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BUG: KCSAN: data-race in ep_modify / ep_poll_callback

write to 0xffff88813f3ea9e8 of 4 bytes by task 18112 on cpu 0:
 ep_modify+0x51/0x3f0 fs/eventpoll.c:1618
 do_epoll_ctl+0x4ea/0x950 fs/eventpoll.c:2238
 __do_sys_epoll_ctl fs/eventpoll.c:2275 [inline]
 __se_sys_epoll_ctl fs/eventpoll.c:2266 [inline]
 __x64_sys_epoll_ctl+0xc6/0xf0 fs/eventpoll.c:2266
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff88813f3ea9e8 of 4 bytes by task 18094 on cpu 1:
 ep_poll_callback+0x4b5/0x5a0 fs/eventpoll.c:1245
 __wake_up_common kernel/sched/wait.c:89 [inline]
 __wake_up_common_lock kernel/sched/wait.c:106 [inline]
 __wake_up+0x64/0xa0 kernel/sched/wait.c:127
 sock_def_wakeup+0x5d/0x80 net/core/sock.c:3317
 unix_shutdown+0x106/0x370 net/unix/af_unix.c:2941
 __sys_shutdown_sock net/socket.c:2425 [inline]
 __sys_shutdown net/socket.c:2437 [inline]
 __do_sys_shutdown net/socket.c:2445 [inline]
 __se_sys_shutdown+0xfe/0x140 net/socket.c:2443
 __x64_sys_shutdown+0x31/0x40 net/socket.c:2443
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000018 -> 0xc0000019

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 18094 Comm: syz-executor.4 Not tainted 6.8.0-rc5-syzkaller-00121-g1c892cdd8fe0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
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