diff mbox series

[19/54] mm/gup: frame_vector: convert get_user_pages() --> pin_user_pages()

Message ID 20200608044105.MIbT3ImsG%akpm@linux-foundation.org (mailing list archive)
State New, archived
Headers show
Series [01/54] mm/page_idle.c: skip offline pages | expand

Commit Message

Andrew Morton June 8, 2020, 4:41 a.m. UTC 
From: John Hubbard <jhubbard@nvidia.com>
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@nvidia.com
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/frame_vector.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)
diff mbox series

Patch

--- 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;