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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: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David 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: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
John Hubbard 2020-06-07 21:41:05 -07:00 committed by Linus Torvalds
parent 420c2091b6
commit 55a650c35f
1 changed files with 3 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
mm/frame_vector.c
View File

@ -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;