[PATCH 2/2] mm: khugepaged: kick khugepaged for enabling none-PMD-sized mTHPs

[Baolin Wang]

When only non-PMD-sized mTHP is enabled (such as only 64K mTHP enabled),
we should also allow kicking khugepaged to attempt scanning and collapsing
64K mTHP. Modify hugepage_pmd_enabled() to support mTHP collapse, and
while we are at it, rename it to make the function name more clear.

Signed-off-by: Baolin Wang <baolin.w...@linux.alibaba.com>
---
 mm/khugepaged.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 16542ecf02dc..155ef8d286e2 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -430,7 +430,7 @@ static inline int khugepaged_test_exit_or_disable(struct 
mm_struct *mm)
               test_bit(MMF_DISABLE_THP, &mm->flags);
 }
 
-static bool hugepage_pmd_enabled(void)
+static bool hugepage_enabled(void)
 {
        /*
         * We cover the anon, shmem and the file-backed case here; file-backed
@@ -442,11 +442,11 @@ static bool hugepage_pmd_enabled(void)
        if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) &&
            hugepage_global_enabled())
                return true;
-       if (test_bit(PMD_ORDER, &huge_anon_orders_always))
+       if (READ_ONCE(huge_anon_orders_always))
                return true;
-       if (test_bit(PMD_ORDER, &huge_anon_orders_madvise))
+       if (READ_ONCE(huge_anon_orders_madvise))
                return true;
-       if (test_bit(PMD_ORDER, &huge_anon_orders_inherit) &&
+       if (READ_ONCE(huge_anon_orders_inherit) &&
            hugepage_global_enabled())
                return true;
        if (IS_ENABLED(CONFIG_SHMEM) && shmem_hpage_pmd_enabled())
@@ -490,7 +490,7 @@ void khugepaged_enter_vma(struct vm_area_struct *vma,
                          unsigned long vm_flags)
 {
        if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
-           hugepage_pmd_enabled()) {
+           hugepage_enabled()) {
                unsigned long orders = vma_is_anonymous(vma) ?
                                        THP_ORDERS_ALL_ANON : BIT(PMD_ORDER);
 
@@ -2711,7 +2711,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int 
pages, int *result,
 
 static int khugepaged_has_work(void)
 {
-       return !list_empty(&khugepaged_scan.mm_head) && hugepage_pmd_enabled();
+       return !list_empty(&khugepaged_scan.mm_head) && hugepage_enabled();
 }
 
 static int khugepaged_wait_event(void)
@@ -2784,7 +2784,7 @@ static void khugepaged_wait_work(void)
                return;
        }
 
-       if (hugepage_pmd_enabled())
+       if (hugepage_enabled())
                wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
 }
 
@@ -2815,7 +2815,7 @@ static void set_recommended_min_free_kbytes(void)
        int nr_zones = 0;
        unsigned long recommended_min;
 
-       if (!hugepage_pmd_enabled()) {
+       if (!hugepage_enabled()) {
                calculate_min_free_kbytes();
                goto update_wmarks;
        }
@@ -2865,7 +2865,7 @@ int start_stop_khugepaged(void)
        int err = 0;
 
        mutex_lock(&khugepaged_mutex);
-       if (hugepage_pmd_enabled()) {
+       if (hugepage_enabled()) {
                if (!khugepaged_thread)
                        khugepaged_thread = kthread_run(khugepaged, NULL,
                                                        "khugepaged");
@@ -2891,7 +2891,7 @@ int start_stop_khugepaged(void)
 void khugepaged_min_free_kbytes_update(void)
 {
        mutex_lock(&khugepaged_mutex);
-       if (hugepage_pmd_enabled() && khugepaged_thread)
+       if (hugepage_enabled() && khugepaged_thread)
                set_recommended_min_free_kbytes();
        mutex_unlock(&khugepaged_mutex);
 }
-- 
2.43.5