====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.2.20/6603 is trying to acquire lock: ffff88813bc1c740 ((softirq_ctrl.lock)){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] ffff88813bc1c740 ((softirq_ctrl.lock)){+.+.}-{3:3}, at: __local_bh_disable_ip+0x112/0x1c0 kernel/softirq.c:154 but task is already holding lock: ffff8881073da150 (&group->lock#2){+.+.}-{3:3}, at: spin_lock_irq include/linux/spinlock_rt.h:94 [inline] ffff8881073da150 (&group->lock#2){+.+.}-{3:3}, at: snd_pcm_group_lock_irq sound/core/pcm_native.c:97 [inline] ffff8881073da150 (&group->lock#2){+.+.}-{3:3}, at: snd_pcm_stream_lock_irq sound/core/pcm_native.c:136 [inline] ffff8881073da150 (&group->lock#2){+.+.}-{3:3}, at: class_pcm_stream_lock_irq_constructor include/sound/pcm.h:672 [inline] ffff8881073da150 (&group->lock#2){+.+.}-{3:3}, at: snd_pcm_drop+0xaa/0x140 sound/core/pcm_native.c:2211 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&group->lock#2){+.+.}-{3:3}: rt_spin_lock+0x26/0xd0 kernel/locking/spinlock_rt.c:56 spin_lock include/linux/spinlock_rt.h:45 [inline] _snd_pcm_stream_lock_irqsave+0x45/0x50 sound/core/pcm_native.c:170 class_pcm_stream_lock_irqsave_constructor include/sound/pcm.h:675 [inline] snd_pcm_period_elapsed+0x21/0x120 sound/core/pcm_lib.c:1935 dummy_hrtimer_callback+0x2e/0x90 sound/drivers/dummy.c:385 __run_hrtimer kernel/time/hrtimer.c:1691 [inline] __hrtimer_run_queues+0x251/0x5c0 kernel/time/hrtimer.c:1755 hrtimer_run_softirq+0xa5/0x230 kernel/time/hrtimer.c:1772 handle_softirqs+0x124/0x360 kernel/softirq.c:554 run_ksoftirqd+0x5f/0xc0 kernel/softirq.c:927 smpboot_thread_fn+0x210/0x380 kernel/smpboot.c:164 kthread+0x117/0x140 kernel/kthread.c:389 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 -> #1 (&base->softirq_expiry_lock){+...}-{3:3}: rt_spin_lock+0x26/0xd0 kernel/locking/spinlock_rt.c:56 spin_lock include/linux/spinlock_rt.h:45 [inline] hrtimer_cpu_base_lock_expiry kernel/time/hrtimer.c:1356 [inline] hrtimer_run_softirq+0x3c/0x230 kernel/time/hrtimer.c:1768 handle_softirqs+0x124/0x360 kernel/softirq.c:554 __do_softirq kernel/softirq.c:588 [inline] __local_bh_enable_ip+0xcf/0x160 kernel/softirq.c:243 local_bh_enable include/linux/bottom_half.h:33 [inline] smack_netlbl_add+0xc3/0xe0 security/smack/smack_lsm.c:2599 security_socket_post_create+0xa6/0x300 security/security.c:4544 __sock_create+0x357/0x5f0 net/socket.c:1593 inet_ctl_sock_create+0x4c/0xd0 net/ipv4/af_inet.c:1649 igmp_net_init+0x87/0x100 net/ipv4/igmp.c:3037 ops_init+0x1fa/0x350 net/core/net_namespace.c:139 __register_pernet_operations net/core/net_namespace.c:1239 [inline] register_pernet_operations+0x18f/0x280 net/core/net_namespace.c:1315 register_pernet_subsys+0x28/0x40 net/core/net_namespace.c:1356 igmp_mc_init+0x17/0x70 net/ipv4/igmp.c:3095 inet_init+0x2c1/0x3d0 net/ipv4/af_inet.c:1983 do_one_initcall+0x104/0x550 init/main.c:1269 do_initcall_level+0xcb/0x1a0 init/main.c:1331 do_initcalls+0x69/0xc0 init/main.c:1347 kernel_init_freeable+0x21a/0x2c0 init/main.c:1580 kernel_init+0x1b/0x1c0 init/main.c:1469 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 -> #0 ((softirq_ctrl.lock)){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3158 [inline] check_prevs_add kernel/locking/lockdep.c:3277 [inline] validate_chain kernel/locking/lockdep.c:3901 [inline] __lock_acquire+0x12bf/0x20d0 kernel/locking/lockdep.c:5199 lock_acquire+0xea/0x270 kernel/locking/lockdep.c:5822 rt_spin_lock+0x26/0xd0 kernel/locking/spinlock_rt.c:56 spin_lock include/linux/spinlock_rt.h:45 [inline] __local_bh_disable_ip+0x112/0x1c0 kernel/softirq.c:154 local_bh_disable include/linux/bottom_half.h:20 [inline] spin_lock_bh include/linux/spinlock_rt.h:88 [inline] hrtimer_cancel_wait_running kernel/time/hrtimer.c:1421 [inline] hrtimer_cancel+0x95/0x100 kernel/time/hrtimer.c:1452 dummy_hrtimer_stop+0x3d/0x50 sound/drivers/dummy.c:409 snd_pcm_do_stop+0x7f/0xa0 sound/core/pcm_native.c:1513 snd_pcm_action_single sound/core/pcm_native.c:1293 [inline] snd_pcm_action+0x8e/0x170 