Description

SpecLad

opened on Nov 19, 2025

Issue body actions

Feature or enhancement

Proposal:

In Linux 5.17 a new feature was added, PR_SET_VMA_ANON_NAME, which lets you give names to anonymous virtual memory ranges. These names are shown in /proc/<pid>/maps, which can help with debugging.

The pymalloc allocator uses mmap to allocate arenas. It should use PR_SET_VMA_ANON_NAME to give names to the memory ranges containing arenas, e.g. "Python: arena".

Some examples of this done for other languages are in Glibc and Go.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• gh-141770: Annotate anonymous mmap usage if "-X dev" is used #142079

Activity

1. SpecLad

   added

   type-featureA feature request or enhancementA feature request or enhancement

   on Nov 19, 2025
2. StanFromIreland

   added

   interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)

   on Nov 19, 2025
3. picnixz commented on Nov 22, 2025

   

   picnixz

   on Nov 22, 2025 · Hidden as resolved

   show commentMore actions
4. picnixz

   changed the title [-]Name arena memory regions[/-] [+]Name arenas allocated by `mmap` in `_PyMem_ArenaAlloc` for debugging[/+] on Nov 22, 2025
5. picnixz

   self-assigned this

   on Nov 22, 2025
6. picnixz commented on Nov 22, 2025

   

   picnixz

   on Nov 22, 2025

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   Urhg... It's funny but... I cannot test this because I don't have a recent enough Linux kernel :D
7. picnixz

   removed their assignment

   on Nov 22, 2025
8. corona10

   self-assigned this

   on Nov 28, 2025
9. corona10

   added a commit that references this issue on Nov 28, 2025

   pythongh-141770: Annotate anonymous mmap only for debug build

   0e3933d
10. corona10 commented on Nov 29, 2025

    

    corona10

    on Nov 29, 2025

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    Working and verifying in my local environment.
    This feature should be enabled by kernel config itself too.
    https://bugzilla.redhat.com/show_bug.cgi?id=2302746
11. encukou commented on Dec 1, 2025

    

    encukou

    on Dec 1, 2025

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    Should this be exposed to users, with something like mmap.mmap(..., name=...)?

    Reacted by Sam James and Donghee Na
12. corona10

    added 2 commits that reference this issue on Dec 4, 2025

    Merge remote-tracking branch 'upstream/main' into pythongh-141770

    8f77e0d

    gh-141770: Annotate anonymous mmap usage if "-X dev" is used (gh-142079)

    c4ccaf4
13. corona10

    closed this as completedon Dec 8, 2025
14. corona10 commented on Dec 8, 2025

    

    corona10

    on Dec 8, 2025

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    Should this be exposed to users, with something like mmap.mmap(..., name=...)?

    Nice idea, I will pile a new issue.
15. vstinner commented on Dec 8, 2025

    

    vstinner

    on Dec 8, 2025

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    Should this be exposed to users, with something like mmap.mmap(..., name=...)?

    Since it's only supported on Linux, I'm not sure that it's a good idea.
16. hugovk

    added a commit that references this issue on Dec 10, 2025

    Revert "pythongh-141770: Annotate anonymous mmap usage if "-X dev" is…

    702ab91

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