On 24.04.24 21:19, Matthew Wilcox (Oracle) wrote:
Nit: s/gup_devmap/gup_fast_devmap/
Use try_grab_folio() instead of try_grab_page() so we get the folio
back that we calculated, and then use folio_set_referenced() instead
of SetPageReferenced(). Correspondingly, use gup_put_folio() to
put any unneeded references.
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
mm/gup.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index 49376f756936..e4cc12b8e985 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2877,13 +2877,10 @@ static void __maybe_unused gup_fast_undo_dev_pagemap(int *nr, int nr_start,
unsigned int flags, struct page **pages)
{
while ((*nr) - nr_start) {
- struct page *page = pages[--(*nr)];
+ struct folio *folio = page_folio(pages[--(*nr)]);
- ClearPageReferenced(page);
I stumbled over that likely unwarranted ClearPageReferenced() recently
as well: what if the page was already referenced before we called
SetPageReferenced?
- if (flags & FOLL_PIN)
- unpin_user_page(page);
- else
- put_page(page);
+ folio_clear_referenced(folio);
+ gup_put_folio(folio, 1, flags);
For !FOLL_PIN, we wouldn't have done the
if (!put_devmap_managed_page_refs(&folio->page, refs))
folio_put_refs(folio, refs);
Magic in gup_put_folio()
... was that a BUG?
This devmap crap is so confusing.
--
Cheers,
David / dhildenb
