On 12/16/22 14:27, Andrew Morton wrote:
On Tue, 13 Dec 2022 13:20:53 -0800 Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx> wrote:
folio_set_compound_order() is moved to an mm-internal location so external
folio users cannot misuse this function. Change the name of the function
to folio_set_order() and use WARN_ON_ONCE() rather than BUG_ON. Also,
handle the case if a non-large folio is passed and add clarifying comments
to the function.
This differs from the version I previously merged:
--- a/mm/internal.h~mm-move-folio_set_compound_order-to-mm-internalh-update
+++ a/mm/internal.h
@@ -384,8 +384,10 @@ int split_free_page(struct page *free_pa
*/
static inline void folio_set_order(struct folio *folio, unsigned int order)
{
- if (WARN_ON_ONCE(!folio_test_large(folio)))
+ if (!folio_test_large(folio)) {
+ WARN_ON_ONCE(order);
return;
+ }
I think that's out of date?
We eventually settled on the version that is (as of this a few minutes
ago) already in mm-unstable (commit fdea060a130d: "mm: move
folio_set_compound_order() to mm/internal.h"), which has it like this:
if (WARN_ON_ONCE(!folio_test_large(folio)))
return;
folio->_folio_order = order;
#ifdef CONFIG_64BIT
Makes sense. But wouldn't
if (WARN_ON_ONCE(order && !folio_test_large(folio)))
be clearer?
That's a little narrower of a check. But maybe that's desirable. Could
someone (Mike, Muchun, Sidhartha) comment on which behavior is
preferable, please? I think I'm a little dizzy at this point. :)
thanks,
--
John Hubbard
NVIDIA
