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BUG: KCSAN: data-race in _prb_read_valid / data_alloc

write to 0xffffffff86888eb0 of 8 bytes by task 16689 on cpu 1:
 data_alloc+0x271/0x2b0 kernel/printk/printk_ringbuffer.c:1095
 prb_reserve+0x808/0xaf0 kernel/printk/printk_ringbuffer.c:1669
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2326
 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2475
 __netdev_printk+0x321/0x3e0 net/core/dev.c:12517
 netdev_info+0x9b/0xd0 net/core/dev.c:12564
 __dev_set_promiscuity+0x233/0x450 net/core/dev.c:9270
 __dev_set_rx_mode+0x113/0x160 net/core/dev.c:-1
 dev_uc_add+0x8d/0xb0 net/core/dev_addr_lists.c:693
 vlan_dev_set_mac_address+0x123/0x200 net/8021q/vlan_dev.c:324
 netif_set_mac_address+0x1a5/0x260 net/core/dev.c:9688
 do_setlink+0x5a5/0x2810 net/core/rtnetlink.c:3093
 rtnl_changelink net/core/rtnetlink.c:3759 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3918 [inline]
 rtnl_newlink+0xe75/0x12d0 net/core/rtnetlink.c:4055
 rtnetlink_rcv_msg+0x5fe/0x6d0 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x120/0x220 net/netlink/af_netlink.c:2552
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6971
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x5a8/0x680 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x58b/0x6b0 net/netlink/af_netlink.c:1896
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x145/0x180 net/socket.c:727
 __sys_sendto+0x268/0x330 net/socket.c:2180
 __do_sys_sendto net/socket.c:2187 [inline]
 __se_sys_sendto net/socket.c:2183 [inline]
 __x64_sys_sendto+0x76/0x90 net/socket.c:2183
 x64_sys_call+0x2eb6/0x2fb0 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 0xffffffff86888eb0 of 16 bytes by task 16828 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:482 [inline]
 desc_read_finalized_seq kernel/printk/printk_ringbuffer.c:1874 [inline]
 prb_read kernel/printk/printk_ringbuffer.c:1922 [inline]
 _prb_read_valid+0x1bc/0x920 kernel/printk/printk_ringbuffer.c:2113
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2185
 printk_get_next_message+0xc8/0x510 kernel/printk/printk.c:3005
 console_emit_next_record kernel/printk/printk.c:3092 [inline]
 console_flush_all+0x290/0x730 kernel/printk/printk.c:3226
 __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
 console_unlock+0xa1/0x330 kernel/printk/printk.c:3325
 do_con_write+0x28d7/0x2940 drivers/tty/vt/vt.c:-1
 con_put_char+0x38/0x60 drivers/tty/vt/vt.c:3524
 tty_put_char+0x65/0xc0 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+0x85b/0xb10 drivers/tty/n_tty.c:2388
 iterate_tty_write drivers/tty/tty_io.c:1006 [inline]
 file_tty_write+0x389/0x670 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+0x4a0/0x8e0 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+0x2cdd/0x2fb0 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 16828 Comm: syz.5.4141 Not tainted 6.16.0-rc6-syzkaller-00121-g6832a9317eee #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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