From: Ran Xiaokai <[email protected]>
is_transparent_hugepage() was first introduced to ensure the page is
2M THP page. After commit de53c05f2ae3 ("mm: add large_rmappable
page flag") and commit fc4d182316bd ("mm: huge_memory: enable debugfs
to split huge pages to any order"), any large folio of mTHP suitable order
can be split, not only 2M THP page.
so the check in split_huge_pages_pid() is not needed here, instead
a folio_test_large() check is sufficient. To ensure a 2M THP folio,
we should use "folio_order(folio) == HPAGE_PMD_ORDER" for now.
As split_huge_pages_pid() is the only user of is_transparent_hugepage(),
we can remove this helper.
Signed-off-by: Ran Xiaokai <[email protected]>
---
mm/huge_memory.c | 11 +----------
1 file changed, 1 insertion(+), 10 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 317de2afd371..f1a992945007 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -839,15 +839,6 @@ struct deferred_split *get_deferred_split_queue(struct folio *folio)
}
#endif
-static inline bool is_transparent_hugepage(const struct folio *folio)
-{
- if (!folio_test_large(folio))
- return false;
-
- return is_huge_zero_folio(folio) ||
- folio_test_large_rmappable(folio);
-}
-
static unsigned long __thp_get_unmapped_area(struct file *filp,
unsigned long addr, unsigned long len,
loff_t off, unsigned long flags, unsigned long size,
@@ -3439,7 +3430,7 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
continue;
folio = page_folio(page);
- if (!is_transparent_hugepage(folio))
+ if (!folio_test_large(folio))
goto next;
if (new_order >= folio_order(folio))
--
2.15.2
On 05.06.24 10:37, [email protected] wrote:
> From: Ran Xiaokai <[email protected]>
>
> is_transparent_hugepage() was first introduced to ensure the page is
> 2M THP page. After commit de53c05f2ae3 ("mm: add large_rmappable
> page flag") and commit fc4d182316bd ("mm: huge_memory: enable debugfs
> to split huge pages to any order"), any large folio of mTHP suitable order
> can be split, not only 2M THP page.
Yes.
> so the check in split_huge_pages_pid() is not needed here, instead
> a folio_test_large() check is sufficient. To ensure a 2M THP folio,
> we should use "folio_order(folio) == HPAGE_PMD_ORDER" for now.
What about some kernel-allocated large folio that got mapped using
vm_insert_pages() and friends? Are we sure these pages (that are not
large_rmappable and not splittable) are properly handled?
--
Cheers,
David / dhildenb