==================================================================
BUG: KCSAN: data-race in data_alloc / prb_reserve

write to 0xffffffff8687cba0 of 8 bytes by task 19983 on cpu 1:
 data_alloc+0x31c/0x390 kernel/printk/printk_ringbuffer.c:1130
 prb_reserve+0x8d7/0xad0 kernel/printk/printk_ringbuffer.c:1724
 vprintk_store+0x53c/0x830 kernel/printk/printk.c:2302
 vprintk_emit+0x15a/0x5c0 kernel/printk/printk.c:2402
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2441
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2451
 bt_err+0x9d/0xd0 net/bluetooth/lib.c:296
 hci_cmd_timeout+0x97/0x140 net/bluetooth/hci_core.c:1469
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3340
 worker_thread+0x582/0x770 kernel/workqueue.c:3421
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

read to 0xffffffff8687cba0 of 8 bytes by task 3535 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:496 [inline]
 desc_push_tail kernel/printk/printk_ringbuffer.c:792 [inline]
 desc_reserve kernel/printk/printk_ringbuffer.c:938 [inline]
 prb_reserve+0x207/0xad0 kernel/printk/printk_ringbuffer.c:1674
 vprintk_store+0x53c/0x830 kernel/printk/printk.c:2302
 vprintk_emit+0x15a/0x5c0 kernel/printk/printk.c:2402
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2441
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2451
 bt_err+0x9d/0xd0 net/bluetooth/lib.c:296
 __hci_cmd_sync_status_sk net/bluetooth/hci_sync.c:271 [inline]
 __hci_cmd_sync_status net/bluetooth/hci_sync.c:287 [inline]
 hci_read_local_features_sync net/bluetooth/hci_sync.c:3708 [inline]
 hci_init_stage_sync net/bluetooth/hci_sync.c:3623 [inline]
 hci_init1_sync net/bluetooth/hci_sync.c:3755 [inline]
 hci_init_sync net/bluetooth/hci_sync.c:4885 [inline]
 hci_dev_init_sync net/bluetooth/hci_sync.c:5077 [inline]
 hci_dev_open_sync+0xfa4/0x2290 net/bluetooth/hci_sync.c:5155
 hci_dev_do_open net/bluetooth/hci_core.c:430 [inline]
 hci_power_on+0xef/0x390 net/bluetooth/hci_core.c:959
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3340
 worker_thread+0x582/0x770 kernel/workqueue.c:3421
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

value changed: 0x0000000000005ed0 -> 0x00000000000ab728

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3535 Comm: kworker/u9:2 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: hci0 hci_power_on
==================================================================
Bluetooth: hci0: Opcode 0x1003 failed: -110