syzbot

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BUG: KCSAN: data-race in ktime_get_coarse_ts64 / timekeeping_update_from_shadow

write to 0xffffffff895d8488 of 304 bytes by interrupt on cpu 1:
 timekeeping_update_from_shadow+0x40d/0x440 kernel/time/timekeeping.c:829
 __timekeeping_advance+0xa5d/0xc10 kernel/time/timekeeping.c:2532
 timekeeping_advance kernel/time/timekeeping.c:2540 [inline]
 update_wall_time+0x21/0x50 kernel/time/timekeeping.c:2550
 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+0x8d/0x3d0 kernel/time/tick-sched.c:312
 __run_hrtimer kernel/time/hrtimer.c:1930 [inline]
 __hrtimer_run_queues+0x276/0x4f0 kernel/time/hrtimer.c:1994
 hrtimer_interrupt+0x261/0x850 kernel/time/hrtimer.c:2113
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 __sysvec_apic_timer_interrupt+0x5f/0x1c0 arch/x86/kernel/apic/apic.c:1067
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
 sysvec_apic_timer_interrupt+0x6f/0x80 arch/x86/kernel/apic/apic.c:1061
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
 native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
 pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:62
 arch_safe_halt arch/x86/kernel/process.c:766 [inline]
 default_idle+0x9/0x20 arch/x86/kernel/process.c:767
 default_idle_call+0x3b/0x60 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:199 [inline]
 do_idle+0x17f/0x2b0 kernel/sched/idle.c:352
 cpu_startup_entry+0x24/0x30 kernel/sched/idle.c:451
 start_secondary+0x95/0xa0 arch/x86/kernel/smpboot.c:312
 common_startup_64+0x13e/0x147

read to 0xffffffff895d84f8 of 4 bytes by task 4851 on cpu 0:
 tk_xtime_coarse kernel/time/timekeeping.c:212 [inline]
 ktime_get_coarse_ts64+0x6d/0x120 kernel/time/timekeeping.c:2685
 ktime_get_coarse include/linux/timekeeping.h:133 [inline]
 ktime_get_coarse_ns include/linux/timekeeping.h:139 [inline]
 ____bpf_ktime_get_coarse_ns kernel/bpf/helpers.c:204 [inline]
 bpf_ktime_get_coarse_ns+0x39/0xb0 kernel/bpf/helpers.c:202
 bpf_prog_ce3dfd7f9330a559+0x1e/0x29
 bpf_dispatcher_nop_func include/linux/bpf.h:1402 [inline]
 __bpf_prog_run include/linux/filter.h:722 [inline]
 bpf_prog_run include/linux/filter.h:729 [inline]
 bpf_prog_run_pin_on_cpu include/linux/filter.h:746 [inline]
 bpf_flow_dissect+0x158/0x350 net/core/flow_dissector.c:1024
 bpf_prog_test_run_flow_dissector+0x25d/0x360 net/bpf/test_run.c:1525
 bpf_prog_test_run+0x204/0x340 kernel/bpf/syscall.c:4742
 __sys_bpf+0x52e/0x7e0 kernel/bpf/syscall.c:6266
 __do_sys_bpf kernel/bpf/syscall.c:6361 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6359 [inline]
 __x64_sys_bpf+0x41/0x50 kernel/bpf/syscall.c:6359
 x64_sys_call+0x10cb/0x3020 arch/x86/include/generated/asm/syscalls_64.h:322
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x1972605a -> 0x1a0c2809

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4851 Comm: syz.6.270 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
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