incorrect malloc_stats output

[Prem Gopalan]

>Submitter-Id:  net
>Originator:    root
>Organization:
 <organization of PR author (multiple lines)>
>Confidential:  no
>Synopsis:      <synopsis of the problem (one line)>
>Severity:      <[ non-critical | serious | critical ] (one line)>
>Priority:      <[ low | medium | high ] (one line)>
>Category:      libc
>Class:         <[ sw-bug | doc-bug | change-request | support ] (one 
line)>
>Release:       libc-2.3.2
>Environment:
        <machine, os, target, libraries (multiple lines)>
Host type: i386-redhat-linux-gnu
System: Linux tm11-2.mazunetworks.com 2.4.18 #2 SMP Mon Aug 18 05:40:35 
EDT 2003 i686 i686 i386 GNU/Linux
Architecture: i686

Addons: linuxthreads
Build CFLAGS: -march=i386 -DNDEBUG=1 -finline-limit=2000 -g -O3
Build CC: gcc
Compiler version: 3.2.2 20030222 (Red Hat Linux 3.2.2-5)
Kernel headers: 2.4.18
Symbol versioning: yes
Build static: yes
Build shared: yes
Build pic-default: no
Build profile: yes
Build omitfp: no
Build bounded: no
Build static-nss: no

>Description:
     malloc_stats shows incorrect memory usage for Arena 0 after sbrk()  
memory is utilized. malloc_stats is output every 1 seconds from a thread.
Once Arena 0 reaches its limit of 1GB (TASK_UNMAPPED_BASE) malloc_stats
output shows a large incorrect value (1.54Gb) for system bytes and in use
bytes (which affects Total). The actual total memory usage here is about
1.5 - 1.6Gb (as reported by top) instead of 2.1gb.

Arena 0:
system bytes     =  848936380
in use bytes     =  848935740
Arena 1:
system bytes     =  446341120
in use bytes     =  446337056
Total (incl. mmap):
system bytes     = 1417297340
in use bytes     = 1417292636
max mmap regions =         15
max mmap bytes   =  122019840

Arena 0:
system bytes     = 1534700988
in use bytes     = 1534490044
Arena 1:
system bytes     =  446341120
in use bytes     =  446339552
Total (incl. mmap):
system bytes     = 2103061948
in use bytes     = 2102849436
max mmap regions =         15
max mmap bytes   =  122019840


Secondly, the memory does seem to be allocated from main arena (sbrk'ed?)
although TASK_UNMAPPED_BASE is supposed to limit it to 1GB. What is
happening here ?? I ran a simple single threaded program that continually
allocates memory and found main arena could exceed 1GB. Is that expected ?

However, the above is independent of the bug. malloc_stats actually ends
up  going to 4.5GB or so on my 4GB box. The Total below of 3.67Gb is 
ridiculous as user space ends at 3GB. 

Arena 0:
system bytes     = 2995479196
in use bytes     = 2994988452
Arena 1:
system bytes     =   50745344
in use bytes     =   50739752
Arena 2:
system bytes     =  208867328
in use bytes     =  208865872
Arena 3:
system bytes     =  171769856
in use bytes     =  171767664
Total (incl. mmap):
system bytes     = 3670499996
in use bytes     = 3670000012
max mmap regions =         29
max mmap bytes   =  243638272


>How-To-Repeat:

A simple pthreads based program that allocates and deallocates large
amounts of memory shd suffice to reproduce it.

>Fix:
        <how to correct or work around the problem, if known (multiple 
lines)>