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BUG: KCSAN: data-race in fasync_remove_entry / kill_fasync

write to 0xffff888120901300 of 8 bytes by task 21700 on cpu 0:
 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:6011
 __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: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+0x384/0x3a0 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888120901300 of 8 bytes by interrupt on cpu 1:
 kill_fasync+0x3f/0x180 fs/fcntl.c:1019
 perf_event_wakeup+0x11f/0x160 kernel/events/core.c:6051
 perf_pending_event+0x12d/0x170 kernel/events/core.c:6107
 irq_work_run_list+0x136/0x190 kernel/irq_work.c:156
 irq_work_run+0x48/0xa0 kernel/irq_work.c:172
 smp_irq_work_interrupt+0x3f/0x100 arch/x86/kernel/irq_work.c:21
 irq_work_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:860
 find_watchpoint kernel/kcsan/core.c:124 [inline]
 check_access kernel/kcsan/core.c:551 [inline]
 __tsan_read4+0x61/0x100 kernel/kcsan/core.c:699
 get_next_corpse net/netfilter/nf_conntrack_core.c:1998 [inline]
 nf_ct_iterate_cleanup+0x135/0x2e0 net/netfilter/nf_conntrack_core.c:2035
 nf_ct_iterate_cleanup_net net/netfilter/nf_conntrack_core.c:2120 [inline]
 nf_ct_iterate_cleanup_net+0xe2/0xf0 net/netfilter/nf_conntrack_core.c:2105
 masq_inet_event+0xaf/0xc0 net/netfilter/nf_nat_masquerade.c:125
 notifier_call_chain+0xd7/0x160 kernel/notifier.c:83
 __blocking_notifier_call_chain+0x89/0xd0 kernel/notifier.c:284
 blocking_notifier_call_chain+0x37/0x50 kernel/notifier.c:295
 __inet_del_ifa+0x38a/0x6e0 net/ipv4/devinet.c:427
 inet_del_ifa net/ipv4/devinet.c:464 [inline]
 devinet_ioctl+0x881/0xf30 net/ipv4/devinet.c:1159
 inet_ioctl+0x12b/0x240 net/ipv4/af_inet.c:957
 sock_do_ioctl+0x61/0x230 net/socket.c:1053
 sock_ioctl+0x3a3/0x5e0 net/socket.c:1204
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x109/0x150 fs/ioctl.c:763
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x4c/0x60 fs/ioctl.c:770
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 21703 Comm: syz-executor.5 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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