Adding upstream version 6.7.7.upstream/6.7.7

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 86 insertions, 21 deletions

diff --git a/mm/mremap.c b/mm/mremap.c
index 382e81c33f..38d98465f3 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -489,10 +489,62 @@ static bool move_pgt_entry(enum pgt_entry entry, struct vm_area_struct *vma,
 	return moved;
 }
 
+/*
+ * A helper to check if aligning down is OK. The aligned address should fall
+ * on *no mapping*. For the stack moving down, that's a special move within
+ * the VMA that is created to span the source and destination of the move,
+ * so we make an exception for it.
+ */
+static bool can_align_down(struct vm_area_struct *vma, unsigned long addr_to_align,
+			    unsigned long mask, bool for_stack)
+{
+	unsigned long addr_masked = addr_to_align & mask;
+
+	/*
+	 * If @addr_to_align of either source or destination is not the beginning
+	 * of the corresponding VMA, we can't align down or we will destroy part
+	 * of the current mapping.
+	 */
+	if (!for_stack && vma->vm_start != addr_to_align)
+		return false;
+
+	/* In the stack case we explicitly permit in-VMA alignment. */
+	if (for_stack && addr_masked >= vma->vm_start)
+		return true;
+
+	/*
+	 * Make sure the realignment doesn't cause the address to fall on an
+	 * existing mapping.
+	 */
+	return find_vma_intersection(vma->vm_mm, addr_masked, vma->vm_start) == NULL;
+}
+
+/* Opportunistically realign to specified boundary for faster copy. */
+static void try_realign_addr(unsigned long *old_addr, struct vm_area_struct *old_vma,
+			     unsigned long *new_addr, struct vm_area_struct *new_vma,
+			     unsigned long mask, bool for_stack)
+{
+	/* Skip if the addresses are already aligned. */
+	if ((*old_addr & ~mask) == 0)
+		return;
+
+	/* Only realign if the new and old addresses are mutually aligned. */
+	if ((*old_addr & ~mask) != (*new_addr & ~mask))
+		return;
+
+	/* Ensure realignment doesn't cause overlap with existing mappings. */
+	if (!can_align_down(old_vma, *old_addr, mask, for_stack) ||
+	    !can_align_down(new_vma, *new_addr, mask, for_stack))
+		return;
+
+	*old_addr = *old_addr & mask;
+	*new_addr = *new_addr & mask;
+}
+
 unsigned long move_page_tables(struct vm_area_struct *vma,
 		unsigned long old_addr, struct vm_area_struct *new_vma,
 		unsigned long new_addr, unsigned long len,
-		bool need_rmap_locks)
+		bool need_rmap_locks, bool for_stack)
 {
 	unsigned long extent, old_end;
 	struct mmu_notifier_range range;
@@ -508,6 +560,14 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
 		return move_hugetlb_page_tables(vma, new_vma, old_addr,
 						new_addr, len);
 
+	/*
+	 * If possible, realign addresses to PMD boundary for faster copy.
+	 * Only realign if the mremap copying hits a PMD boundary.
+	 */
+	if (len >= PMD_SIZE - (old_addr & ~PMD_MASK))
+		try_realign_addr(&old_addr, vma, &new_addr, new_vma, PMD_MASK,
+				 for_stack);
+
 	flush_cache_range(vma, old_addr, old_end);
 	mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma->vm_mm,
 				old_addr, old_end);
@@ -577,6 +637,13 @@ again:
 
 	mmu_notifier_invalidate_range_end(&range);
 
+	/*
+	 * Prevent negative return values when {old,new}_addr was realigned
+	 * but we broke out of the above loop for the first PMD itself.
+	 */
+	if (len + old_addr < old_end)
+		return 0;
+
 	return len + old_addr - old_end;	/* how much done */
 }
 
@@ -646,7 +713,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
 	}
 
 	moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len,
-				     need_rmap_locks);
+				     need_rmap_locks, false);
 	if (moved_len < old_len) {
 		err = -ENOMEM;
 	} else if (vma->vm_ops && vma->vm_ops->mremap) {
@@ -660,7 +727,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
 		 * and then proceed to unmap new area instead of old.
 		 */
 		move_page_tables(new_vma, new_addr, vma, old_addr, moved_len,
-				 true);
+				 true, false);
 		vma = new_vma;
 		old_len = new_len;
 		old_addr = new_addr;
@@ -1029,36 +1096,34 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 	/* old_len exactly to the end of the area..
 	 */
 	if (old_len == vma->vm_end - addr) {
+		unsigned long delta = new_len - old_len;
+
 		/* can we just expand the current mapping? */
-		if (vma_expandable(vma, new_len - old_len)) {
-			long pages = (new_len - old_len) >> PAGE_SHIFT;
-			unsigned long extension_start = addr + old_len;
-			unsigned long extension_end = addr + new_len;
-			pgoff_t extension_pgoff = vma->vm_pgoff +
-				((extension_start - vma->vm_start) >> PAGE_SHIFT);
-			VMA_ITERATOR(vmi, mm, extension_start);
+		if (vma_expandable(vma, delta)) {
+			long pages = delta >> PAGE_SHIFT;
+			VMA_ITERATOR(vmi, mm, vma->vm_end);
+			long charged = 0;
 
 			if (vma->vm_flags & VM_ACCOUNT) {
 				if (security_vm_enough_memory_mm(mm, pages)) {
 					ret = -ENOMEM;
 					goto out;
 				}
+				charged = pages;
 			}
 
 			/*
-			 * Function vma_merge() is called on the extension we
-			 * are adding to the already existing vma, vma_merge()
-			 * will merge this extension with the already existing
-			 * vma (expand operation itself) and possibly also with
-			 * the next vma if it becomes adjacent to the expanded
-			 * vma and  otherwise compatible.
+			 * Function vma_merge_extend() is called on the
+			 * extension we are adding to the already existing vma,
+			 * vma_merge_extend() will merge this extension with the
+			 * already existing vma (expand operation itself) and
+			 * possibly also with the next vma if it becomes
+			 * adjacent to the expanded vma and otherwise
+			 * compatible.
 			 */
-			vma = vma_merge(&vmi, mm, vma, extension_start,
-				extension_end, vma->vm_flags, vma->anon_vma,
-				vma->vm_file, extension_pgoff, vma_policy(vma),
-				vma->vm_userfaultfd_ctx, anon_vma_name(vma));
+			vma = vma_merge_extend(&vmi, vma, delta);
 			if (!vma) {
-				vm_unacct_memory(pages);
+				vm_unacct_memory(charged);
 				ret = -ENOMEM;
 				goto out;
 			}