linux-kernel - Re: iommu/amd: lock splitting & GFP

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Message-ID: <20180315130144.v25fugc2kfglptby@8bytes.org>
Date:   Thu, 15 Mar 2018 14:01:45 +0100
From:   Joerg Roedel <joro@...tes.org>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        tglx@...utronix.de
Subject: Re: iommu/amd: lock splitting & GFP_KERNEL allocation

Hi Sebastian,

On Fri, Feb 23, 2018 at 11:27:26PM +0100, Sebastian Andrzej Siewior wrote:
> I have no idea why but suddenly my A10 box complained loudly about
> locking and memory allocations within the iommu code under RT. Looking
> at the code it has been like this for a longer time so the iommu must
> have appeared recently (well there was a bios upgrade due to other
> issues so it might have enabled it).
> 
> The goal here is to make the memory allocation in get_irq_table() not
> with disabled interrupts and having as little raw_spin_lock as possible
> while having them if the caller is also holding one (like desc->lock
> during IRQ-affinity changes).
> 
> The patches were boot tested on an AMD EPYC 7601.

Thanks for these patches, I really like the cleanups and the improved
locking. Please rebase against x86/amd in the iommu branch and address
the other comment I have, then I put them into my tree.


Thanks,

	Joerg