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From: Thomas Gleixner <tglx@linutronix.de>
To: Marc Zyngier <maz@kernel.org>,
	Valentin Schneider <valentin.schneider@arm.com>
Cc: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Mel Gorman <mgorman@techsingularity.net>,
	Ard Biesheuvel <ardb@kernel.org>
Subject: Re: [SPLAT 2/3] irqchip/gic-v3-its: Sleeping spinlocks down gic_reserve_range()
Date: Wed, 11 Aug 2021 14:28:21 +0200	[thread overview]
Message-ID: <87a6lop3mi.ffs@tglx> (raw)
In-Reply-To: <87y2989xhh.wl-maz@kernel.org>

On Wed, Aug 11 2021 at 09:50, Marc Zyngier wrote:
> On Tue, 10 Aug 2021 14:41:26 +0100,
> Valentin Schneider <valentin.schneider@arm.com> wrote:
> The issue is that although the redistributor tables have been
> allocated ahead of time (outside of any cpuhp callback), they cannot
> be programmed into the RDs until the corresponding CPUs have been
> brought up (the registers may not be accessible).
>
> For the same reason, we don't know whether we can free them (because
> there is already a table programmed there) or have to reserve them
> with an efi_mem_reserve_persistent() call. efi_mem_reserve_iomem()
> uses GFP_ATOMIC for its allocation, but this is not sufficient for RT
> anymore.
>
> We could postpone the reservation of the memory to a later point (it
> is only useful for kexec), but it isn't clear where that point is. The
> CPU is not quite up yet, and we can't easily IPI the boot CPU to do
> the reserve call.

Right, but don't you know about the need for reservation _before_
bringing the CPU up?

Thanks,

        tglx

  reply	other threads:[~2021-08-11 12:31 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-10 13:41 [SPLAT 0/3] Sleeping spinlocks in troublesome contexts on v5.14-rc4-rt6 Valentin Schneider
2021-08-10 13:41 ` [SPLAT 1/3] arm_pmu: Sleeping spinlocks down armpmu_alloc_atomic() Valentin Schneider
2021-08-10 13:54   ` Sebastian Andrzej Siewior
2021-08-10 17:16     ` Thomas Gleixner
2021-08-10 18:39       ` Sebastian Andrzej Siewior
2021-08-10 19:56         ` Thomas Gleixner
2021-08-10 13:41 ` [SPLAT 2/3] irqchip/gic-v3-its: Sleeping spinlocks down gic_reserve_range() Valentin Schneider
2021-08-11  8:50   ` Marc Zyngier
2021-08-11 12:28     ` Thomas Gleixner [this message]
2021-08-11 15:14       ` Marc Zyngier
2021-08-17 15:16     ` Ard Biesheuvel
2021-08-10 13:41 ` [SPLAT 3/3] gpio: dwapb: Sleeping spinlocks down IRQ mapping Valentin Schneider
2021-08-10 20:33   ` Thomas Gleixner
2021-08-11 10:52   ` Andy Shevchenko

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