============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.8.1709/13428 is trying to acquire lock: ffff88806bca6b30 (&chip->mutex){+.+.}-{3:3}, at: snd_usb_endpoint_close+0x3c/0x4c0 sound/usb/endpoint.c:964 but task is already holding lock: ffff88806bca6b30 (&chip->mutex){+.+.}-{3:3}, at: snd_usb_endpoint_set_params+0x6d/0x2b40 sound/usb/endpoint.c:1362 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&chip->mutex); lock(&chip->mutex); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by syz.8.1709/13428: #0: ffff888021c354e0 (&runtime->oss.params_lock){+.+.}-{3:3}, at: snd_pcm_oss_sync+0x2a7/0xc20 sound/core/oss/pcm_oss.c:1675 #1: ffff888021c35238 (&runtime->buffer_mutex){+.+.}-{3:3}, at: snd_pcm_buffer_access_lock sound/core/pcm_native.c:696 [inline] #1: ffff888021c35238 (&runtime->buffer_mutex){+.+.}-{3:3}, at: snd_pcm_hw_params+0x163/0x1ce0 sound/core/pcm_native.c:735 #2: ffff88806bca6b30 (&chip->mutex){+.+.}-{3:3}, at: snd_usb_endpoint_set_params+0x6d/0x2b40 sound/usb/endpoint.c:1362 stack backtrace: CPU: 0 PID: 13428 Comm: syz.8.1709 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106 check_deadlock kernel/locking/lockdep.c:3062 [inline] validate_chain kernel/locking/lockdep.c:3856 [inline] __lock_acquire+0x5dbc/0x7d40 kernel/locking/lockdep.c:5137 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x136/0xcc0 kernel/locking/mutex.c:747 snd_usb_endpoint_close+0x3c/0x4c0 sound/usb/endpoint.c:964 close_endpoints sound/usb/pcm.c:454 [inline] snd_usb_hw_params+0x1356/0x19d0 sound/usb/pcm.c:573 snd_pcm_hw_params+0x8a6/0x1ce0 sound/core/pcm_native.c:779 snd_pcm_oss_change_params_locked+0x2040/0x3cd0 sound/core/oss/pcm_oss.c:976 snd_pcm_oss_make_ready_locked sound/core/oss/pcm_oss.c:1197 [inline] snd_pcm_oss_sync+0x363/0xc20 sound/core/oss/pcm_oss.c:1679 snd_pcm_oss_release+0x102/0x240 sound/core/oss/pcm_oss.c:2589 __fput+0x234/0x970 fs/file_table.c:384 task_work_run+0x1d4/0x260 kernel/task_work.c:245 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302 do_syscall_64+0x61/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f6b9c35b58e Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08 RSP: 002b:00007f6b9d2dab28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffea RBX: 00007f6b9d2db6c0 RCX: 00007f6b9c35b58e RDX: 00000000008c4201 RSI: 00007f6b9d2dac00 RDI: ffffffffffffff9c RBP: 00007f6b9d2dac00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: cccccccccccccccd R13: 00007f6b9c616038 R14: 00007f6b9c615fa0 R15: 00007ffee60c0d28