linux-ext4 - Re: [PATCH v11 14/26] locking/lockdep, cpu/hotplus: Use a weaker annotation in AP thread

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Date: Tue, 13 Feb 2024 10:18:04 +0900
From: Byungchul Park <byungchul@...com>
To: Thomas Gleixner <tglx@...utronix.de>
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Subject: Re: [PATCH v11 14/26] locking/lockdep, cpu/hotplus: Use a weaker
 annotation in AP thread

On Mon, Feb 12, 2024 at 04:16:41PM +0100, Thomas Gleixner wrote:
> On Tue, Jan 30 2024 at 11:58, Byungchul Park wrote:
> > On Fri, Jan 26, 2024 at 06:30:02PM +0100, Thomas Gleixner wrote:
> >> On Wed, Jan 24 2024 at 20:59, Byungchul Park wrote:
> >> 
> >> Why is lockdep in the subsystem prefix here? You are changing the CPU
> >> hotplug (not hotplus) code, right?
> >> 
> >> > cb92173d1f0 ("locking/lockdep, cpu/hotplug: Annotate AP thread") was
> >> > introduced to make lockdep_assert_cpus_held() work in AP thread.
> >> >
> >> > However, the annotation is too strong for that purpose. We don't have to
> >> > use more than try lock annotation for that.
> >> 
> >> This lacks a proper explanation why this is too strong.
> >> 
> >> > Furthermore, now that Dept was introduced, false positive alarms was
> >> > reported by that. Replaced it with try lock annotation.
> >> 
> >> I still have zero idea what this is about.
> >
> > 1. can track PG_locked that is a potential deadlock trigger.
> >
> >    https://lore.kernel.org/lkml/1674268856-31807-1-git-send-email-byungchul.park@lge.com/
> 
> Sure, but that wants to be explicitely explained in the changelog and
> not with a link. 'Now that Dept was introduced ...' is not an
> explanation.

Admit. I will fix it from the next spin. Thanks.

	Byungchul