Starting Load/Save RF Kill Switch Status... Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.10.36' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 67.670929][ T6529] [ 67.673399][ T6529] ============================================ [ 67.679546][ T6529] WARNING: possible recursive locking detected [ 67.685680][ T6529] 5.15.0-rc6-next-20211022-syzkaller #0 Not tainted [ 67.692241][ T6529] -------------------------------------------- [ 67.698366][ T6529] syz-executor206/6529 is trying to acquire lock: [ 67.704766][ T6529] ffff888021ff09c8 (&mixer->reg_mutex){+.+.}-{3:3}, at: snd_mixer_oss_ioctl1+0x630/0x19a0 [ 67.714675][ T6529] [ 67.714675][ T6529] but task is already holding lock: [ 67.722016][ T6529] ffff888021ff09c8 (&mixer->reg_mutex){+.+.}-{3:3}, at: snd_mixer_oss_ioctl1+0x4b1/0x19a0 [ 67.731969][ T6529] [ 67.731969][ T6529] other info that might help us debug this: [ 67.740187][ T6529] Possible unsafe locking scenario: [ 67.740187][ T6529] [ 67.747639][ T6529] CPU0 [ 67.750929][ T6529] ---- [ 67.754189][ T6529] lock(&mixer->reg_mutex); [ 67.758769][ T6529] lock(&mixer->reg_mutex); [ 67.763345][ T6529] [ 67.763345][ T6529] *** DEADLOCK *** [ 67.763345][ T6529] [ 67.771470][ T6529] May be due to missing lock nesting notation [ 67.771470][ T6529] [ 67.779782][ T6529] 1 lock held by syz-executor206/6529: [ 67.785235][ T6529] #0: ffff888021ff09c8 (&mixer->reg_mutex){+.+.}-{3:3}, at: snd_mixer_oss_ioctl1+0x4b1/0x19a0 [ 67.795602][ T6529] [ 67.795602][ T6529] stack backtrace: [ 67.801479][ T6529] CPU: 0 PID: 6529 Comm: syz-executor206 Not tainted 5.15.0-rc6-next-20211022-syzkaller #0 [ 67.811446][ T6529] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 67.821487][ T6529] Call Trace: [ 67.824752][ T6529] [ 67.827672][ T6529] dump_stack_lvl+0xcd/0x134 [ 67.832265][ T6529] __lock_acquire.cold+0x149/0x3ab [ 67.837377][ T6529] ? lockdep_hardirqs_on_prepare+0x400/0x400 [ 67.843356][ T6529] lock_acquire+0x1ab/0x510 [ 67.847854][ T6529] ? snd_mixer_oss_ioctl1+0x630/0x19a0 [ 67.853319][ T6529] ? lock_release+0x720/0x720 [ 67.857996][ T6529] __mutex_lock+0x12f/0x12f0 [ 67.862580][ T6529] ? snd_mixer_oss_ioctl1+0x630/0x19a0 [ 67.868029][ T6529] ? slab_free_freelist_hook+0x8b/0x1c0 [ 67.873565][ T6529] ? snd_mixer_oss_ioctl1+0x630/0x19a0 [ 67.879014][ T6529] ? kfree+0xf6/0x560 [ 67.882987][ T6529] ? mutex_lock_io_nested+0x1150/0x1150 [ 67.888529][ T6529] ? snd_mixer_oss_put_volume1_sw.constprop.0.isra.0+0x286/0x410 [ 67.896415][ T6529] ? snd_mixer_oss_put_volume1+0x1e0/0xd20 [ 67.902217][ T6529] snd_mixer_oss_ioctl1+0x630/0x19a0 [ 67.907708][ T6529] ? snd_mixer_oss_put_volume1_vol.constprop.0.isra.0+0x470/0x470 [ 67.915528][ T6529] ? snd_mixer_oss_conv1.isra.0+0x130/0x130 [ 67.921425][ T6529] ? find_held_lock+0x2d/0x110 [ 67.926185][ T6529] ? ncsi_find_package_and_channel+0x20/0x270 [ 67.932245][ T6529] ? lock_downgrade+0x6e0/0x6e0 [ 67.937086][ T6529] ? lock_downgrade+0x6e0/0x6e0 [ 67.941951][ T6529] snd_mixer_oss_ioctl+0x40/0x50 [ 67.946969][ T6529] ? snd_mixer_oss_ioctl_compat+0x60/0x60 [ 67.952788][ T6529] __x64_sys_ioctl+0x193/0x200 [ 67.957547][ T6529] do_syscall_64+0x35/0xb0 [ 67.961964][ T6529] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 67.967880][ T6529] RIP: 0033:0x7f0c06979fe9 [ 67.972381][ T6529] Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 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 c0 ff ff ff f7 d8 64 89 01 48 [ 67.991986][ T6529] RSP: 002b:00007ffea97dd558 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 68.000387][ T6529] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f0c06979fe9 [ 68.008345][ T6529] RDX: 0000000020000080 RSI: 00000000c0044d00 RDI: 0000000000000003 [ 68.016302][ T6529] RBP: 00007f0c0693dfd0 R08: 0000000000000000 R09: 0000000000000000 [ 68.024284][ T6529] R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0c0693e060 [ 68.032255][ T6529] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 68.040228][ T6529]