Re: [PATCH v4 05/11] iommu/sva: Assign a PASID to mm on PASID allocation and free it on mm exit

[Fenghua Yu]

On Thu, Apr 14, 2022 at 06:08:09PM +0800, zhangfei.gao@xxxxxxxxxxx wrote:
> 
> On 2022/4/12 下午11:35, zhangfei.gao@xxxxxxxxxxx wrote:
> > Hi, Fenghua
> > 
> > On 2022/4/12 下午9:41, Fenghua Yu wrote:
> > > Hi, Zhangfei,
> > > 
> > > On Tue, Apr 12, 2022 at 03:04:09PM +0800, zhangfei.gao@xxxxxxxxxxx
> > > wrote:
> > > > 
> > > > On 2022/4/11 下午10:52, Dave Hansen wrote:
> > > > > On 4/11/22 07:44, zhangfei.gao@xxxxxxxxxxx wrote:
> > > > > > On 2022/4/11 下午10:36, Dave Hansen wrote:
> > > > > > > On 4/11/22 07:20, zhangfei.gao@xxxxxxxxxxx wrote:
> > Agree with Dave, I think user space should not be broken.
> > 
> > Thanks
> 
> Any plan about this regression?
> Currently I need this patch to workaround the issue.
> 
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> index 22ddd05bbdcd..2d74ac53d11c 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> @@ -4,6 +4,7 @@
>   */
> 
>  #include <linux/mm.h>
> +#include <linux/sched/mm.h>
>  #include <linux/mmu_context.h>
>  #include <linux/mmu_notifier.h>
>  #include <linux/slab.h>
> @@ -363,6 +364,7 @@ arm_smmu_sva_bind(struct device *dev, struct mm_struct
> *mm, void *drvdata)
> 
>         mutex_lock(&sva_lock);
>         handle = __arm_smmu_sva_bind(dev, mm);
> +       mmget(mm);
>         mutex_unlock(&sva_lock);
>         return handle;
>  }
> @@ -377,6 +379,7 @@ void arm_smmu_sva_unbind(struct iommu_sva *handle)
>                 arm_smmu_mmu_notifier_put(bond->smmu_mn);
>                 kfree(bond);
>         }
> +       mmput(bond->mm);
>         mutex_unlock(&sva_lock);
>  }

Could you please review and/or test this patch? It's supposed to fix
the PASID issue on both ARM and X86.