| Date | Sat, 5 Feb 2022 18:12:18 -0800 | Subject | Re: [PATCH 16/75] mm/gup: Convert try_grab_page() to use a folio | From | John Hubbard <> |
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On 2/4/22 11:57, Matthew Wilcox (Oracle) wrote: > Hoist the folio conversion and the folio_ref_count() check to the > top of the function instead of using the one buried in try_get_page(). > > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > --- > mm/gup.c | 28 +++++++++++++--------------- > 1 file changed, 13 insertions(+), 15 deletions(-)
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
thanks, -- John Hubbard NVIDIA
> > diff --git a/mm/gup.c b/mm/gup.c > index 4f1669db92f5..d18ce4da573f 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -174,15 +174,14 @@ static void put_compound_head(struct page *page, int refs, unsigned int flags) > > /** > * try_grab_page() - elevate a page's refcount by a flag-dependent amount > + * @page: pointer to page to be grabbed > + * @flags: gup flags: these are the FOLL_* flag values. > * > * This might not do anything at all, depending on the flags argument. > * > * "grab" names in this file mean, "look at flags to decide whether to use > * FOLL_PIN or FOLL_GET behavior, when incrementing the page's refcount. > * > - * @page: pointer to page to be grabbed > - * @flags: gup flags: these are the FOLL_* flag values. > - * > * Either FOLL_PIN or FOLL_GET (or neither) may be set, but not both at the same > * time. Cases: please see the try_grab_folio() documentation, with > * "refs=1". > @@ -193,29 +192,28 @@ static void put_compound_head(struct page *page, int refs, unsigned int flags) > */ > bool __must_check try_grab_page(struct page *page, unsigned int flags) > { > + struct folio *folio = page_folio(page); > + > WARN_ON_ONCE((flags & (FOLL_GET | FOLL_PIN)) == (FOLL_GET | FOLL_PIN)); > + if (WARN_ON_ONCE(folio_ref_count(folio) <= 0)) > + return false; > > if (flags & FOLL_GET) > - return try_get_page(page); > + folio_ref_inc(folio); > else if (flags & FOLL_PIN) { > - page = compound_head(page); > - > - if (WARN_ON_ONCE(page_ref_count(page) <= 0)) > - return false; > - > /* > - * Similar to try_grab_compound_head(): be sure to *also* > + * Similar to try_grab_folio(): be sure to *also* > * increment the normal page refcount field at least once, > * so that the page really is pinned. > */ > - if (PageHead(page)) { > - page_ref_add(page, 1); > - atomic_add(1, compound_pincount_ptr(page)); > + if (folio_test_large(folio)) { > + folio_ref_add(folio, 1); > + atomic_add(1, folio_pincount_ptr(folio)); > } else { > - page_ref_add(page, GUP_PIN_COUNTING_BIAS); > + folio_ref_add(folio, GUP_PIN_COUNTING_BIAS); > } > > - mod_node_page_state(page_pgdat(page), NR_FOLL_PIN_ACQUIRED, 1); > + node_stat_mod_folio(folio, NR_FOLL_PIN_ACQUIRED, 1); > } > > return true;
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