memremap: add a migrate_to_ram method to struct dev_pagemap_ops

This replaces the hacky ->fault callback, which is currently directly
called from common code through a hmm specific data structure as an
exercise in layering violations.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

1 files changed, 2 insertions, 7 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 2d14f4c7e152..d437ccdb210c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2748,13 +2748,8 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
                         migration_entry_wait(vma->vm_mm, vmf->pmd,
                                              vmf->address);
                 } else if (is_device_private_entry(entry)) {
-                        /*
-                         * For un-addressable device memory we call the pgmap
-                         * fault handler callback. The callback must migrate
-                         * the page back to some CPU accessible page.
-                         */
-                        ret = device_private_entry_fault(vma, vmf->address, entry,
-                                                 vmf->flags, vmf->pmd);
+                        vmf->page = device_private_entry_to_page(entry);
+                        ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
                 } else if (is_hwpoison_entry(entry)) {
                         ret = VM_FAULT_HWPOISON;
                 } else {