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BUG: KCSAN: data-race in calc_timer_values / perf_event_update_time

write to 0xffff888096c878c8 of 8 bytes by task 8206 on cpu 0:
 __perf_update_times kernel/events/core.c:631 [inline]
 perf_event_update_time+0x170/0x1f0 kernel/events/core.c:638
 perf_event_set_state.part.0+0x46/0x100 kernel/events/core.c:657
 perf_event_set_state kernel/events/core.c:654 [inline]
 event_sched_out kernel/events/core.c:2117 [inline]
 event_sched_out.isra.0+0x220/0x530 kernel/events/core.c:2089
 group_sched_out.part.0+0x52/0x120 kernel/events/core.c:2143
 group_sched_out kernel/events/core.c:2138 [inline]
 ctx_sched_out+0x52f/0x560 kernel/events/core.c:3094
 task_ctx_sched_out+0x53/0x80 kernel/events/core.c:2516
 perf_event_context_sched_out kernel/events/core.c:3280 [inline]
 __perf_event_task_sched_out+0x538/0xaa0 kernel/events/core.c:3371
 perf_event_task_sched_out include/linux/perf_event.h:1196 [inline]
 prepare_task_switch kernel/sched/core.c:3159 [inline]
 context_switch kernel/sched/core.c:3338 [inline]
 __schedule+0x3f3/0x690 kernel/sched/core.c:4082
 schedule+0x41/0xe0 kernel/sched/core.c:4156
 freezable_schedule include/linux/freezer.h:172 [inline]
 futex_wait_queue_me+0x18b/0x290 kernel/futex.c:2705
 futex_wait+0x17e/0x400 kernel/futex.c:2811
 do_futex+0xe2/0x1820 kernel/futex.c:3882
 __do_sys_futex kernel/futex.c:3943 [inline]
 __se_sys_futex kernel/futex.c:3911 [inline]
 __x64_sys_futex+0x2dc/0x410 kernel/futex.c:3911
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888096c878c8 of 8 bytes by task 8205 on cpu 1:
 __perf_update_times kernel/events/core.c:629 [inline]
 calc_timer_values+0xfc/0x1b0 kernel/events/core.c:5430
 perf_event_update_userpage+0x7f/0x340 kernel/events/core.c:5485
 perf_mmap+0xe0f/0xf10 kernel/events/core.c:5971
 call_mmap include/linux/fs.h:1906 [inline]
 mmap_region+0x834/0xdd0 mm/mmap.c:1774
 do_mmap+0x717/0xc20 mm/mmap.c:1545
 do_mmap_pgoff include/linux/mm.h:2334 [inline]
 vm_mmap_pgoff+0x12f/0x190 mm/util.c:506
 ksys_mmap_pgoff+0x2db/0x420 mm/mmap.c:1597
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8205 Comm: syz-executor.2 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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