syzbot

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BUG: KCSAN: data-race in get_cpu_iowait_time_us / tick_irq_enter

write to 0xffff888237d1e07c of 1 bytes by interrupt on cpu 1:
 tick_nohz_stop_idle kernel/time/tick-sched.c:665 [inline]
 tick_nohz_irq_enter kernel/time/tick-sched.c:1429 [inline]
 tick_irq_enter+0x152/0x210 kernel/time/tick-sched.c:1455
 sysvec_apic_timer_interrupt+0x80/0xb0 arch/x86/kernel/apic/apic.c:1107
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:649
 native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
 arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
 acpi_safe_halt drivers/acpi/processor_idle.c:112 [inline]
 acpi_idle_do_entry drivers/acpi/processor_idle.c:572 [inline]
 acpi_idle_enter+0x283/0x340 drivers/acpi/processor_idle.c:709
 cpuidle_enter_state+0x2de/0x960 drivers/cpuidle/cpuidle.c:239
 cpuidle_enter+0x3c/0x60 drivers/cpuidle/cpuidle.c:356
 call_cpuidle kernel/sched/idle.c:155 [inline]
 cpuidle_idle_call kernel/sched/idle.c:236 [inline]
 do_idle+0x1a7/0x250 kernel/sched/idle.c:303
 cpu_startup_entry+0x15/0x20 kernel/sched/idle.c:400
 start_secondary+0x78/0x80 arch/x86/kernel/smpboot.c:262
 secondary_startup_64_no_verify+0xcf/0xdb

read to 0xffff888237d1e07c of 1 bytes by task 6699 on cpu 0:
 get_cpu_iowait_time_us+0x68/0x1d0
 get_iowait_time fs/proc/stat.c:70 [inline]
 show_stat+0x1af/0xcd0 fs/proc/stat.c:135
 seq_read_iter+0x2c3/0x8e0 fs/seq_file.c:230
 proc_reg_read_iter+0xd4/0x170 fs/proc/inode.c:301
 call_read_iter include/linux/fs.h:2185 [inline]
 generic_file_splice_read+0xde/0x2b0 fs/splice.c:309
 do_splice_to fs/splice.c:793 [inline]
 splice_direct_to_actor+0x26c/0x620 fs/splice.c:865
 do_splice_direct+0xfb/0x180 fs/splice.c:974
 do_sendfile+0x3bf/0x910 fs/read_write.c:1255
 __do_sys_sendfile64 fs/read_write.c:1323 [inline]
 __se_sys_sendfile64 fs/read_write.c:1309 [inline]
 __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1309
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0d -> 0x19

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 6699 Comm: syz-executor.4 Not tainted 6.1.0-rc6-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
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