RFR: NMT: Don't record uncommits unconditionally

[Per Liden]

Hi,

On 01/10/2018 05:01 PM, Stefan Karlsson wrote:
> Hi all,
> 
> Please review this patch to fix a bug in the recent NMT implementation 
> for ZGC.
> 
> http://cr.openjdk.java.net/~stefank/zgc/zNMTBugFix/webrev.01

Change looks good, but the memTracker.cpp part should probably be split 
out into an upstream patch. Also, it feels like we should adjust the 
other user of this in os.cpp to use the new function.

cheers,
Per

> 
> The uncommit path was executed even when NMT was turned off. Because of 
> this we hit the following assertion when pages were detached:
> 
> #  Internal Error (.../services/memTracker.hpp:231), pid=12751, tid=2738
> #  assert(tracking_level() >= NMT_summary) failed: Check by caller
> 
> Thanks,
> StefanK