The patch titled
Subject: mm/gup.c: don't pass gup_flags to check_and_migrate_movable_pages()
has been added to the -mm mm-unstable branch. Its filename is
mm-gupc-dont-pass-gup_flags-to-check_and_migrate_movable_pages.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-gupc-dont-pass-gup_flags-to-check_and_migrate_movable_pages.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Alistair Popple <apopple@xxxxxxxxxx>
Subject: mm/gup.c: don't pass gup_flags to check_and_migrate_movable_pages()
Date: Wed, 24 Aug 2022 15:09:51 +1000
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@xxxxxxxxxx
Signed-off-by: Alistair Popple <apopple@xxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Alex Sierra <alex.sierra@xxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Felix Kuehling <felix.kuehling@xxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Cc: Shigeru Yoshida <syoshida@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/gup.c | 23 +++++++++--------------
1 file changed, 9 insertions(+), 14 deletions(-)
--- a/mm/gup.c~mm-gupc-dont-pass-gup_flags-to-check_and_migrate_movable_pages
+++ a/mm/gup.c
@@ -1910,8 +1910,7 @@ struct page *get_dump_page(unsigned long
* 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;
@@ -1944,10 +1943,8 @@ static long check_and_migrate_movable_pa
* 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;
@@ -2000,10 +1997,7 @@ static long check_and_migrate_movable_pa
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)) {
@@ -2026,8 +2020,7 @@ static long check_and_migrate_movable_pa
}
#else
static long check_and_migrate_movable_pages(unsigned long nr_pages,
- struct page **pages,
- unsigned int gup_flags)
+ struct page **pages)
{
return 0;
}
@@ -2050,6 +2043,9 @@ static long __gup_longterm_locked(struct
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,
@@ -2057,8 +2053,7 @@ static long __gup_longterm_locked(struct
gup_flags);
if (nr_pinned_pages <= 0)
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);
_
Patches currently in -mm which might be from apopple@xxxxxxxxxx are
mm-migrate_devicec-copy-pte-dirty-bit-to-page.patch
mm-gupc-simplify-and-fix-check_and_migrate_movable_pages-return-codes.patch
selftests-hmm-tests-add-test-for-dirty-bits.patch
mm-gupc-dont-pass-gup_flags-to-check_and_migrate_movable_pages.patch
mm-gupc-refactor-check_and_migrate_movable_pages.patch
