Hi,
I want to access task->mm->ANY_FIELD. where task is a pointer of type struct task_struct. But I am sure that without allocating the space to task, I can not access the fields in the structure pointed by mm.

How do we allocate memory in a kernel module.
I can't declare task = (struct task_struct *)malloc(sizeof(task_struct));
How do I go about it.

Thanks in advance.....

kmalloc perhaps?
http://www.win.tue.nl/~aeb/linux/lk/lk-9.html

I have *no* idea about this, just googled

You should use kmalloc within a kernel module. Kernel does not have access to library function such as malloc.

This is one thing. I am not clear about your objective but here are few guidelines.

You need not to allocate any memory for the tast_struct. Also I am not sure how you are accessing the tast_struct, but generally you can access using some macro such as current. These macros will return a tas_struct, so you just need a pointer to it. For example

struct task_struct *task = current; Will return tast_struct of the current process and then you can user the tast->"any thing you want". You need to study others macros too. You can also use the list_head structure to iterate over all the tasks.

I you are dealing with kernal 2.6 you may use struct threas_info->tast to access a task_struct.

I hope this helps.

"Read the source, Luke!"

The full kernel source-code is right there in front of you and it's full of copious working examples, as well as substantial documentation files. You don't have to "figure out" anything you can discover.

This is correct that you can discover. The kernel source is the best way place to learn itself.

But every one need pointers and correct directions at the starting. Some help will make them learn faster which is good. In my view one should pose as many question as possible but first they should work on it.

As far as kernel internals is concern I would suggest linuxdoniv to read few more things about kernel basics, if really interested in learning. Tldp would be a good source. If you basics are strong you will catch things faster, and do feel free to ask questions.