mm/gup.c: don't pass gup_flags to check_and_migrate_movable_pages()

gup_flags is passed to check_and_migrate_movable_pages() so that it can
call either put_page() or unpin_user_page() to drop the page reference.
However check_and_migrate_movable_pages() is only called for
FOLL_LONGTERM, which implies FOLL_PIN so there is no need to pass
gup_flags.

Link: https://lkml.kernel.org/r/d611c65a9008ff55887307df457c6c2220ad6163.1661317396.git-series.apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Alex Sierra <alex.sierra@amd.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Felix Kuehling <felix.kuehling@amd.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Shigeru Yoshida <syoshida@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/gup.c b/mm/gup.c
index b05810e..1800af4 100644 (file)
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1933,8 +1933,7 @@ struct page *get_dump_page(unsigned long addr)
  * migration failure.
  */
 static long check_and_migrate_movable_pages(unsigned long nr_pages,
-                                           struct page **pages,
-                                           unsigned int gup_flags)
+                                           struct page **pages)
 {
        unsigned long i;
        struct folio *prev_folio = NULL;
@@ -1967,10 +1966,8 @@ static long check_and_migrate_movable_pages(unsigned long nr_pages,
                         * Migration will fail if the page is pinned, so convert
                         * the pin on the source page to a normal reference.
                         */
-                       if (gup_flags & FOLL_PIN) {
-                               get_page(&folio->page);
-                               unpin_user_page(&folio->page);
-                       }
+                       get_page(&folio->page);
+                       unpin_user_page(&folio->page);
 
                        if (migrate_device_coherent_page(&folio->page)) {
                                ret = -EBUSY;
@@ -2023,10 +2020,7 @@ static long check_and_migrate_movable_pages(unsigned long nr_pages,
                if (!pages[i])
                        continue;
 
-               if (gup_flags & FOLL_PIN)
-                       unpin_user_page(pages[i]);
-               else
-                       put_page(pages[i]);
+               unpin_user_page(pages[i]);
        }
 
        if (!list_empty(&movable_page_list)) {
@@ -2049,8 +2043,7 @@ static long check_and_migrate_movable_pages(unsigned long nr_pages,
 }
 #else
 static long check_and_migrate_movable_pages(unsigned long nr_pages,
-                                           struct page **pages,
-                                           unsigned int gup_flags)
+                                           struct page **pages)
 {
        return 0;
 }
@@ -2073,6 +2066,9 @@ static long __gup_longterm_locked(struct mm_struct *mm,
        if (!(gup_flags & FOLL_LONGTERM))
                return __get_user_pages_locked(mm, start, nr_pages, pages, vmas,
                                               NULL, gup_flags);
+       /* check_and_migrate_movable_pages() assumes pages have been pinned. */
+       if (WARN_ON(!(gup_flags & FOLL_PIN)))
+               return -EINVAL;
        flags = memalloc_pin_save();
        do {
                nr_pinned_pages = __get_user_pages_locked(mm, start, nr_pages,
@@ -2082,8 +2078,7 @@ static long __gup_longterm_locked(struct mm_struct *mm,
                        rc = nr_pinned_pages;
                        break;
                }
-               rc = check_and_migrate_movable_pages(nr_pinned_pages, pages,
-                                                    gup_flags);
+               rc = check_and_migrate_movable_pages(nr_pinned_pages, pages);
        } while (rc == -EAGAIN);
        memalloc_pin_restore(flags);