[modules] Fix NewJSModuleNamespace to avoid GC being able to see incomplete JSModuleNamespace.

[modules] Fix NewJSModuleNamespace to avoid GC being able to see incomplete JSModuleNamespace.

A GC could happen when creating the Module string, which would cause the
JSModuleNamespace to be seen in an incomplete state. Instead make this
string a root object so that we don't need to allocate it during
NewJSModuleNamespace construction.

BUG=v8:1569
Review-Url: https://codereview.chromium.org/2631223002
Cr-Commit-Position: refs/heads/master@{#42393}
Committed: https://chromium.googlesource.com/v8/v8/+/01b684cf6869f52ff37b2a5d584314e07f7028a2

[rmcilroy, 2017-01-16 16:54:28]

The CQ bit was checked by rmcilroy@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-01-16 16:54:37]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[rmcilroy, 2017-01-16 16:56:24]

rmcilroy@chromium.org changed reviewers:
+ neis@chromium.org

[rmcilroy, 2017-01-16 16:56:24]

Georg, I was seeing crashes on GC Stress with an unrelated CL
(https://codereview.chromium.org/2630343002/) which showed the GC observing
JSModuleNamespace in an incomplete state (e.g., without the module object[1]).
This fix should avoid that situation. PTAL, thanks.


[1]
https://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20gc%20stress/...

[commit-bot: I haz the power, 2017-01-16 17:25:30]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-01-16 17:25:31]

Dry run: This issue passed the CQ dry run.

[neis, 2017-01-17 09:53:41]

On 2017/01/16 16:56:24, rmcilroy wrote:
> Georg, I was seeing crashes on GC Stress with an unrelated CL
> (https://codereview.chromium.org/2630343002/) which showed the GC observing
> JSModuleNamespace in an incomplete state (e.g., without the module object[1]).
> This fix should avoid that situation. PTAL, thanks.
> 
> 
> [1]
>
https://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20gc%20stress/...

Thanks, lgtm! This was caused by a recent restructuring related to constant
field tracking (https://codereview.chromium.org/2625093005).

[neis, 2017-01-17 09:56:50]

Description was changed from

==========
[Modules] Fix NewJSModuleNamespace to avoid GC being able to see incomplete
JSModuleNamespace.

A GC could happen when creating the Module string, which would cause the
JSModuleNamespace to be seen in an incomplete state. Instead make this
string a root object so that we don't need to allocate it during
NewJSModuleNamespace construction.
==========

to

==========
[modules] Fix NewJSModuleNamespace to avoid GC being able to see incomplete
JSModuleNamespace.

A GC could happen when creating the Module string, which would cause the
JSModuleNamespace to be seen in an incomplete state. Instead make this
string a root object so that we don't need to allocate it during
NewJSModuleNamespace construction.

BUG=v8:1569
==========

[rmcilroy, 2017-01-17 10:12:00]

The CQ bit was checked by rmcilroy@chromium.org

[commit-bot: I haz the power, 2017-01-17 10:12:08]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-01-17 10:14:02]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1484647920579410, "parent_rev":
"dd9cf43ef2fec61a04ba5c9c1030fb307077fc75", "commit_rev":
"01b684cf6869f52ff37b2a5d584314e07f7028a2"}

[commit-bot: I haz the power, 2017-01-17 10:14:07]

Description was changed from

==========
[modules] Fix NewJSModuleNamespace to avoid GC being able to see incomplete
JSModuleNamespace.

A GC could happen when creating the Module string, which would cause the
JSModuleNamespace to be seen in an incomplete state. Instead make this
string a root object so that we don't need to allocate it during
NewJSModuleNamespace construction.

BUG=v8:1569
==========

to

==========
[modules] Fix NewJSModuleNamespace to avoid GC being able to see incomplete
JSModuleNamespace.

A GC could happen when creating the Module string, which would cause the
JSModuleNamespace to be seen in an incomplete state. Instead make this
string a root object so that we don't need to allocate it during
NewJSModuleNamespace construction.

BUG=v8:1569

Review-Url: https://codereview.chromium.org/2631223002
Cr-Commit-Position: refs/heads/master@{#42393}
Committed:
https://chromium.googlesource.com/v8/v8/+/01b684cf6869f52ff37b2a5d584314e07f7...
==========

[commit-bot: I haz the power, 2017-01-17 10:14:08]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/v8/v8/+/01b684cf6869f52ff37b2a5d584314e07f7...