Re: [PATCH v7 20/21] PCI/P2PDMA: Introduce pci_mmap_p2pmem()

Christoph Hellwig
2022-07-05T16:43:23Z

On Tue, Jul 05, 2022 at 10:41:52AM -0600, Logan Gunthorpe wrote:
> Using sysfs means we don't need all the messy callbacks from the nvme
> driver, which is a plus. But I'm not sure how we'd get or unmap the
> mapping of a sysfs file or avoid the anonymous inode. Seems with the
> existing PCI resources, it uses an bin_attribute->f_mapping() callback
> to pass back the iomem_get_mapping() mapping on file open.
> revoke_iomem() is then used to nuke the VMAs. I don't think we can use
> the same infrastructure here as that would add a dependency on
> CONFIG_IO_STRICT_DEVMEM; which would be odd. And I'm not sure whether
> there is a better way.

Why can't we do the revoke on the actual sysfs inode?