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BUG: KCSAN: data-race in do_epoll_wait / ep_poll_callback

write to 0xffff8881249a26e8 of 4 bytes by task 6395 on cpu 0:
 ep_send_events fs/eventpoll.c:1708 [inline]
 ep_poll fs/eventpoll.c:1823 [inline]
 do_epoll_wait+0x863/0xf20 fs/eventpoll.c:2258
 do_epoll_pwait fs/eventpoll.c:2292 [inline]
 __do_sys_epoll_pwait fs/eventpoll.c:2305 [inline]
 __se_sys_epoll_pwait+0x136/0x250 fs/eventpoll.c:2299
 __x64_sys_epoll_pwait+0x74/0x80 fs/eventpoll.c:2299
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff8881249a26e8 of 4 bytes by task 6406 on cpu 1:
 ep_poll_callback+0x145/0x4f0 fs/eventpoll.c:1155
 __wake_up_common+0xbc/0x130 kernel/sched/wait.c:107
 __wake_up_common_lock kernel/sched/wait.c:138 [inline]
 __wake_up_sync_key+0x83/0xc0 kernel/sched/wait.c:208
 unix_write_space+0xc9/0x140 net/unix/af_unix.c:537
 sock_wfree+0x125/0x370 net/core/sock.c:2449
 unix_destruct_scm+0x165/0x190 net/unix/scm.c:152
 skb_release_head_state+0xb3/0x1a0 net/core/skbuff.c:903
 skb_release_all net/core/skbuff.c:914 [inline]
 __kfree_skb net/core/skbuff.c:930 [inline]
 kfree_skb_reason+0xca/0x360 net/core/skbuff.c:956
 kfree_skb include/linux/skbuff.h:1218 [inline]
 unix_release_sock+0x66a/0x7b0 net/unix/af_unix.c:649
 unix_release+0x4e/0x70 net/unix/af_unix.c:1041
 __sock_release net/socket.c:650 [inline]
 sock_close+0x6c/0x150 net/socket.c:1365
 __fput+0x245/0x570 fs/file_table.c:320
 ____fput+0x11/0x20 fs/file_table.c:348
 task_work_run+0xde/0x110 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0x124/0x130 kernel/entry/common.c:171
 exit_to_user_mode_prepare kernel/entry/common.c:203 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x6a/0x90 kernel/entry/common.c:296
 do_syscall_64+0x37/0x70 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x6000001c -> 0x60000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 6406 Comm: syz-executor.2 Not tainted 6.1.0-syzkaller-13872-gb6bb9676f216-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
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