syzbot

INFO: task syz.5.211:7041 blocked for more than 143 seconds.
      Not tainted 6.14.0-rc4-syzkaller-00090-gdd83757f6e68 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.211       state:D stack:27536 pid:7041  tgid:7040  ppid:6208   task_flags:0x400040 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5378 [inline]
 __schedule+0xf43/0x5890 kernel/sched/core.c:6765
 __schedule_loop kernel/sched/core.c:6842 [inline]
 schedule+0xe7/0x350 kernel/sched/core.c:6857
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6914
 __mutex_lock_common kernel/locking/mutex.c:662 [inline]
 __mutex_lock+0x6bd/0xb10 kernel/locking/mutex.c:730
 sync_bdevs+0xfd/0x360 block/bdev.c:1246
 ksys_sync+0xb3/0x150 fs/sync.c:105
 __do_sys_sync+0xe/0x20 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f935a18d169
RSP: 002b:00007f935b069038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f935a3a5fa0 RCX: 00007f935a18d169
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f935a3a5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f935a3a5fa0 R15: 00007ffe7a66be88
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/u8:1/12:
 #0: ffff88801b081148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1293/0x1ba0 kernel/workqueue.c:3213
 #1: ffffc90000117d18 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x921/0x1ba0 kernel/workqueue.c:3214
 #2: ffffffff8fef7068 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0x51/0xc0 net/core/link_watch.c:285
1 lock held by khungtaskd/30:
 #0: ffffffff8e1bccc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #0: ffffffff8e1bccc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e1bccc0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x7f/0x390 kernel/locking/lockdep.c:6746
3 locks held by kworker/0:2/933:
2 locks held by pvrusb2-context/2324:
 #0: ffff8880333a8188 (&hdw->big_lock_mutex){+.+.}-{4:4}, at: pvr2_hdw_initialize+0xb7/0x4500 drivers/media/usb/pvrusb2/pvrusb2-hdw.c:2326
 #1: ffffffff8e073050 (umhelper_sem){++++}-{4:4}, at: usermodehelper_read_trylock+0xaa/0x250 kernel/umh.c:214
5 locks held by kworker/u8:8/3509:
 #0: ffff88801beeb148 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x1293/0x1ba0 kernel/workqueue.c:3213
 #1: ffffc9000d6a7d18 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x921/0x1ba0 kernel/workqueue.c:3214
 #2: ffffffff8fee13d0 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xca/0xb30 net/core/net_namespace.c:606
 #3: ffffffff8fef7068 (rtnl_mutex){+.+.}-{4:4}, at: cleanup_net+0x512/0xb30 net/core/net_namespace.c:642
 #4: ffffffff8e1c8138 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x1a4/0x3b0 kernel/rcu/tree_exp.h:334
2 locks held by kworker/u8:11/3589:
1 lock held by klogd/5185:
 #0: ffff8880b863ec18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:606 [inline]
 #0: ffff8880b863ec18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x7e/0x130 kernel/sched/core.c:591
1 lock held by dhcpcd/5490:
 #0: ffffffff8fef7068 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:129 [inline]
 #0: ffffffff8fef7068 (rtnl_mutex){+.+.}-{4:4}, at: devinet_ioctl+0x26e/0x1f50 net/ipv4/devinet.c:1129
2 locks held by getty/5578:
 #0: ffff88803183f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002fde2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0xfba/0x1480 drivers/tty/n_tty.c:2211
3 locks held by syz-executor/5825:
 #0: ffff888028590d80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0x90 net/bluetooth/hci_core.c:480
 #1: ffff888028590078 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x3ab/0x11a0 net/bluetooth/hci_sync.c:5185
 #2: ffff88802c079338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x7f/0x730 net/bluetooth/l2cap_core.c:1760
6 locks held by kworker/1:3/5831:
 #0: ffff88814469b948 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x1293/0x1ba0 kernel/workqueue.c:3213
 #1: ffffc900040cfd18 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x921/0x1ba0 kernel/workqueue.c:3214
