syzbot

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BUG: KCSAN: data-race in get_cpu_iowait_time_us / update_ts_time_stats

write to 0xffff88812c120298 of 8 bytes by task 0 on cpu 1:
 update_ts_time_stats+0x142/0x150 kernel/time/tick-sched.c:537
 tick_nohz_stop_idle kernel/time/tick-sched.c:550 [inline]
 tick_nohz_irq_enter kernel/time/tick-sched.c:1270 [inline]
 tick_irq_enter+0x181/0x1c0 kernel/time/tick-sched.c:1289
 irq_enter+0x4f/0x60 kernel/softirq.c:354
 entering_irq arch/x86/include/asm/apic.h:527 [inline]
 do_IRQ+0x3d/0x130 arch/x86/kernel/irq.c:240
 ret_from_intr+0x0/0x21
 native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60
 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:686
 default_idle_call+0x1e/0x40 kernel/sched/idle.c:94
 cpuidle_idle_call kernel/sched/idle.c:154 [inline]
 do_idle+0x1c2/0x290 kernel/sched/idle.c:269
 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:361
 start_secondary+0x168/0x1b0 arch/x86/kernel/smpboot.c:264
 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242

read to 0xffff88812c120298 of 8 bytes by task 27076 on cpu 0:
 get_cpu_iowait_time_us+0x15c/0x180 kernel/time/tick-sched.c:634
 get_iowait_time.isra.0+0x6e/0xa0 fs/proc/stat.c:69
 show_stat+0x267/0xa20 fs/proc/stat.c:132
 seq_read+0x350/0x9d0 fs/seq_file.c:229
 proc_reg_read+0xe9/0x140 fs/proc/inode.c:223
 do_loop_readv_writev fs/read_write.c:714 [inline]
 do_loop_readv_writev fs/read_write.c:701 [inline]
 do_iter_read+0x357/0x3d0 fs/read_write.c:935
 vfs_readv+0x9c/0xf0 fs/read_write.c:1053
 do_preadv+0x131/0x1d0 fs/read_write.c:1145
 __do_sys_preadv fs/read_write.c:1195 [inline]
 __se_sys_preadv fs/read_write.c:1190 [inline]
 __x64_sys_preadv+0x61/0x80 fs/read_write.c:1190
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 27076 Comm: syz-executor.4 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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