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BUG: KCSAN: data-race in ktime_get_ts64 / timekeeping_update_from_shadow

write to 0xffffffff895f9508 of 320 bytes by interrupt on cpu 0:
 timekeeping_update_from_shadow+0x448/0x480 kernel/time/timekeeping.c:866
 __timekeeping_advance+0xb36/0xcf0 kernel/time/timekeeping.c:2663
 timekeeping_advance kernel/time/timekeeping.c:2671 [inline]
 update_wall_time+0x21/0x50 kernel/time/timekeeping.c:2681
 tick_do_update_jiffies64+0x169/0x1c0 kernel/time/tick-sched.c:149
 tick_sched_do_timer kernel/time/tick-sched.c:253 [inline]
 tick_nohz_handler+0x88/0x380 kernel/time/tick-sched.c:310
 __run_hrtimer kernel/time/hrtimer.c:2074 [inline]
 __hrtimer_run_queues+0x1f8/0x510 kernel/time/hrtimer.c:2131
 hrtimer_interrupt+0x27b/0x860 kernel/time/hrtimer.c:2250
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline]
 __sysvec_apic_timer_interrupt+0x5f/0x1c0 arch/x86/kernel/apic/apic.c:1068
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0x6f/0x80 arch/x86/kernel/apic/apic.c:1062
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
 kcsan_setup_watchpoint+0x42b/0x4a0 kernel/kcsan/core.c:713
 get_counters net/ipv4/netfilter/ip_tables.c:762 [inline]
 alloc_counters+0x208/0x2d0 net/ipv4/netfilter/ip_tables.c:804
 copy_entries_to_user net/ipv6/netfilter/ip6_tables.c:842 [inline]
 get_entries net/ipv6/netfilter/ip6_tables.c:1042 [inline]
 do_ip6t_get_ctl+0x8ae/0xcb0 net/ipv6/netfilter/ip6_tables.c:1683
 nf_getsockopt+0x190/0x1b0 net/netfilter/nf_sockopt.c:116
 ipv6_getsockopt+0x170/0x1e0 net/ipv6/ipv6_sockglue.c:1464
 tcp_getsockopt+0xad/0xe0 net/ipv4/tcp.c:4873
 sock_common_getsockopt+0x60/0x70 net/core/sock.c:4028
 do_sock_getsockopt+0x2f5/0x570 net/socket.c:2503
 __sys_getsockopt net/socket.c:2534 [inline]
 __do_sys_getsockopt net/socket.c:2541 [inline]
 __se_sys_getsockopt net/socket.c:2538 [inline]
 __x64_sys_getsockopt+0x11d/0x1a0 net/socket.c:2538
 x64_sys_call+0x1032/0x2550 arch/x86/include/generated/asm/syscalls_64.h:56
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff895f9528 of 8 bytes by task 8300 on cpu 1:
 timekeeping_cycles_to_ns kernel/time/timekeeping.c:477 [inline]
 timekeeping_get_ns kernel/time/timekeeping.c:482 [inline]
 ktime_get_ts64+0x155/0x350 kernel/time/timekeeping.c:1147
 posix_get_monotonic_timespec+0x2f/0x120 kernel/time/posix-timers.c:212
 __do_sys_clock_gettime kernel/time/posix-timers.c:1152 [inline]
 __se_sys_clock_gettime kernel/time/posix-timers.c:1142 [inline]
 __x64_sys_clock_gettime+0x117/0x180 kernel/time/posix-timers.c:1142
 x64_sys_call+0x24f2/0x2550 arch/x86/include/generated/asm/syscalls_64.h:229
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x001cd72d94a3dbca -> 0x001d237895c84819

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 8300 Comm: syz.2.1039 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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