e list of known hosts.
executing program
BUG: memory leak
unreferenced object 0xffff88811ba63fc0 (size 64):
  comm "softirq", pid 0, jiffies 4294942971 (age 8.140s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 e0 00 00 01 00 00 00 00  ................
    02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<000000005196006d>] kmemleak_alloc_recursive include/linux/kmemleak.h:55 [inline]
    [<000000005196006d>] slab_post_alloc_hook mm/slab.h:439 [inline]
    [<000000005196006d>] slab_alloc mm/slab.c:3326 [inline]
    [<000000005196006d>] kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553
    [<00000000e8b5477c>] kmalloc include/linux/slab.h:547 [inline]
    [<00000000e8b5477c>] kzalloc include/linux/slab.h:742 [inline]
    [<00000000e8b5477c>] ip_mc_add1_src net/ipv4/igmp.c:1976 [inline]
    [<00000000e8b5477c>] ip_mc_add_src+0x36b/0x400 net/ipv4/igmp.c:2100
    [<00000000079be45d>] ip_mc_msfilter+0x22d/0x310 net/ipv4/igmp.c:2484
    [<000000008bc82e73>] do_ip_setsockopt.isra.0+0x1795/0x1930 net/ipv4/ip_sockglue.c:959
    [<00000000f5688cdd>] ip_setsockopt+0x3b/0xb0 net/ipv4/ip_sockglue.c:1248
    [<00000000d46a0e4e>] udp_setsockopt+0x4e/0x90 net/ipv4/udp.c:2611
    [<0000000027d2f9d4>] sock_common_setsockopt+0x38/0x50 net/core/sock.c:3124
    [<000000001d746cb5>] __sys_setsockopt+0x98/0x120 net/socket.c:2072
    [<0000000093aa3a05>] __do_sys_setsockopt net/socket.c:2083 [inline]
    [<0000000093aa3a05>] __se_sys_setsockopt net/socket.c:2080 [inline]
    [<0000000093aa3a05>] __x64_sys_setsockopt+0x26/0x30 net/socket.c:2080
    [<000000004b21631f>] do_syscall_64+0x76/0x1a0 arch/x86/entry/common.c:301
    [<00000000cc2baace>] entry_SYSCALL_64_after_hwframe+0x44/0xa9