linux-kernel - Re: [PATCH] iommu/vt-d: Clean up si_domain in the init

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Date:   Mon, 10 Oct 2022 19:32:43 +0800
From:   Baolu Lu <baolu.lu@...ux.intel.com>
To:     Jerry Snitselaar <jsnitsel@...hat.com>, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Cc:     baolu.lu@...ux.intel.com, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>
Subject: Re: [PATCH] iommu/vt-d: Clean up si_domain in the init_dmars() error
 path

On 2022/10/10 14:56, Jerry Snitselaar wrote:
> A splat from kmem_cache_destroy() was seen with a kernel prior to
> commit ee2653bbe89d ("iommu/vt-d: Remove domain and devinfo mempool")
> when there was a failure in init_dmars(), because the iommu_domain
> cache still had objects. While the mempool code is now gone, there
> still is a leak of the si_domain memory if init_dmars() fails. So
> clean up si_domain in the init_dmars() error path.
> 
> Cc: Lu Baolu <baolu.lu@...ux.intel.com>
> Cc: Joerg Roedel <joro@...tes.org>
> Cc: Will Deacon <will@...nel.org>
> Cc: Robin Murphy <robin.murphy@....com>
> Fixes: 86080ccc223a ("iommu/vt-d: Allocate si_domain in init_dmars()")
> Signed-off-by: Jerry Snitselaar <jsnitsel@...hat.com>
> ---
>   drivers/iommu/intel/iommu.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 31bc50e538a3..8f1f80a4d0c5 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -3042,6 +3042,8 @@ static int __init init_dmars(void)
>   		disable_dmar_iommu(iommu);
>   		free_dmar_iommu(iommu);
>   	}
> +	if (si_domain)
> +		domain_exit(si_domain);

Thank you for the patch.

Above requires si_domain to be NULL or a valid pointer. So do you also
need to add the following change?

--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -2410,6 +2410,7 @@ static int __init si_domain_init(int hw)

         if (md_domain_init(si_domain, DEFAULT_DOMAIN_ADDRESS_WIDTH)) {
                 domain_exit(si_domain);
+               si_domain = NULL;
                 return -EFAULT;
         }

Best regards,
baolu