| Date | Mon, 10 Jan 2022 20:14:04 -0800 | Subject | Re: [PATCH v2 12/28] mm: Add folio_put_refs() | From | John Hubbard <> |
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On 1/9/22 20:23, Matthew Wilcox (Oracle) wrote: > This is like folio_put(), but puts N references at once instead of > just one. It's like put_page_refs(), but does one atomic operation > instead of two, and is available to more than just gup.c. > > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > --- > include/linux/mm.h | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 598be27d4d2e..bf9624ca61c3 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -1234,6 +1234,26 @@ static inline void folio_put(struct folio *folio) > __put_page(&folio->page); > } > > +/** > + * folio_put_refs - Reduce the reference count on a folio. > + * @folio: The folio. > + * @refs: The number of references to reduce.
Tiny rewording suggestion, if you end up sending another version:
* @refs: The amount to subtract from the folio's reference count.
> + * > + * If the folio's reference count reaches zero, the memory will be > + * released back to the page allocator and may be used by another > + * allocation immediately. Do not access the memory or the struct folio > + * after calling folio_put_refs() unless you can be sure that these weren't > + * the last references. > + * > + * Context: May be called in process or interrupt context, but not in NMI > + * context. May be called while holding a spinlock. > + */ > +static inline void folio_put_refs(struct folio *folio, int refs) > +{ > + if (folio_ref_sub_and_test(folio, refs)) > + __put_page(&folio->page); > +} > + > static inline void put_page(struct page *page) > { > struct folio *folio = page_folio(page);
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
thanks, -- John Hubbard NVIDIA
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