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BUG: KCSAN: data-race in ktime_get_coarse_real_ts64_mg / timekeeping_update_from_shadow

write to 0xffffffff895fb508 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:2074 [inline]
 __hrtimer_run_queues+0x1f8/0x510 kernel/time/hrtimer.c:2131
 hrtimer_interrupt+0x27b/0x860 kernel/time/hrtimer.c:2250
 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
 kcsan_setup_watchpoint+0x42b/0x4a0 kernel/kcsan/core.c:713
 avc_search_node security/selinux/avc.c:530 [inline]
 avc_lookup+0x109/0x1a0 security/selinux/avc.c:557
 avc_has_perm_noaudit+0x54/0x160 security/selinux/avc.c:1159
 avc_has_perm+0x60/0x190 security/selinux/avc.c:1197
 selinux_socket_unix_may_send+0x116/0x140 security/selinux/hooks.c:5498
 security_unix_may_send+0x3c/0x70 security/security.c:4174
 unix_dgram_sendmsg+0x825/0x1030 net/unix/af_unix.c:2251
 sock_sendmsg_nosec net/socket.c:800 [inline]
 __sock_sendmsg net/socket.c:815 [inline]
 ____sys_sendmsg+0x532/0x580 net/socket.c:2713
 ___sys_sendmsg+0x195/0x1e0 net/socket.c:2767
 __sys_sendmmsg+0x185/0x320 net/socket.c:2856
 __do_sys_sendmmsg net/socket.c:2883 [inline]
 __se_sys_sendmmsg net/socket.c:2880 [inline]
 __x64_sys_sendmmsg+0x57/0x70 net/socket.c:2880
 x64_sys_call+0x1fb4/0x2550 arch/x86/include/generated/asm/syscalls_64.h:308
 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 0xffffffff895fb578 of 4 bytes by task 4885 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:2430
 need_cmtime_update fs/inode.c:2452 [inline]
 file_update_time_flags+0x85/0x2d0 fs/inode.c:2473
 file_update_time+0x17/0x20 fs/inode.c:2503
 shmem_file_write_iter+0x9c/0xf0 mm/shmem.c:3440
 iter_file_splice_write+0x6a0/0xa60 fs/splice.c:736
 do_splice_from fs/splice.c:936 [inline]
 direct_splice_actor+0x158/0x280 fs/splice.c:1159
 splice_direct_to_actor+0x2f9/0x680 fs/splice.c:1103
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x119/0x1a0 fs/splice.c:1228
 do_sendfile+0x37d/0x640 fs/read_write.c:1371
 __do_sys_sendfile64 fs/read_write.c:1432 [inline]
 __se_sys_sendfile64 fs/read_write.c:1418 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1418
 x64_sys_call+0x1015/0x2550 arch/x86/include/generated/asm/syscalls_64.h:41
 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: 0x32a9f843 -> 0x33428ec3

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4885 Comm: syz.3.333 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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