======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.1.2776/12156 is trying to acquire lock:
ffff8880b8923d90 ((softirq_ctrl.lock)){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:44 [inline]
ffff8880b8923d90 ((softirq_ctrl.lock)){+.+.}-{3:3}, at: __local_bh_disable_ip+0x264/0x400 kernel/softirq.c:168
but task is already holding lock:
ffff88814d393950 (&group->lock#2){+.+.}-{3:3}, at: spin_lock_irq include/linux/spinlock_rt.h:93 [inline]
ffff88814d393950 (&group->lock#2){+.+.}-{3:3}, at: snd_pcm_group_lock_irq sound/core/pcm_native.c:98 [inline]
ffff88814d393950 (&group->lock#2){+.+.}-{3:3}, at: snd_pcm_stream_lock_irq sound/core/pcm_native.c:137 [inline]
ffff88814d393950 (&group->lock#2){+.+.}-{3:3}, at: class_pcm_stream_lock_irq_constructor include/sound/pcm.h:679 [inline]
ffff88814d393950 (&group->lock#2){+.+.}-{3:3}, at: snd_pcm_drop+0x10d/0x270 sound/core/pcm_native.c:2223
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&group->lock#2){+.+.}-{3:3}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
rt_spin_lock+0x88/0x2c0 kernel/locking/spinlock_rt.c:56
spin_lock include/linux/spinlock_rt.h:44 [inline]
_snd_pcm_stream_lock_irqsave+0x7c/0xa0 sound/core/pcm_native.c:171
class_pcm_stream_lock_irqsave_constructor include/sound/pcm.h:682 [inline]
snd_pcm_period_elapsed+0x1e/0x80 sound/core/pcm_lib.c:1938
dummy_hrtimer_callback+0x80/0x180 sound/drivers/dummy.c:386
__run_hrtimer kernel/time/hrtimer.c:1761 [inline]
__hrtimer_run_queues+0x54f/0xd40 kernel/time/hrtimer.c:1825
hrtimer_run_softirq+0x1a3/0x2e0 kernel/time/hrtimer.c:1842
handle_softirqs+0x22c/0x710 kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
run_ktimerd+0xcf/0x190 kernel/softirq.c:1043
smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #1 (&base->softirq_expiry_lock){+...}-{3:3}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
rt_spin_lock+0x88/0x2c0 kernel/locking/spinlock_rt.c:56
spin_lock include/linux/spinlock_rt.h:44 [inline]
hrtimer_cpu_base_lock_expiry kernel/time/hrtimer.c:1383 [inline]
hrtimer_run_softirq+0x7c/0x2e0 kernel/time/hrtimer.c:1838
handle_softirqs+0x22c/0x710 kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
run_ktimerd+0xcf/0x190 kernel/softirq.c:1043
smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #0 ((softirq_ctrl.lock)){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
__lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
reacquire_held_locks+0x127/0x1d0 kernel/locking/lockdep.c:5385
__lock_release kernel/locking/lockdep.c:5574 [inline]
lock_release+0x1b4/0x3e0 kernel/locking/lockdep.c:5889
__local_bh_enable_ip+0x10c/0x270 kernel/softirq.c:228
hrtimer_cancel+0x39/0x60 kernel/time/hrtimer.c:1491
dummy_hrtimer_stop+0xcf/0x100 sound/drivers/dummy.c:410
snd_pcm_do_stop+0x12a/0x1c0 sound/core/pcm_native.c:1525
snd_pcm_action_single sound/core/pcm_native.c:1305 [inline]
snd_pcm_action+0xe7/0x240 sound/core/pcm_native.c:1388
snd_pcm_stop sound/core/pcm_native.c:1561 [inline]
snd_pcm_drop+0x160/0x270 sound/core/pcm_native.c:2228
snd_pcm_release_substream+0x6d/0x480 sound/core/pcm_native.c:2727
snd_pcm_oss_release_file sound/core/oss/pcm_oss.c:2397 [inline]
snd_pcm_oss_release+0x147/0x250 sound/core/oss/pcm_oss.c:2576
__fput+0x45b/0xa80 fs/file_table.c:468
task_work_run+0x1d1/0x260 kernel/task_work.c:227
get_signal+0x11c5/0x1310 kernel/signal.c:2807
arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop+0x75/0x110 kernel/entry/common.c:40
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
other info that might help us debug this:
Chain exists of:
(softirq_ctrl.lock) --> &base->softirq_expiry_lock --> &group->lock#2
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&group->lock#2);
lock(&base->softirq_expiry_lock);
lock(&group->lock#2);
lock((softirq_ctrl.lock));
*** DEADLOCK ***
3 locks held by syz.1.2776/12156:
#0: ffff88814d3932b0 (&pcm->open_mutex){+.+.}-{4:4}, at: snd_pcm_oss_release+0x113/0x250 sound/core/oss/pcm_oss.c:2575
#1: ffff88814d393950 (&group->lock#2){+.+.}-{3:3}, at: spin_lock_irq include/linux/spinlock_rt.h:93 [inline]
#1: ffff88814d393950 (&group->lock#2){+.+.}-{3:3}, at: snd_pcm_group_lock_irq sound/core/pcm_native.c:98 [inline]
#1: ffff88814d393950 (&group->lock#2){+.+.}-{3:3}, at: snd_pcm_stream_lock_irq sound/core/pcm_native.c:137 [inline]
#1: ffff88814d393950 (&group->lock#2){+.+.}-{3:3}, at: class_pcm_stream_lock_irq_constructor include/sound/pcm.h:679 [inline]
#1: ffff88814d393950 (&group->lock#2){+.+.}-{3:3}, at: snd_pcm_drop+0x10d/0x270 sound/core/pcm_native.c:2223
#2: ffffffff8d9a8dc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#2: ffffffff8d9a8dc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
#2: ffffffff8d9a8dc0 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
#2: ffffffff8d9a8dc0 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1bb/0x2c0 kernel/locking/spinlock_rt.c:57
stack backtrace:
CPU: 1 UID: 0 PID: 12156 Comm: syz.1.2776 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043
check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2175
check_prev_add kernel/locking/lockdep.c:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
__lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
reacquire_held_locks+0x127/0x1d0 kernel/locking/lockdep.c:5385
__lock_release kernel/locking/lockdep.c:5574 [inline]
lock_release+0x1b4/0x3e0 kernel/locking/lockdep.c:5889
__local_bh_enable_ip+0x10c/0x270 kernel/softirq.c:228
hrtimer_cancel+0x39/0x60 kernel/time/hrtimer.c:1491
dummy_hrtimer_stop+0xcf/0x100 sound/drivers/dummy.c:410
snd_pcm_do_stop+0x12a/0x1c0 sound/core/pcm_native.c:1525
snd_pcm_action_single sound/core/pcm_native.c:1305 [inline]
snd_pcm_action+0xe7/0x240 sound/core/pcm_native.c:1388
snd_pcm_stop sound/core/pcm_native.c:1561 [inline]
snd_pcm_drop+0x160/0x270 sound/core/pcm_native.c:2228
snd_pcm_release_substream+0x6d/0x480 sound/core/pcm_native.c:2727
snd_pcm_oss_release_file sound/core/oss/pcm_oss.c:2397 [inline]
snd_pcm_oss_release+0x147/0x250 sound/core/oss/pcm_oss.c:2576
__fput+0x45b/0xa80 fs/file_table.c:468
task_work_run+0x1d1/0x260 kernel/task_work.c:227
get_signal+0x11c5/0x1310 kernel/signal.c:2807
arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop+0x75/0x110 kernel/entry/common.c:40
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f952eddeec9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f952d046038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: 0000000000009b5a RBX: 00007f952f035fa0 RCX: 00007f952eddeec9
RDX: 000000000000fc36 RSI: 0000200000000500 RDI: 0000000000000003
RBP: 00007f952ee61f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f952f036038 R14: 00007f952f035fa0 R15: 00007fff4f024bf8
</TASK>