linux-kernel - Re: [PATCH v5 09/29] iommufd: Do not unmap an owned iopt

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Message-ID: <aEEdbha8TNCUtTgQ@Asurada-Nvidia>
Date: Wed, 4 Jun 2025 21:30:38 -0700
From: Nicolin Chen <nicolinc@...dia.com>
To: Jason Gunthorpe <jgg@...dia.com>
CC: <kevin.tian@...el.com>, <corbet@....net>, <will@...nel.org>,
	<bagasdotme@...il.com>, <robin.murphy@....com>, <joro@...tes.org>,
	<thierry.reding@...il.com>, <vdumpa@...dia.com>, <jonathanh@...dia.com>,
	<shuah@...nel.org>, <jsnitsel@...hat.com>, <nathan@...nel.org>,
	<peterz@...radead.org>, <yi.l.liu@...el.com>, <mshavit@...gle.com>,
	<praan@...gle.com>, <zhangzekun11@...wei.com>, <iommu@...ts.linux.dev>,
	<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-tegra@...r.kernel.org>,
	<linux-kselftest@...r.kernel.org>, <patches@...ts.linux.dev>,
	<mochs@...dia.com>, <alok.a.tiwari@...cle.com>, <vasant.hegde@....com>,
	<dwmw2@...radead.org>, <baolu.lu@...ux.intel.com>
Subject: Re: [PATCH v5 09/29] iommufd: Do not unmap an owned iopt_area

On Wed, May 28, 2025 at 02:08:45PM -0300, Jason Gunthorpe wrote:
> @@ -740,11 +740,16 @@ static int iopt_unmap_iova_range(struct io_pagetable *iopt, unsigned long start,
>  			up_write(&iopt->iova_rwsem);
>  			up_read(&iopt->domains_rwsem);
>  
> -			iommufd_access_notify_unmap(iopt, area_first, length);
> +			rc = iommufd_access_notify_unmap(iopt, area_first, length);
> +			if (rc)
> +				goto out_unmapped;
> +

I found that we have to re-take those rwsems to unset a flag:

			rc = iommufd_access_notify_unmap(iopt, area_first, length);
			if (rc) {
				down_read(&iopt->domains_rwsem);
  				down_write(&iopt->iova_rwsem);
				area->prevent_access = false;
				goto out_unlock_iova;
			}

Will include this in the patch.

Thanks
Nicolin