linux-kernel - Re: [PATCH v2 0/4] Workqueue: rename system workqueue and add WQ

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Message-ID: <aEilufYKeex0diW-@slm.duckdns.org>
Date: Tue, 10 Jun 2025 11:38:01 -1000
From: Tejun Heo <tj@...nel.org>
To: Marco Crivellari <marco.crivellari@...e.com>
Cc: linux-kernel@...r.kernel.org, Lai Jiangshan <jiangshanlai@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Frederic Weisbecker <frederic@...nel.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Michal Hocko <mhocko@...e.com>
Subject: Re: [PATCH v2 0/4] Workqueue: rename system workqueue and add
 WQ_PERCPU

Hello, Marco.

On Tue, Jun 10, 2025 at 10:34:15AM +0200, Marco Crivellari wrote:
> >- Separate out patches to add the new flag and wq. Don't add the warnings
> >  yet. I'll commit these patches to a separate wq branch.
> 
> Basically these means have 2 more patches, one for WQ_PERCPU (only the
> new flag, like in the v1 let's say) and another patch that adds the wq(s).
> 
> So, all the logic changes (also in __alloc_workqueue), pr_warn_once() will
> stay in the other patch (that you will apply later); this is not only 1 patch,
> following your next point.
> 
> If I understood correctly, it makes sense to me.

Yeah.

> >- Split out patches by subsystems. I know this is tedious but think it'd
> > still be worth doing. It doesn't have to be completely granular. e.g. We
> > know that network changes go through a single tree, so all network changes
> >  can be in a single patch. Each patch can explain the workqueue changes and
> >  that the patch can be either routed through the subysstem which would
> >  require pulling from the above wq branch, or, as the default option, we'd
> >  be happy to route the patch through the workqueue tree. I can create a
> >  separate branch to collect the conversion patches that can go through wq
> >  tree.
> 
> This impacts patch 3, so instead of 1 big patch, you are thinking of N patches,
> in order to add WQ_PERCPU to the callers of subsystems first.
> 
> So, something like:
> - net/
> - mm/
> - fs/
> 
> Do you have something different in mind?

No, that sounds fine.

> >- After the next rc1 drops, I can apply the patches to add warnings to the
> >  -fixes branch and then send them to Linus.
> 
> Sounds good.

I think we're in agreement.

Thanks.

-- 
tejun