Re: [PATCH v3 3/3] iova: defer maple tree erase on GFP_ATOMIC failure

[Jason Gunthorpe <jgg@ziepe.ca>]

On Tue, Jun 02, 2026 at 11:35:48PM -0400, Rik van Riel wrote:
> +/*
> + * Remove an IOVA entry from the maple tree. Returns true on success.
> + * On failure (maple tree node allocation under GFP_ATOMIC failed),
> + * returns false — the entry remains in the tree and the caller must
> + * not free the struct iova.
> + */
> +static bool remove_iova(struct iova_domain *iovad, struct iova *iova)
>  {
>  	MA_STATE(mas, &iovad->mtree, iova->pfn_lo, iova->pfn_hi);
>  
> @@ -165,7 +175,36 @@ static void remove_iova(struct iova_domain *iovad, struct iova *iova)
>  	if (iova->pfn_lo < iovad->dma_32bit_pfn)
>  		iovad->max32_alloc_size = iovad->dma_32bit_pfn;
>  
> -	mas_store_gfp(&mas, NULL, GFP_ATOMIC);
> +	if (mas_store_gfp(&mas, NULL, GFP_ATOMIC))
> +		return false;

But why does it use mas_store(NULL) instead of mas_erase()? I thought
the iova alloc/free has to be pair wise, we don't split allocations?

Jason