Commit 55a650c3 authored by John Hubbard's avatar John Hubbard Committed by Linus Torvalds
Browse files

mm/gup: frame_vector: convert get_user_pages() --> pin_user_pages() 

This code was using get_user_pages*(), and all of the callers so far
were in a "Case 2" scenario (DMA/RDMA), using the categorization from [1].

That means that it's time to convert the get_user_pages*() + put_page()
calls to pin_user_pages*() + unpin_user_pages() calls.

There is some helpful background in [2]: basically, this is a small part
of fixing a long-standing disconnect between pinning pages, and file
systems' use of those pages.

[1] Documentation/core-api/pin_user_pages.rst

[2] "Explicit pinning of user-space pages":
    https://lwn.net/Articles/807108/



Signed-off-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Link: http://lkml.kernel.org/r/20200527223243.884385-3-jhubbard@nvidia.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 420c2091

mm/frame_vector.c

+3 −4
Original line number Diff line number Diff line
@@ -72,7 +72,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, 
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) {

		vec->got_ref = true;

		vec->is_pfns = false;

		ret = get_user_pages_locked(start, nr_frames,

		ret = pin_user_pages_locked(start, nr_frames,

			gup_flags, (struct page **)(vec->ptrs), &locked);

		goto out;

	}
@@ -122,7 +122,6 @@ EXPORT_SYMBOL(get_vaddr_frames); 
 */

void put_vaddr_frames(struct frame_vector *vec)

{

	int i;

	struct page **pages;



	if (!vec->got_ref)
@@ -135,8 +134,8 @@ void put_vaddr_frames(struct frame_vector *vec) 
	 */

	if (WARN_ON(IS_ERR(pages)))

		goto out;

	for (i = 0; i < vec->nr_frames; i++)

		put_page(pages[i]);



	unpin_user_pages(pages, vec->nr_frames);

	vec->got_ref = false;

out:

	vec->nr_frames = 0;