[uClinux-dev] memory leak

From: David Beckemeyer (david@bdt.com)
Date: Wed Jul 19 2000 - 20:39:08 EDT 

I'm using uClinux with the Rt-control uCsimm.  I posted on the uCsimm
list a problem with an apparent memory leak.  It appears that munmap()
doesn't release memory acquired with mmap() (or there is a bug in the
libc malloc/free calls).

The following simple program demonstrates the problem and consumes 
all memory under uClinux (2.0.381pre5 from Rt-Control CD):

----------------------------------------------------------------
#define MEMSIZ 512

extern char *malloc (int x);

main ()
{
  char *p;
  int i;

  i = 0;
  do
    {
      p = malloc (MEMSIZ);
      if (p)
        free (p);
      i++;
      sleep (5);
    }
  while (p);
  printf ("failed after %d iterations\n", i);
  perror ("malloc");
  exit (1);
}
----------------------------------------------------------------

I actually hacked up a quick and dirty implementation of malloc/free
that grabs chunks from uClinux via mmap() and then carves them up.
This solved my problem.  I posted that code to the uCsimm list.  
I haven't heard much about the problem over there.  Has anyone
else seen this?  Is this a known behavior of mmap/munmap for
uClinix, a bug in malloc/free, or what?

I don't want to post the hack of malloc/free I wrote if this is a
"well duh" problem.

Thanks,

  - david

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