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BUG: KCSAN: data-race in ktime_get_coarse_real_ts64_mg / timekeeping_update_from_shadow

write to 0xffffffff895ee508 of 320 bytes by interrupt on cpu 1:
 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
 __tsan_read8+0x12/0x190 kernel/kcsan/core.c:1033
 x2apic_send_IPI+0x19/0x80 arch/x86/kernel/apic/x2apic_phys.c:46
 __apic_send_IPI arch/x86/include/asm/apic.h:430 [inline]
 native_send_call_func_single_ipi+0xe/0x20 arch/x86/kernel/apic/ipi.c:79
 arch_send_call_function_single_ipi arch/x86/include/asm/smp.h:95 [inline]
 send_call_function_single_ipi kernel/smp.c:127 [inline]
 __smp_call_single_queue+0x10e/0x330 kernel/smp.c:468
 generic_exec_single+0x11b/0x2d0 kernel/smp.c:505
 smp_call_function_single_async+0x5d/0xb0 kernel/smp.c:807
 rdmsrq_safe_on_cpu+0xb2/0x130 arch/x86/lib/msr-smp.c:163
 msr_read+0x9e/0x150 arch/x86/kernel/msr.c:69
 vfs_read+0x18e/0x7c0 fs/read_write.c:572
 ksys_read+0xdc/0x1a0 fs/read_write.c:716
 __do_sys_read fs/read_write.c:725 [inline]
 __se_sys_read fs/read_write.c:723 [inline]
 __x64_sys_read+0x40/0x50 fs/read_write.c:723
 x64_sys_call+0x2135/0x2550 arch/x86/include/generated/asm/syscalls_64.h:1
 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

read to 0xffffffff895ee578 of 4 bytes by task 20379 on cpu 0:
 tk_xtime_coarse kernel/time/timekeeping.c:217 [inline]
 ktime_get_coarse_real_ts64_mg+0x89/0x1a0 kernel/time/timekeeping.c:2737
 current_time+0x41/0x250 fs/inode.c:2431
 need_cmtime_update fs/inode.c:2453 [inline]
 file_update_time_flags+0x85/0x2d0 fs/inode.c:2474
 file_update_time+0x17/0x20 fs/inode.c:2504
 shmem_file_write_iter+0x9c/0xf0 mm/shmem.c:3437
 __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

value changed: 0x0726eda9 -> 0x07bf8429

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 20379 Comm: syz.1.3719 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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