syzbot

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BUG: KCSAN: data-race in print_cpu / tick_nohz_stop_idle

write to 0xffff888237c1b878 of 8 bytes by interrupt on cpu 0:
 tick_nohz_stop_idle+0xbf/0x120 kernel/time/tick-sched.c:738
 tick_nohz_irq_enter kernel/time/tick-sched.c:1528 [inline]
 tick_irq_enter+0xa1/0x150 kernel/time/tick-sched.c:1554
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
 sysvec_apic_timer_interrupt+0x67/0x80 arch/x86/kernel/apic/apic.c:1052
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
 native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
 pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:81
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:767
 default_idle_call+0x3c/0x60 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:190 [inline]
 do_idle+0xcb/0x240 kernel/sched/idle.c:330
 cpu_startup_entry+0x25/0x30 kernel/sched/idle.c:428
 rest_init+0xee/0xf0 init/main.c:757
 start_kernel+0x4dc/0x510 init/main.c:1111
 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
 x86_64_start_kernel+0xfc/0x100 arch/x86/kernel/head64.c:291
 common_startup_64+0x13e/0x147

read to 0xffff888237c1b878 of 8 bytes by task 11526 on cpu 1:
 print_cpu+0x4e1/0x660 kernel/time/timer_list.c:160
 timer_list_show+0x107/0x170 kernel/time/timer_list.c:293
 seq_read_iter+0x636/0x950 fs/seq_file.c:272
 proc_reg_read_iter+0x110/0x180 fs/proc/inode.c:299
 copy_splice_read+0x442/0x660 fs/splice.c:363
 do_splice_read fs/splice.c:982 [inline]
 splice_direct_to_actor+0x26f/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+0x2bb4/0x3000 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: 0x0000002968576303 -> 0x00000029685a4c37

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 11526 Comm: syz.9.2338 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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