linux-kernel - Re: [PATCH for-next v3 4/7] RDMA/rxe: Add page invalidation support

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Message-ID: <Y8WWPAHvZsXpwc0M@nvidia.com>
Date:   Mon, 16 Jan 2023 14:23:56 -0400
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Daisuke Matsuda <matsuda-daisuke@...itsu.com>
Cc:     linux-rdma@...r.kernel.org, leonro@...dia.com,
        zyjzyj2000@...il.com, nvdimm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, rpearsonhpe@...il.com,
        yangx.jy@...itsu.com, lizhijian@...itsu.com, y-goto@...itsu.com
Subject: Re: [PATCH for-next v3 4/7] RDMA/rxe: Add page invalidation support

On Fri, Dec 23, 2022 at 03:51:55PM +0900, Daisuke Matsuda wrote:

> +static bool rxe_ib_invalidate_range(struct mmu_interval_notifier *mni,
> +				    const struct mmu_notifier_range *range,
> +				    unsigned long cur_seq)
> +{
> +	struct ib_umem_odp *umem_odp =
> +		container_of(mni, struct ib_umem_odp, notifier);
> +	unsigned long start;
> +	unsigned long end;
> +
> +	if (!mmu_notifier_range_blockable(range))
> +		return false;
> +
> +	mutex_lock(&umem_odp->umem_mutex);
> +	mmu_interval_set_seq(mni, cur_seq);
> +
> +	start = max_t(u64, ib_umem_start(umem_odp), range->start);
> +	end = min_t(u64, ib_umem_end(umem_odp), range->end);
> +
> +	ib_umem_odp_unmap_dma_pages(umem_odp, start, end);

After bob's xarray conversion this can be done alot faster, it just an
xa_for_each_range and make the xarray items non-present

non-present is probably just a null struct page in the xarray.

Jason