[Bug 1081734] Re: malloc hangs when ltp mallocstress is run repeatedly

[Alex Chiang]

Adam,

I tried reproducing on my 12.04 machine, simply doing:

apt-get install ltp
$ /usr/lib/ltp/testcases/bin/mallocstress -l 10000
<top output indicates a peak of ~81GB peak VM use>
<wait a while>
<debug output>
main(): test passed.

Using following old libc:
ii  libc6                                  2.15-0ubuntu10.3                        Embedded GNU C Library: Shared libraries

Advice?

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https://bugs.launchpad.net/bugs/1081734

Title:
  malloc hangs when ltp mallocstress is run repeatedly

Status in “eglibc” package in Ubuntu:
  Fix Released
Status in “eglibc” source package in Precise:
  Fix Committed
Status in “eglibc” source package in Quantal:
  Fix Committed

Bug description:
  [Impact / Justification]
  There's a malloc deadlock in glibc, easily reproduced by the mallocstress part of ltp, but otherwise tripped in regular usage here and there.  The upstream patch applied in this SRU resolves that.

  [Test Case]
  Run mallocstress repeatedly before and after upgrade and watch the deadlocks be less deadlocky.

  [Regression Potential]
  This has been tested quite extensively upstream and in 2.16 in raring, and seems to be a marked improvement with no one reporting any adverse effects, so should be fine.

  [Original Report]
  - malloc sleeps continously when the mallocstress application which part of ltp package is executed in a loop.
  - From gdb backtrace it appears to be for a futex to be released in libc code. This is deadlock in glibc

  There are some discussions going on for including this fix in next eglibc release.
  emails
  http://sourceware.org/ml/libc-alpha/2012-06/msg00648.html
  http://permalink.gmane.org/gmane.comp.lib.glibc.alpha/23397
  http://sourceware.org/ml/libc-alpha/2012-07/msg00027.html
  http://sourceware.org/ml/libc-alpha/2012-08/msg00163.html
  http://permalink.gmane.org/gmane.linux.redhat.fedora.extras.cvs/832985

  discussion in http://sourceware-org.1504.n7.nabble.com/BZ-13939
  -malloc-deadlock-td13648.html#none

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