Re: perf: use after free in perf_remove_from_context

From: Dave Jones
Date: Wed May 14 2014 - 13:21:33 EST


On Wed, May 14, 2014 at 01:09:31PM -0400, Sasha Levin wrote:

> > *** Error in `./trinity': double free or corruption (top): 0x000000000135af60 ***
> > [main] Random reseed: 3671679404
> > [main] Random reseed: 67838733
> > *** Error in `./trinity': double free or corruption (top): 0x000000000135ef60 ***
> > [main] Random reseed: 943044433
> > *** Error in `./trinity': double free or corruption (top): 0x00000000012bb210 ***
> > [main] Random reseed: 3627649145
> > *** Error in `./trinity': double free or corruption (top): 0x000000000139dbe0 ***
> > [main] Random reseed: 935036390
> > [main] Random reseed: 3922349807
> > [main] Random reseed: 835563887
> > *** Error in `./trinity': double free or corruption (top): 0x0000000001323890 ***
> > [main] Random reseed: 974945617
> > *** Error in `./trinity': double free or corruption (top): 0x0000000001308190 ***
> > [main] Random reseed: 2912296953
> > [main] Random reseed: 681900861
> >
> > Is this 'expected' behaviour?
>
> I've talked about it with Dave a while ago, he said it happens because the threads that
> do all the testing sometimes corrupt themselves which result in that error. It shouldn't
> be harmful as the thread will just get killed and a fresh one will be started in it's
> place.
>
> Since then I set MALLOC_CHECK_=0 to avoid seeing that in my logs.

Pretty strong odds it's mremap causing those double frees. You can
-xmremap that to see if it goes away.

Dave

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