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@xxxxxxxxxxxxx>
---
mm/gup.c | 28 +++++++++++++---------------
1 file changed, 13 insertions(+), 15 deletions(-)
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
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;
