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BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff86eaf968 of 88 bytes by task 12012 on cpu 0:
 prb_reserve+0x6fb/0xaf0 kernel/printk/printk_ringbuffer.c:1691
 vprintk_store+0x54e/0x910 kernel/printk/printk.c:2354
 vprintk_emit+0x1a4/0x580 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
 tipc_set_node_addr+0x18c/0x1f0 net/tipc/addr.c:79
 tipc_net_finalize+0x108/0x160 net/tipc/net.c:137
 tipc_net_finalize_work+0x49/0x60 net/tipc/net.c:149
 process_one_work kernel/workqueue.c:3495 [inline]
 process_scheduled_works+0x53f/0xa20 kernel/workqueue.c:3578
 worker_thread+0x56c/0x770 kernel/workqueue.c:3659
 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 0xffffffff86eaf968 of 8 bytes by task 30 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:499 [inline]
 desc_read_finalized_seq kernel/printk/printk_ringbuffer.c:1932 [inline]
 prb_read kernel/printk/printk_ringbuffer.c:1980 [inline]
 _prb_read_valid+0x19b/0x8f0 kernel/printk/printk_ringbuffer.c:2170
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2242
 nbcon_kthread_should_wakeup kernel/printk/nbcon.c:1207 [inline]
 nbcon_kthread_func+0x206/0x6d0 kernel/printk/nbcon.c:1244
 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: 0x0000000000006515 -> 0x0000000000008515

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 30 Comm: pr/ttyS0 Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
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