syzbot

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BUG: KCSAN: data-race in do_epoll_wait / ep_poll_callback

write to 0xffff888120e76050 of 8 bytes by interrupt on cpu 1:
 list_add_tail_lockless fs/eventpoll.c:1158 [inline]
 ep_poll_callback+0x29c/0x510 fs/eventpoll.c:1248
 __wake_up_common+0xbc/0x130 kernel/sched/wait.c:93
 __wake_up_common_lock kernel/sched/wait.c:123 [inline]
 __wake_up_sync_key+0x83/0xc0 kernel/sched/wait.c:190
 sock_def_readable+0x61/0xe0 net/core/sock.c:2909
 tcp_data_ready net/ipv4/tcp_input.c:4796 [inline]
 tcp_rcv_established+0x13c0/0x1520 net/ipv4/tcp_input.c:5725
 tcp_v4_do_rcv+0x25e/0x480 net/ipv4/tcp_ipv4.c:1641
 tcp_v4_rcv+0x219b/0x2420 net/ipv4/tcp_ipv4.c:2023
 ip_protocol_deliver_rcu+0x1f9/0x400 net/ipv4/ip_input.c:204
 ip_local_deliver_finish net/ipv4/ip_input.c:231 [inline]
 NF_HOOK include/linux/netfilter.h:307 [inline]
 ip_local_deliver+0x1d6/0x2a0 net/ipv4/ip_input.c:252
 dst_input include/net/dst.h:449 [inline]
 ip_sublist_rcv_finish net/ipv4/ip_input.c:550 [inline]
 ip_list_rcv_finish net/ipv4/ip_input.c:600 [inline]
 ip_sublist_rcv+0x4d4/0x5a0 net/ipv4/ip_input.c:608
 ip_list_rcv+0x262/0x290 net/ipv4/ip_input.c:643
 __netif_receive_skb_list_ptype net/core/dev.c:5324 [inline]
 __netif_receive_skb_list_core+0x34b/0x450 net/core/dev.c:5372
 __netif_receive_skb_list+0x298/0x310 net/core/dev.c:5424
 netif_receive_skb_list_internal+0xda/0x330 net/core/dev.c:5531
 gro_normal_list net/core/dev.c:5642 [inline]
 gro_normal_one net/core/dev.c:5654 [inline]
 napi_skb_finish net/core/dev.c:5982 [inline]
 napi_gro_receive+0x329/0x5a0 net/core/dev.c:6014
 receive_buf+0x7a4/0xcf0 drivers/net/virtio_net.c:1082
 virtnet_receive drivers/net/virtio_net.c:1346 [inline]
 virtnet_poll+0x2fa/0x780 drivers/net/virtio_net.c:1451
 napi_poll+0x178/0x4a0 net/core/dev.c:6684
 net_rx_action+0x1ba/0x530 net/core/dev.c:6752
 __do_softirq+0x198/0x360 kernel/softirq.c:292
 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
 do_softirq_own_stack+0x5d/0x80 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:387 [inline]
 __irq_exit_rcu+0x115/0x120 kernel/softirq.c:417
 common_interrupt+0x14e/0x1e0 arch/x86/kernel/irq.c:239
 asm_common_interrupt+0x1e/0x40 arch/x86/include/asm/idtentry.h:576

read to 0xffff888120e76050 of 8 bytes by task 8653 on cpu 0:
 list_empty_careful include/linux/list.h:300 [inline]
 ep_events_available fs/eventpoll.c:379 [inline]
 ep_poll fs/eventpoll.c:1855 [inline]
 do_epoll_wait+0x2e2/0x870 fs/eventpoll.c:2333
 __do_sys_epoll_pwait fs/eventpoll.c:2364 [inline]
 __se_sys_epoll_pwait fs/eventpoll.c:2350 [inline]
 __x64_sys_epoll_pwait+0x92/0x150 fs/eventpoll.c:2350
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8653 Comm: syz-fuzzer Not tainted 5.8.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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