IPVS: starting estimator thread 0...
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BUG: KCSAN: data-race in data_alloc / data_push_tail

write to 0xffffffff88e3d928 of 8 bytes by task 24502 on cpu 0:
 data_alloc+0x203/0x2b0 kernel/printk/printk_ringbuffer.c:1082
 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
 ip_vs_scheduler_err+0x190/0x1a0 net/netfilter/ipvs/ip_vs_sched.c:-1
 ip_vs_wrr_schedule+0x208/0x250 net/netfilter/ipvs/ip_vs_wrr.c:227
 ip_vs_schedule+0x5b4/0xe20 net/netfilter/ipvs/ip_vs_core.c:528
 udp_conn_schedule+0x230/0x3b0 net/netfilter/ipvs/ip_vs_proto_udp.c:78
 ip_vs_try_to_schedule net/netfilter/ipvs/ip_vs_core.c:1482 [inline]
 ip_vs_in_hook+0x5e2/0x1250 net/netfilter/ipvs/ip_vs_core.c:2054
 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
 nf_hook_slow+0x78/0x180 net/netfilter/core.c:623
 nf_hook include/linux/netfilter.h:273 [inline]
 __ip_local_out+0x2cb/0x2f0 net/ipv4/ip_output.c:118
 ip_local_out net/ipv4/ip_output.c:127 [inline]
 ip_send_skb+0x34/0x160 net/ipv4/ip_output.c:1506
 udp_send_skb+0x6e3/0xa40 net/ipv4/udp.c:1195
 udp_sendmsg+0x1050/0x13c0 net/ipv4/udp.c:1484
 inet_sendmsg+0xac/0xd0 net/ipv4/af_inet.c:851
 sock_sendmsg_nosec net/socket.c:714 [inline]
 __sock_sendmsg+0x102/0x180 net/socket.c:729
 ____sys_sendmsg+0x345/0x4e0 net/socket.c:2614
 ___sys_sendmsg+0x17b/0x1d0 net/socket.c:2668
 __sys_sendmmsg+0x178/0x300 net/socket.c:2757
 __do_sys_sendmmsg net/socket.c:2784 [inline]
 __se_sys_sendmmsg net/socket.c:2781 [inline]
 __x64_sys_sendmmsg+0x57/0x70 net/socket.c:2781
 x64_sys_call+0x1c4a/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:308
 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 0xffffffff88e3d928 of 8 bytes by task 2958 on cpu 1:
 data_make_reusable kernel/printk/printk_ringbuffer.c:594 [inline]
 data_push_tail+0xfd/0x420 kernel/printk/printk_ringbuffer.c:679
 data_alloc+0xbf/0x2b0 kernel/printk/printk_ringbuffer.c:1054
 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
 ip_vs_est_kthread_start+0x191/0x1b0 net/netfilter/ipvs/ip_vs_est.c:271
 est_reload_work_handler+0x1ab/0x3b0 net/netfilter/ipvs/ip_vs_ctl.c:269
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3319
 worker_thread+0x582/0x770 kernel/workqueue.c:3400
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x11f/0x1b0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x0000000100000aaf -> 0x0000000100001751

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 2958 Comm: kworker/1:2 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: events_long est_reload_work_handler
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