From: naruse@...
Date: 2021-03-11T11:34:45+00:00
Subject: [ruby-core:102827] [Ruby master Bug#17636] Race condition in check_rvalue_consistency_force when using ractors

Issue #17636 has been updated by naruse (Yui NARUSE).

Backport changed from 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: REQUIRED to 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: DONE

ruby_3_0 d3863cb2e80f27d26b521b2c957b21feacb900de merged revision(s) 07ab172ebef28bb82c2650694548d123802d6c22.

----------------------------------------
Bug #17636: Race condition in check_rvalue_consistency_force when using ractors
https://bugs.ruby-lang.org/issues/17636#change-90886

* Author: peterzhu2118 (Peter Zhu)
* Status: Closed
* Priority: Normal
* Assignee: ko1 (Koichi Sasada)
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: DONE
----------------------------------------
[GitHub PR](https://github.com/ruby/ruby/pull/4191)

When `RGENGC_CHECK_MODE` is enabled and we use multiple ractors, there is a race condition in `check_rvalue_consistency_force` that causes an assertion to fail. It happens when a page is created during the call to `is_pointer_to_heap`, which causes the binary search to fail.

# Reproduction

```ruby
NUM_RACTORS = 10

rs = NUM_RACTORS.times.map do |i|
  Ractor.new(i) do |i|
    arr = []
    
    10_000.times do |j|
      arr << "foo.#{i}.#{j}"
    end

    arr
  end
end

arrs = rs.map { |r| r.take }
```
The crash log is attached below in `crash.log`.


---Files--------------------------------
crash.log (20.1 KB)


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