valgrind 3.8.1 warning in jemalloc 3.2

Jason Evans jasone at
Wed Dec 12 10:07:53 PST 2012

On Dec 12, 2012, at 10:01 AM, Daniel Mezzatto Rodrigues <danielm at> wrote:
> Configuring jemalloc with --enable-munmap made valgrind error messages vanish! No more error messages as far as I could test.
> Are there any disadvantages of using --enable-munmap? I see that it enables virtual memory deallocation via munmap. It seens that it was enabled by default in previous version of jemalloc. Is that correct?

The disadvantage of using --enable-munmap on Linux is that the kernel's heuristics for finding available virtual memory are quite naive, and they routinely result in virtual memory map fragmentation.  That wouldn't be a big deal, except that the kernel also uses linear VM map searches for some common operations, so performance can suffer badly for large-memory applications.

> Will you change this VALGRIND_MAKE_MEM_UNDEFINED() call in chunk_recycle() so that configuring jemalloc with --enable-munmap won't be in future versions?

Yes, I will fix chunk_recycle() and include the fix in the next jemalloc release.  Thank you for your bug report and help in diagnosing the cause.


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