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BUG: KCSAN: data-race in _prb_read_valid / data_alloc

write to 0xffffffff86c7f4a8 of 8 bytes by interrupt on cpu 1:
 data_alloc+0x2fc/0x380 kernel/printk/printk_ringbuffer.c:1129
 prb_reserve+0x8e3/0xaf0 kernel/printk/printk_ringbuffer.c:1727
 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2354
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2455
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 print_daily_error_info+0x210/0x300 fs/ext4/super.c:3712
 call_timer_fn+0x3b/0x240 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1799 [inline]
 __run_timers kernel/time/timer.c:2374 [inline]
 __run_timer_base+0x40c/0x5f0 kernel/time/timer.c:2386
 run_timer_base kernel/time/timer.c:2395 [inline]
 run_timer_softirq+0x31/0x70 kernel/time/timer.c:2405
 handle_softirqs+0xb9/0x280 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x42/0xd0 kernel/softirq.c:735
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
 sysvec_apic_timer_interrupt+0x74/0x80 arch/x86/kernel/apic/apic.c:1061
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
 console_flush_one_record arch/x86/include/asm/irqflags.h:-1 [inline]
 console_flush_all+0x513/0x6b0 kernel/printk/printk.c:3343
 __console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
 console_unlock+0xa1/0x280 kernel/printk/printk.c:3413
 vprintk_emit+0x3e4/0x600 kernel/printk/printk.c:2479
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 hashlimit_mt_check_common+0x443/0x6b0 net/netfilter/xt_hashlimit.c:854
 hashlimit_mt_check+0x64/0x80 net/netfilter/xt_hashlimit.c:959
 xt_checkentry_match net/netfilter/x_tables.c:543 [inline]
 xt_check_match+0x3b7/0x5e0 net/netfilter/x_tables.c:576
 check_match net/ipv6/netfilter/ip6_tables.c:488 [inline]
 find_check_match net/ipv6/netfilter/ip6_tables.c:505 [inline]
 find_check_entry net/ipv6/netfilter/ip6_tables.c:556 [inline]
 translate_table+0xbd5/0x1210 net/ipv6/netfilter/ip6_tables.c:733
 do_replace net/ipv6/netfilter/ip6_tables.c:1152 [inline]
 do_ip6t_set_ctl+0x6ce/0x8e0 net/ipv6/netfilter/ip6_tables.c:1641
 nf_setsockopt+0x199/0x1b0 net/netfilter/nf_sockopt.c:101
 ipv6_setsockopt+0x11a/0x130 net/ipv6/ipv6_sockglue.c:970
 rawv6_setsockopt+0x1cc/0x3f0 net/ipv6/raw.c:1048
 sock_common_setsockopt+0x69/0x80 net/core/sock.c:3998
 do_sock_setsockopt net/socket.c:2382 [inline]
 __sys_setsockopt+0x184/0x200 net/socket.c:2407
 __do_sys_setsockopt net/socket.c:2413 [inline]
 __se_sys_setsockopt net/socket.c:2410 [inline]
 __x64_sys_setsockopt+0x64/0x80 net/socket.c:2410
 x64_sys_call+0x2327/0x3020 arch/x86/include/generated/asm/syscalls_64.h:55
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86c7f4a8 of 16 bytes by task 2977 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:496 [inline]
 desc_read_finalized_seq kernel/printk/printk_ringbuffer.c:1934 [inline]
 prb_read kernel/printk/printk_ringbuffer.c:1982 [inline]
 _prb_read_valid+0x183/0x930 kernel/printk/printk_ringbuffer.c:2173
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2245
 syslog_print+0x164/0x560 kernel/printk/printk.c:1612
 do_syslog+0x52b/0x7f0 kernel/printk/printk.c:1763
 __do_sys_syslog kernel/printk/printk.c:1855 [inline]
 __se_sys_syslog kernel/printk/printk.c:1853 [inline]
 __x64_sys_syslog+0x41/0x50 kernel/printk/printk.c:1853
 x64_sys_call+0x2b9e/0x3020 arch/x86/include/generated/asm/syscalls_64.h:104
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 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: 2977 Comm: klogd Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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