From: Matthew Wilcox <willy@infradead.org>
To: Sebastian Siewior <bigeasy@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Anna-Maria Gleixner <anna-maria@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>,
Julia Cartwright <julia@ni.com>, Jan Kara <jack@suse.cz>,
Theodore Tso <tytso@mit.edu>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Jan Kara <jack@suse.com>, Mark Fasheh <mark@fasheh.com>,
Joseph Qi <joseph.qi@linux.alibaba.com>,
Christoph Hellwig <hch@infradead.org>,
Joel Becker <jlbec@evilplan.org>
Subject: Re: [PATCH] fs/buffer: Make BH_Uptodate_Lock bit_spin_lock a regular spinlock_t
Date: Tue, 20 Aug 2019 10:17:21 -0700 [thread overview]
Message-ID: <20190820171721.GA4949@bombadil.infradead.org> (raw)
In-Reply-To: <20190820170818.oldsdoumzashhcgh@linutronix.de>
On Tue, Aug 20, 2019 at 07:08:18PM +0200, Sebastian Siewior wrote:
> Bit spinlocks are problematic if PREEMPT_RT is enabled, because they
> disable preemption, which is undesired for latency reasons and breaks when
> regular spinlocks are taken within the bit_spinlock locked region because
> regular spinlocks are converted to 'sleeping spinlocks' on RT. So RT
> replaces the bit spinlocks with regular spinlocks to avoid this problem.
> Bit spinlocks are also not covered by lock debugging, e.g. lockdep.
>
> Substitute the BH_Uptodate_Lock bit spinlock with a regular spinlock.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> [bigeasy: remove the wrapper and use always spinlock_t]
Uhh ... always grow the buffer_head, even for non-PREEMPT_RT? Why?
next prev parent reply other threads:[~2019-08-20 17:17 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-20 17:08 [PATCH] fs/buffer: Make BH_Uptodate_Lock bit_spin_lock a regular spinlock_t Sebastian Siewior
2019-08-20 17:17 ` Matthew Wilcox [this message]
2019-08-20 18:01 ` Thomas Gleixner
2019-10-11 11:25 ` Sebastian Siewior
2019-11-15 14:56 ` Jan Kara
2019-11-15 17:36 ` Theodore Y. Ts'o
2019-11-18 9:35 ` Jan Kara
2019-11-15 17:54 ` [PATCH v2] " Sebastian Siewior
2019-11-18 9:38 ` Jan Kara
2019-11-18 13:28 ` [PATCH v3] " Sebastian Siewior
2019-11-19 9:30 ` Jan Kara
2019-11-19 10:00 ` Sebastian Siewior
2019-11-19 11:59 ` Jan Kara
2020-03-28 12:26 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
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