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BUG: KCSAN: data-race in ktime_get_ts64 / timekeeping_update_from_shadow

write to 0xffffffff895ee508 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: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
 __preempt_count_dec_and_test arch/x86/include/asm/preempt.h:123 [inline]
 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:220 [inline]
 _raw_spin_unlock_irq+0x12/0x30 kernel/locking/spinlock.c:229
 spin_unlock_irq include/linux/spinlock.h:413 [inline]
 shmem_add_to_page_cache+0x3e6/0x5b0 mm/shmem.c:939
 shmem_alloc_and_add_folio mm/shmem.c:2001 [inline]
 shmem_get_folio_gfp+0x517/0xd90 mm/shmem.c:2528
 shmem_get_folio mm/shmem.c:2634 [inline]
 shmem_write_begin+0xfc/0x1f0 mm/shmem.c:3265
 generic_perform_write+0x186/0x490 mm/filemap.c:4374
 shmem_file_write_iter+0xc5/0xf0 mm/shmem.c:3440
 __kernel_write_iter+0x30f/0x590 fs/read_write.c:621
 dump_emit_page fs/coredump.c:1293 [inline]
 dump_user_range+0xa73/0xd00 fs/coredump.c:1367
 elf_core_dump+0x21c0/0x2340 fs/binfmt_elf.c:2106
 coredump_write+0xafb/0xdd0 fs/coredump.c:1047
 do_coredump fs/coredump.c:1126 [inline]
 vfs_coredump+0x2750/0x3270 fs/coredump.c:1195
 get_signal+0xd33/0xf10 kernel/signal.c:3024
 arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:101 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:244 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:315 [inline]
 irqentry_exit+0x14d/0x610 kernel/entry/common.c:165
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595

read to 0xffffffff895ee528 of 8 bytes by task 6666 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: 0x00027df2d1681df3 -> 0x0002ca3dd28c8a42

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 6666 Comm: syz.7.730 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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