syzbot

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BUG: KCSAN: data-race in event_sched_in / perf_event_update_userpage

write to 0xffff88812dd84c68 of 8 bytes by task 13199 on cpu 0:
 __perf_update_times kernel/events/core.c:638 [inline]
 perf_event_update_time kernel/events/core.c:646 [inline]
 perf_event_set_state kernel/events/core.c:665 [inline]
 event_sched_in+0x1fe/0xdd0 kernel/events/core.c:2540
 group_sched_in kernel/events/core.c:2594 [inline]
 merge_sched_in kernel/events/core.c:3722 [inline]
 visit_groups_merge+0x84b/0x15e0 kernel/events/core.c:3695
 ctx_flexible_sched_in kernel/events/core.c:3763 [inline]
 ctx_sched_in+0x1db/0x200 kernel/events/core.c:3808
 perf_event_sched_in kernel/events/core.c:2698 [inline]
 perf_event_context_sched_in kernel/events/core.c:3852 [inline]
 __perf_event_task_sched_in+0x236/0x4c0 kernel/events/core.c:3895
 perf_event_task_sched_in include/linux/perf_event.h:1205 [inline]
 finish_task_switch+0x1fd/0x290 kernel/sched/core.c:4208
 context_switch kernel/sched/core.c:4342 [inline]
 __schedule+0x427/0x5b0 kernel/sched/core.c:5147
 schedule+0x67/0x90 kernel/sched/core.c:5226
 exit_to_user_mode_loop kernel/entry/common.c:162 [inline]
 exit_to_user_mode_prepare+0xbb/0x190 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:301
 do_syscall_64+0x56/0x90 arch/x86/entry/common.c:57
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88812dd84c68 of 8 bytes by task 13186 on cpu 1:
 __perf_update_times kernel/events/core.c:637 [inline]
 calc_timer_values kernel/events/core.c:5763 [inline]
 perf_event_update_userpage+0x107/0x2f0 kernel/events/core.c:5818
 perf_mmap+0xb6f/0xce0 kernel/events/core.c:6305
 call_mmap include/linux/fs.h:2119 [inline]
 mmap_region+0xbb6/0x13e0 mm/mmap.c:1811
 do_mmap+0x77d/0xc90 mm/mmap.c:1587
 vm_mmap_pgoff+0xfc/0x1d0 mm/util.c:519
 ksys_mmap_pgoff+0x2a8/0x380 mm/mmap.c:1638
 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: 13186 Comm: syz-executor.3 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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