[uClibc]Re: malloc, munmap, etc...

[Miles Bader]

On Thu, Nov 07, 2002 at 10:53:20AM +0100, Uwe Beutin wrote:
> I've applied the patches to the malloc directory and re-compiled it all 
> but the boa-0.94-13 munmap problem is still there, I believe, worse than 
> it was before since I am not making any page requests at all:
> 
> munmap of non-mmaped memory by process 57 (boa): 10dd6d80
> 
> Phew, it's probably a boa-thing with its implementatin of free()?! 
> 
> But apart from that, it seems that my heap is cleaner now.. at least 
> I've not seen the free mem go down whilst my apps are running :)

I'm a bit confused; so you mean:

 (1) The major memory leak seems to be fixed
 (2) BUT you're still getting wierd messages from boa
     (what do you mean by `not making any page requests at all'?)

Also, what does `it's probably a boa-thing with its implementatin of free'
mean?  Does boa implement it's own version of the `free' function (what about
malloc)?

If it's still possibly a bug with uClibc malloc, does it happen reliably
enough that you could turn on malloc debugging messages to get some verbose
debug output?  That might help track down a malloc bug.  If you can do this,
use something like the following patch to compile in malloc debugging into
uClibc [I'm not sure if this patch still applies cleanly, but you get the
idea]:


diff -u libc/stdlib/malloc/Makefile /tmp/m
--- libc/stdlib/malloc/Makefile	    2002-08-19 17:48:22 +0900
+++ /tmp/m			    2002-09-13 16:46:39 +0900
@@ -26,10 +26,12 @@
 
 # calloc.c can be found at uClibc/libc/stdlib/calloc.c 
 CSRC = malloc.c free.c realloc.c memalign.c \
-     heap_alloc.c heap_alloc_at.c heap_free.c
+     heap_alloc.c heap_alloc_at.c heap_free.c heap_debug.c
 COBJS=$(patsubst %.c,%.o, $(CSRC))
 OBJS=$(COBJS)
 
+CFLAGS += -DMALLOC_DEBUGGING -DHEAP_DEBUGGING
+
 all: $(OBJS) $(LIBC)
 
 $(LIBC): ar-target


Once you do that, there will be two new global variables, `__heap_debug' and
`__malloc_debug', which if set to non-0 values, will cause all calls to
malloc/free/etc. to record of their activity on stderr.  So you could add
something like this to boa's main function:

  __malloc_debug = 1;
  __heap_debug = 1;

[actually, for this case, __malloc_debug may be good enough]

Thanks,

-Miles

-- 
P.S.  All information contained in the above letter is false,
      for reasons of military security.