mm: multi-gen LRU: add helpers in page table walks

Add helpers to page table walking code:
 - Clarifies intent via name "should_walk_mmu" and "should_clear_pmd_young"
 - Avoids repeating same logic in two places

Link: https://lkml.kernel.org/r/20230522112058.2965866-3-talumbau@google.com
Signed-off-by: T.J. Alumbaugh <talumbau@google.com>
Reviewed-by: Yuanchu Xie <yuanchu@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index a51a7e0..dbbfcc6 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3234,6 +3234,16 @@ DEFINE_STATIC_KEY_ARRAY_FALSE(lru_gen_caps, NR_LRU_GEN_CAPS);
 #define get_cap(cap)   static_branch_unlikely(&lru_gen_caps[cap])
 #endif
 
+static bool should_walk_mmu(void)
+{
+       return arch_has_hw_pte_young() && get_cap(LRU_GEN_MM_WALK);
+}
+
+static bool should_clear_pmd_young(void)
+{
+       return arch_has_hw_nonleaf_pmd_young() && get_cap(LRU_GEN_NONLEAF_YOUNG);
+}
+
 /******************************************************************************
  *                          shorthand helpers
  ******************************************************************************/
@@ -4098,7 +4108,7 @@ static void walk_pmd_range_locked(pud_t *pud, unsigned long addr, struct vm_area
                        goto next;
 
                if (!pmd_trans_huge(pmd[i])) {
-                       if (arch_has_hw_nonleaf_pmd_young() && get_cap(LRU_GEN_NONLEAF_YOUNG))
+                       if (should_clear_pmd_young())
                                pmdp_test_and_clear_young(vma, addr, pmd + i);
                        goto next;
                }
@@ -4191,7 +4201,7 @@ restart:
 #endif
                walk->mm_stats[MM_NONLEAF_TOTAL]++;
 
-               if (arch_has_hw_nonleaf_pmd_young() && get_cap(LRU_GEN_NONLEAF_YOUNG)) {
+               if (should_clear_pmd_young()) {
                        if (!pmd_young(val))
                                continue;
 
@@ -4493,7 +4503,7 @@ static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long max_seq,
         * handful of PTEs. Spreading the work out over a period of time usually
         * is less efficient, but it avoids bursty page faults.
         */
-       if (!arch_has_hw_pte_young() || !get_cap(LRU_GEN_MM_WALK)) {
+       if (!should_walk_mmu()) {
                success = iterate_mm_list_nowalk(lruvec, max_seq);
                goto done;
        }
@@ -5730,10 +5740,10 @@ static ssize_t enabled_show(struct kobject *kobj, struct kobj_attribute *attr, c
        if (get_cap(LRU_GEN_CORE))
                caps |= BIT(LRU_GEN_CORE);
 
-       if (arch_has_hw_pte_young() && get_cap(LRU_GEN_MM_WALK))
+       if (should_walk_mmu())
                caps |= BIT(LRU_GEN_MM_WALK);
 
-       if (arch_has_hw_nonleaf_pmd_young() && get_cap(LRU_GEN_NONLEAF_YOUNG))
+       if (should_clear_pmd_young())
                caps |= BIT(LRU_GEN_NONLEAF_YOUNG);
 
        return sysfs_emit(buf, "0x%04x\n", caps);