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

[Adam Conrad]

The ARM-specific futex issue and this one don't relate, no, the fact
that you can trigger both from the same testsuite does muddy the waters
a bit, though.

Testing this one on x86 is likely the best way to isolate it from the
lowlevellock fix, since that fix only applied to arm, parisc, and sparc,
but didn't touch x86 (while the fix for this bug hit all arches).

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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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