FAILED: patch "[PATCH] mm/madvise: make MADV_POPULATE_(READ|WRITE) handle" failed to apply to 6.1-stable tree

index af8edadc05d1..1611e73b1121 100644
@@ -1206,6 +1206,22 @@ static long __get_user_pages(struct mm_struct *mm,
 
 		/* first iteration or cross vma bound */
 		if (!vma || start >= vma->vm_end) {
+			/*
+			 * MADV_POPULATE_(READ|WRITE) wants to handle VMA
+			 * lookups+error reporting differently.
+			 */
+			if (gup_flags & FOLL_MADV_POPULATE) {
+				vma = vma_lookup(mm, start);
+				if (!vma) {
+					ret = -ENOMEM;
+					goto out;
+				}
+				if (check_vma_flags(vma, gup_flags)) {
+					ret = -EINVAL;
+					goto out;
+				}
+				goto retry;
+			}
 			vma = gup_vma_lookup(mm, start);
 			if (!vma && in_gate_area(mm, start)) {
 				ret = get_gate_page(mm, start & PAGE_MASK,

@@ -1685,35 +1701,35 @@ long populate_vma_page_range(struct vm_area_struct *vma,
 }
 
 /*
- * faultin_vma_page_range() - populate (prefault) page tables inside the
- *			      given VMA range readable/writable
+ * faultin_page_range() - populate (prefault) page tables inside the
+ *			  given range readable/writable
  *
  * This takes care of mlocking the pages, too, if VM_LOCKED is set.
  *
- * @vma: target vma
+ * @mm: the mm to populate page tables in
  * @start: start address
  * @end: end address
  * @write: whether to prefault readable or writable
  * @locked: whether the mmap_lock is still held
  *
- * Returns either number of processed pages in the vma, or a negative error
- * code on error (see __get_user_pages()).
+ * Returns either number of processed pages in the MM, or a negative error
+ * code on error (see __get_user_pages()). Note that this function reports
+ * errors related to VMAs, such as incompatible mappings, as expected by
+ * MADV_POPULATE_(READ|WRITE).
  *
- * vma->vm_mm->mmap_lock must be held. The range must be page-aligned and
- * covered by the VMA. If it's released, *@locked will be set to 0.
+ * The range must be page-aligned.
+ *
+ * mm->mmap_lock must be held. If it's released, *@locked will be set to 0.
  */
-long faultin_vma_page_range(struct vm_area_struct *vma, unsigned long start,
-			    unsigned long end, bool write, int *locked)
+long faultin_page_range(struct mm_struct *mm, unsigned long start,
+			unsigned long end, bool write, int *locked)
 {
-	struct mm_struct *mm = vma->vm_mm;
 	unsigned long nr_pages = (end - start) / PAGE_SIZE;
 	int gup_flags;
 	long ret;
 
 	VM_BUG_ON(!PAGE_ALIGNED(start));
 	VM_BUG_ON(!PAGE_ALIGNED(end));
-	VM_BUG_ON_VMA(start < vma->vm_start, vma);
-	VM_BUG_ON_VMA(end > vma->vm_end, vma);
 	mmap_assert_locked(mm);
 
 	/*

@@ -1725,19 +1741,13 @@ long faultin_vma_page_range(struct vm_area_struct *vma, unsigned long start,
 	 *		  a poisoned page.
 	 * !FOLL_FORCE: Require proper access permissions.
 	 */
-	gup_flags = FOLL_TOUCH | FOLL_HWPOISON | FOLL_UNLOCKABLE;
+	gup_flags = FOLL_TOUCH | FOLL_HWPOISON | FOLL_UNLOCKABLE |
+		    FOLL_MADV_POPULATE;
 	if (write)
 		gup_flags |= FOLL_WRITE;
 
-	/*
-	 * We want to report -EINVAL instead of -EFAULT for any permission
-	 * problems or incompatible mappings.
-	 */
-	if (check_vma_flags(vma, gup_flags))
-		return -EINVAL;
-
-	ret = __get_user_pages(mm, start, nr_pages, gup_flags,
-			       NULL, locked);
+	ret = __get_user_pages_locked(mm, start, nr_pages, NULL, locked,
+				      gup_flags);
 	lru_add_drain();
 	return ret;
 }

index 7e486f2c502c..07ad2675a88b 100644
@@ -686,9 +686,8 @@ struct anon_vma *folio_anon_vma(struct folio *folio);
 void unmap_mapping_folio(struct folio *folio);
 extern long populate_vma_page_range(struct vm_area_struct *vma,
 		unsigned long start, unsigned long end, int *locked);
-extern long faultin_vma_page_range(struct vm_area_struct *vma,
-				   unsigned long start, unsigned long end,
-				   bool write, int *locked);
+extern long faultin_page_range(struct mm_struct *mm, unsigned long start,
+		unsigned long end, bool write, int *locked);
 extern bool mlock_future_ok(struct mm_struct *mm, unsigned long flags,
 			       unsigned long bytes);
 

@@ -1127,10 +1126,13 @@ enum {
 	FOLL_FAST_ONLY = 1 << 20,
 	/* allow unlocking the mmap lock */
 	FOLL_UNLOCKABLE = 1 << 21,
+	/* VMA lookup+checks compatible with MADV_POPULATE_(READ|WRITE) */
+	FOLL_MADV_POPULATE = 1 << 22,
 };
 
 #define INTERNAL_GUP_FLAGS (FOLL_TOUCH | FOLL_TRIED | FOLL_REMOTE | FOLL_PIN | \
-			    FOLL_FAST_ONLY | FOLL_UNLOCKABLE)
+			    FOLL_FAST_ONLY | FOLL_UNLOCKABLE | \
+			    FOLL_MADV_POPULATE)
 
 /*
  * Indicates for which pages that are write-protected in the page table,

index 44a498c94158..1a073fcc4c0c 100644
@@ -908,27 +908,14 @@ static long madvise_populate(struct vm_area_struct *vma,
 {
 	const bool write = behavior == MADV_POPULATE_WRITE;
 	struct mm_struct *mm = vma->vm_mm;
-	unsigned long tmp_end;
 	int locked = 1;
 	long pages;
 
 	*prev = vma;
 
 	while (start < end) {
-		/*
-		 * We might have temporarily dropped the lock. For example,
-		 * our VMA might have been split.
-		 */
-		if (!vma || start >= vma->vm_end) {
-			vma = vma_lookup(mm, start);
-			if (!vma)
-				return -ENOMEM;
-		}
-
-		tmp_end = min_t(unsigned long, end, vma->vm_end);
 		/* Populate (prefault) page tables readable/writable. */
-		pages = faultin_vma_page_range(vma, start, tmp_end, write,
-					       &locked);
+		pages = faultin_page_range(mm, start, end, write, &locked);
 		if (!locked) {
 			mmap_read_lock(mm);
 			locked = 1;

@@ -949,7 +936,7 @@ static long madvise_populate(struct vm_area_struct *vma,
 				pr_warn_once("%s: unhandled return value: %ld\n",
 					     __func__, pages);
 				fallthrough;
-			case -ENOMEM:
+			case -ENOMEM: /* No VMA or out of memory. */
 				return -ENOMEM;
 			}
 		}