From: Byungchul Park <byungchul.park@lge.com>
To: Boqun Feng <boqun.feng@gmail.com>,
mingo@kernel.org, peterz@infradead.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
walken@google.com, kirill@shutemov.name,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
akpm@linux-foundation.org, willy@infradead.org,
npiggin@gmail.com, kernel-team@lge.com
Subject: Re: [PATCH v8 00/14] lockdep: Implement crossrelease feature
Date: Wed, 16 Aug 2017 18:38:36 +0900 [thread overview]
Message-ID: <20170816093836.GV20323@X58A-UD3R> (raw)
In-Reply-To: <20170816080622.GU20323@X58A-UD3R>
On Wed, Aug 16, 2017 at 05:06:23PM +0900, Byungchul Park wrote:
> On Wed, Aug 16, 2017 at 04:14:21PM +0900, Byungchul Park wrote:
> > On Wed, Aug 16, 2017 at 01:58:08PM +0800, Boqun Feng wrote:
> > > > I'm not sure this caused the lockdep warning but, if they belongs to the
> > > > same class even though they couldn't be the same instance as you said, I
> > > > also think that is another problem and should be fixed.
> > > >
> > >
> > > My point was more like this is a false positive case, which we should
> > > avoid as hard as we can, because this very case doesn't look like a
> > > deadlock to me.
> > >
> > > Maybe the pattern above does exist in current kernel, but we need to
> > > guide/adjust lockdep to find the real case showing it's happening.
> >
> > As long as they are initialized as a same class, there's no way to
> > distinguish between them within lockdep.
> >
> > And I also think we should avoid false positive cases. Do you think
> > there are many places where completions are initialized in a same place
> > even though they could never be the same instance?
> >
> > If no, it would be better to fix it whenever we face it, as you did.
>
> BTW, of course, the same problem would have occured when applying
> lockdep for the first time. How did you solve it?
>
> I mean that lockdep basically identifies classes even for typical locks
> with the call site. So two locks could be the same class even though
> they should not be the same. Of course, for now, we avoid the problemaic
> cases with sub-class. Anyway, the problems certainly would have arised
^
or setting a class or re-design code like what Boqun
suggested. And so on...
> for the first time. I want to follow that solution you did.
>
> Thanks,
> Byungchul
next prev parent reply other threads:[~2017-08-16 9:39 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-07 7:12 [PATCH v8 00/14] lockdep: Implement crossrelease feature Byungchul Park
2017-08-07 7:12 ` [PATCH v8 01/14] lockdep: Refactor lookup_chain_cache() Byungchul Park
2017-08-10 12:18 ` [tip:locking/core] locking/lockdep: " tip-bot for Byungchul Park
2017-08-07 7:12 ` [PATCH v8 02/14] lockdep: Add a function building a chain between two classes Byungchul Park
2017-08-10 12:18 ` [tip:locking/core] locking/lockdep: " tip-bot for Byungchul Park
2017-08-07 7:12 ` [PATCH v8 03/14] lockdep: Change the meaning of check_prev_add()'s return value Byungchul Park
2017-08-10 12:19 ` [tip:locking/core] locking/lockdep: " tip-bot for Byungchul Park
2017-08-07 7:12 ` [PATCH v8 04/14] lockdep: Make check_prev_add() able to handle external stack_trace Byungchul Park
2017-08-10 12:19 ` [tip:locking/core] locking/lockdep: " tip-bot for Byungchul Park
2017-08-07 7:12 ` [PATCH v8 05/14] lockdep: Implement crossrelease feature Byungchul Park
2017-08-09 14:05 ` Peter Zijlstra
2017-08-10 1:30 ` Byungchul Park
2017-08-10 9:21 ` Peter Zijlstra
2017-08-10 12:19 ` [tip:locking/core] locking/lockdep: Implement the 'crossrelease' feature tip-bot for Byungchul Park
