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From: Long Li <longli@microsoft.com>
To: Konstantin Taranov <kotaranov@linux.microsoft.com>, Konstantin Taranov
	<kotaranov@microsoft.com>, "sharmaajay@microsoft.com"
	<sharmaajay@microsoft.com>, "jgg@ziepe.ca" <jgg@ziepe.ca>, "leon@kernel.org"
	<leon@kernel.org>
CC: "linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH rdma-next v1 1/1] RDMA/mana_ib: Fix bug in creation of dma
 regions
Thread-Topic: [PATCH rdma-next v1 1/1] RDMA/mana_ib: Fix bug in creation of
 dma regions
Thread-Index: AQHaWdeqNtbLWJ8n+0aIBnpvWAnAXLEAyQjw
Date: Thu, 8 Feb 2024 18:42:51 +0000
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>=20
>  	/* Hardware requires dma region to align to chosen page size */
> -	page_sz =3D ib_umem_find_best_pgsz(umem, PAGE_SZ_BM, 0);
> +	page_sz =3D ib_umem_find_best_pgsz(umem, PAGE_SZ_BM, virt);
>  	if (!page_sz) {
>  		ibdev_dbg(&dev->ib_dev, "failed to find page size.\n");
>  		return -ENOMEM;
>  	}

How about doing:
page_sz =3D ib_umem_find_best_pgsz(umem, PAGE_SZ_BM, force_zero_offset  ? 0=
 : virt);

Will this work? This can get rid of the following while loop.

> +
> +	if (force_zero_offset) {
> +		while (ib_umem_dma_offset(umem, page_sz) && page_sz >
> PAGE_SIZE)
> +			page_sz /=3D 2;
> +		if (ib_umem_dma_offset(umem, page_sz) !=3D 0) {
> +			ibdev_dbg(&dev->ib_dev, "failed to find page size to
> force zero offset.\n");
> +			return -ENOMEM;
> +		}
> +	}
> +