INFO: task kworker/u4:1:11 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:23248 pid:11 ppid:2 flags:0x00004000
Workqueue: writeback wb_workfn
(flush-7:0)
Call Trace:
context_switch kernel/sched/core.c:5244 [inline]
__schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
schedule+0xb9/0x180 kernel/sched/core.c:6637
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6696
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x555/0xaf0 kernel/locking/mutex.c:747
hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
hfsplus_cat_write_inode+0x1e3/0x820 fs/hfsplus/inode.c:590
write_inode fs/fs-writeback.c:1470 [inline]
__writeback_single_inode+0x75b/0x1160 fs/fs-writeback.c:1687
writeback_sb_inodes+0xad8/0x17d0 fs/fs-writeback.c:1913
__writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:1984
wb_writeback+0x47a/0xd00 fs/fs-writeback.c:2089
wb_check_background_flush fs/fs-writeback.c:2155 [inline]
wb_do_writeback fs/fs-writeback.c:2243 [inline]
wb_workfn+0xbdd/0xec0 fs/fs-writeback.c:2270
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
Showing all locks held in the system:
4 locks held by kworker/u4:1/11:
#0: ffff88801ca4d938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#1: ffffc90000107d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#2: ffff888079fd40e0 (&type->s_umount_key#53){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:415
#3: ffff88807c8900b0 (&tree->tree_lock){+.+.}-{3:3}, at: hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
1 lock held by rcu_tasks_kthre/12:
#0:
ffffffff8c92bab0
(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: ffffffff8c92c2d0 (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: ffffffff8c92b120 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#0: ffffffff8c92b120 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#0: ffffffff8c92b120 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6513
4 locks held by kworker/u4:2/32:
#0: ffff88801ca4d938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#1: ffffc90000a8fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#2: ffff888074dea0e0 (&type->s_umount_key#53){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:415
#3: ffff88805df4e0b0 (&tree->tree_lock){+.+.}-{3:3}, at: hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
4 locks held by kworker/u4:3/46:
#0: ffff88801ca4d938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#1: ffffc90000b77d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#2: ffff8880755e00e0 (&type->s_umount_key#53){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:415
#3: ffff8880755e60b0 (
&tree->tree_lock
){+.+.}-{3:3}
, at: hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
3 locks held by kworker/u4:4/56:
#0: ffff8880b8e3aad8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:537
#1: ffff8880b8e27848 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x398/0x6d0 kernel/sched/psi.c:999
#2: ffff888027768d40 (&wdev->mtx){+.+.}-{3:3}, at: sdata_lock net/mac80211/ieee80211_i.h:1113 [inline]
#2: ffff888027768d40 (&wdev->mtx){+.+.}-{3:3}, at: ieee80211_ibss_work+0xa0/0x10b0 net/mac80211/ibss.c:1680
2 locks held by getty/4027:
#0:
ffff88802fc2a098
(
&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
#1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41b/0x1380 drivers/tty/n_tty.c:2198
2 locks held by kworker/1:5/4318:
#0: ffff888017472138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#1:
ffffc90004247d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
3 locks held by kworker/1:6/4320:
4 locks held by kworker/u4:5/4425:
#0: ffff88801ca4d938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#1: ffffc900034a7d00 ((work_completion)(&(&wb->dwork)->work)
){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#2: ffff8880779c40e0 (&type->s_umount_key#53){.+.+}-{3:3}
, at: trylock_super+0x1c/0xf0 fs/super.c:415
#3: ffff88807dfaa0b0 (&tree->tree_lock){+.+.}-{3:3}, at: hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
4 locks held by syz.0.17/4441:
4 locks held by syz.1.18/4469:
3 locks held by kworker/u4:7/4486:
4 locks held by syz.2.19/4492:
4 locks held by syz.3.20/4517:
4 locks held by kworker/u4:9/4522:
#0: ffff88801ca4d938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#1: ffffc90003827d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#2:
ffff8880594780e0
(
&type->s_umount_key#53){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:415
#3: ffff8880242180b0 (&tree->tree_lock){+.+.}-{3:3}, at: hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
4 locks held by syz.4.21/4552:
3 locks held by syz-executor/4554:
#0:
ffffffff8db9b3f0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x15/0x40 net/netlink/genetlink.c:860
#1: ffffffff8db9b208 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffffffff8db9b208 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0x103/0x780 net/netlink/genetlink.c:848
#2: ffffffff8db3b3a8 (rtnl_mutex){+.+.}-{3:3}, at: ieee80211_register_hw+0x285c/0x39e0 net/mac80211/main.c:1335
=============================================
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 10/25/2025
Call Trace:
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
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4509 Comm: kworker/u4:8 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: bat_events batadv_nc_worker
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4728 [inline]
RIP: 0010:__lock_acquire+0x664/0x7c50 kernel/locking/lockdep.c:4999
Code: c3 b9 00 00 00 48 89 d8 48 c1 e8 03 42 0f b6 04 00 84 c0 0f 85 37 61 00 00 45 84 f6 0f 84 1f 05 00 00 0f b6 1b 48 8b 44 24 50 <42> 0f b6 04 00 84 c0 0f 85 00 62 00 00 41 f6 47 01 80 0f 85 ff 04
RSP: 0018:ffffc900037c7840 EFLAGS: 00000002
RAX: 1ffff1100f7a0c92 RBX: 0000000000000001 RCX: ffffffff81630d43
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff908c8240
RBP: ffffc900037c7a90 R08: dffffc0000000000 R09: fffffbfff2119049
R10: fffffbfff2119049 R11: 1ffffffff2119048 R12: ffff88807bd05940
R13: 0000000000000000 R14: 0000000000000002 R15: ffff88807bd06490
FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff0f816368 CR3: 000000000c68e000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
rcu_read_lock include/linux/rcupdate.h:791 [inline]
batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline]
batadv_nc_worker+0xeb/0x600 net/batman-adv/network-coding.c:719
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