RE: How can I trace when the allocated memory is free after kmalloc ?

[ììíB <jaehyek dot choi at lge dot com>]

Hi Mark.

Thanks for your help.
But  vm.kfree is not working. ( make target phone reset )
( vm.kmalloc  is ok  .)

Below is my test code .

-------------------------------------
probe vm.kfree { println(vm.kfree \n")}
-------------------------------------


please recommand what I should try .

My environment is 
- target OS :  Android OS  kernel ver 2.6.35.11
- host : Ubuntu 11.04 64bit.
- systemtap ver :systemtap-20110917.tar.bz2





-----Original Message-----
From: Mark Wielaard [mailto:mjw@redhat.com] 
Sent: Friday, September 16, 2011 7:04 PM
To: ììíB
Cc: 'Turgis, Frederic'; 'Josh Stone'; systemtap@sourceware.org
Subject: Re: How can I trace when the allocated memory is free after kmalloc ?

On Fri, 2011-09-16 at 17:19 +0900, ììíB wrote:
> Hi Mark.
> 
> If  "A thead" get a kernel memory by kmalloc, and "B thead" can free the memory, 
> how can I trace  when the allocated memory is returned after kmalloc ?

I suppose you can save the address that kmalloc returned and check for
that address while probing kfree. Maybe something like:

global addrs;

probe vm.kmalloc
{
  addrs[ptr] = get_cycles();
}

probe vm.kfree
{
  if (addrs[ptr] != 0)
    {
      printf("%x released after %d cycles\n",
             ptr, get_cycles() - addrs[ptr]);
    }
  delete(addrs[ptr]);
}

That will probably overflow MAXMAPENTRIES pretty quickly though.

Cheers,

Mark