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BUG: KCSAN: data-race in data_alloc / prb_reserve

write to 0xffffffff86084110 of 8 bytes by task 27990 on cpu 0:
 data_alloc+0x291/0x2c0 kernel/printk/printk_ringbuffer.c:1096
 prb_reserve+0x85e/0xb60 kernel/printk/printk_ringbuffer.c:1669
 vprintk_store+0x53f/0x810 kernel/printk/printk.c:2269
 vprintk_emit+0x10c/0x5e0 kernel/printk/printk.c:2329
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2363
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2373
 selinux_netlink_send+0x400/0x470 security/selinux/hooks.c:5967
 security_netlink_send+0x42/0x70 security/security.c:4132
 netlink_sendmsg+0x496/0x6e0 net/netlink/af_netlink.c:1895
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x140/0x180 net/socket.c:745
 ____sys_sendmsg+0x312/0x410 net/socket.c:2584
 ___sys_sendmsg net/socket.c:2638 [inline]
 __sys_sendmsg+0x1e9/0x280 net/socket.c:2667
 __do_sys_sendmsg net/socket.c:2676 [inline]
 __se_sys_sendmsg net/socket.c:2674 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2674
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

read to 0xffffffff86084110 of 8 bytes by task 27980 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:482 [inline]
 desc_push_tail kernel/printk/printk_ringbuffer.c:778 [inline]
 desc_reserve kernel/printk/printk_ringbuffer.c:924 [inline]
 prb_reserve+0x235/0xb60 kernel/printk/printk_ringbuffer.c:1619
 vprintk_store+0x53f/0x810 kernel/printk/printk.c:2269
 vprintk_emit+0x10c/0x5e0 kernel/printk/printk.c:2329
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2363
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2373
 selinux_netlink_send+0x400/0x470 security/selinux/hooks.c:5967
 security_netlink_send+0x42/0x70 security/security.c:4132
 netlink_sendmsg+0x496/0x6e0 net/netlink/af_netlink.c:1895
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x140/0x180 net/socket.c:745
 ____sys_sendmsg+0x312/0x410 net/socket.c:2584
 ___sys_sendmsg net/socket.c:2638 [inline]
 __sys_sendmsg+0x1e9/0x280 net/socket.c:2667
 __do_sys_sendmsg net/socket.c:2676 [inline]
 __se_sys_sendmsg net/socket.c:2674 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2674
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

value changed: 0x00000000002f1e90 -> 0x0000000000395b28

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 27980 Comm: syz-executor.2 Tainted: G        W          6.9.0-rc2-syzkaller-00040-gb1e6ec0a0fd0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pid=27980 comm=syz-executor.2