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BUG: KCSAN: data-race in event_sched_in / perf_event_update_userpage

write to 0xffff888150561ca0 of 8 bytes by task 31017 on cpu 0:
 __perf_update_times kernel/events/core.c:635 [inline]
 perf_event_update_time kernel/events/core.c:647 [inline]
 perf_event_set_state kernel/events/core.c:666 [inline]
 event_sched_in+0x1d2/0xdd0 kernel/events/core.c:2541
 group_sched_in kernel/events/core.c:2595 [inline]
 merge_sched_in kernel/events/core.c:3723 [inline]
 visit_groups_merge+0x84b/0x15e0 kernel/events/core.c:3696
 ctx_flexible_sched_in kernel/events/core.c:3764 [inline]
 ctx_sched_in+0x1db/0x200 kernel/events/core.c:3809
 perf_event_sched_in kernel/events/core.c:2699 [inline]
 perf_event_context_sched_in kernel/events/core.c:3860 [inline]
 __perf_event_task_sched_in+0x2f9/0x850 kernel/events/core.c:3903
 perf_event_task_sched_in include/linux/perf_event.h:1205 [inline]
 finish_task_switch+0x1fd/0x290 kernel/sched/core.c:4550
 context_switch kernel/sched/core.c:4684 [inline]
 __schedule+0x42a/0x670 kernel/sched/core.c:5938
 schedule+0x67/0x90 kernel/sched/core.c:6017
 freezable_schedule include/linux/freezer.h:172 [inline]
 futex_wait_queue_me+0x162/0x210 kernel/futex.c:2602
 futex_wait+0x143/0x430 kernel/futex.c:2704
 do_futex+0x9c1/0x1f10 kernel/futex.c:3730
 __do_sys_futex kernel/futex.c:3807 [inline]
 __se_sys_futex+0xc6/0x370 kernel/futex.c:3788
 __x64_sys_futex+0x74/0x80 kernel/futex.c:3788
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888150561ca0 of 8 bytes by task 31016 on cpu 1:
 __perf_update_times kernel/events/core.c:634 [inline]
 calc_timer_values kernel/events/core.c:5773 [inline]
 perf_event_update_userpage+0xcc/0x2f0 kernel/events/core.c:5828
 perf_mmap+0xb6f/0xce0 kernel/events/core.c:6315
 call_mmap include/linux/fs.h:2119 [inline]
 mmap_region+0xbcb/0x1400 mm/mmap.c:1808
 do_mmap+0x73f/0xc40 mm/mmap.c:1584
 vm_mmap_pgoff+0xf9/0x1d0 mm/util.c:519
 ksys_mmap_pgoff+0x2a8/0x380 mm/mmap.c:1635
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000008a01 -> 0x000000000000f6a6

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 31016 Comm: syz-executor.5 Tainted: G        W         5.14.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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