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BUG: KCSAN: data-race in do_epoll_ctl / do_epoll_wait

write to 0xffff888104226658 of 8 bytes by task 1797 on cpu 1:
 __list_add include/linux/list.h:72 [inline]
 list_add_tail include/linux/list.h:102 [inline]
 ep_insert fs/eventpoll.c:1542 [inline]
 do_epoll_ctl+0x1331/0x1880 fs/eventpoll.c:2141
 __do_sys_epoll_ctl fs/eventpoll.c:2192 [inline]
 __se_sys_epoll_ctl fs/eventpoll.c:2183 [inline]
 __x64_sys_epoll_ctl+0xc2/0xf0 fs/eventpoll.c:2183
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x50 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888104226658 of 8 bytes by task 1798 on cpu 0:
 list_empty_careful include/linux/list.h:329 [inline]
 ep_events_available fs/eventpoll.c:381 [inline]
 ep_poll fs/eventpoll.c:1797 [inline]
 do_epoll_wait+0x2b9/0xf50 fs/eventpoll.c:2234
 do_epoll_pwait fs/eventpoll.c:2268 [inline]
 __do_sys_epoll_pwait fs/eventpoll.c:2281 [inline]
 __se_sys_epoll_pwait+0x12b/0x240 fs/eventpoll.c:2275
 __x64_sys_epoll_pwait+0x74/0x80 fs/eventpoll.c:2275
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x50 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffff888104226650 -> 0xffff8881269f0398

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1798 Comm: syz-fuzzer Tainted: G        W         5.17.0-syzkaller-13673-ge8b767f5e040-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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