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BUG: KCSAN: data-race in hrtimer_interrupt / print_cpu

read-write to 0xffff888237d1b254 of 4 bytes by interrupt on cpu 1:
 hrtimer_interrupt+0x70/0x460 kernel/time/hrtimer.c:1865
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline]
 __sysvec_apic_timer_interrupt+0x5c/0x1d0 arch/x86/kernel/apic/apic.c:1056
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0x6f/0x80 arch/x86/kernel/apic/apic.c:1050
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
 __tsan_read8+0x12/0x190 kernel/kcsan/core.c:1025
 fib6_walk_continue+0x1fa/0x440 net/ipv6/ip6_fib.c:2153
 fib6_walk+0xc5/0x180 net/ipv6/ip6_fib.c:2219
 fib6_clean_tree net/ipv6/ip6_fib.c:2299 [inline]
 __fib6_clean_all net/ipv6/ip6_fib.c:2315 [inline]
 fib6_flush_trees+0x122/0x1f0 net/ipv6/ip6_fib.c:2340
 rt_genid_bump_ipv6 include/net/net_namespace.h:550 [inline]
 __ipv6_ifa_notify+0x5c6/0x880 net/ipv6/addrconf.c:6313
 addrconf_ifdown+0x8e3/0xf30 net/ipv6/addrconf.c:3977
 addrconf_notify+0x222/0x930 net/ipv6/addrconf.c:-1
 notifier_call_chain kernel/notifier.c:85 [inline]
 raw_notifier_call_chain+0x6f/0x1b0 kernel/notifier.c:453
 call_netdevice_notifiers_info+0xae/0x100 net/core/dev.c:2229
 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
 call_netdevice_notifiers net/core/dev.c:2281 [inline]
 netif_close_many+0x170/0x240 net/core/dev.c:1784
 unregister_netdevice_many_notify+0x437/0x15d0 net/core/dev.c:12136
 unregister_netdevice_many net/core/dev.c:12229 [inline]
 default_device_exit_batch+0x50c/0x560 net/core/dev.c:12733
 ops_exit_list net/core/net_namespace.c:204 [inline]
 ops_undo_list+0x2c0/0x410 net/core/net_namespace.c:251
 cleanup_net+0x2de/0x4d0 net/core/net_namespace.c:682
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3319
 worker_thread+0x582/0x770 kernel/workqueue.c:3400
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x11f/0x1b0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff888237d1b254 of 4 bytes by task 20473 on cpu 0:
 print_cpu+0x359/0x680 kernel/time/timer_list.c:135
 timer_list_show+0x107/0x170 kernel/time/timer_list.c:295
 seq_read_iter+0x62a/0x940 fs/seq_file.c:272
 proc_reg_read_iter+0x110/0x180 fs/proc/inode.c:299
 copy_splice_read+0x43f/0x660 fs/splice.c:363
 do_splice_read fs/splice.c:982 [inline]
 splice_direct_to_actor+0x26c/0x680 fs/splice.c:1086
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1230
 do_sendfile+0x380/0x650 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
 x64_sys_call+0x2bb0/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0001a053 -> 0x0001a054

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 20473 Comm: syz.4.6090 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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