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 va0OGdd5 UfpHM9dXo5uD2BrUNuLneNdy29yf3HWHR6hlEh4hzYsUEOdM+isSXiVocyjVU1jFl9ulXqzlAduRzTG/uXWu6vf+y8oGkuj7xChQY0dNa0nKeEaQ= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 12/8/22 2:14 PM, John Hubbard wrote: > On 12/8/22 14:12, Sidhartha Kumar wrote: >> On 12/8/22 2:01 PM, John Hubbard wrote: >>> On 12/8/22 13:58, Sidhartha Kumar wrote: >>>> Thanks John, Mike, Matthew, and Muchun for the feedback. >>>> >>>> To summarize this discussion and outline the next version of this >>>> patch, the changes I'll make include: >>>> >>>> 1) change the name of folio_set_compound_order() to folio_set_order() >>>> 2) change the placement of this function from mm.h to mm/internal.h >>>> 3) folio_set_order() will set both _folio_order and _folio_nr_pages >>>> and handle the zero order case correctly. >>>> 4) remove the comment about hugetlb's specific use for zero orders >>>> 5) improve the style of folio_set_order() by removing ifdefs from >>>> inside the function to doing >>>> >>>> #ifdef CONFIG_64BIT >>>>   static inline void folio_set_order(struct folio *folio, >>>>                   unsigned int order) >>>>   { >>>>       VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); >>> >>> Sounds good, except for this part: why is a function named >>> folio_set_order() BUG-ing on a non-large folio? The naming >>> is still wrong, perhaps? >>> >> >> This is because the _folio_nr_pages and _folio_order fields are part >> of the first tail page in the folio. folio_test_large returns if the >> folio is larger than one page which would be required for setting the >> fields. > > OK, but then as I said, the name is wrong. One can either: > > a) handle the non-large case, or > > b) rename the function to indicate that it only works on large folios. > Discussed here[1], the BUG_ON line seemed more appropriate over if (!folio_test_large(folio)) return; as the misuse would not be silent. I think I would be against renaming the function as I don't see any large folio specific function names for other accessors of tail page fields. Would both the BUG_ON and return on non-large folio be included then? [1]: https://lore.kernel.org/linux-mm/20221129225039.82257-1-sidhartha.kumar@oracle.com/T/#m98cf80bb21ae533b7385f2e363c602e2c9e2802d > > thanks,