[PATCH v6 20/21] PCI/P2PDMA: Introduce pci_mmap_p2pmem()

[Jason Gunthorpe]

On Thu, Apr 07, 2022 at 09:47:16AM -0600, Logan Gunthorpe wrote:
> +static void pci_p2pdma_unmap_mappings(void *data)
> +{
> +	struct pci_dev *pdev = data;
> +	struct pci_p2pdma *p2pdma = rcu_dereference_protected(pdev->p2pdma, 1);
> +
> +	/* Ensure no new pages can be allocated in mappings */
> +	p2pdma->active = false;
> +	synchronize_rcu();
> +
> +	unmap_mapping_range(p2pdma->inode->i_mapping, 0, 0, 1);
> +
> +	/*
> +	 * On some architectures, TLB flushes are done with call_rcu()
> +	 * so to ensure GUP fast is done with the pages, call synchronize_rcu()
> +	 * before freeing them.
> +	 */
> +	synchronize_rcu();
> +	pci_p2pdma_free_mappings(p2pdma->inode->i_mapping);

With the series from Felix getting close this should get updated to
not set pte_devmap and use proper natural refcounting without any of
this stuff.

Jason