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[Bug 2120904] [NEW] top crashes on high process creation/deletion pressure

To: debcrafters-packages@xxxxxxxxxxxxxxxxxxx
From: Tsukasa OI <2120904@xxxxxxxxxxxxxxxxxx>
Date: Tue, 19 Aug 2025 05:18:36 -0000
Reply-to: Bug 2120904 <2120904@xxxxxxxxxxxxxxxxxx>
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Public bug reported:

I encountered with crashes on top.

Reproduced Version: 2:4.0.4-4ubuntu3.2 (noble; Ubuntu 24.04 LTS)
Affected Versions: All currently supported versions (I guess)

It requires:
*   A libproc2-0 depending program like `top` (as I encountered) and `ps` (as reported upstream).
*   Printing certain columns like RUSER is enabled.

Still, (as I explain later) this is a race condition issue and for
reproduction, some randomness is involved (the upstream GitLab issue
page provides patching method for reliable crash reproduction).

1.  The system should be under high process creation/deletion pressure (where many processed are created and destroyed in a short period of time).
2.  On top, reproducibility raises if higher number of processes are printed (i.e. the terminal is large and/or zoomed out) and the delay value (default: 3 seconds) is lower.

On upstream, it is found to be a race condition issue on libproc2-0
(cause is discovered by me) and fixed by Jim Warner (the main commit is
https://gitlab.com/procps-
ng/procps/-/commit/a5708118a4f3184cb5a3e2faa219807e73f007d3).

As suggested by Mike Gulick, there may be a possibility synchronizing
with Debian (for backporting the fix).

cf. https://gitlab.com/procps-ng/procps/-/issues/380

** Affects: procps (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/2120904

Title:
  top crashes on high process creation/deletion pressure

Status in procps package in Ubuntu:
  New

Bug description:
  I encountered with crashes on top.

  Reproduced Version: 2:4.0.4-4ubuntu3.2 (noble; Ubuntu 24.04 LTS)
  Affected Versions: All currently supported versions (I guess)

  It requires:
  *   A libproc2-0 depending program like `top` (as I encountered) and `ps` (as reported upstream).
  *   Printing certain columns like RUSER is enabled.

  Still, (as I explain later) this is a race condition issue and for
  reproduction, some randomness is involved (the upstream GitLab issue
  page provides patching method for reliable crash reproduction).

  1.  The system should be under high process creation/deletion pressure (where many processed are created and destroyed in a short period of time).
  2.  On top, reproducibility raises if higher number of processes are printed (i.e. the terminal is large and/or zoomed out) and the delay value (default: 3 seconds) is lower.

  On upstream, it is found to be a race condition issue on libproc2-0
  (cause is discovered by me) and fixed by Jim Warner (the main commit
  is https://gitlab.com/procps-
  ng/procps/-/commit/a5708118a4f3184cb5a3e2faa219807e73f007d3).

  As suggested by Mike Gulick, there may be a possibility synchronizing
  with Debian (for backporting the fix).

  cf. https://gitlab.com/procps-ng/procps/-/issues/380

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