x13a0 kernel/locking/rwsem.c:1165 f2fs_balance_fs+0x47a/0x650 fs/f2fs/segment.c:528 f2fs_write_inode+0x463/0x660 fs/f2fs/inode.c:745 write_inode fs/fs-writeback.c:1505 [inline] __writeback_single_inode+0x6c4/0xda0 fs/fs-writeback.c:1715 writeback_sb_inodes+0xaaa/0x1750 fs/fs-writeback.c:1940 __writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:2011 wb_writeback+0x45e/0xbc0 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+0x867/0xff0 kernel/workqueue.c:2310 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457 kthread+0x42e/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Showing all locks held in the system: 1 lock held by khungtaskd/27: #0: ffffffff8c31ef20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30 4 locks held by kworker/u4:1/144: #0: ffff888141bc0138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1 #1: ffffc900010afd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285 #2: ffff888073e800e0 (&type->s_umount_key#52){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:418 #3: ffff888073d9d1b0 (&sbi->gc_lock){+.+.}-{3:3}, at: f2fs_balance_fs+0x47a/0x650 fs/f2fs/segment.c:528 2 locks held by getty/3946: #0: ffff88802c026098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252 #1: ffffc90002cf62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158 5 locks held by syz.0.15/5090: 1 lock held by syz.0.205/5687: ============================================= 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 05/09/2026 Call Trace: 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+0xe1b/0xe60 kernel/hung_task.c:369 kthread+0x42e/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 151 Comm: kworker/u4:2 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: events_unbound cfg80211_wiphy_work RIP: 0010:mutex_unlock+0x0/0x10 kernel/locking/mutex.c:536 Code: 10 80 e1 07 80 c1 03 38 c1 0f 8c f5 fe ff ff 48 8b 7c 24 10 e8 81 61 fc f7 e9 e6 fe ff ff 00 00 cc cc 00 00 cc cc 00 00 cc cc <48> 8b 34 24 eb 0a 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 41 57 RSP: 0018:ffffc900010cf958 EFLAGS: 00000286 RAX: 1f978728d9f58900 RBX: 0000000000000000 RCX: 1f978728d9f58900 RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffff8880738cccd8 RBP: ffffc900010cfb70 R08: ffffffff901c812f R09: 1ffffffff2039025 R10: dffffc0000000000 R11: fffffbfff2039026 R12: dffffc0000000000 R13: 1ffff92000219f48 R14: dffffc0000000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5ff73a8000 CR3: 000000001f651000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: sdata_unlock net/mac80211/ieee80211_i.h:1043 [inline] ieee80211_ibss_rx_queued_mgmt+0x259/0x2b50 net/mac80211/ibss.c:1677 ieee80211_iface_process_skb net/mac80211/iface.c:1459 [inline] ieee80211_iface_work+0x714/0xc50 net/mac80211/iface.c:1513 cfg80211_wiphy_work+0x224/0x260 net/wireless/core.c:433 process_one_work+0x867/0xff0 kernel/workqueue.c:2310 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457 kthread+0x42e/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287