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BUG: KCSAN: data-race in data_alloc / prb_reserve

write to 0xffffffff860834d8 of 8 bytes by task 24315 on cpu 1:
 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:2266
 vprintk_emit+0x10c/0x5e0 kernel/printk/printk.c:2326
 dev_vprintk_emit+0x1df/0x210 drivers/base/core.c:4951
 dev_printk_emit+0x82/0xb0 drivers/base/core.c:4962
 __netdev_printk+0x352/0x3e0 net/core/dev.c:11624
 netdev_info+0x99/0xc0 net/core/dev.c:11679
 dev_change_name+0x5a5/0x610 net/core/dev.c:1239
 do_setlink+0x66d/0x2490 net/core/rtnetlink.c:2880
 __rtnl_newlink net/core/rtnetlink.c:3696 [inline]
 rtnl_newlink+0x11a1/0x1690 net/core/rtnetlink.c:3743
 rtnetlink_rcv_msg+0x82e/0x8e0 net/core/rtnetlink.c:6595
 netlink_rcv_skb+0x12c/0x230 net/netlink/af_netlink.c:2564
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6613
 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
 netlink_unicast+0x58d/0x660 net/netlink/af_netlink.c:1361
 netlink_sendmsg+0x5ca/0x6e0 net/netlink/af_netlink.c:1905
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x140/0x180 net/socket.c:745
 __sys_sendto+0x1e5/0x260 net/socket.c:2192
 __do_sys_sendto net/socket.c:2204 [inline]
 __se_sys_sendto net/socket.c:2200 [inline]
 __x64_sys_sendto+0x78/0x90 net/socket.c:2200
 x64_sys_call+0x16d7/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:45
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff860834d8 of 8 bytes by task 20837 on cpu 0:
 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:2266
 vprintk_emit+0x10c/0x5e0 kernel/printk/printk.c:2326
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2360
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2370
 __ext4_msg+0x18e/0x1a0 fs/ext4/super.c:990
 ext4_put_super+0x91/0x7e0 fs/ext4/super.c:1295
 generic_shutdown_super+0xde/0x210 fs/super.c:642
 kill_block_super+0x2a/0x70 fs/super.c:1676
 ext4_kill_sb+0x44/0x80 fs/ext4/super.c:7301
 deactivate_locked_super+0x7d/0x1c0 fs/super.c:473
 deactivate_super+0x9f/0xb0 fs/super.c:506
 cleanup_mnt+0x268/0x2e0 fs/namespace.c:1267
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1274
 task_work_run+0x13a/0x1a0 kernel/task_work.c:180
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xbe/0x130 kernel/entry/common.c:218
 do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000032148 -> 0x00000000000e5540

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 20837 Comm: syz-executor.4 Not tainted 6.9.0-syzkaller-12398-gc13320499ba0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
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EXT4-fs (loop4): unmounting filesystem 76b65be2-f6da-4727-8c75-0525a5b65a09.