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BUG: KCSAN: data-race in ktime_get / timekeeping_update_from_shadow

write to 0xffffffff895f6508 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
 security_vm_enough_memory_mm+0x97/0x130 security/security.c:747
 shmem_acct_blocks mm/shmem.c:212 [inline]
 shmem_inode_acct_blocks+0x8a/0x230 mm/shmem.c:228
 shmem_alloc_and_add_folio mm/shmem.c:2005 [inline]
 shmem_get_folio_gfp+0x5d3/0xd90 mm/shmem.c:2528
 shmem_get_folio mm/shmem.c:2634 [inline]
 shmem_fallocate+0x631/0x8d0 mm/shmem.c:3736
 vfs_fallocate+0x3ac/0x400 fs/open.c:338
 ksys_fallocate fs/open.c:362 [inline]
 __do_sys_fallocate fs/open.c:367 [inline]
 __se_sys_fallocate fs/open.c:365 [inline]
 __x64_sys_fallocate+0x7a/0xd0 fs/open.c:365
 x64_sys_call+0x1e1d/0x2550 arch/x86/include/generated/asm/syscalls_64.h:286
 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 0xffffffff895f6518 of 8 bytes by interrupt on cpu 0:
 timekeeping_cycles_to_ns kernel/time/timekeeping.c:459 [inline]
 timekeeping_get_ns kernel/time/timekeeping.c:482 [inline]
 ktime_get+0xcf/0x240 kernel/time/timekeeping.c:1004
 gate_get_time net/sched/act_gate.c:23 [inline]
 gate_timer_func+0xda/0x1d0 net/sched/act_gate.c:101
 __run_hrtimer kernel/time/hrtimer.c:2074 [inline]
 __hrtimer_run_queues+0x1f8/0x510 kernel/time/hrtimer.c:2131
 hrtimer_run_softirq+0xde/0x290 kernel/time/hrtimer.c:2148
 handle_softirqs+0xcc/0x2a0 kernel/softirq.c:645
 do_softirq+0x46/0x60 kernel/softirq.c:546
 __local_bh_enable_ip+0x79/0x80 kernel/softirq.c:473
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 rcu_read_unlock_bh include/linux/rcupdate.h:923 [inline]
 __dev_queue_xmit+0x1361/0x1e90 net/core/dev.c:4961
 dev_queue_xmit include/linux/netdevice.h:3461 [inline]
 __netlink_deliver_tap_skb net/netlink/af_netlink.c:308 [inline]
 __netlink_deliver_tap+0x3c8/0x510 net/netlink/af_netlink.c:326
 netlink_deliver_tap net/netlink/af_netlink.c:339 [inline]
 netlink_deliver_tap_kernel net/netlink/af_netlink.c:348 [inline]
 netlink_unicast_kernel net/netlink/af_netlink.c:1337 [inline]
 netlink_unicast+0x656/0x680 net/netlink/af_netlink.c:1364
 netlink_sendmsg+0x5be/0x6f0 net/netlink/af_netlink.c:1919
 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_sendmsg net/socket.c:2799 [inline]
 __do_sys_sendmsg net/socket.c:2804 [inline]
 __se_sys_sendmsg net/socket.c:2802 [inline]
 __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2802
 x64_sys_call+0x22ab/0x2550 arch/x86/include/generated/asm/syscalls_64.h:47
 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: 0x000000583a6a613d -> 0x000000583bba12aa

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 9576 Comm: syz.2.960 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
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