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

write to 0xffffffff86e71f48 of 8 bytes by task 7364 on cpu 1:
 data_alloc+0x308/0x380 kernel/printk/printk_ringbuffer.c:1130
 prb_reserve+0x8e3/0xaf0 kernel/printk/printk_ringbuffer.c:1727
 vprintk_store+0x54e/0x910 kernel/printk/printk.c:2354
 vprintk_emit+0x1a4/0x610 kernel/printk/printk.c:2455
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 bt_err+0xa7/0xd0 net/bluetooth/lib.c:293
 __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:3848 [inline]
 hci_init_stage_sync net/bluetooth/hci_sync.c:3761 [inline]
 hci_init1_sync net/bluetooth/hci_sync.c:3895 [inline]
 hci_init_sync net/bluetooth/hci_sync.c:5162 [inline]
 hci_dev_init_sync net/bluetooth/hci_sync.c:5354 [inline]
 hci_dev_open_sync+0xf8e/0x22b0 net/bluetooth/hci_sync.c:5432
 hci_dev_do_open net/bluetooth/hci_core.c:431 [inline]
 hci_power_on+0xef/0x390 net/bluetooth/hci_core.c:923
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0x56a/0xa50 kernel/workqueue.c:3479
 worker_thread+0x569/0x750 kernel/workqueue.c:3560
 kthread+0x223/0x270 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffffffff86e71f48 of 8 bytes by task 3568 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+0x21a/0xaf0 kernel/printk/printk_ringbuffer.c:1677
 vprintk_store+0x54e/0x910 kernel/printk/printk.c:2354
 vprintk_emit+0x1a4/0x610 kernel/printk/printk.c:2455
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 bt_err+0xa7/0xd0 net/bluetooth/lib.c:293
 hci_cmd_timeout+0x97/0x140 net/bluetooth/hci_core.c:1433
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0x56a/0xa50 kernel/workqueue.c:3479
 worker_thread+0x569/0x750 kernel/workqueue.c:3560
 kthread+0x223/0x270 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0xfffffffffffeb828 -> 0x000000000009d638

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3568 Comm: kworker/u9:1 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: hci0 hci_cmd_timeout
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Bluetooth: hci0: command 0x1003 tx timeout