[Madwifi-users] Possible memory leak in station mode

[Ray O. <rov...@mi...>]

I believe I've found a memory leak with the madwifi driver and I'm hoping for help in 
resolving/confirming the problem.

Set up:

I am running madwifi on an IXP425 embedded platform with the Snapgear 3.4 distro (kernel 
version 2.6.17). I have verified that the problem exists in madwifi trunk r2708 (which we 
are using) as well madwifi-ng r3117.

I wrote a test script (for the station) that automates restarting our radio, verifying an 
association, and then pings the AP. This is done in a while loop that I set up for 30,000 
iterations.

I ran this over the weekend and got an oom (out of memory) failure on the 4,664th 
iteration. I dug into the details for a while and realized that the slab allocation was 
climbing slowly and steadily. Over 40 MBytes had been allocated to the size-2048 slab. I 
isolated it to the madwifi driver (got rid of all other supporting processes such as 
syslog, wpa_supplicant, etc). The problem still occurs even if I modprobe/rmmod ath_pci in 
the restart script. I can see the slab allocation go up by 4kbytes almost every restart 
with /proc/meminfo and I can see the size-2048 slab slowly increase with /proc/slabinfo.

My system has 64MBytes of DRAM, but if I set min_free_kbytes to 40Meg, the unit runs out 
of memory very quickly, as expected.

Should I open a ticket? I haven't tested the AP side yet but I will...

Here is the script (apologies for the cryptic variable names):

#!/bin/sh
var1=0
var2=0
var3=0
result=0
pinged=0
text=""

while [ $var1 -lt 200000 ]
do
   echo ""
   text=`date -R`
   echo "Iteration $var1 at $text"
   service radio restart
   #dmesg
   var2=0
   text=""

   while [ "$text" == "" ];
   do
     #echo "Not associated on iteration $var2"
     #text=""
     text=`wlanconfig ath0 list`
     #echo "text = $text"

     if [ $var2 -gt 60 ]; then
       echo "Could not associate, aborting test"
       exit
     fi

     let var2=$var2+1
     sleep 1

   done 


   echo "Associated on iteration $var2"

   #check if can ping, 30 times, once a second
   var3=0
   pinged=0
   while [ $pinged -eq 0 ]
   do
     ping 192.168.3.200 -c 1 > /dev/null
     let result=$?
     #echo "Return value == $result"

     if [ $result -ne 0 ]; then
       #echo "Return value == $result"
       echo "Failed to ping host"
       let var3=$var3+1
       if [ $var3 -gt 30 ]; then
         echo "Could not ping host, aborting test..."
         exit
         fi
     else
       #echo "AP contacted"
       let pinged=1
     fi

     #sleep 1
   done

   #ping 192.168.3.200 -c 1
   auth=1
   echo "Host found on iteration $var3"

   let var1=$var1+1
done


Start script:
wlanconfig ath0 create wlandev wifi0 wlanmode sta nosbeacon -bssid
ifconfig wifi0 up

if [ "$RATE" == "auto" ]; then
   iwconfig ath0 rate auto
else
   iwconfig ath0 rate $RATE fixed
fi

iwconfig ath0 channel $CHANNEL
#iwpriv ath0 mode $MODE
iwconfig ath0 txpower 0
iwconfig ath0 essid $SSID

if [ "$ALG" = "WEP" ]; then 

   iwconfig ath0 key [1] $KEY1
   iwconfig ath0 key [2] $KEY2
   iwconfig ath0 key [3] $KEY3
   iwconfig ath0 key [4] $KEY4
   iwconfig ath0 key [$IDX]
fi

if [ "$ALG" = "NONE" ]; then
   iwconfig ath0 key 0
fi

iwpriv ath0 wds 1
iwpriv ath0 inact 60

# Load Networking Config
echo -n "Adding into bridge ..."
brctl addif br0 ath0
ifconfig ath0 0.0.0.0 up
sleep 2
iwconfig ath0 txpower $TXP

echo "done."

Stop script
#Destroy all vaps!
vaps=$(ifconfig -a -s | grep ath | sed -e 's/\(ath[0-9]\+\).*/\1/g')
for vap in $vaps; do
   ifconfig $vap down
   brctl delif br0 $vap
   wlanconfig $vap destroy
done

-- 
Ray Overland BSc. EE
Senior Software Engineer
Microhard Systems Inc.
http://www.microhardcorp.com
Phone: (403)248-0028 ext 230
Email: rov...@mi...