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BUG: KCSAN: data-race in ktime_get / timekeeping_update_from_shadow

write to 0xffffffff893da4c8 of 304 bytes by interrupt on cpu 0:
 timekeeping_update_from_shadow+0x40d/0x440 kernel/time/timekeeping.c:835
 __timekeeping_advance+0xa68/0xc10 kernel/time/timekeeping.c:2614
 timekeeping_advance kernel/time/timekeeping.c:2622 [inline]
 update_wall_time+0x21/0x50 kernel/time/timekeeping.c:2632
 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:2032 [inline]
 __hrtimer_run_queues+0x1f8/0x510 kernel/time/hrtimer.c:2096
 hrtimer_interrupt+0x257/0x810 kernel/time/hrtimer.c:2215
 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
 is_atomic kernel/kcsan/core.c:249 [inline]
 should_watch kernel/kcsan/core.c:277 [inline]
 check_access kernel/kcsan/core.c:752 [inline]
 __tsan_read8+0xec/0x190 kernel/kcsan/core.c:1025
 __x64_sys_ppoll+0x52/0x80 fs/select.c:1092
 x64_sys_call+0x28d3/0x3020 arch/x86/include/generated/asm/syscalls_64.h:272
 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 0xffffffff893da4e8 of 8 bytes by interrupt on cpu 1:
 timekeeping_cycles_to_ns kernel/time/timekeeping.c:450 [inline]
 timekeeping_get_ns kernel/time/timekeeping.c:455 [inline]
 ktime_get+0x130/0x240 kernel/time/timekeeping.c:973
 gate_get_time net/sched/act_gate.c:23 [inline]
 gate_timer_func+0xda/0x1d0 net/sched/act_gate.c:101
 __run_hrtimer kernel/time/hrtimer.c:2032 [inline]
 __hrtimer_run_queues+0x1f8/0x510 kernel/time/hrtimer.c:2096
 hrtimer_run_softirq+0xde/0x290 kernel/time/hrtimer.c:2113
 handle_softirqs+0xb9/0x280 kernel/softirq.c:622
 run_ksoftirqd+0x1c/0x30 kernel/softirq.c:1076
 smpboot_thread_fn+0x32a/0x510 kernel/smpboot.c:160
 kthread+0x221/0x270 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x0015980018301620 -> 0x00163833d27dc0e6

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 22 Comm: ksoftirqd/1 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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