Very confused about malloc in Linux, Help!!!

[Shigang Zan]

Hi,
Now I have met a problem about my software in Linux. The memory usage kept increasing until no memory to use.

I found that malloc will return many addresses higher than 0x40000000 when I requested memory using malloc, the addresses were not in heap area (below 0x40000000). I don't know why this scenario happened. And it seemed many blocks (1020K 1024K ...) were created and until memory was exhausted by them.
What can I do to found the root cause of this problem. I found many blocks had no content, but why system crote more and more blocks.

Thanks Very Much!!!!