RFR(xs): 8202772: NMT erroneously assumes thread stack boundaries to be page aligned

Thomas Stüfe thomas.stuefe at gmail.com
Wed Jun 13 04:38:00 UTC 2018

Hi guys,

I pushed. Just to avoid confusion: I changed the text of the bug id to
"8202772: NMT thread stack tracking causes crashes on AIX" since my
fix did nothing to address the underlying issue at all.

Best Regards, Thomas

On Tue, Jun 12, 2018 at 6:59 AM, Thomas Stüfe <thomas.stuefe at gmail.com> wrote:
> Dear all,
> may I please have reviews for this fix, which - for now - disables
> thread stack tracking for NMT on AIX.
> Bug: https://bugs.openjdk.java.net/browse/JDK-8202772
> Webrev: http://cr.openjdk.java.net/~stuefe/webrevs/8202772-NMT-erroneously-assumes-thread-stack-boundaries-to-be-page-aligned/webrev.00/webrev/
> On AIX, we have two problems:
> - NMT assumes stack boundaries to be page aligned. This is wrong but
> on all platforms other than AIX does not matter.
> - the way mincore() is used to read residency of pages needs to be
> adapted since on AIX, os::vm_page_size() is not necessarily the page
> size used by mincore() - which is quite dangerous.
> Since JDK-8204552 was added to deal with the first point, it makes
> sense to wait until that issue is finished. Until then, I'd like to
> disable thread stack recognition in NMT for AIX. We can revisit this
> topic again once we can spare time for it and JDK-8204552 has been
> done.

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