syzbot

==================================================================
BUG: KCSAN: data-race in fasync_remove_entry / kill_fasync

write to 0xffff8880b93fdf00 of 8 bytes by task 7860 on cpu 0:
 fasync_remove_entry+0xd5/0x130 fs/fcntl.c:886
 fasync_helper+0x92/0xc0 fs/fcntl.c:985
 perf_fasync+0x5a/0x80 kernel/events/core.c:6237
 __fput+0x49f/0x4e0 fs/file_table.c:277
 ____fput+0x11/0x20 fs/file_table.c:313
 task_work_run+0x8e/0x110 kernel/task_work.c:140
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x16b/0x1a0 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:302
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880b93fdf00 of 8 bytes by interrupt on cpu 1:
 kill_fasync+0x1e/0x160 fs/fcntl.c:1023
 perf_event_wakeup kernel/events/core.c:6277 [inline]
 perf_pending_event+0x231/0x2a0 kernel/events/core.c:6333
 irq_work_single kernel/irq_work.c:153 [inline]
 irq_work_run_list kernel/irq_work.c:175 [inline]
 irq_work_run+0xc9/0x1f0 kernel/irq_work.c:184
 __sysvec_irq_work+0x21/0xc0 arch/x86/kernel/irq_work.c:22
 asm_call_irq_on_stack+0xf/0x20
 __run_sysvec_on_irqstack arch/x86/include/asm/irq_stack.h:37 [inline]
 run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:89 [inline]
 sysvec_irq_work+0x55/0x90 arch/x86/kernel/irq_work.c:17
 asm_sysvec_irq_work+0x12/0x20 arch/x86/include/asm/idtentry.h:654
 native_restore_fl arch/x86/include/asm/irqflags.h:41 [inline]
 arch_local_irq_restore arch/x86/include/asm/irqflags.h:84 [inline]
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
 _raw_spin_unlock_irqrestore+0x32/0x50 kernel/locking/spinlock.c:191
 try_to_wake_up+0x26e/0x470 kernel/sched/core.c:3456
 wake_up_process kernel/sched/core.c:3524 [inline]
 wake_up_q+0x46/0x80 kernel/sched/core.c:589
 futex_wake+0x375/0x3d0 kernel/futex.c:1623
 do_futex+0x96c/0x20c0 kernel/futex.c:3768
 __do_sys_futex kernel/futex.c:3826 [inline]
 __se_sys_futex+0x2a8/0x390 kernel/futex.c:3792
 __x64_sys_futex+0x74/0x80 kernel/futex.c:3792
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 7861 Comm: syz-executor.0 Not tainted 5.10.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================