imemo_fields: store owner object in RBasic.klass #14147
Closed
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Given `ObjectSpace._id2ref` is a deprecated API, it is assumed it won't ever be called, hence we optimistically don't keep an `id -> ref` mapping. So when `object_id_to_ref` is called for the first time, we go over the entire heap to build that missing table. At that point we must be very careful about garbage objects. If they have an object id, the GC will attempt to remove them from the `id2ref` table when sweeping them. Until now, the strategy was to insert them anyway, but this actually cause issue with objects that rely on `IMEMO/fields` because the object fields may be already sweeped (hence ASAN poisoned). Unfortunately I'm not able to craft a reproduction script to validate this theory, as the GC need to be in a precise state for the bug to happen.
It is much more convenient than storing the klass, especially when dealing with `object_id` as it allows to update the id2ref table without having to dereference the owner, which may be garbage at that point.
|
Superseeded by #14202 |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Followup on #14146
It is much more convenient than storing the klass, especially when dealing with
object_idas it allows to update the id2ref table without having to dereference the owner, which may be garbage at that point.