Re: [PATCH v11 8/9] PCI/P2PDMA: Allow userspace VMA allocations through sysfs

Chaitanya Kulkarni
2022-10-25T01:29:18Z

On 10/21/22 10:41, Logan Gunthorpe wrote:
> Create a sysfs bin attribute called "allocate" under the existing
> "p2pmem" group. The only allowable operation on this file is the mmap()
> call.
>
> When mmap() is called on this attribute, the kernel allocates a chunk of
> memory from the genalloc and inserts the pages into the VMA. The
> dev_pagemap .page_free callback will indicate when these pages are no
> longer used and they will be put back into the genalloc.
>
> On device unbind, remove the sysfs file before the memremap_pages are
> cleaned up. This ensures unmap_mapping_range() is called on the files
> inode and no new mappings can be created.
>
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> Acked-by: Bjorn Helgaas <bhelgaas@google.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>

-ck