r0 = openat$procfs(0xffffffffffffff9c, &(0x7f0000000040)='/proc/key-users\x00', 0x0, 0x0)
r1 = openat$tcp_mem(0xffffffffffffff9c, &(0x7f0000000140)='/proc/sys/net/ipv4/tcp_rmem\x00', 0x1, 0x0)
sendfile(r1, r0, 0x0, 0x4)