Red Hat Bugzilla – Bug 112907
free() doesn't release the memory via sbrk() if the core is larger than approx 1GB
Last modified: 2016-11-24 10:03:36 EST
From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.5) Gecko/20031030 Description of problem: free() normally decreases the program core via sbr(-negative_value) if it finds its possible. Somehow it fails to do it when the program core exceeds 0.9GB. I wrote a small program testmalloc.c that malloc() and free() a specified number of kilobytes. I run it on machine with 1GB RAM and 512MB swap. Version-Release number of selected component (if applicable): glibc-2.3.2-27.9.7, gcc-3.2.2-5 How reproducible: Always Steps to Reproduce: 1. gcc -Wall -pedantic -o testmalloc testmalloc.c 2. You must have a machine with 1GB of free memory, if you don't have as much RAM, create some swap. 3. ./testmem 900000 4. ./testmem 1000000 Actual Results: The first program (testmem 900000) produces the output: $ ./testmalloc 900000 All chunks have been allocated, current core=921969948 bytes All chunks have been free()d, current core=1308 bytes The second one: $ ./testmalloc 1000000 All chunks have been allocated, current core=940897564 bytes All chunks have been free()d, current core=940897564 bytes Note that in the second case the core was not released. Expected Results: I would expect that program releases its core. Additional info: I don't think it's a bug in Red Hat, it looks like a bug in glibc. I have tested this behaviour on PLD Linux. Both Red Hat and PLD demonstrate the same problem. Many thanks to Sebastian Zagrodzki from PLD team for testing it on his PLD machine.
Created attachment 96772 [details] A program mentioned in the bug report.
Red Hat apologizes that these issues have not been resolved yet. We do want to make sure that no important bugs slip through the cracks. Red Hat Linux 7.3 and Red Hat Linux 9 are no longer supported by Red Hat, Inc. They are maintained by the Fedora Legacy project (http://www.fedoralegacy.org/) for security updates only. If this is a security issue, please reassign to the 'Fedora Legacy' product in bugzilla. Please note that Legacy security update support for these products will stop on December 31st, 2006. If this is not a security issue, please check if this issue is still present in a current Fedora Core release. If so, please change the product and version to match, and check the box indicating that the requested information has been provided. If you are currently still running Red Hat Linux 7.3 or 9, please note that Fedora Legacy security update support for these products will stop on December 31st, 2006. You are strongly advised to upgrade to a current Fedora Core release or Red Hat Enterprise Linux or comparable. Some information on which option may be right for you is available at http://www.redhat.com/rhel/migrate/redhatlinux/. Any bug still open against Red Hat Linux 7.3 or 9 at the end of 2006 will be closed 'CANTFIX'. Again, if this bug still exists in a current release, or is a security issue, please change the product as necessary. We thank you for your help, and apologize again that we haven't handled these issues to this point.
Red Hat Linux 7.3 and Red Hat Linux 9 are no longer supported by Red Hat, Inc. f you are currently still running Red Hat Linux 7.3 or 9, you are strongly advised to upgrade to a current Fedora Core release or Red Hat Enterprise Linux or comparable. Some information on which option may be right for you is available at http://www.redhat.com/rhel/migrate/redhatlinux/. Closing as CANTFIX.