[PATCH] mm/khugepaged: replace hugepage_pmd_enabled with hugepage_global_enabled

[Zi Yan]

thp_vma_allowable_orders() is used to guard khugepaged scanning logic in
collapse_scan_mm_slot() based on enabled THP/mTHP orders by only allowing
PMD_ORDER. hugepage_pmd_enabled() is a duplication of it for khugepaged
start/stop control. Simplify the control by checking
hugepage_global_enabled() instead and let thp_vma_allowable_orders() filter
khugepaged scanning.

Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
---
 mm/khugepaged.c | 36 ++++++------------------------------
 1 file changed, 6 insertions(+), 30 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index b8452dbdb043..459c486a5a75 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -406,30 +406,6 @@ static inline int collapse_test_exit_or_disable(struct=
 mm_struct *mm)
 		mm_flags_test(MMF_DISABLE_THP_COMPLETELY, mm);
 }

-static bool hugepage_pmd_enabled(void)
-{
-	/*
-	 * We cover the anon, shmem and the file-backed case here; file-backed
-	 * hugepages, when configured in, are determined by the global control.
-	 * Anon pmd-sized hugepages are determined by the pmd-size control.
-	 * Shmem pmd-sized hugepages are also determined by its pmd-size control,
-	 * except when the global shmem_huge is set to SHMEM_HUGE_DENY.
-	 */
-	if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) &&
-	    hugepage_global_enabled())
-		return true;
-	if (test_bit(PMD_ORDER, &huge_anon_orders_always))
-		return true;
-	if (test_bit(PMD_ORDER, &huge_anon_orders_madvise))
-		return true;
-	if (test_bit(PMD_ORDER, &huge_anon_orders_inherit) &&
-	    hugepage_global_enabled())
-		return true;
-	if (IS_ENABLED(CONFIG_SHMEM) && shmem_hpage_pmd_enabled())
-		return true;
-	return false;
-}
-
 void __khugepaged_enter(struct mm_struct *mm)
 {
 	struct mm_slot *slot;
@@ -463,7 +439,7 @@ void khugepaged_enter_vma(struct vm_area_struct *vma,
 			  vm_flags_t vm_flags)
 {
 	if (!mm_flags_test(MMF_VM_HUGEPAGE, vma->vm_mm) &&
-	    hugepage_pmd_enabled()) {
+	    hugepage_global_enabled()) {
 		if (thp_vma_allowable_order(vma, vm_flags, TVA_KHUGEPAGED, PMD_ORDER))
 			__khugepaged_enter(vma->vm_mm);
 	}
@@ -2599,7 +2575,7 @@ static void collapse_scan_mm_slot(unsigned int progre=
ss_max,

 static int khugepaged_has_work(void)
 {
-	return !list_empty(&khugepaged_scan.mm_head) && hugepage_pmd_enabled();
+	return !list_empty(&khugepaged_scan.mm_head) && hugepage_global_enabled()=
;
 }

 static int khugepaged_wait_event(void)
@@ -2672,7 +2648,7 @@ static void khugepaged_wait_work(void)
 		return;
 	}

-	if (hugepage_pmd_enabled())
+	if (hugepage_global_enabled())
 		wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
 }

@@ -2703,7 +2679,7 @@ void set_recommended_min_free_kbytes(void)
 	int nr_zones =3D 0;
 	unsigned long recommended_min;

-	if (!hugepage_pmd_enabled()) {
+	if (!hugepage_global_enabled()) {
 		calculate_min_free_kbytes();
 		goto update_wmarks;
 	}
@@ -2753,7 +2729,7 @@ int start_stop_khugepaged(void)
 	int err =3D 0;

 	mutex_lock(&khugepaged_mutex);
-	if (hugepage_pmd_enabled()) {
+	if (hugepage_global_enabled()) {
 		if (!khugepaged_thread)
 			khugepaged_thread =3D kthread_run(khugepaged, NULL,
 							"khugepaged");
@@ -2779,7 +2755,7 @@ int start_stop_khugepaged(void)
 void khugepaged_min_free_kbytes_update(void)
 {
 	mutex_lock(&khugepaged_mutex);
-	if (hugepage_pmd_enabled() && khugepaged_thread)
+	if (hugepage_global_enabled() && khugepaged_thread)
 		set_recommended_min_free_kbytes();
 	mutex_unlock(&khugepaged_mutex);
 }
--=20
2.43.0



>
>>
>> BTW, this conflicts with Patch 12 from Nico=E2=80=99s khugepaged for mTH=
P patchset.
>
> Right. I guess it can be handled.
>
> --=20
> Cheers,
>
> David


Best Regards,
Yan, Zi