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From: Will Deacon <will@kernel.org>
To: Robin Murphy <robin.murphy@arm.com>,
	iommu@lists.linux.dev,
	Jason Gunthorpe <jgg@nvidia.com>,
	linux-arm-kernel@lists.infradead.org,
	Joerg Roedel <joro@8bytes.org>
Cc: catalin.marinas@arm.com,
	kernel-team@android.com,
	Will Deacon <will@kernel.org>,
	Michael Shavit <mshavit@google.com>,
	Dan Carpenter <dan.carpenter@linaro.org>,
	Nicolin Chen <nicolinc@nvidia.com>,
	patches@lists.linux.dev
Subject: Re: [PATCH v3] iommu/arm-smmu-v3: Do not use GFP_KERNEL under as spinlock
Date: Thu, 22 Feb 2024 13:21:09 +0000
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In-Reply-To: <0-v3-11978fc67151+112-smmu_cd_atomic_jgg@nvidia.com>
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On Wed, 21 Feb 2024 20:27:02 -0400, Jason Gunthorpe wrote:
> If the SMMU is configured to use a two level CD table then
> arm_smmu_write_ctx_desc() allocates a CD table leaf internally using
> GFP_KERNEL. Due to recent changes this is being done under a spinlock to
> iterate over the device list - thus it will trigger a sleeping while
> atomic warning:
> 
>   arm_smmu_sva_set_dev_pasid()
>     mutex_lock(&sva_lock);
>     __arm_smmu_sva_bind()
>      arm_smmu_mmu_notifier_get()
>       spin_lock_irqsave()
>       arm_smmu_write_ctx_desc()
> 	arm_smmu_get_cd_ptr()
>          arm_smmu_alloc_cd_leaf_table()
> 	  dmam_alloc_coherent(GFP_KERNEL)
> 
> [...]

Thanks guys, this looks really good now.

Applied to will (for-joerg/arm-smmu/fixes), thanks!

[1/1] iommu/arm-smmu-v3: Do not use GFP_KERNEL under as spinlock
      https://git.kernel.org/will/c/b5bf7778b722

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev