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BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff86e9a1c8 of 88 bytes by interrupt on cpu 1:
 prb_reserve+0x6fb/0xaf0 kernel/printk/printk_ringbuffer.c:1693
 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
 lapbeth_xmit+0x1bd/0x1c0 drivers/net/wan/lapbether.c:-1
 __netdev_start_xmit include/linux/netdevice.h:5429 [inline]
 netdev_start_xmit include/linux/netdevice.h:5438 [inline]
 xmit_one net/core/dev.c:3937 [inline]
 dev_hard_start_xmit+0x10c/0x380 net/core/dev.c:3953
 __dev_queue_xmit+0xbfd/0x1e90 net/core/dev.c:4926
 dev_queue_xmit include/linux/netdevice.h:3461 [inline]
 x25_send_frame+0xfe/0x130 net/x25/x25_dev.c:193
 x25_transmit_restart_confirmation net/x25/x25_link.c:178 [inline]
 x25_link_control+0x3d1/0x500 net/x25/x25_link.c:-1
 __napi_poll+0x61/0x300 net/core/dev.c:7787
 nbcon_emit_next_record+0x4af/0x1bc0 kernel/printk/nbcon.c:1017

value changed: 0x000000000000610b -> 0x000000000000810b

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 15 Comm: pr/ttyS0 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/08/2026
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