RFR: 8195979: [Graal] crash in src/hotspot/share/runtime/mutex.cpp:1341 when Graal JIT is used

[coleen.phillimore at oracle.com]

Yeah it's ugly.  But it's good for unblocking testing.
thanks,
Coleen

On 1/24/18 2:52 PM, Kim Barrett wrote:
> Please review this workaround for a lock rank ordering issue. When
> using Graal, JNI references are released while holding the
> Patching_lock (a rank=special lock).
>
> Before the reimplementation of JNI global and weak global handles
> using OopStorage (JDK-8194312), releasing such references was
> accomplished without any locking. However, OopStorage::release
> sometimes locks its allocation mutex. This change led to the reported
> lock rank order problem for Graal.
>
> As a temporary workaround we're reducing the ranks of the JNI
> oopstorage mutexes, making them more special than "special", so they
> can be locked while holding the Patching_lock. A better solution
> (JDK-8196083) is being developed, but may take a little time. In the
> interest of unblocking Graal testing, the simple rank reduction is
> being proposed, even though it's ugly.
>
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8195979
>
> Webrev:
> http://cr.openjdk.java.net/~kbarrett/8195979/open.00/
>
> Testing:
> Mach5 hs-tier{1-5}, jdk-tier{1-3}
> Local testing of Ekaterina's reproducer in CR.
>