2017-08-07 7:12 ` [PATCH v8 06/14] lockdep: Detect and handle hist_lock ring buffer overwrite Byungchul Park
2017-08-09 14:16 ` Peter Zijlstra
2017-08-10 1:32 ` Byungchul Park
2017-08-10 9:22 ` Peter Zijlstra
2017-08-10 10:32 ` Byungchul Park
2017-08-10 11:59 ` Boqun Feng
2017-08-10 12:11 ` Byungchul Park
2017-08-10 12:51 ` Boqun Feng
2017-08-10 13:17 ` Boqun Feng
2017-08-11 0:44 ` Byungchul Park
2017-08-11 3:43 ` Byungchul Park
2017-08-11 8:03 ` Boqun Feng
2017-08-11 8:52 ` Byungchul Park
2017-08-11 9:44 ` Byungchul Park
2017-08-11 13:06 ` Byungchul Park
2017-08-14 7:05 ` Boqun Feng
2017-08-14 7:22 ` Byungchul Park
2017-08-14 7:29 ` Byungchul Park
2017-08-11 0:40 ` Byungchul Park
2017-08-11 1:03 ` Boqun Feng
2017-08-10 12:20 ` [tip:locking/core] locking/lockdep: " tip-bot for Byungchul Park
2017-08-07 7:12 ` [PATCH v8 07/14] lockdep: Handle non(or multi)-acquisition of a crosslock Byungchul Park
2017-08-10 12:20 ` [tip:locking/core] locking/lockdep: " tip-bot for Byungchul Park
2017-08-07 7:12 ` [PATCH v8 08/14] lockdep: Make print_circular_bug() aware of crossrelease Byungchul Park
2017-08-10 12:21 ` [tip:locking/core] locking/lockdep: " tip-bot for Byungchul Park
2017-08-07 7:12 ` [PATCH v8 09/14] lockdep: Apply crossrelease to completions Byungchul Park
2017-08-07 10:20 ` kbuild test robot
2017-08-07 11:45 ` kbuild test robot
2017-08-09 9:51 ` Peter Zijlstra
2017-08-09 10:24 ` Peter Zijlstra
2017-08-10 1:24 ` Byungchul Park
2017-08-10 12:21 ` [tip:locking/core] locking/lockdep: " tip-bot for Byungchul Park
2017-08-14 8:50 ` [PATCH v8 09/14] lockdep: " Arnd Bergmann
2017-08-18 23:43 ` Boqun Feng
2017-08-19 12:51 ` Arnd Bergmann
2017-08-19 13:34 ` Arnd Bergmann
2017-08-23 14:43 ` Boqun Feng
2017-08-20 3:18 ` Boqun Feng
2017-08-07 7:12 ` [PATCH v8 10/14] pagemap.h: Remove trailing white space Byungchul Park
2017-08-07 7:12 ` [PATCH v8 11/14] lockdep: Apply crossrelease to PG_locked locks Byungchul Park
2017-08-07 10:36 ` kbuild test robot
2017-08-10 1:35 ` Byungchul Park
2017-08-10 9:25 ` Peter Zijlstra
2017-09-05 1:03 ` Byungchul Park
2017-08-07 7:12 ` [PATCH v8 12/14] lockdep: Apply lock_acquire(release) on __Set(__Clear)PageLocked Byungchul Park
2017-08-07 7:13 ` [PATCH v8 13/14] lockdep: Move data of CONFIG_LOCKDEP_PAGELOCK from page to page_ext Byungchul Park
2017-08-07 10:43 ` kbuild test robot
2017-08-07 7:13 ` [PATCH v8 14/14] lockdep: Crossrelease feature documentation Byungchul Park
2017-08-07 15:58 ` kbuild test robot
2017-08-10 12:22 ` [tip:locking/core] locking/lockdep: Add 'crossrelease' " tip-bot for Byungchul Park
2017-08-09 15:50 ` [PATCH v8 00/14] lockdep: Implement crossrelease feature Peter Zijlstra
2017-08-10 0:55 ` Byungchul Park
2017-08-10 3:47 ` Byungchul Park
2017-08-10 10:52 ` Byungchul Park
2017-08-10 9:37 ` Byungchul Park
2017-08-10 10:52 ` Peter Zijlstra
2017-08-10 11:10 ` Ingo Molnar
2017-08-10 11:45 ` Byungchul Park
2017-08-14 10:57 ` Ingo Molnar
2017-08-14 11:10 ` Byungchul Park
2017-08-15 8:20 ` Ingo Molnar
2017-08-16 0:16 ` Byungchul Park
2017-08-16 4:05 ` Boqun Feng
2017-08-16 4:37 ` Byungchul Park
2017-08-16 5:40 ` Boqun Feng
2017-08-16 6:37 ` Byungchul Park
2017-08-16 5:05 ` Byungchul Park
2017-08-16 5:58 ` Boqun Feng
2017-08-16 7:14 ` Byungchul Park
2017-08-16 8:06 ` Byungchul Park
2017-08-16 9:38 ` Byungchul Park [this message]
2017-08-17 7:48 ` Ingo Molnar
2017-08-17 8:04 ` Boqun Feng
2017-08-17 8:12 ` Ingo Molnar
2017-08-17 8:33 ` Boqun Feng
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