From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
"Luis Claudio R. Goncalves" <lgoncalv@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Boqun Feng <boqun.feng@gmail.com>, Ingo Molnar <mingo@redhat.com>,
John Ogness <john.ogness@linutronix.de>,
Mel Gorman <mgorman@techsingularity.net>,
Michal Hocko <mhocko@suse.com>,
Peter Zijlstra <peterz@infradead.org>,
Petr Mladek <pmladek@suse.com>,
Thomas Gleixner <tglx@linutronix.de>,
Waiman Long <longman@redhat.com>, Will Deacon <will@kernel.org>
Subject: Re: [PATCH v2 1/2] seqlock: Do the lockdep annotation before locking in do_write_seqcount_begin_nested()
Date: Mon, 26 Jun 2023 18:25:56 +0900 [thread overview]
Message-ID: <0a0c768c-227d-c0cd-1b91-5a884d161c1b@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <20230626081254.XmorFrhs@linutronix.de>
On 2023/06/26 17:12, Sebastian Andrzej Siewior wrote:
> On 2023-06-24 15:54:12 [+0900], Tetsuo Handa wrote:
>> Why not to do the same on the end side?
>>
>> static inline void do_write_seqcount_end(seqcount_t *s)
>> {
>> - seqcount_release(&s->dep_map, _RET_IP_);
>> do_raw_write_seqcount_end(s);
>> + seqcount_release(&s->dep_map, _RET_IP_);
>> }
>
> I don't have a compelling argument for doing it. It is probably better
> to release the lock from lockdep's point of view and then really release
> it (so it can't be acquired before it is released).
We must do it because this is a source of possible printk() deadlock.
Otherwise, I will nack on PATCH 2/2.
>
> Looking at other locking primitives (spin_lock_unlock(),
> mutex_unlock(),…) that is what they do in the unlock path: lockdep
> annotation followed by the actual operation. Therefore I would keep the
> current ordering to remain in-sync with the other primitives.
next prev parent reply other threads:[~2023-06-26 9:26 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-23 17:12 [PATCH v2 0/2] seqlock,mm: lockdep annotation + write_seqlock_irqsave() Sebastian Andrzej Siewior
2023-06-23 17:12 ` [PATCH v2 1/2] seqlock: Do the lockdep annotation before locking in do_write_seqcount_begin_nested() Sebastian Andrzej Siewior
2023-06-24 6:54 ` Tetsuo Handa
2023-06-26 8:12 ` Sebastian Andrzej Siewior
2023-06-26 9:25 ` Tetsuo Handa [this message]
2023-06-26 10:48 ` Peter Zijlstra
2023-06-26 11:26 ` Tetsuo Handa
2023-06-26 11:35 ` Michal Hocko
2023-06-26 12:27 ` Tetsuo Handa
2023-06-26 13:16 ` Michal Hocko
2023-06-26 12:46 ` Sebastian Andrzej Siewior
2023-06-26 13:13 ` Sebastian Andrzej Siewior
2023-06-26 14:44 ` Petr Mladek
2023-06-28 12:14 ` Tetsuo Handa
2023-07-27 15:10 ` Sebastian Andrzej Siewior
2023-07-29 5:31 ` Tetsuo Handa
2023-07-29 11:05 ` Tetsuo Handa
2023-07-31 14:25 ` Michal Hocko
2023-08-03 13:18 ` Tetsuo Handa
2023-08-03 14:49 ` Michal Hocko
2023-08-04 13:27 ` Tetsuo Handa
2023-08-07 8:20 ` Michal Hocko
2023-06-26 12:56 ` Mel Gorman
2023-06-23 17:12 ` [PATCH v2 2/2] mm/page_alloc: Use write_seqlock_irqsave() instead write_seqlock() + local_irq_save() Sebastian Andrzej Siewior
2023-06-23 18:17 ` Michal Hocko
2023-06-23 20:15 ` [PATCH v3 " Sebastian Andrzej Siewior
2023-06-26 7:56 ` David Hildenbrand
2023-06-26 13:14 ` Mel Gorman
2023-06-28 13:56 ` Michal Hocko
2023-06-25 2:27 ` [PATCH v2 0/2] seqlock,mm: lockdep annotation + write_seqlock_irqsave() Tetsuo Handa
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