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BUG: KCSAN: data-race in fasync_remove_entry / kill_fasync

write to 0xffff88809fc7df00 of 8 bytes by task 2015 on cpu 0:
 fasync_remove_entry+0xb7/0x120 fs/fcntl.c:882
 fasync_helper+0xc9/0xd6 fs/fcntl.c:981
 perf_fasync+0x64/0x90 kernel/events/core.c:6011
 __fput+0x448/0x4f0 fs/file_table.c:277
 ____fput+0x1b/0x30 fs/file_table.c:313
 task_work_run+0xf5/0x130 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2ae/0x2c0 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x36e/0x390 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88809fc7df00 of 8 bytes by interrupt on cpu 1:
 kill_fasync+0x3c/0x170 fs/fcntl.c:1019
 perf_event_wakeup+0x115/0x160 kernel/events/core.c:6051
 perf_pending_event+0x129/0x170 kernel/events/core.c:6107
 irq_work_run_list+0x13e/0x190 kernel/irq_work.c:156
 irq_work_run+0x43/0x90 kernel/irq_work.c:172
 smp_irq_work_interrupt+0x3b/0xf0 arch/x86/kernel/irq_work.c:21
 irq_work_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:860
 is_atomic kernel/kcsan/core.c:213 [inline]
 should_watch kernel/kcsan/core.c:243 [inline]
 check_access kernel/kcsan/core.c:549 [inline]
 __tsan_read8+0x8e/0x100 kernel/kcsan/core.c:686
 security_file_permission+0x61/0x270 security/security.c:1407
 rw_verify_area+0xd8/0x230 fs/read_write.c:399
 do_splice_to+0x5f/0x100 fs/splice.c:880
 splice_direct_to_actor+0x1b9/0x540 fs/splice.c:971
 do_splice_direct+0x152/0x1d0 fs/splice.c:1080
 do_sendfile+0x396/0x810 fs/read_write.c:1520
 __do_sys_sendfile64 fs/read_write.c:1581 [inline]
 __se_sys_sendfile64 fs/read_write.c:1567 [inline]
 __x64_sys_sendfile64+0x121/0x140 fs/read_write.c:1567
 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: 2018 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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