syzbot

INFO: task syz.2.703:8536 blocked for more than 143 seconds.
      Not tainted 6.15.0-rc7-syzkaller-00175-g0f8c0258bf04 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.703       state:D stack:26400 pid:8536  tgid:8535  ppid:5811   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x116f/0x5de0 kernel/sched/core.c:6767
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6860
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6917
 __mutex_lock_common kernel/locking/mutex.c:678 [inline]
 __mutex_lock+0x6c7/0xb90 kernel/locking/mutex.c:746
 sync_bdevs+0xfd/0x360 block/bdev.c:1288
 ksys_sync+0xb2/0x150 fs/sync.c:105
 __do_sys_sync+0xe/0x20 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff5ac38e969
RSP: 002b:00007ff5ad1c8038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007ff5ac5b5fa0 RCX: 00007ff5ac38e969
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ff5ac5b5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007ff5ac5b5fa0 R15: 00007ffdaf8fd498
 </TASK>
INFO: task syz.2.703:8538 blocked for more than 144 seconds.
      Not tainted 6.15.0-rc7-syzkaller-00175-g0f8c0258bf04 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.703       state:D stack:27384 pid:8538  tgid:8535  ppid:5811   task_flags:0x400040 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x116f/0x5de0 kernel/sched/core.c:6767
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6860
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6917
 __mutex_lock_common kernel/locking/mutex.c:678 [inline]
 __mutex_lock+0x6c7/0xb90 kernel/locking/mutex.c:746
 sync_bdevs+0xfd/0x360 block/bdev.c:1288
 ksys_sync+0xb2/0x150 fs/sync.c:105
 __do_sys_sync+0xe/0x20 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff5ac38e969
RSP: 002b:00007ff5ad1a7038 EFLAGS: 00000246
 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007ff5ac5b6080 RCX: 00007ff5ac38e969
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ff5ac5b6080 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007ff5ac5b6080 R15: 00007ffdaf8fd498
 </TASK>
INFO: task syz.2.703:8539 blocked for more than 144 seconds.
      Not tainted 6.15.0-rc7-syzkaller-00175-g0f8c0258bf04 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.703       state:D stack:29048 pid:8539  tgid:8535  ppid:5811   task_flags:0x400040 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x116f/0x5de0 kernel/sched/core.c:6767
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6860
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6917
 __mutex_lock_common kernel/locking/mutex.c:678 [inline]
 __mutex_lock+0x6c7/0xb90 kernel/locking/mutex.c:746
 sync_bdevs+0xfd/0x360 block/bdev.c:1288
 ksys_sync+0xb2/0x150 fs/sync.c:105
 __do_sys_sync+0xe/0x20 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff5ac38e969
RSP: 002b:00007ff5ad186038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007ff5ac5b6160 RCX: 00007ff5ac38e969
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ff5ac5b6160 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007ff5ac5b6160 R15: 00007ffdaf8fd498
 </TASK>

