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BUG: KCSAN: data-race in fasync_remove_entry / kill_fasync

read to 0xffff8880a90ec2f8 of 8 bytes by interrupt on cpu 0:
 kill_fasync+0x3f/0x180 fs/fcntl.c:1019
 perf_event_wakeup+0x11f/0x160 kernel/events/core.c:5955
 perf_pending_event+0x12d/0x170 kernel/events/core.c:6011
 irq_work_run_list+0xea/0x140 kernel/irq_work.c:165
 irq_work_run+0x48/0xa0 kernel/irq_work.c:180
 smp_irq_work_interrupt+0x71/0x1c0 arch/x86/kernel/irq_work.c:21
 irq_work_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:861
 __tsan_read8+0x8/0x30 kernel/kcsan/kcsan.c:36
 xfrm_tmpl_resolve_one net/xfrm/xfrm_policy.c:2391 [inline]
 xfrm_tmpl_resolve+0x21e/0x890 net/xfrm/xfrm_policy.c:2436
 xfrm_resolve_and_create_bundle+0x9d/0x12d0 net/xfrm/xfrm_policy.c:2727
 xfrm_lookup_with_ifid+0x1b7/0x1310 net/xfrm/xfrm_policy.c:3050
 xfrm_lookup net/xfrm/xfrm_policy.c:3174 [inline]
 xfrm_lookup_route+0x44/0x100 net/xfrm/xfrm_policy.c:3185
 ip6_dst_lookup_flow+0xde/0x120 net/ipv6/ip6_output.c:1156
 rawv6_sendmsg+0x82c/0x21e0 net/ipv6/raw.c:928

write to 0xffff8880a90ec2f8 of 8 bytes by task 11572 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: 11572 Comm: syz-executor.5 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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