[RFC 06/11] khugepaged: generalize alloc_charge_folio for mTHP support

Nico Pache
2025-01-08T23:34:04Z

alloc_charge_folio allocates the new folio for the khugepaged collapse.
Generalize the order of the folio allocations to support future mTHP
collapsing.

No functional changes in this patch.

Signed-off-by: Nico Pache <npache@redhat.com>
---
mm/khugepaged.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index e2e6ca9265ab..6daf3a943a1a 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1070,14 +1070,14 @@ static int __collapse_huge_page_swapin(struct mm_struct *mm,
}

static int alloc_charge_folio(struct folio **foliop, struct mm_struct *mm,
- struct collapse_control *cc)
+ struct collapse_control *cc, int order)
{
gfp_t gfp = (cc->is_khugepaged ? alloc_hugepage_khugepaged_gfpmask() :
GFP_TRANSHUGE);
int node = khugepaged_find_target_node(cc);
struct folio *folio;

- folio = __folio_alloc(gfp, HPAGE_PMD_ORDER, node, &cc->alloc_nmask);
+ folio = __folio_alloc(gfp, order, node, &cc->alloc_nmask);
if (!folio) {
*foliop = NULL;
count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
@@ -1121,7 +1121,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
*/
mmap_read_unlock(mm);

- result = alloc_charge_folio(&folio, mm, cc);
+ result = alloc_charge_folio(&folio, mm, cc, HPAGE_PMD_ORDER);
if (result != SCAN_SUCCEED)
goto out_nolock;

@@ -1834,7 +1834,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem);
VM_BUG_ON(start & (HPAGE_PMD_NR - 1));

- result = alloc_charge_folio(&new_folio, mm, cc);
+ result = alloc_charge_folio(&new_folio, mm, cc, HPAGE_PMD_ORDER);
if (result != SCAN_SUCCEED)
goto out;

--
2.47.1