1 files changed, 31 insertions, 24 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2f2a521e5d68..1192e62531cd 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1642,17 +1642,30 @@ vm_fault_t vmf_insert_folio_pud(struct vm_fault *vmf, struct folio *folio,
 EXPORT_SYMBOL_GPL(vmf_insert_folio_pud);
 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 
-void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
+/**
+ * touch_pmd - Mark page table pmd entry as accessed and dirty (for write)
+ * @vma: The VMA covering @addr
+ * @addr: The virtual address
+ * @pmd: pmd pointer into the page table mapping @addr
+ * @write: Whether it's a write access
+ *
+ * Return: whether the pmd entry is changed
+ */
+bool touch_pmd(struct vm_area_struct *vma, unsigned long addr,
 	       pmd_t *pmd, bool write)
 {
-	pmd_t _pmd;
+	pmd_t entry;
 
-	_pmd = pmd_mkyoung(*pmd);
+	entry = pmd_mkyoung(*pmd);
 	if (write)
-		_pmd = pmd_mkdirty(_pmd);
+		entry = pmd_mkdirty(entry);
 	if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
-				  pmd, _pmd, write))
+				  pmd, entry, write)) {
 		update_mmu_cache_pmd(vma, addr, pmd);
+		return true;
+	}
+
+	return false;
 }
 
 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
@@ -1842,18 +1855,14 @@ unlock:
 }
 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 
-void huge_pmd_set_accessed(struct vm_fault *vmf)
+bool huge_pmd_set_accessed(struct vm_fault *vmf)
 {
 	bool write = vmf->flags & FAULT_FLAG_WRITE;
 
-	vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
 	if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd)))
-		goto unlock;
-
-	touch_pmd(vmf->vma, vmf->address, vmf->pmd, write);
+		return false;
 
-unlock:
-	spin_unlock(vmf->ptl);
+	return touch_pmd(vmf->vma, vmf->address, vmf->pmd, write);
 }
 
 static vm_fault_t do_huge_zero_wp_pmd(struct vm_fault *vmf)
@@ -3619,6 +3628,16 @@ static int __folio_split(struct folio *folio, unsigned int new_order,
 	if (folio != page_folio(split_at) || folio != page_folio(lock_at))
 		return -EINVAL;
 
+	/*
+	 * Folios that just got truncated cannot get split. Signal to the
+	 * caller that there was a race.
+	 *
+	 * TODO: this will also currently refuse shmem folios that are in the
+	 * swapcache.
+	 */
+	if (!is_anon && !folio->mapping)
+		return -EBUSY;
+
 	if (new_order >= folio_order(folio))
 		return -EINVAL;
 
@@ -3659,18 +3678,6 @@ static int __folio_split(struct folio *folio, unsigned int new_order,
 		gfp_t gfp;
 
 		mapping = folio->mapping;
-
-		/* Truncated ? */
-		/*
-		 * TODO: add support for large shmem folio in swap cache.
-		 * When shmem is in swap cache, mapping is NULL and
-		 * folio_test_swapcache() is true.
-		 */
-		if (!mapping) {
-			ret = -EBUSY;
-			goto out;
-		}
-
 		min_order = mapping_min_folio_order(folio->mapping);
 		if (new_order < min_order) {
 			ret = -EINVAL;