Thank you wang zhe for a quick reply.
But my problem as like mentioned is to find out the exact used heap size of the user process instead of total allocated space.

in cat /proc/pid/mpas i am able to see that whenver a user process forks kernel allocating almost 33 page size of heap.But if the  Process is having only few dynamic allocation it may be using only few KB heap.


So  i just want to find out the exactly used heap not mm->brk or Vm->end of heap ,so that i can dump only that portion

if anyone knows please help

Thanks
Dhyan

On Mon, May 14, 2012 at 3:44 PM, 王哲 <wangzhe5004@gmail.com> wrote:


2012/5/14 Dhyan <linuxdhyan@gmail.com>
Dear All,

 I am writing a kernel module which will accept  user process id (PID) as input and dump all the address space of that user process,like  stack,heap segment.

I took mm->start_brk as start of heap ,mm->brk as end of heap,then i am seeing, even though user process is not using 33 pages heap size shows as 33 pages
 (mm->brk -mm->start_brk) . (This i verified using /proc/pid/maps) .Stack also behaves in similar way,

So is there any way i can find out the really used heap staring from mm->start_brk,So that i can dump only the used heap

--
Thanks
Dhyan

I am a kernelnewby and used to write a same kernel module.and hope to help you.
   please see the link
   http://blog.163.com/zhe_wang_2009/blog/static/17228212120123493614715/

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