From: Byungchul Park <byungchul@sk.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org, kernel_team@skhynix.com,
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Subject: Re: [PATCH v11 14/26] locking/lockdep, cpu/hotplus: Use a weaker annotation in AP thread
Date: Mon, 29 Jan 2024 13:20:52 +0900 [thread overview]
Message-ID: <20240129042052.GA64402@system.software.com> (raw)
In-Reply-To: <87il3ggfz9.ffs@tglx>
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?
I will fix the typo ;( Thank you.
I referred to the commit cb92173d1f047. I will remove the prefix if the
way is more desirable.
> > 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.
rwsem_acquire() implies:
1. might be a waiter on contention of the lock.
2. enter to the critical section of the lock.
All we need in here is to act 2, not 1. That's why I suggested trylock
version of annotation for that purpose.
Now that dept partially replies on lockdep annotaions for the waiters
and events, dept is interpeting rwsem_acquire() as a potential waiter
and reports a deadlock by the wait.
Of course, the first priority should be not to change the current
behavior. I think the change from non-trylock to trylock for the
annotation won't. Or am I missing something?
Byungchul
> > 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.
>
> Thanks,
>
> tglx
next prev parent reply other threads:[~2024-01-29 4:21 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-24 11:59 [PATCH v11 00/26] DEPT(Dependency Tracker) Byungchul Park
2024-01-24 11:59 ` [PATCH v11 01/26] llist: Move llist_{head,node} definition to types.h Byungchul Park
2024-01-24 11:59 ` [PATCH v11 02/26] dept: Implement Dept(Dependency Tracker) Byungchul Park
2024-01-24 11:59 ` [PATCH v11 03/26] dept: Add single event dependency tracker APIs Byungchul Park
2024-01-24 11:59 ` [PATCH v11 04/26] dept: Add lock " Byungchul Park
2024-01-24 11:59 ` [PATCH v11 05/26] dept: Tie to Lockdep and IRQ tracing Byungchul Park
2024-01-28 13:10 ` kernel test robot
2024-01-28 15:58 ` kernel test robot
2024-01-24 11:59 ` [PATCH v11 06/26] dept: Add proc knobs to show stats and dependency graph Byungchul Park
2024-01-24 11:59 ` [PATCH v11 07/26] dept: Apply sdt_might_sleep_{start,end}() to wait_for_completion()/complete() Byungchul Park
2024-01-24 11:59 ` [PATCH v11 08/26] dept: Apply sdt_might_sleep_{start,end}() to swait Byungchul Park
2024-01-24 11:59 ` [PATCH v11 09/26] dept: Apply sdt_might_sleep_{start,end}() to waitqueue wait Byungchul Park
2024-01-24 11:59 ` [PATCH v11 10/26] dept: Apply sdt_might_sleep_{start,end}() to hashed-waitqueue wait Byungchul Park
2024-01-24 11:59 ` [PATCH v11 11/26] dept: Distinguish each syscall context from another Byungchul Park
2024-01-24 11:59 ` [PATCH v11 12/26] dept: Distinguish each work " Byungchul Park
2024-01-24 11:59 ` [PATCH v11 13/26] dept: Add a mechanism to refill the internal memory pools on running out Byungchul Park
2024-01-24 11:59 ` [PATCH v11 14/26] locking/lockdep, cpu/hotplus: Use a weaker annotation in AP thread Byungchul Park
2024-01-26 17:30 ` Thomas Gleixner
2024-01-29 4:20 ` Byungchul Park [this message]
2024-01-30 2:58 ` Byungchul Park
2024-02-12 15:16 ` Thomas Gleixner
2024-02-13 1:18 ` Byungchul Park
2024-01-24 11:59 ` [PATCH v11 15/26] dept: Apply sdt_might_sleep_{start,end}() to dma fence wait Byungchul Park
2024-01-24 11:59 ` [PATCH v11 16/26] dept: Track timeout waits separately with a new Kconfig Byungchul Park
2024-01-24 11:59 ` [PATCH v11 17/26] dept: Apply timeout consideration to wait_for_completion()/complete() Byungchul Park
2024-01-24 11:59 ` [PATCH v11 18/26] dept: Apply timeout consideration to swait Byungchul Park
2024-01-24 11:59 ` [PATCH v11 19/26] dept: Apply timeout consideration to waitqueue wait Byungchul Park
2024-01-24 11:59 ` [PATCH v11 20/26] dept: Apply timeout consideration to hashed-waitqueue wait Byungchul Park
2024-01-24 11:59 ` [PATCH v11 21/26] dept: Apply timeout consideration to dma fence wait Byungchul Park
2024-01-24 11:59 ` [PATCH v11 22/26] dept: Record the latest one out of consecutive waits of the same class Byungchul Park
2024-01-24 11:59 ` [PATCH v11 23/26] dept: Make Dept able to work with an external wgen Byungchul Park
2024-01-24 11:59 ` [PATCH v11 24/26] dept: Track PG_locked with dept Byungchul Park
2024-01-24 11:59 ` [PATCH v11 25/26] dept: Print event context requestor's stacktrace on report Byungchul Park
2024-01-28 14:44 ` kernel test robot
2024-01-24 11:59 ` [PATCH v11 26/26] locking/lockdep, fs/jbd2: Use a weaker annotation in journal handling Byungchul Park
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