Message-ID: <688aa543.a00a0220.26d0e1.0030.GAE@google.com>
Date: Wed, 30 Jul 2025 16:05:39 -0700
From: syzbot <syzbot+234fdcc5f6633833a35c@...kaller.appspotmail.com>
To: anna-maria@...utronix.de, frederic@...nel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com, 
	tglx@...utronix.de
Subject: [syzbot] [kernel?] INFO: task hung in hidp_session_remove

Hello,

syzbot found the following issue on:

HEAD commit:    733923397fd9 Merge tag 'pwm/for-6.16-rc6-fixes' of git://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10997f70580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b309c907eaab29da
dashboard link: https://syzkaller.appspot.com/bug?extid=234fdcc5f6633833a35c
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10aa4a8c580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12997f70580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-73392339.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/be7feaa77b8c/vmlinux-73392339.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a663b3e31463/bzImage-73392339.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+234fdcc5f6633833a35c@...kaller.appspotmail.com

INFO: task khidpd_15e20040:5506 blocked for more than 143 seconds.
      Not tainted 6.16.0-rc5-syzkaller-00038-g733923397fd9 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:khidpd_15e20040 state:D stack:29000 pid:5506  tgid:5506  ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5401 [inline]
 __schedule+0x16f5/0x4d00 kernel/sched/core.c:6790
 __schedule_loop kernel/sched/core.c:6868 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6883
 schedule_timeout+0x9a/0x270 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x2bf/0x5d0 kernel/sched/completion.c:148
 __flush_work+0x9b9/0xbc0 kernel/workqueue.c:4246
 __cancel_work_sync+0xbe/0x110 kernel/workqueue.c:4366
 hidp_session_remove+0x62/0x260 net/bluetooth/hidp/core.c:1169
 l2cap_unregister_user+0x18e/0x1b0 net/bluetooth/l2cap_core.c:1734
 hidp_session_thread+0x3c9/0x410 net/bluetooth/hidp/core.c:1304
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: task syz.0.171:5661 blocked for more than 143 seconds.
      Not tainted 6.16.0-rc5-syzkaller-00038-g733923397fd9 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.171       state:D stack:27240 pid:5661  tgid:5661  ppid:5462   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5401 [inline]
 __schedule+0x16f5/0x4d00 kernel/sched/core.c:6790
 __schedule_loop kernel/sched/core.c:6868 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6883
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6940
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x724/0xe80 kernel/locking/mutex.c:747
 l2cap_chan_connect+0x102/0xe30 net/bluetooth/l2cap_core.c:6964
 l2cap_sock_connect+0x5c5/0x7a0 net/bluetooth/l2cap_sock.c:256
 __sys_connect_file net/socket.c:2038 [inline]
 __sys_connect+0x313/0x440 net/socket.c:2057
 __do_sys_connect net/socket.c:2063 [inline]
 __se_sys_connect net/socket.c:2060 [inline]
 __x64_sys_connect+0x7a/0x90 net/socket.c:2060
 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: 0033:0x7f3e5c78e929
RSP: 002b:00007ffe356d7bb8 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f3e5c9b5fa0 RCX: 00007f3e5c78e929
RDX: 000000000000000e RSI: 0000200000000080 RDI: 0000000000000004
RBP: 00007f3e5c810b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3e5c9b5fa0 R14: 00007f3e5c9b5fa0 R15: 0000000000000003
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/0:0/9:
2 locks held by kworker/0:1/10:
1 lock held by khungtaskd/26:
 #0: ffffffff8e13f160 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e13f160 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e13f160 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6770
2 locks held by getty/5125:
 #0: ffff8880317890a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000018e2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
2 locks held by khidpd_15e20040/5506:
 #0: ffff8880330c80b8 (&hdev->lock){+.+.}-{4:4}, at: l2cap_unregister_user+0x6a/0x1b0 net/bluetooth/l2cap_core.c:1728
 #1: ffffffff8f6ae9b0 (hidp_session_sem){++++}-{4:4}, at: hidp_session_remove+0x2c/0x260 net/bluetooth/hidp/core.c:1165
1 lock held by syz.0.171/5661:
 #0: ffff8880330c80b8 (&hdev->lock){+.+.}-{4:4}, at: l2cap_chan_connect+0x102/0xe30 net/bluetooth/l2cap_core.c:6964
1 lock held by syz.1.172/5698:
 #0: ffffffff8f6ae9b0 (hidp_session_sem){++++}-{4:4}, at: hidp_session_find+0x1a/0x100 net/bluetooth/hidp/core.c:1026
1 lock held by syz.2.173/5730:
 #0: ffffffff8f6ae9b0 (hidp_session_sem){++++}-{4:4}, at: hidp_session_find+0x1a/0x100 net/bluetooth/hidp/core.c:1026
1 lock held by syz.3.174/5761:
 #0: ffffffff8f6ae9b0 (hidp_session_sem){++++}-{4:4}, at: hidp_session_find+0x1a/0x100 net/bluetooth/hidp/core.c:1026
1 lock held by syz.4.175/5805:
 #0: ffffffff8f6ae9b0 (hidp_session_sem){++++}-{4:4}, at: hidp_session_find+0x1a/0x100 net/bluetooth/hidp/core.c:1026
1 lock held by syz.5.176/5841:
 #0: ffffffff8f6ae9b0 (hidp_session_sem){++++}-{4:4}, at: hidp_session_find+0x1a/0x100 net/bluetooth/hidp/core.c:1026
1 lock held by syz.6.177/5879:
 #0: ffffffff8f6ae9b0 (hidp_session_sem){++++}-{4:4}, at: hidp_session_find+0x1a/0x100 net/bluetooth/hidp/core.c:1026
1 lock held by syz.7.178/5914:
 #0: ffffffff8f6ae9b0 (hidp_session_sem){++++}-{4:4}, at: hidp_session_find+0x1a/0x100 net/bluetooth/hidp/core.c:1026
1 lock held by syz.8.179/5957:
 #0: ffffffff8f6ae9b0 (hidp_session_sem){++++}-{4:4}, at: hidp_session_find+0x1a/0x100 net/bluetooth/hidp/core.c:1026

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 26 Comm: khungtaskd Not tainted 6.16.0-rc5-syzkaller-00038-g733923397fd9 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 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:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:307 [inline]
 watchdog+0xfee/0x1030 kernel/hung_task.c:470
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


---
This report is generated by a bot. It may contain errors.
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If the report is already addressed, let syzbot know by replying with:
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