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BUG: KCSAN: data-race in ip_tunnel_xmit / ip_tunnel_xmit

write to 0xffff8880a0d67130 of 8 bytes by task 6415 on cpu 0:
 ip_tunnel_xmit+0xb28/0x11c0 net/ipv4/ip_tunnel.c:825
 __gre_xmit net/ipv4/ip_gre.c:466 [inline]
 ipgre_xmit+0x53e/0x590 net/ipv4/ip_gre.c:650
 __netdev_start_xmit include/linux/netdevice.h:4611 [inline]
 netdev_start_xmit include/linux/netdevice.h:4625 [inline]
 xmit_one+0xc0/0x310 net/core/dev.c:3556
 dev_hard_start_xmit net/core/dev.c:3572 [inline]
 __dev_queue_xmit+0xf00/0x15a0 net/core/dev.c:4131
 dev_queue_xmit+0x13/0x20 net/core/dev.c:4164
 __bpf_tx_skb net/core/filter.c:2086 [inline]
 __bpf_redirect_no_mac net/core/filter.c:2111 [inline]
 __bpf_redirect+0x56a/0x7c0 net/core/filter.c:2134
 ____bpf_clone_redirect net/core/filter.c:2165 [inline]
 bpf_clone_redirect+0x168/0x1c0 net/core/filter.c:2137
 bpf_prog_bebbfe2050753572+0x5c/0x2dc
 bpf_dispatcher_nop_func include/linux/bpf.h:556 [inline]
 bpf_test_run+0x26d/0x4a0 net/bpf/test_run.c:49
 bpf_prog_test_run_skb+0x463/0xb00 net/bpf/test_run.c:442
 bpf_prog_test_run kernel/bpf/syscall.c:2985 [inline]
 __do_sys_bpf+0x3871/0x98d0 kernel/bpf/syscall.c:4137
 __se_sys_bpf kernel/bpf/syscall.c:4077 [inline]
 __x64_sys_bpf+0x3d/0x50 kernel/bpf/syscall.c:4077
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880a0d67130 of 8 bytes by task 6455 on cpu 1:
 ip_tunnel_xmit+0xb16/0x11c0 net/ipv4/ip_tunnel.c:825
 __gre_xmit net/ipv4/ip_gre.c:466 [inline]
 ipgre_xmit+0x53e/0x590 net/ipv4/ip_gre.c:650
 __netdev_start_xmit include/linux/netdevice.h:4611 [inline]
 netdev_start_xmit include/linux/netdevice.h:4625 [inline]
 xmit_one+0xc0/0x310 net/core/dev.c:3556
 dev_hard_start_xmit net/core/dev.c:3572 [inline]
 __dev_queue_xmit+0xf00/0x15a0 net/core/dev.c:4131
 dev_queue_xmit+0x13/0x20 net/core/dev.c:4164
 __bpf_tx_skb net/core/filter.c:2086 [inline]
 __bpf_redirect_no_mac net/core/filter.c:2111 [inline]
 __bpf_redirect+0x56a/0x7c0 net/core/filter.c:2134
 ____bpf_clone_redirect net/core/filter.c:2165 [inline]
 bpf_clone_redirect+0x168/0x1c0 net/core/filter.c:2137
 bpf_prog_bebbfe2050753572+0x5c/0xd3c
 bpf_dispatcher_nop_func include/linux/bpf.h:556 [inline]
 bpf_test_run+0x26d/0x4a0 net/bpf/test_run.c:49
 bpf_prog_test_run_skb+0x463/0xb00 net/bpf/test_run.c:442
 bpf_prog_test_run kernel/bpf/syscall.c:2985 [inline]
 __do_sys_bpf+0x3871/0x98d0 kernel/bpf/syscall.c:4137
 __se_sys_bpf kernel/bpf/syscall.c:4077 [inline]
 __x64_sys_bpf+0x3d/0x50 kernel/bpf/syscall.c:4077
 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: 1 PID: 6455 Comm: syz-executor.5 Not tainted 5.8.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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