From: John Hubbard <jhubbard@xxxxxxxxxx>
Subject: 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/
Link: http://lkml.kernel.org/r/20200527223243.884385-3-jhubbard@xxxxxxxxxx
Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Pankaj Gupta <pankaj.gupta.linux@xxxxxxxxx>
Cc: Souptick Joarder <jrdr.linux@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/frame_vector.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
--- a/mm/frame_vector.c~mm-gup-frame_vector-convert-get_user_pages-pin_user_pages
+++ a/mm/frame_vector.c
@@ -72,7 +72,7 @@ int get_vaddr_frames(unsigned long start
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_vecto
*/
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;
_