Showing all locks held in the system:
5 locks held by kworker/u8:1/13:
1 lock held by khungtaskd/31:
 #0: ffffffff8e3bfc00 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e3bfc00 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e3bfc00 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6764
5 locks held by kworker/u8:2/36:
 #0: ffff8880b8439dd8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x29/0x130 kernel/sched/core.c:605
 #1: ffff8880b8423c48 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x2c1/0x8e0 kernel/sched/psi.c:987
 #2: ffff888057638768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6092 [inline]
 #2: ffff888057638768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: cfg80211_wiphy_work+0x99/0x550 net/wireless/core.c:421
 #3: ffffffff9ad0ffb0 (&obj_hash[i].lock){-.-.}-{2:2}, at: debug_object_activate+0x14c/0x4c0 lib/debugobjects.c:818
 #4: ffffffff8e3bfc00 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #4: ffffffff8e3bfc00 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #4: ffffffff8e3bfc00 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1155 [inline]
 #4: ffffffff8e3bfc00 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0xbd/0x20a0 arch/x86/kernel/unwind_orc.c:479
3 locks held by kworker/u9:0/55:
 #0: ffff88802c781948 ((wq_completion)hci6){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3213
 #1: ffffc9000121fd18 ((work_completion)(&hdev->power_on)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3214
 #2: ffff888076194d80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_open+0x22/0x90 net/bluetooth/hci_core.c:410
6 locks held by kworker/1:1/81:
 #0: ffff888022e88d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3213
 #1: ffffc900015d7d18 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3214
 #2: ffff88802974b198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:922 [inline]
 #2: ffff88802974b198 (&dev->mutex){....}-{4:4}, at: hub_event+0x1c0/0x4fa0 drivers/usb/core/hub.c:5859
 #3: ffff888036b50198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:922 [inline]
 #3: ffff888036b50198 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4b0 drivers/base/dd.c:1004
 #4: ffff88802fd4a160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:922 [inline]
 #4: ffff88802fd4a160 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4b0 drivers/base/dd.c:1004
 #5: ffffffff8e2745d0 (umhelper_sem){++++}-{4:4}, at: usermodehelper_read_trylock+0xa9/0x250 kernel/umh.c:214
2 locks held by getty/5578:
 #0: ffff88814d1880a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002ffe2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222
1 lock held by udevd/5829:
 #0: ffff88802663b358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe40 block/bdev.c:945
1 lock held by syz.2.703/8536:
 #0: ffff88802663b358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0xfd/0x360 block/bdev.c:1288
1 lock held by syz.2.703/8538:
 #0: ffff88802663b358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0xfd/0x360 block/bdev.c:1288
1 lock held by syz.2.703/8539:
 #0: ffff88802663b358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0xfd/0x360 block/bdev.c:1288
4 locks held by udevd/8573:
 #0: ffff88803666ac30 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xe1/0x12c0 fs/seq_file.c:182
 #1: ffff88802a838488 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_seq_start+0x4d/0x240 fs/kernfs/file.c:154
 #2: ffff88807fe8b5a8 (kn->active#25){++++}-{0:0}, at: kernfs_seq_start+0x71/0x240 fs/kernfs/file.c:155
 #3: ffff888036b50198 (&dev->mutex){....}-{4:4}, at: device_lock_interruptible include/linux/device.h:927 [inline]
 #3: ffff888036b50198 (&dev->mutex){....}-{4:4}, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142
2 locks held by kworker/0:8/9364:
1 lock held by syz.0.1223/10492:
 #0: ffffffff8e3cb138 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x1a3/0x3c0 kernel/rcu/tree_exp.h:336

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.15.0-rc7-syzkaller-00175-g0f8c0258bf04 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:274 [inline]
 watchdog+0xf70/0x12c0 kernel/hung_task.c:437
 kthread+0x3c2/0x780 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 9364 Comm: kworker/0:8 Not tainted 6.15.0-rc7-syzkaller-00175-g0f8c0258bf04 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: usb_hub_wq hub_event
RIP: 0010:delay_tsc+0x11/0xc0 arch/x86/lib/delay.c:64
Code: bf e9 43 ff ff ff 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 41 55 49 89 fd bf 01 00 00 00 41 54 55 <53> e8 69 01 1d f6 e8 84 28 01 00 41 89 c4 0f 01 f9 66 90 48 c1 e2
RSP: 0018:ffffc9001fff7308 EFLAGS: 00000092
RAX: ffffffff8b6c33f0 RBX: 0000000000000000 RCX: ffffc9001a42c000
RDX: 0000000000000af0 RSI: ffffffff854fd8f9 RDI: 0000000000000001
RBP: ffffffff9adfe560 R08: 0000000000000005 R09: 0000000000000000
R10: 000000000000081f R11: 0000000000000000 R12: 000000000000081f
R13: 0000000000000af1 R14: fffffbfff35bfd06 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8881249da000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2ebedff8 CR3: 000000007ae59000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 udelay include/asm-generic/delay.h:62 [inline]
 wait_for_lsr+0xf3/0x210 drivers/tty/serial/8250/8250_port.c:2104
 fifo_wait_for_lsr drivers/tty/serial/8250/8250_port.c:3348 [inline]
 serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3371 [inline]
 serial8250_console_write+0xf83/0x1890 drivers/tty/serial/8250/8250_port.c:3456
 console_emit_next_record kernel/printk/printk.c:3138 [inline]
 console_flush_all+0x801/0xc60 kernel/printk/printk.c:3226
 __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
 console_unlock+0xd8/0x210 kernel/printk/printk.c:3325
 vprintk_emit+0x418/0x6d0 kernel/printk/printk.c:2450
 dev_vprintk_emit drivers/base/core.c:4917 [inline]
 dev_printk_emit+0xfa/0x140 drivers/base/core.c:4928
 __dev_printk+0xf5/0x270 drivers/base/core.c:4940
 _dev_info+0xe4/0x120 drivers/base/core.c:4986
 usb_disconnect+0xec/0x920 drivers/usb/core/hub.c:2298
 hub_port_connect drivers/usb/core/hub.c:5371 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5671 [inline]
 port_event drivers/usb/core/hub.c:5831 [inline]
 hub_event+0x1c57/0x4fa0 drivers/usb/core/hub.c:5913
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c2/0x780 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>