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BUG: KCSAN: data-race in hrtimer_interrupt / print_cpu

write to 0xffff88812c01ec14 of 4 bytes by interrupt on cpu 0:
 hrtimer_interrupt+0x9d/0xa40 kernel/time/hrtimer.c:1624
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1080 [inline]
 __sysvec_apic_timer_interrupt+0xa3/0x280 arch/x86/kernel/apic/apic.c:1097
 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
 sysvec_apic_timer_interrupt+0x80/0xd0 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:585
 is_atomic kernel/kcsan/core.c:244 [inline]
 should_watch kernel/kcsan/core.c:257 [inline]
 check_access kernel/kcsan/core.c:581 [inline]
 __tsan_read4+0x13a/0x180 kernel/kcsan/core.c:776
 vsnprintf+0x53a/0xed0 lib/vsprintf.c:2620
 seq_vprintf+0x71/0xd0 fs/seq_file.c:379
 SEQ_printf+0x76/0xb0 kernel/time/timer_list.c:38
 print_cpu+0x6e8/0x7f0 kernel/time/timer_list.c:176
 timer_list_show+0x114/0x180 kernel/time/timer_list.c:311
 seq_read+0x2ee/0x900 fs/seq_file.c:208
 pde_read fs/proc/inode.c:306 [inline]
 proc_reg_read+0x116/0x1a0 fs/proc/inode.c:318
 do_loop_readv_writev fs/read_write.c:734 [inline]
 do_iter_read+0x2fe/0x480 fs/read_write.c:955
 vfs_readv+0xa0/0xe0 fs/read_write.c:1073
 kernel_readv fs/splice.c:355 [inline]
 default_file_splice_read+0x3c6/0x630 fs/splice.c:412
 do_splice_to fs/splice.c:871 [inline]
 splice_direct_to_actor+0x2c7/0x660 fs/splice.c:950
 do_splice_direct+0xf2/0x170 fs/splice.c:1059
 do_sendfile+0x562/0xb10 fs/read_write.c:1540
 __do_sys_sendfile64 fs/read_write.c:1601 [inline]
 __se_sys_sendfile64 fs/read_write.c:1587 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1587
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812c01ec14 of 4 bytes by task 13816 on cpu 1:
 print_cpu+0x4ca/0x7f0 kernel/time/timer_list.c:150
 timer_list_show+0x114/0x180 kernel/time/timer_list.c:311
 seq_read+0x2ee/0x900 fs/seq_file.c:208
 pde_read fs/proc/inode.c:306 [inline]
 proc_reg_read+0x116/0x1a0 fs/proc/inode.c:318
 do_loop_readv_writev fs/read_write.c:734 [inline]
 do_iter_read+0x2fe/0x480 fs/read_write.c:955
 vfs_readv+0xa0/0xe0 fs/read_write.c:1073
 kernel_readv fs/splice.c:355 [inline]
 default_file_splice_read+0x3c6/0x630 fs/splice.c:412
 do_splice_to fs/splice.c:871 [inline]
 splice_direct_to_actor+0x2c7/0x660 fs/splice.c:950
 do_splice_direct+0xf2/0x170 fs/splice.c:1059
 do_sendfile+0x562/0xb10 fs/read_write.c:1540
 __do_sys_sendfile64 fs/read_write.c:1601 [inline]
 __se_sys_sendfile64 fs/read_write.c:1587 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1587
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 13816 Comm: syz-executor.4 Not tainted 5.8.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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