From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Michal Hocko <mhocko@suse.com>
Cc: linux-mm@kvack.org,
"Luis Claudio R. Goncalves" <lgoncalv@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@techsingularity.net>,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] mm/page_alloc: Use write_seqlock_irqsave() instead write_seqlock() + local_irq_save().
Date: Wed, 21 Jun 2023 15:11:25 +0200 [thread overview]
Message-ID: <20230621131125.XC2Pgojw@linutronix.de> (raw)
In-Reply-To: <ZJLjssXepzsMkD6w@dhcp22.suse.cz>
On 2023-06-21 13:49:06 [+0200], Michal Hocko wrote:
> > On PREEMPT_RT what you can happen is that the writer is preempted by a
> > high-priority reader which then deadlocks because the reader spins while
> > waiting and the writer is blocked. For this issue we have lock + unlock
> > in the seq reader to PI boost the seq writer so it can make progress.
>
> Please state the the problem explicitly in the changelog. You are
> marking this patch as a fix so the underlying issue should be stated.
The problem is the "local_irq_save()" which I believe I stated. The lock
+ unlock story was just a side story and is already covered. I really
need just the local_irq_save() invocation to be part of the seqlock API
so it can be substituted away.
> Thanks!
Sebastian
next prev parent reply other threads:[~2023-06-21 13:11 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-21 10:40 [PATCH] mm/page_alloc: Use write_seqlock_irqsave() instead write_seqlock() + local_irq_save() Sebastian Andrzej Siewior
2023-06-21 10:59 ` Michal Hocko
2023-06-21 11:16 ` Sebastian Andrzej Siewior
2023-06-21 11:49 ` Michal Hocko
2023-06-21 13:11 ` Sebastian Andrzej Siewior [this message]
2023-06-21 13:22 ` Michal Hocko
2023-06-21 13:25 ` Sebastian Andrzej Siewior
2023-06-21 11:14 ` David Hildenbrand
2023-06-21 11:33 ` Tetsuo Handa
2023-06-21 12:40 ` Petr Mladek
2023-06-21 13:08 ` Sebastian Andrzej Siewior
2023-06-21 13:06 ` Sebastian Andrzej Siewior
2023-06-21 13:32 ` Tetsuo Handa
2023-06-21 14:34 ` Sebastian Andrzej Siewior
2023-06-21 14:50 ` Tetsuo Handa
2023-06-21 23:24 ` Tetsuo Handa
2023-06-22 7:18 ` Michal Hocko
2023-06-22 10:58 ` Tetsuo Handa
2023-06-22 12:09 ` Michal Hocko
2023-06-22 13:36 ` Tetsuo Handa
2023-06-22 14:11 ` Petr Mladek
2023-06-22 14:28 ` Tetsuo Handa
2023-06-23 9:35 ` Sebastian Andrzej Siewior
2023-06-22 15:04 ` Petr Mladek
2023-06-22 15:43 ` Tetsuo Handa
2023-06-23 9:45 ` Sebastian Andrzej Siewior
2023-06-23 9:51 ` Tetsuo Handa
2023-06-23 10:11 ` Sebastian Andrzej Siewior
2023-06-23 10:36 ` Tetsuo Handa
2023-06-23 12:44 ` Sebastian Andrzej Siewior
2023-06-23 12:57 ` Michal Hocko
2023-06-23 10:53 ` Petr Mladek
2023-06-23 11:16 ` Tetsuo Handa
2023-06-23 13:31 ` Sebastian Andrzej Siewior
2023-06-23 15:38 ` Petr Mladek
2023-06-23 16:04 ` Sebastian Andrzej Siewior
2023-06-23 9:31 ` Sebastian Andrzej Siewior
2023-06-23 7:27 ` Sebastian Andrzej Siewior
2023-06-21 15:38 ` Petr Mladek
2023-06-23 8:12 ` Sebastian Andrzej Siewior
2023-06-23 9:21 ` Michal Hocko
2023-06-23 9:58 ` Sebastian Andrzej Siewior
2023-06-23 10:43 ` Michal Hocko
2023-06-23 10:45 ` Sebastian Andrzej Siewior
2023-06-23 10:50 ` Sebastian Andrzej Siewior
2023-06-23 11:32 ` Michal Hocko
2023-06-23 10:40 ` Petr Mladek
2023-06-23 13:24 ` Sebastian Andrzej Siewior
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