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BUG: KCSAN: data-race in ktime_get_mono_fast_ns / update_fast_timekeeper

write to 0xffffffff86d4fb88 of 56 bytes by interrupt on cpu 0:
 update_fast_timekeeper+0x38/0x70 kernel/time/timekeeping.c:482
 timekeeping_update_from_shadow+0x3ab/0x440 kernel/time/timekeeping.c:818
 __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
 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
 dev_vprintk_emit+0x242/0x2a0 drivers/base/core.c:4996
 dev_printk_emit+0x84/0xb0 drivers/base/core.c:5007
 __netdev_printk+0x34b/0x370 net/core/dev.c:12958
 netdev_warn+0xa6/0xd0 net/core/dev.c:13011
 ieee802154_subif_start_xmit+0xd7/0x100 net/mac802154/tx.c:232
 __netdev_start_xmit include/linux/netdevice.h:5400 [inline]
 netdev_start_xmit include/linux/netdevice.h:5409 [inline]
 xmit_one net/core/dev.c:3889 [inline]
 dev_hard_start_xmit+0x10c/0x380 net/core/dev.c:3905
 sch_direct_xmit+0x199/0x580 net/sched/sch_generic.c:372
 __dev_xmit_skb net/core/dev.c:4211 [inline]
 __dev_queue_xmit+0xd81/0x1e60 net/core/dev.c:4833
 dev_queue_xmit include/linux/netdevice.h:3446 [inline]
 raw_sendmsg+0x2e4/0x500 net/ieee802154/socket.c:299
 ieee802154_sock_sendmsg+0x51/0x60 net/ieee802154/socket.c:96
 sock_sendmsg_nosec net/socket.c:775 [inline]
 __sock_sendmsg net/socket.c:790 [inline]
 ____sys_sendmsg+0x532/0x580 net/socket.c:2684
 ___sys_sendmsg+0x195/0x1e0 net/socket.c:2738
 __sys_sendmmsg+0x185/0x320 net/socket.c:2827
 __do_sys_sendmmsg net/socket.c:2854 [inline]
 __se_sys_sendmmsg net/socket.c:2851 [inline]
 __x64_sys_sendmmsg+0x57/0x70 net/socket.c:2851
 x64_sys_call+0x27aa/0x3020 arch/x86/include/generated/asm/syscalls_64.h:308
 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 0xffffffff86d4fba8 of 8 bytes by task 542 on cpu 1:
 timekeeping_cycles_to_ns kernel/time/timekeeping.c:450 [inline]
 timekeeping_get_ns kernel/time/timekeeping.c:455 [inline]
 __ktime_get_fast_ns kernel/time/timekeeping.c:503 [inline]
 ktime_get_mono_fast_ns+0xdf/0x1a0 kernel/time/timekeeping.c:543
 ____bpf_ktime_get_ns kernel/bpf/helpers.c:181 [inline]
 bpf_ktime_get_ns+0xe/0x20 kernel/bpf/helpers.c:178
 bpf_prog_f001251d91318e6f+0x28/0x2e
 bpf_dispatcher_nop_func include/linux/bpf.h:1454 [inline]
 __bpf_prog_run include/linux/filter.h:724 [inline]
 bpf_prog_run include/linux/filter.h:731 [inline]
 bpf_prog_run_pin_on_cpu include/linux/filter.h:748 [inline]
 bpf_flow_dissect+0x14f/0x340 net/core/flow_dissector.c:1024
 bpf_prog_test_run_flow_dissector+0x25d/0x360 net/bpf/test_run.c:1558
 bpf_prog_test_run+0x208/0x340 kernel/bpf/syscall.c:4859
 __sys_bpf+0x8da/0xc30 kernel/bpf/syscall.c:6436
 __do_sys_bpf kernel/bpf/syscall.c:6537 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6534 [inline]
 __x64_sys_bpf+0x69/0x80 kernel/bpf/syscall.c:6534
 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+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x003b23295073f49b -> 0x000020f5d0844d18

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 542 Comm: syz.4.9087 Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
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