sound/core/pcm_native.c:1376 snd_pcm_stop sound/core/pcm_native.c:1549 [inline] snd_pcm_drop+0xef/0x140 sound/core/pcm_native.c:2216 snd_pcm_release_substream+0x42/0x1e0 sound/core/pcm_native.c:2711 snd_pcm_oss_release_file sound/core/oss/pcm_oss.c:2398 [inline] snd_pcm_oss_release+0x97/0x130 sound/core/oss/pcm_oss.c:2577 __fput+0xfa/0x540 fs/file_table.c:431 task_work_run+0xec/0x120 kernel/task_work.c:228 get_signal+0xc1c/0xd90 kernel/signal.c:2690 arch_do_signal_or_restart+0x98/0x480 arch/x86/kernel/signal.c:310 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x70/0x120 kernel/entry/common.c:218 do_syscall_64+0xb1/0x180 arch/x86/entry/common.c:89 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.2.20/6603: #0: ffff8881073d9eb0 (&pcm->open_mutex){+.+.}-{4:4}, at: snd_pcm_oss_release+0x7d/0x130 sound/core/oss/pcm_oss.c:2576 #1: ffff8881073da150 (&group->lock#2){+.+.}-{3:3}, at: spin_lock_irq include/linux/spinlock_rt.h:94 [inline] #1: ffff8881073da150 (&group->lock#2){+.+.}-{3:3}, at: snd_pcm_group_lock_irq sound/core/pcm_native.c:97 [inline] #1: ffff8881073da150 (&group->lock#2){+.+.}-{3:3}, at: snd_pcm_stream_lock_irq sound/core/pcm_native.c:136 [inline] #1: ffff8881073da150 (&group->lock#2){+.+.}-{3:3}, at: class_pcm_stream_lock_irq_constructor include/sound/pcm.h:672 [inline] #1: ffff8881073da150 (&group->lock#2){+.+.}-{3:3}, at: snd_pcm_drop+0xaa/0x140 sound/core/pcm_native.c:2211 #2: ffffffff85a6d948 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:326 [inline] #2: ffffffff85a6d948 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #2: ffffffff85a6d948 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline] #2: ffffffff85a6d948 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x63/0xd0 kernel/locking/spinlock_rt.c:57 stack backtrace: CPU: 0 UID: 0 PID: 6603 Comm: syz.2.20 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Call Trace: dump_stack_lvl+0x12a/0x1c0 lib/dump_stack.c:119 print_circular_bug+0x29b/0x2b0 kernel/locking/lockdep.c:2074 check_noncircular+0x110/0x130 kernel/locking/lockdep.c:2203 check_prev_add kernel/locking/lockdep.c:3158 [inline] check_prevs_add kernel/locking/lockdep.c:3277 [inline] validate_chain kernel/locking/lockdep.c:3901 [inline] __lock_acquire+0x12bf/0x20d0 kernel/locking/lockdep.c:5199 lock_acquire+0xea/0x270 kernel/locking/lockdep.c:5822 rt_spin_lock+0x26/0xd0 kernel/locking/spinlock_rt.c:56 spin_lock include/linux/spinlock_rt.h:45 [inline] __local_bh_disable_ip+0x112/0x1c0 kernel/softirq.c:154 local_bh_disable include/linux/bottom_half.h:20 [inline] spin_lock_bh include/linux/spinlock_rt.h:88 [inline] hrtimer_cancel_wait_running kernel/time/hrtimer.c:1421 [inline] hrtimer_cancel+0x95/0x100 kernel/time/hrtimer.c:1452 dummy_hrtimer_stop+0x3d/0x50 sound/drivers/dummy.c:409 snd_pcm_do_stop+0x7f/0xa0 sound/core/pcm_native.c:1513 snd_pcm_action_single sound/core/pcm_native.c:1293 [inline] snd_pcm_action+0x8e/0x170 sound/core/pcm_native.c:1376 snd_pcm_stop sound/core/pcm_native.c:1549 [inline] snd_pcm_drop+0xef/0x140 sound/core/pcm_native.c:2216 snd_pcm_release_substream+0x42/0x1e0 sound/core/pcm_native.c:2711 snd_pcm_oss_release_file sound/core/oss/pcm_oss.c:2398 [inline] snd_pcm_oss_release+0x97/0x130 sound/core/oss/pcm_oss.c:2577 __fput+0xfa/0x540 fs/file_table.c:431 task_work_run+0xec/0x120 kernel/task_work.c:228 get_signal+0xc1c/0xd90 kernel/signal.c:2690 arch_do_signal_or_restart+0x98/0x480 arch/x86/kernel/signal.c:310 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x70/0x120 kernel/entry/common.c:218 do_syscall_64+0xb1/0x180 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe3b4a5ebe9 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:00007fe3b48cf038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: 0000000000009ae1 RBX: 00007fe3b4c85fa0 RCX: 00007fe3b4a5ebe9 RDX: 000000000000fc36 RSI: 0000200000000500 RDI: 0000000000000003 RBP: 00007fe3b4ae1e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fe3b4c86038 R14: 00007fe3b4c85fa0 R15: 00007ffc04ba2098