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BUG: KCSAN: data-race in ep_poll / ep_poll_callback

write to 0xffff8880b8e43b90 of 8 bytes by task 5278 on cpu 0:
 list_add_tail_lockless fs/eventpoll.c:1158 [inline]
 ep_poll_callback+0x5f2/0x6c0 fs/eventpoll.c:1248
 __wake_up_common+0x76/0x180 kernel/sched/wait.c:93
 __wake_up_common_lock+0x77/0xb0 kernel/sched/wait.c:123
 sock_def_readable+0x9d/0x130 net/core/sock.c:2819
 __netlink_sendskb+0x5f/0x70 net/netlink/af_netlink.c:1250
 netlink_sendskb net/netlink/af_netlink.c:1256 [inline]
 netlink_unicast+0x46d/0x4c0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x4cf/0x8a0 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0x98/0xc0 net/socket.c:672
 ____sys_sendmsg+0x493/0x4c0 net/socket.c:2362
 ___sys_sendmsg+0xb5/0x100 net/socket.c:2416
 __sys_sendmsg+0x9b/0x150 net/socket.c:2449
 __do_sys_sendmsg net/socket.c:2458 [inline]
 __se_sys_sendmsg net/socket.c:2456 [inline]
 __x64_sys_sendmsg+0x4c/0x60 net/socket.c:2456
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880b8e43b90 of 8 bytes by task 13239 on cpu 1:
 list_empty_careful include/linux/list.h:300 [inline]
 ep_events_available fs/eventpoll.c:379 [inline]
 ep_poll+0x5ad/0x910 fs/eventpoll.c:1902
 do_epoll_wait+0x15a/0x180 fs/eventpoll.c:2320
 __do_sys_epoll_wait fs/eventpoll.c:2330 [inline]
 __se_sys_epoll_wait fs/eventpoll.c:2327 [inline]
 __x64_sys_epoll_wait+0x5a/0x70 fs/eventpoll.c:2327
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 13239 Comm: systemd-udevd Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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