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BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff868d9ec0 of 88 bytes by task 25571 on cpu 0:
 prb_reserve+0x695/0xaf0 kernel/printk/printk_ringbuffer.c:1651
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2299
 vprintk_emit+0x10d/0x580 kernel/printk/printk.c:2399
 dev_vprintk_emit+0x242/0x2a0 drivers/base/core.c:4914
 dev_printk_emit+0x84/0xb0 drivers/base/core.c:4925
 __netdev_printk+0x35c/0x3e0 net/core/dev.c:12716
 netdev_info+0x9b/0xd0 net/core/dev.c:12771
 netif_change_name+0x628/0x6b0 net/core/dev.c:1465
 do_setlink+0x80b/0x2810 net/core/rtnetlink.c:3131
 rtnl_changelink net/core/rtnetlink.c:3769 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3928 [inline]
 rtnl_newlink+0xe75/0x12d0 net/core/rtnetlink.c:4065
 rtnetlink_rcv_msg+0x5fe/0x6d0 net/core/rtnetlink.c:6951
 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2552
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6978
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x5c0/0x690 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x58b/0x6b0 net/netlink/af_netlink.c:1896
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x145/0x180 net/socket.c:742
 __sys_sendto+0x268/0x330 net/socket.c:2244
 __do_sys_sendto net/socket.c:2251 [inline]
 __se_sys_sendto net/socket.c:2247 [inline]
 __x64_sys_sendto+0x76/0x90 net/socket.c:2247
 x64_sys_call+0x2d14/0x3000 arch/x86/include/generated/asm/syscalls_64.h:45
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff868d9ec0 of 8 bytes by task 25668 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:483 [inline]
 desc_read_finalized_seq kernel/printk/printk_ringbuffer.c:1892 [inline]
 prb_read kernel/printk/printk_ringbuffer.c:1940 [inline]
 _prb_read_valid+0x1c4/0x920 kernel/printk/printk_ringbuffer.c:2131
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2203
 printk_get_next_message+0xc8/0x510 kernel/printk/printk.c:2978
 console_emit_next_record kernel/printk/printk.c:3065 [inline]
 console_flush_all+0x290/0x6a0 kernel/printk/printk.c:3199
 __console_flush_and_unlock kernel/printk/printk.c:3258 [inline]
 console_unlock+0xa1/0x2e0 kernel/printk/printk.c:3298
 class_console_lock_destructor include/linux/console.h:669 [inline]
 do_con_write+0x28df/0x2940 drivers/tty/vt/vt.c:3243
 con_put_char+0x38/0x60 drivers/tty/vt/vt.c:3573
 tty_put_char+0x68/0xc0 drivers/tty/tty_io.c:3153
 do_output_char+0x4de/0x500 drivers/tty/n_tty.c:463
 process_output drivers/tty/n_tty.c:486 [inline]
 n_tty_write+0x869/0xb40 drivers/tty/n_tty.c:2388
 iterate_tty_write drivers/tty/tty_io.c:1006 [inline]
 file_tty_write+0x378/0x690 drivers/tty/tty_io.c:1081
 tty_write+0x25/0x30 drivers/tty/tty_io.c:1102
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x52a/0x960 fs/read_write.c:686
 ksys_write+0xda/0x1a0 fs/read_write.c:738
 __do_sys_write fs/read_write.c:749 [inline]
 __se_sys_write fs/read_write.c:746 [inline]
 __x64_sys_write+0x40/0x50 fs/read_write.c:746
 x64_sys_call+0x2802/0x3000 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000006bf6 -> 0x0000000000008bf6

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 25668 Comm: syz.8.28527 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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