 #2: ffff888029768190 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1030 [inline]
 #2: ffff888029768190 (&dev->mutex){....}-{4:4}, at: hub_event+0x1c1/0x4e10 drivers/usb/core/hub.c:5861
 #3: ffff888050989190 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1030 [inline]
 #3: ffff888050989190 (&dev->mutex){....}-{4:4}, at: usb_disconnect+0x10a/0x920 drivers/usb/core/hub.c:2307
 #4: ffff888063f7f160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1030 [inline]
 #4: ffff888063f7f160 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1095 [inline]
 #4: ffff888063f7f160 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xa4/0x610 drivers/base/dd.c:1293
 #5: ffff8880333a8188 (&hdw->big_lock_mutex){+.+.}-{4:4}, at: pvr2_hdw_disconnect+0x8a/0x630 drivers/media/usb/pvrusb2/pvrusb2-hdw.c:2710
1 lock held by udevd/5838:
 #0: ffff8880260af4c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe20 block/bdev.c:903
3 locks held by kworker/0:6/5907:
 #0: ffff88801b078d48 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x1293/0x1ba0 kernel/workqueue.c:3213
 #1: ffffc9000444fd18 (free_ipc_work){+.+.}-{0:0}, at: process_one_work+0x921/0x1ba0 kernel/workqueue.c:3214
 #2: ffffffff8e1c8138 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x1a4/0x3b0 kernel/rcu/tree_exp.h:334
3 locks held by kworker/u8:18/6930:
1 lock held by syz.5.211/7041:
 #0: ffff8880260af4c8 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0xfd/0x360 block/bdev.c:1246
4 locks held by udevd/7137:
 #0: ffff8880364ccd58 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xd8/0x12b0 fs/seq_file.c:182
 #1: ffff888062e3b888 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_seq_start+0x4d/0x240 fs/kernfs/file.c:154
 #2: ffff888027d84698 (kn->active#5){++++}-{0:0}, at: kernfs_seq_start+0x71/0x240 fs/kernfs/file.c:155
 #3: ffff888050989190 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1030 [inline]
 #3: ffff888050989190 (&dev->mutex){....}-{4:4}, at: uevent_show+0x188/0x3b0 drivers/base/core.c:2729
1 lock held by syz.6.490/8636:
 #0: ffff8880260af4c8 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0xfd/0x360 block/bdev.c:1246
1 lock held by syz.0.493/8652:
 #0: ffff8880260af4c8 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0xfd/0x360 block/bdev.c:1246
1 lock held by syz.0.493/8653:
 #0: ffff8880260af4c8 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0xfd/0x360 block/bdev.c:1246
1 lock held by syz.4.503/8721:
 #0: ffffffff8e1c8000 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x48/0x700 kernel/rcu/tree.c:3741

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.14.0-rc4-syzkaller-00090-gdd83757f6e68 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:236 [inline]
 watchdog+0xf62/0x12b0 kernel/hung_task.c:399
 kthread+0x3af/0x750 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6930 Comm: kworker/u8:18 Not tainted 6.14.0-rc4-syzkaller-00090-gdd83757f6e68 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: bat_events batadv_nc_worker
RIP: 0010:batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:406 [inline]
RIP: 0010:batadv_nc_worker+0x126/0x1060 net/batman-adv/network-coding.c:719
Code: ed 4c 89 64 24 40 49 bf 00 00 00 00 00 fc ff df 48 c7 44 24 08 00 02 e1 8d 48 c1 e8 03 4c 01 f8 48 89 44 24 50 e8 aa 1d 94 f6 <48> 8b 44 24 50 80 38 00 0f 85 0f 0e 00 00 48 8b 4c 24 40 89 e8 48
RSP: 0018:ffffc90005e37b28 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000400 RCX: ffffffff8b25ca4c
RDX: ffff88806375a440 RSI: ffffffff8b25c2b6 RDI: 0000000000000004
RBP: 0000000000000040 R08: 0000000000000004 R09: 0000000000000040
R10: 0000000000000400 R11: 0000000000000002 R12: 0000000000000001
R13: 0000000000000001 R14: 0000000000000000 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2faedff8 CR3: 000000000df80000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3400
 kthread+0x3af/0x750 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
vkms_vblank_simulate: vblank timer overrun