syzbot

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BUG: KCSAN: data-race in hrtimer_interrupt / print_tickdevice

write to 0xffff888237c16f18 of 8 bytes by interrupt on cpu 0:
 hrtimer_interrupt+0x95/0xaf0 kernel/time/hrtimer.c:1642
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1089 [inline]
 __sysvec_apic_timer_interrupt+0x6f/0x1c0 arch/x86/kernel/apic/apic.c:1106
 sysvec_apic_timer_interrupt+0x64/0x80 arch/x86/kernel/apic/apic.c:1100
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:647
 check_access kernel/kcsan/core.c:634 [inline]
 __tsan_unaligned_write8+0x15f/0x190 kernel/kcsan/core.c:845
 format_decode+0x16e/0x8a0 lib/vsprintf.c:2505
 vsnprintf+0xcd/0xed0 lib/vsprintf.c:2704
 seq_vprintf+0x71/0xd0 fs/seq_file.c:395
 SEQ_printf+0x76/0xb0 kernel/time/timer_list.c:38
 print_timer kernel/time/timer_list.c:49 [inline]
 print_active_timers kernel/time/timer_list.c:91 [inline]
 print_base kernel/time/timer_list.c:112 [inline]
 print_cpu+0x28e/0x690 kernel/time/timer_list.c:123
 timer_list_show+0x114/0x180 kernel/time/timer_list.c:283
 seq_read_iter+0x2ef/0x910 fs/seq_file.c:227
 proc_reg_read_iter+0xfc/0x170 fs/proc/inode.c:300
 call_read_iter include/linux/fs.h:2108 [inline]
 generic_file_splice_read+0x22a/0x310 fs/splice.c:311
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:870
 do_splice_direct+0xf5/0x170 fs/splice.c:979
 do_sendfile+0x773/0xda0 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1325 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1311
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888237c16f18 of 8 bytes by task 8511 on cpu 1:
 print_tickdevice+0x157/0x300 kernel/time/timer_list.c:204
 timer_list_show+0x74/0x180 kernel/time/timer_list.c:288
 seq_read_iter+0x60b/0x910 fs/seq_file.c:269
 proc_reg_read_iter+0xfc/0x170 fs/proc/inode.c:300
 call_read_iter include/linux/fs.h:2108 [inline]
 generic_file_splice_read+0x22a/0x310 fs/splice.c:311
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:870
 do_splice_direct+0xf5/0x170 fs/splice.c:979
 do_sendfile+0x773/0xda0 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1325 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1311
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8511 Comm: syz-executor.2 Not tainted 5.13.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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