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BUG: KCSAN: data-race in ktime_get_with_offset / timekeeping_update_from_shadow

write to 0xffffffff895e9508 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+0x1d/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:2067 [inline]
 __hrtimer_run_queues+0x1f8/0x510 kernel/time/hrtimer.c:2124
 hrtimer_interrupt+0x27b/0x860 kernel/time/hrtimer.c:2243
 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
 native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
 pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63
 arch_safe_halt arch/x86/kernel/process.c:767 [inline]
 default_idle+0x9/0x20 arch/x86/kernel/process.c:768
 default_idle_call+0x3b/0x60 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:199 [inline]
 do_idle+0x183/0x2d0 kernel/sched/idle.c:355
 cpu_startup_entry+0x24/0x30 kernel/sched/idle.c:454
 rest_init+0x101/0x110 init/main.c:727
 start_kernel+0x49f/0x4d0 init/main.c:1185
 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
 x86_64_start_kernel+0xfc/0x100 arch/x86/kernel/head64.c:291
 common_startup_64+0x13e/0x157

read to 0xffffffff895e9518 of 8 bytes by task 22751 on cpu 1:
 timekeeping_cycles_to_ns kernel/time/timekeeping.c:459 [inline]
 timekeeping_get_ns kernel/time/timekeeping.c:482 [inline]
 ktime_get_with_offset+0xed/0x260 kernel/time/timekeeping.c:1048
 ktime_get_real include/linux/timekeeping.h:87 [inline]
 net_timestamp_set net/core/dev.c:2448 [inline]
 dev_queue_xmit_nit+0x3bd/0x510 net/core/dev.c:2604
 xmit_one net/core/dev.c:3933 [inline]
 dev_hard_start_xmit+0xba/0x380 net/core/dev.c:3953
 __dev_queue_xmit+0xbfd/0x1e90 net/core/dev.c:4926
 dev_queue_xmit include/linux/netdevice.h:3461 [inline]
 __bpf_tx_skb net/core/filter.c:2160 [inline]
 __bpf_redirect_common net/core/filter.c:2204 [inline]
 __bpf_redirect+0x83a/0x960 net/core/filter.c:2211
 ____bpf_clone_redirect net/core/filter.c:2501 [inline]
 bpf_clone_redirect+0x206/0x280 net/core/filter.c:2464
 bpf_prog_f5b5f63885e62d73+0x22/0x2a
 bpf_dispatcher_nop_func include/linux/bpf.h:1451 [inline]
 __bpf_prog_run include/linux/filter.h:779 [inline]
 bpf_prog_run include/linux/filter.h:786 [inline]
 bpf_test_run+0x29b/0x620 net/bpf/test_run.c:422
 bpf_prog_test_run_skb+0xe67/0x11b0 net/bpf/test_run.c:1225
 bpf_prog_test_run+0x208/0x340 kernel/bpf/syscall.c:4804
 __sys_bpf+0x8da/0xc30 kernel/bpf/syscall.c:6385
 __do_sys_bpf kernel/bpf/syscall.c:6486 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6483 [inline]
 __x64_sys_bpf+0x69/0x80 kernel/bpf/syscall.c:6483
 x64_sys_call+0xf26/0x2550 arch/x86/include/generated/asm/syscalls_64.h:322
 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: 0x000001726eeb5778 -> 0x00000172703b117b

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 22751 Comm: syz.1.6793 Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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