[PATCH v3 3/3] mm: huge_memory: use folio_needs_prot_numa() for pmd folio

[Kefeng Wang <wangkefeng.wang@huawei.com>]

Rename prot_numa_skip() to folio_needs_prot_numa(), and remove
ret by directly return value instead of goto style.

The folio checks for prot numa should be suitable for pmd folio
too, which helps to avoid unnecessary pmd change and folio
migration attempts.

Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 mm/huge_memory.c | 21 +++++++--------------
 mm/internal.h    |  2 ++
 mm/mprotect.c    | 45 +++++++++++++++++++++++----------------------
 3 files changed, 32 insertions(+), 36 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 1d1b74950332..c7364dcb96c1 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2395,8 +2395,7 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 #endif
 
 	if (prot_numa) {
-		struct folio *folio;
-		bool toptier;
+		int target_node = NUMA_NO_NODE;
 		/*
 		 * Avoid trapping faults against the zero page. The read-only
 		 * data is likely to be read-cached on the local CPU and
@@ -2408,19 +2407,13 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		if (pmd_protnone(*pmd))
 			goto unlock;
 
-		folio = pmd_folio(*pmd);
-		toptier = node_is_toptier(folio_nid(folio));
-		/*
-		 * Skip scanning top tier node if normal numa
-		 * balancing is disabled
-		 */
-		if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
-		    toptier)
-			goto unlock;
+		/* Get target node for single threaded private VMAs */
+		if (!(vma->vm_flags & VM_SHARED) &&
+		    atomic_read(&vma->vm_mm->mm_users) == 1)
+			target_node = numa_node_id();
 
-		if (folio_use_access_time(folio))
-			folio_xchg_access_time(folio,
-					       jiffies_to_msecs(jiffies));
+		if (!folio_needs_prot_numa(pmd_folio(*pmd), vma, target_node))
+			goto unlock;
 	}
 	/*
 	 * In case prot_numa, we are under mmap_read_lock(mm). It's critical
diff --git a/mm/internal.h b/mm/internal.h
index 1561fc2ff5b8..5f63d5c049b1 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1378,6 +1378,8 @@ void vunmap_range_noflush(unsigned long start, unsigned long end);
 
 void __vunmap_range_noflush(unsigned long start, unsigned long end);
 
+bool folio_needs_prot_numa(struct folio *folio, struct vm_area_struct *vma,
+		int target_node);
 int numa_migrate_check(struct folio *folio, struct vm_fault *vmf,
 		      unsigned long addr, int *flags, bool writable,
 		      int *last_cpupid);
diff --git a/mm/mprotect.c b/mm/mprotect.c
index ed44aadb7aaa..0ae8f4a277b2 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -118,26 +118,30 @@ static int mprotect_folio_pte_batch(struct folio *folio, pte_t *ptep,
 	return folio_pte_batch_flags(folio, NULL, ptep, &pte, max_nr_ptes, flags);
 }
 
-static bool prot_numa_skip(struct vm_area_struct *vma, int target_node,
-		struct folio *folio)
+/**
+ * folio_needs_prot_numa() - Whether the folio needs prot numa
+ * @folio: The folio.
+ * @vma: The VMA mapping.
+ * @target_node: The numa node being accessed.
+ *
+ * Return: Returns true if folio needs prot numa and the access time of
+ *	   folio is adjusted. Returns false otherwise.
+ */
+bool folio_needs_prot_numa(struct folio *folio, struct vm_area_struct *vma,
+		int target_node)
 {
-	bool ret = true;
-	bool toptier;
 	int nid;
 
-	if (!folio)
-		goto skip;
-
-	if (folio_is_zone_device(folio) || folio_test_ksm(folio))
-		goto skip;
+	if (!folio || folio_is_zone_device(folio) || folio_test_ksm(folio))
+		return false;
 
 	/* Also skip shared copy-on-write folios */
 	if (is_cow_mapping(vma->vm_flags) && folio_maybe_mapped_shared(folio))
-		goto skip;
+		return false;
 
 	/* Folios are pinned and can't be migrated */
 	if (folio_maybe_dma_pinned(folio))
-		goto skip;
+		return false;
 
 	/*
 	 * While migration can move some dirty pages,
@@ -145,7 +149,7 @@ static bool prot_numa_skip(struct vm_area_struct *vma, int target_node,
 	 * context.
 	 */
 	if (folio_is_file_lru(folio) && folio_test_dirty(folio))
-		goto skip;
+		return false;
 
 	/*
 	 * Don't mess with PTEs if page is already on the node
@@ -153,23 +157,20 @@ static bool prot_numa_skip(struct vm_area_struct *vma, int target_node,
 	 */
 	nid = folio_nid(folio);
 	if (target_node == nid)
-		goto skip;
-
-	toptier = node_is_toptier(nid);
+		return false;
 
 	/*
 	 * Skip scanning top tier node if normal numa
 	 * balancing is disabled
 	 */
-	if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && toptier)
-		goto skip;
+	if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
+	    node_is_toptier(nid))
+		return false;
 
-	ret = false;
 	if (folio_use_access_time(folio))
 		folio_xchg_access_time(folio, jiffies_to_msecs(jiffies));
 
-skip:
-	return ret;
+	return true;
 }
 
 /* Set nr_ptes number of ptes, starting from idx */
@@ -314,8 +315,8 @@ static long change_pte_range(struct mmu_gather *tlb,
 			 * Avoid trapping faults against the zero or KSM
 			 * pages. See similar comment in change_huge_pmd.
 			 */
-			if (prot_numa && prot_numa_skip(vma, target_node,
-							folio)) {
+			if (prot_numa && !folio_needs_prot_numa(folio, vma,
+								target_node)) {
 				/* determine batch to skip */
 				nr_ptes = mprotect_folio_pte_batch(folio,
 					  pte, oldpte, max_nr_ptes, /* flags = */ 0);
-- 
2.27.0