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BUG: KCSAN: data-race in do_epoll_wait / ep_poll_callback

write to 0xffff888124ac6350 of 8 bytes by task 8628 on cpu 0:
 list_add_tail_lockless fs/eventpoll.c:1158 [inline]
 ep_poll_callback+0x29c/0x510 fs/eventpoll.c:1248
 __wake_up_common+0xbc/0x130 kernel/sched/wait.c:93
 __wake_up_common_lock kernel/sched/wait.c:123 [inline]
 __wake_up_sync_key+0x83/0xc0 kernel/sched/wait.c:190
 pipe_write+0x9bc/0xbc0 fs/pipe.c:599
 call_write_iter include/linux/fs.h:1908 [inline]
 new_sync_write fs/read_write.c:503 [inline]
 vfs_write+0x607/0x690 fs/read_write.c:578
 ksys_write+0xce/0x180 fs/read_write.c:631
 __do_sys_write fs/read_write.c:643 [inline]
 __se_sys_write fs/read_write.c:640 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:640
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888124ac6350 of 8 bytes by task 8630 on cpu 1:
 list_empty_careful include/linux/list.h:300 [inline]
 ep_events_available fs/eventpoll.c:379 [inline]
 ep_poll fs/eventpoll.c:1855 [inline]
 do_epoll_wait+0x2e2/0x870 fs/eventpoll.c:2333
 __do_sys_epoll_pwait fs/eventpoll.c:2364 [inline]
 __se_sys_epoll_pwait fs/eventpoll.c:2350 [inline]
 __x64_sys_epoll_pwait+0x92/0x150 fs/eventpoll.c:2350
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8630 Comm: syz-fuzzer Not tainted 5.8.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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