Re: [PATCH 2/2] iommu/iova: Free global iova rcache on iova alloc failure

[Vijayanand Jitta]

On 7/3/2020 7:47 PM, vjitta@xxxxxxxxxxxxxx wrote:
> From: Vijayanand Jitta <vjitta@xxxxxxxxxxxxxx>
> 
> When ever an iova alloc request fails we free the iova
> ranges present in the percpu iova rcaches and then retry
> but the global iova rcache is not freed as a result we could
> still see iova alloc failure even after retry as global
> rcache is holding the iova's which can cause fragmentation.
> So, free the global iova rcache as well and then go for the
> retry.
> 
> Change-Id: Ib8236dc88ba5516b73d4fbf6bf8e68bbf09bbad2
> Signed-off-by: Vijayanand Jitta <vjitta@xxxxxxxxxxxxxx>
> ---
>  drivers/iommu/iova.c | 23 +++++++++++++++++++++++
>  include/linux/iova.h |  6 ++++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
> index 4e77116..5836c87 100644
> --- a/drivers/iommu/iova.c
> +++ b/drivers/iommu/iova.c
> @@ -442,6 +442,7 @@ struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn)
>  		flush_rcache = false;
>  		for_each_online_cpu(cpu)
>  			free_cpu_cached_iovas(cpu, iovad);
> +		free_global_cached_iovas(iovad);
>  		goto retry;
>  	}
>  
> @@ -1055,5 +1056,27 @@ void free_cpu_cached_iovas(unsigned int cpu, struct iova_domain *iovad)
>  	}
>  }
>  
> +/*
> + * free all the IOVA ranges of global cache
> + */
> +void free_global_cached_iovas(struct iova_domain *iovad)
> +{
> +	struct iova_rcache *rcache;
> +	unsigned long flags;
> +	int i, j;
> +
> +	for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) {
> +		rcache = &iovad->rcaches[i];
> +		spin_lock_irqsave(&rcache->lock, flags);
> +		for (j = 0; j < rcache->depot_size; ++j) {
> +			iova_magazine_free_pfns(rcache->depot[j], iovad);
> +			iova_magazine_free(rcache->depot[j]);
> +			rcache->depot[j] = NULL;
> +		}
> +		rcache->depot_size = 0;
> +		spin_unlock_irqrestore(&rcache->lock, flags);
> +	}
> +}
> +
>  MODULE_AUTHOR("Anil S Keshavamurthy <anil.s.keshavamurthy@xxxxxxxxx>");
>  MODULE_LICENSE("GPL");
> diff --git a/include/linux/iova.h b/include/linux/iova.h
> index a0637ab..a905726 100644
> --- a/include/linux/iova.h
> +++ b/include/linux/iova.h
> @@ -163,6 +163,7 @@ int init_iova_flush_queue(struct iova_domain *iovad,
>  struct iova *split_and_remove_iova(struct iova_domain *iovad,
>  	struct iova *iova, unsigned long pfn_lo, unsigned long pfn_hi);
>  void free_cpu_cached_iovas(unsigned int cpu, struct iova_domain *iovad);
> +void free_global_cached_iovas(struct iova_domain *iovad);
>  #else
>  static inline int iova_cache_get(void)
>  {
> @@ -270,6 +271,11 @@ static inline void free_cpu_cached_iovas(unsigned int cpu,
>  					 struct iova_domain *iovad)
>  {
>  }
> +
> +static inline void free_global_cached_iovas(struct iova_domain *iovad)
> +{
> +}
> +
>  #endif
>  
>  #endif
> 

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