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Date:   Fri, 2 Aug 2019 11:07:53 +0200 (CEST)
From:   Thomas Gleixner <tglx@linutronix.de>
To:     Christoph Hellwig <hch@infradead.org>
cc:     LKML <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
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Subject: Re: [patch V2 0/7] fs: Substitute bit-spinlocks for PREEMPT_RT and
 debugging
In-Reply-To: <20190802075612.GA20962@infradead.org>
Message-ID: <alpine.DEB.2.21.1908021107090.2285@nanos.tec.linutronix.de>
References: <20190801010126.245731659@linutronix.de> <20190802075612.GA20962@infradead.org>
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Christoph,

On Fri, 2 Aug 2019, Christoph Hellwig wrote:

> did you look into killing bіt spinlocks as a public API instead?

Last time I did, there was resistance :)

But I'm happy to try again.

> The main users seems to be buffer heads, which are so bloated that
> an extra spinlock doesn't really matter anyway.
>
> The list_bl and rhashtable uses kinda make sense to be, but they are
> pretty nicely abstracted away anyway.  The remaining users look
> pretty questionable to start with.

What about the page lock?

  mm/slub.c:      bit_spin_lock(PG_locked, &page->flags);

Thanks,

	tglx
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