Bug #21670: 3.4.5 crashing with "try to mark T_NONE object"

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 3.4.5 (2025-07-16 revision 20cda200d3) +PRISM [x86_64-linux]
• Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN

[esaron (Es Aron)]

We're experiencing a large number of crashes while running tests in CI on Ubuntu 22.04 runners. It is inconsistent, and we cannot reproduce reliably, although when the crash happens it appears to always happen in the same place, even if during different tests.

This occurs both with and without YJIT enabled.

[byroot (Jean Boussier)]

It's in mark_method_entry_i, which rings a bell. @jhawthorn (John Hawthorn) didn't you fix that one?

@esaron please try the latest patch release: 3.4.7, your issue looks a lot like a missing write barrier issue and John fixed many of them in 3.4.7: https://github.com/ruby/ruby/compare/v3_4_5...v3_4_7

[nrodriguez (Nicolas Rodriguez)]

@byroot (Jean Boussier) https://bugs.ruby-lang.org/issues/21021

[esaron (Es Aron)]

nrodriguez (Nicolas Rodriguez) wrote in #note-2:

@byroot (Jean Boussier) https://bugs.ruby-lang.org/issues/21021

I don't know if #21021 is the same underlying issue. This instance occurs both with and without YJIT enabled on 3.4.5, and it looks like the fix for #21021 has been present since 3.4.2. I am optimistic that this may be one of the many write barrier issues fixed in 3.4.7 and we will be attempting to upgrade our Ruby version soon.

[jhawthorn (John Hawthorn)]

• Status changed from Open to Closed

I don't believe 21021 is related, "try to mark T_NONE object" is a general symptom of missing a write barrier.

This does show a crash when marking the M_TBL so I would expect this to be fixed by https://github.com/ruby/ruby/commit/5026609f47b79da093642d9a7731c3880d2a054e. Please feel free to reopen if something occurs on 3.4.7 :)