Overview:
Setting an IP address consumes 'ifaddr' typed memory.  When destroying the IP address the memory is not freed.

This memory does not appear to be collected later, as running the below script shows no recovery after continuously re-setting the ip address for 16 hours.

The leaked memory was tracked down to the ifa_alloc() function, see line 845 of https://svnweb.freebsd.org/base/head/sys/net/if.c?revision=355070&view=markup
Instrumenting the code revealed that there are more ifa_ref() calls than ifa_free() calls.  This results in the memory being held, as the system believes there is still a reference to this memory.


Steps to Reproduce:
'ifconfig <interface> inet' an address and then 'ifconfig <interface> inet delete' it.


Actual Results:
# vmstat -m | grep ifaddr
       ifaddr   141    36K       -      235  16,32,64,128,256,512,2048,4096
# 
# ifconfig em1 inet  192.168.200.44
# vmstat -m | grep ifaddr
       ifaddr   142    36K       -      236  16,32,64,128,256,512,2048,4096
# ifconfig em1 inet delete 192.168.200.44
# vmstat -m | grep ifaddr
       ifaddr   142    36K       -      236  16,32,64,128,256,512,2048,4096

# cat /tmp/loop
while true
do
        ifconfig em1 192.168.200.33 
        sleep 1 
        vmstat -m | grep ifaddr
done
# /tmp/loop
       ifaddr   135    37K       -      294  16,32,64,128,256,512,2048,4096
       ifaddr   136    38K       -      295  16,32,64,128,256,512,2048,4096
       ifaddr   137    38K       -      296  16,32,64,128,256,512,2048,4096
       ifaddr   138    39K       -      297  16,32,64,128,256,512,2048,4096
....snip (16 hours worth of logs)...
       ifaddr 1834875 917406K       -  1835088  16,32,64,128,256,512,2048,4096
       ifaddr 1834876 917407K       -  1835089  16,32,64,128,256,512,2048,4096
       ifaddr 1834877 917407K       -  1835090  16,32,64,128,256,512,2048,4096
       ifaddr 1834878 917408K       -  1835091  16,32,64,128,256,512,2048,4096
       ifaddr 1834879 917408K       -  1835092  16,32,64,128,256,512,2048,4096
^C
#


Expected Results:
Not to leak/hold onto memory.


Build Date & Hardware:
HEADr355854 on amd64 target with any networking interface