linux-kernel - Re: [PATCH AUTOSEL 6.9 01/40] workqueue: Refactor worker ID formatting and make wq_worker

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Message-ID: <pp021o2p-2025-7nor-7257-sons6q59rorp@vanv.qr>
Date: Tue, 9 Jul 2024 19:33:13 +0200 (CEST)
From: Jan Engelhardt <jengelh@...i.de>
To: Sasha Levin <sashal@...nel.org>
cc: linux-kernel@...r.kernel.org, stable@...r.kernel.org, 
    Tejun Heo <tj@...nel.org>, Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH AUTOSEL 6.9 01/40] workqueue: Refactor worker ID formatting
 and make wq_worker_comm() use full ID string


On Tuesday 2024-07-09 18:18, Sasha Levin wrote:

>From: Tejun Heo <tj@...nel.org>
>
>[ Upstream commit 2a1b02bcba78f8498ab00d6142e1238d85b01591 ]
>
>TASK_COMM_LEN is only 16 leading to badly truncated names for
>rescuers. For example, the rescuer for the inet_frag_wq workqueue becomes:
>
>  $ ps -ef | grep '[k]worker/R-inet'
>  root         483       2  0 Apr26 ?        00:00:00 [kworker/R-inet_]

* very old Linux: process names are fixed to 16 bytes
* Linux 6.something: we relaxed it for kthreads in principle, but
  oopsie-daisie forgot one case so it's still 16 bytes for that one case
* 2a1b02: now that one case also has length limit lifted

which for me makes this count as a feature rather than a bugfix,
and I would not add it to -stable.
There might even be a poor soul who tests for exact process names in one
obscure shell script of his… would not want to break his setup when going
6.9.8->6.9.9, only with 6.9.8->6.10.