linux-kernel - Re: [PATCH 1/2] iommu/vt-d: Fix dmar_domain leak in iommu_attach

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Message-ID: <20141217213747.GA11569@anatevka.fc.hp.com>
Date:	Wed, 17 Dec 2014 14:37:47 -0700
From:	Jerry Hoemann <jerry.hoemann@...com>
To:	Joerg Roedel <joro@...tes.org>
Cc:	iommu@...ts.linux-foundation.org,
	Alex Williamson <alex.williamson@...hat.com>,
	David Woodhouse <dwmw2@...radead.org>,
	linux-kernel@...r.kernel.org, Joerg Roedel <jroedel@...e.de>,
	stable@...r.kernel.org, Myron Stowe <mstowe@...hat.com>
Subject: Re: [PATCH 1/2] iommu/vt-d: Fix dmar_domain leak in
 iommu_attach_device

On Wed, Dec 17, 2014 at 11:43:36AM +0100, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@...e.de>
> 
> Since commit 1196c2f a domain is only destroyed in the
> notifier path if it is hot-unplugged. This caused a
> domain leakage in iommu_attach_device when a driver was
> unbound from the device and bound to VFIO. In this case the
> device is attached to a new domain and unlinked from the old
> domain. At this point nothing points to the old domain
> anymore and its memory is leaked.
> Fix this by explicitly freeing the old domain in
> iommu_attach_domain.
> 
> Fixes: 1196c2f (iommu/vt-d: Fix dmar_domain leak in iommu_attach_device)
> Cc: <stable@...r.kernel.org> # v3.18
> Signed-off-by: Joerg Roedel <jroedel@...e.de>
> ---
>  drivers/iommu/intel-iommu.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 1232336..7610121 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -4428,6 +4428,10 @@ static int intel_iommu_attach_device(struct iommu_domain *domain,
>  				domain_remove_one_dev_info(old_domain, dev);
>  			else
>  				domain_remove_dev_info(old_domain);
> +
> +			if (!domain_type_is_vm_or_si(old_domain) &&
> +			     list_empty(&old_domain->devices))
> +				domain_exit(old_domain);
>  		}
>  	}
>  
> -- 
> 1.9.1

Joerg,

Before applying this change on a 3.18-rc7 kernel layered on a
RHEL 7.0 root disk, I was able to reproduce the memory
leak that Alex reported when powering on/off a VM w/ a PCI
device assigned to it.

After applying this change, I don't see the memory leak anymore.
Instrumentation shows the new code is being invoked during power on
of the VM.

Looks good.

Thanks!

Tested-by: Jerry Hoemann <jerry.hoemann@...com>
-- 

----------------------------------------------------------------------------
Jerry Hoemann            Software Engineer              Hewlett-Packard

3404 E Harmony Rd. MS 36                        phone:  (970) 898-1022
Ft. Collins, CO 80528                           FAX:    (970) 898-0707
                                                email:  jerry.hoemann@...com
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