From f6d299ec39d8ebb62fc047022d4904575c99a28c Mon Sep 17 00:00:00 2001
From: Alistair Popple <apopple@nvidia.com>
Date: Wed, 24 Aug 2022 15:09:51 +1000
Subject: [PATCH] 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>
---
mm/gup.c | 23 +++++++++--------------
1 file changed, 9 insertions(+), 14 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index b05810e7e9bba..1800af4806e3d 100644
--- 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);
--
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