Messages in this thread | | | Date | Fri, 5 Aug 2022 00:35:08 -0700 | Subject | Re: [PATCH v2 1/2] mm/gup.c: Don't pass gup_flags to check_and_migrate_movable_pages() | From | John Hubbard <> |
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On 8/4/22 23:29, Alistair Popple wrote: > 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
heh, while verifying the above claim, I noticed that __gup_longterm_locked() has been misnamed for some time now. That function handles both FOLL_LONGTERM and !FOLL_LONGTERM. There's always something...
Anyway, though, this patch is a good cleanup step, so:
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
thanks, -- John Hubbard NVIDIA
> gup_flags. > > Signed-off-by: Alistair Popple <apopple@nvidia.com> > --- > mm/gup.c | 21 ++++++++------------- > 1 file changed, 8 insertions(+), 13 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index c6d060d..e26ccc0 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; > } > @@ -2053,7 +2046,9 @@ static long __gup_longterm_locked(struct mm_struct *mm, > NULL, gup_flags); > if (rc <= 0) > break; > - rc = check_and_migrate_movable_pages(rc, pages, gup_flags); > + > + WARN_ON_ONCE(!(gup_flags & FOLL_PIN)); > + rc = check_and_migrate_movable_pages(rc, pages); > } while (!rc); > memalloc_pin_restore(flags); > > > base-commit: 360614c01f81f48a89d8b13f8fa69c3ae0a1f5c7
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