How to debug "__alloc_pages: 0-order allocation failed (gtp=0x20/0)"

["Xiangfei Jia" <xjianz@xxxxxxxxx>]

I've been writing a kernel module for quite a while. Sometimes I got a
error message saying "__alloc_pages: 0-order allocation failed
(gtp=0x20/0)". I think the problem is caused because there's not enough
memory to allocate a new page. But, my module doesn't use much memory
at all. 

Can I get some hints about how to dubug this error??? How can I know which part of my module causes the problem???

Thanks in advance!

Fei