Problem

JNI calls fail on certain objects when a native function invoked by Java in a newly created Java thread. My application attempts to mimic Paragon extfs/NTFS. For now I'm using libaums and some custom native code.

Tested Devices:

x86_64 Android-X86 VM (Android 13: Linux supremegamers 6.1.112-gloria-xanmod1).
armv8l 32-bit physical device (Android 12: Linux kernel 4.9.227-24348486).

Crash Output

java_vm_ext.cc:594] JNI DETECTED ERROR IN APPLICATION: JNI ERROR (app bug): jobject is an invalid JNI transition frame reference or invalid reference: 0x7f0bb7cef65c (use of invalid jobject)
java_vm_ext.cc:594]     in call to CallVoidMethodV

Description

-- A DocumentProvider creates an IO thread when openDocument() is called.
-- I use ParcelFileDescriptor pipes because the files don't exist on disk, and it seems like the only way.
-- The IO thread calls a native read function, then from JNI-env a Java read method is invoked.
-- This should work, but for some reason some JNI objects are invalid in that IO thread (started from Java).
-- I have checked my code, and I don't think it's the issue here. Some notes:

I tried converting some local references (passed from Java) to global references that are stored in the native environment. The JVM crashes in either case.
The objects fail ANY invocation into JNI, which other objects don't (I was able to delete a local reference to the thiz instance passed to the JNI-env).

Steps to Reproduce

Coming soon... I'm creating a separate app that reproduces the issue.

What should happen

The JVM shouldn't crash.

Additional Notes

Could the references to the Java objects become invalidated once the DocumentProvider thread returns, leaving the IO thread running? I don't know the innards of ART enough (types of object references, etc..) to figure it out.

Suggestion

It'd be nice to be able to serve local/remote filesystems over kernel NFSD + DocumentProvider.

Issue 395223721

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