linux-kernel - Re: [PATCH v5 2/2] iommu/iova: Free global iova rcache on iova alloc failure

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Date:   Tue, 20 Oct 2020 14:48:43 +0530
From:   Vijayanand Jitta <vjitta@...eaurora.org>
To:     joro@...tes.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Cc:     vinmenon@...eaurora.org, kernel-team@...roid.com,
        robin.murphy@....com
Subject: Re: [PATCH v5 2/2] iommu/iova: Free global iova rcache on iova alloc
 failure



On 9/30/2020 1:14 PM, vjitta@...eaurora.org wrote:
> From: Vijayanand Jitta <vjitta@...eaurora.org>
> 
> 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.
> 
> Signed-off-by: Vijayanand Jitta <vjitta@...eaurora.org>
> ---
>  drivers/iommu/iova.c | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
> index c3a1a8e..faf9b13 100644
> --- a/drivers/iommu/iova.c
> +++ b/drivers/iommu/iova.c
> @@ -25,6 +25,7 @@ static void init_iova_rcaches(struct iova_domain *iovad);
>  static void free_iova_rcaches(struct iova_domain *iovad);
>  static void fq_destroy_all_entries(struct iova_domain *iovad);
>  static void fq_flush_timeout(struct timer_list *t);
> +static void free_global_cached_iovas(struct iova_domain *iovad);
>  
>  void
>  init_iova_domain(struct iova_domain *iovad, unsigned long granule,
> @@ -442,6 +443,7 @@ alloc_iova_fast(struct iova_domain *iovad, unsigned long size,
>  		flush_rcache = false;
>  		for_each_online_cpu(cpu)
>  			free_cpu_cached_iovas(cpu, iovad);
> +		free_global_cached_iovas(iovad);
>  		goto retry;
>  	}
>  
> @@ -1057,5 +1059,26 @@ void free_cpu_cached_iovas(unsigned int cpu, struct iova_domain *iovad)
>  	}
>  }
>  
> +/*
> + * free all the IOVA ranges of global cache
> + */
> +static 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@...el.com>");
>  MODULE_LICENSE("GPL");
> 

Gentle ping.

Thanks,
Vijay
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