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BUG: KCSAN: data-race in __perf_event_overflow / fasync_remove_entry

read to 0xffff8880ab09f2f8 of 8 bytes by interrupt on cpu 0:
 __perf_event_overflow+0x11d/0x200 kernel/events/core.c:8190
 perf_swevent_hrtimer+0x261/0x280 kernel/events/core.c:9574
 __run_hrtimer kernel/time/hrtimer.c:1514 [inline]
 __hrtimer_run_queues+0x288/0x600 kernel/time/hrtimer.c:1576
 hrtimer_interrupt+0x22a/0x480 kernel/time/hrtimer.c:1638
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
 smp_apic_timer_interrupt+0xdc/0x280 arch/x86/kernel/apic/apic.c:1135
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
 matching_access kernel/kcsan/encoding.h:89 [inline]
 find_watchpoint kernel/kcsan/core.c:73 [inline]
 __kcsan_check_watchpoint+0x7b/0x180 kernel/kcsan/core.c:266
 __tsan_read8+0x15/0x30 kernel/kcsan/kcsan.c:36
 __add_to_page_cache_locked+0x6e2/0x780 mm/filemap.c:902
 add_to_page_cache_lru+0xe2/0x2d0 mm/filemap.c:942
 pagecache_get_page+0x2ab/0x760 mm/filemap.c:1681
 grab_cache_page_write_begin+0x5d/0x90 mm/filemap.c:3254
 mext_page_double_lock fs/ext4/move_extent.c:142 [inline]
 move_extent_per_page fs/ext4/move_extent.c:303 [inline]
 ext4_move_extents+0xfb5/0x1de0 fs/ext4/move_extent.c:673
 ext4_ioctl+0x2a3a/0x3130 fs/ext4/ioctl.c:992

write to 0xffff8880ab09f2f8 of 8 bytes by task 18287 on cpu 1:
 fasync_remove_entry+0xba/0x120 fs/fcntl.c:882
 fasync_helper+0xcf/0xdc fs/fcntl.c:981
 perf_fasync+0x6c/0xa0 kernel/events/core.c:5915
 __fput+0x46a/0x520 fs/file_table.c:277
 ____fput+0x1f/0x30 fs/file_table.c:313
 task_work_run+0xf6/0x130 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2b4/0x2c0 arch/x86/entry/common.c:163
 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
 do_syscall_64+0x353/0x370 arch/x86/entry/common.c:300
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 18287 Comm: syz-executor.3 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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