syzbot

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BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff85b1abd8 of 8 bytes by task 22205 on cpu 1:
 prb_reserve+0x72a/0xbc0
 vprintk_store+0x53e/0x800 kernel/printk/printk.c:2232
 vprintk_emit+0xd0/0x430 kernel/printk/printk.c:2288
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2318
 vprintk+0x83/0x90 kernel/printk/printk_safe.c:50
 _printk+0x7a/0xa0 kernel/printk/printk.c:2328
 vlan_device_event+0x106a/0x1120 net/8021q/vlan.c:383
 notifier_call_chain kernel/notifier.c:93 [inline]
 raw_notifier_call_chain+0x6b/0x1c0 kernel/notifier.c:461
 __dev_notify_flags+0x205/0x3d0
 rtnl_newlink_create net/core/rtnetlink.c:3451 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3660 [inline]
 rtnl_newlink+0x121e/0x15a0 net/core/rtnetlink.c:3673
 rtnetlink_rcv_msg+0x807/0x8c0 net/core/rtnetlink.c:6395
 netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2546
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6413
 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
 netlink_unicast+0x56f/0x640 net/netlink/af_netlink.c:1365
 netlink_sendmsg+0x665/0x770 net/netlink/af_netlink.c:1913
 sock_sendmsg_nosec net/socket.c:724 [inline]
 sock_sendmsg net/socket.c:747 [inline]
 ____sys_sendmsg+0x375/0x4c0 net/socket.c:2503
 ___sys_sendmsg net/socket.c:2557 [inline]
 __sys_sendmsg+0x1e3/0x270 net/socket.c:2586
 __do_sys_sendmsg net/socket.c:2595 [inline]
 __se_sys_sendmsg net/socket.c:2593 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2593
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffffffff85b1abd8 of 8 bytes by task 2733 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:482 [inline]
 prb_first_seq kernel/printk/printk_ringbuffer.c:1846 [inline]
 _prb_read_valid+0x2c1/0x910 kernel/printk/printk_ringbuffer.c:1892
 prb_read_valid+0x3d/0x60 kernel/printk/printk_ringbuffer.c:1940
 syslog_print+0xfc/0x760 kernel/printk/printk.c:1579
 do_syslog+0x3c6/0x860 kernel/printk/printk.c:1732
 __do_sys_syslog kernel/printk/printk.c:1824 [inline]
 __se_sys_syslog kernel/printk/printk.c:1822 [inline]
 __x64_sys_syslog+0x43/0x50 kernel/printk/printk.c:1822
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000001a27 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2733 Comm: klogd Not tainted 6.4.0-rc3-syzkaller-00291-g4e893b5aa4ac #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
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