RFR: 8318586: Explicitly handle upcall stub allocation failure

[Jorn Vernee]

On Wed, 25 Oct 2023 09:13:56 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Explicitly handle UpcallStub allocation failures by terminating. We currently might try to use the returned `nullptr` which would fail sooner or later. This patch just makes the termination explicit.
>
> src/hotspot/share/code/codeBlob.cpp line 761:
> 
>> 759:     MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
>> 760:     blob = new (size) UpcallStub(name, cb, size, receiver, frame_data_offset);
>> 761:     if (blob == nullptr) {
> 
> I think it would be safer to call into `fatal` without having `CodeCache_lock` held. Move it out of `MutexLocker` scope?

This pattern follows what is done in `RuntimeStub::new_runtime_stub`, which also calls `fatal` under the lock.

I agree it's probably better to call outside of the lock (and that is something I noticed in the original change for RuntimeStub as well). I'm happy to fix it for both.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16311#discussion_r1371450770