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BUG: KCSAN: data-race in do_epoll_wait / ep_poll_callback

write to 0xffff888138961868 of 4 bytes by task 1912 on cpu 0:
 ep_send_events fs/eventpoll.c:1708 [inline]
 ep_poll fs/eventpoll.c:1823 [inline]
 do_epoll_wait+0x86c/0xe90 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+0x15f/0x280 fs/eventpoll.c:2299
 __x64_sys_epoll_pwait+0x78/0x90 fs/eventpoll.c:2299
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888138961868 of 4 bytes by task 1918 on cpu 1:
 ep_poll_callback+0x44e/0x530 fs/eventpoll.c:1215
 __wake_up_common+0xb3/0x130 kernel/sched/wait.c:107
 __wake_up_common_lock kernel/sched/wait.c:138 [inline]
 __wake_up_sync_key+0x82/0xc0 kernel/sched/wait.c:208
 unix_write_space+0xcd/0x140 net/unix/af_unix.c:537
 sock_wfree+0x119/0x330 net/core/sock.c:2451
 unix_destruct_scm+0x137/0x160 net/unix/scm.c:152
 skb_release_head_state+0xb7/0x1a0 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+0xa6/0x3b0 net/core/skbuff.c:956
 kfree_skb include/linux/skbuff.h:1218 [inline]
 unix_release_sock+0x63d/0x780 net/unix/af_unix.c:649
 unix_release+0x52/0x70 net/unix/af_unix.c:1041
 __sock_release net/socket.c:650 [inline]
 sock_close+0x70/0x150 net/socket.c:1368
 __fput+0x245/0x570 fs/file_table.c:320
 ____fput+0x15/0x20 fs/file_table.c:348
 task_work_run+0x123/0x160 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xcf/0xe0 kernel/entry/common.c:171
 exit_to_user_mode_prepare+0x6a/0xa0 kernel/entry/common.c:203
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x26/0x140 kernel/entry/common.c:296
 do_syscall_64+0x4d/0xc0 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: 1918 Comm: syz-executor.0 Not tainted 6.2.0-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/21/2023
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