Messages in this thread Patch in this message | | | From | Alistair Popple <> | Subject | [PATCH v4 1/2] mm/gup.c: Don't pass gup_flags to check_and_migrate_movable_pages() | Date | Fri, 12 Aug 2022 12:13:08 +1000 |
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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.
Signed-off-by: Alistair Popple <apopple@nvidia.com> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com>
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Changes for v3:
- Move WARN_ON() out of loop --- mm/gup.c | 23 ++++++++++------------- 1 file changed, 10 insertions(+), 13 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c index c6d060d..a2baa8b 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1907,8 +1907,7 @@ struct page *get_dump_page(unsigned long addr) * Return negative error if migration fails. */ static long check_and_migrate_movable_pages(unsigned long nr_pages, - struct page **pages, - unsigned int gup_flags) + struct page **pages) { unsigned long isolation_error_count = 0, i; struct folio *prev_folio = NULL; @@ -1941,10 +1940,8 @@ 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); ret = migrate_device_coherent_page(&folio->page); if (ret) @@ -1998,10 +1995,7 @@ 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)) { @@ -2023,8 +2017,7 @@ 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 nr_pages; } @@ -2047,13 +2040,17 @@ 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 { rc = __get_user_pages_locked(mm, start, nr_pages, pages, vmas, NULL, gup_flags); if (rc <= 0) break; - rc = check_and_migrate_movable_pages(rc, pages, gup_flags); + + rc = check_and_migrate_movable_pages(rc, pages); } while (!rc); memalloc_pin_restore(flags); base-commit: 360614c01f81f48a89d8b13f8fa69c3ae0a1f5c7 -- git-series 0.9.1
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