int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
	unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert,
	struct vm_area_struct *expand)
{
	struct mm_struct *mm = vma->vm_mm;
	struct vm_area_struct *next = vma->vm_next, *orig_vma = vma;
	struct address_space *mapping = NULL;
	struct rb_root_cached *root = NULL;
	struct anon_vma *anon_vma = NULL;
	struct file *file = vma->vm_file;
	bool start_changed = false, end_changed = false;
	long adjust_next = 0;
	int remove_next = 0;

	if (next && !insert) {
		struct vm_area_struct *exporter = NULL, *importer = NULL;

		if (end >= next->vm_end) {
			/*
			 * vma expands, overlapping all the next, and
			 * perhaps the one after too (mprotect case 6).
			 * The only other cases that gets here are
			 * case 1, case 7 and case 8.
			 */
			if (next == expand) {
				/*
				 * The only case where we don't expand "vma"
				 * and we expand "next" instead is case 8.
				 */
				VM_WARN_ON(end != next->vm_end);
				/*
				 * remove_next == 3 means we're
				 * removing "vma" and that to do so we
				 * swapped "vma" and "next".
				 */
				remove_next = 3;
				VM_WARN_ON(file != next->vm_file);
				swap(vma, next);
			} else {
				VM_WARN_ON(expand != vma);
				/*
				 * case 1, 6, 7, remove_next == 2 is case 6,
				 * remove_next == 1 is case 1 or 7.
				 */
				remove_next = 1 + (end > next->vm_end);
				VM_WARN_ON(remove_next == 2 &&
					   end != next->vm_next->vm_end);
				VM_WARN_ON(remove_next == 1 &&
					   end != next->vm_end);
				/* trim end to next, for case 6 first pass */
				end = next->vm_end;
			}

			exporter = next;
			importer = vma;

			/*
			 * If next doesn't have anon_vma, import from vma after
			 * next, if the vma overlaps with it.
			 */
			if (remove_next == 2 && !next->anon_vma)
				exporter = next->vm_next;

		} else if (end > next->vm_start) {
			/*
			 * vma expands, overlapping part of the next:
			 * mprotect case 5 shifting the boundary up.
			 */
			adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
			exporter = next;
			importer = vma;
			VM_WARN_ON(expand != importer);
		} else if (end < vma->vm_end) {
			/*
			 * vma shrinks, and !insert tells it's not
			 * split_vma inserting another: so it must be
			 * mprotect case 4 shifting the boundary down.
			 */
			adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT);
			exporter = vma;
			importer = next;
			VM_WARN_ON(expand != importer);
		}

		/*
		 * Easily overlooked: when mprotect shifts the boundary,
		 * make sure the expanding vma has anon_vma set if the
		 * shrinking vma had, to cover any anon pages imported.
		 */
		if (exporter && exporter->anon_vma && !importer->anon_vma) {
			int error;

			importer->anon_vma = exporter->anon_vma;
			error = anon_vma_clone(importer, exporter);
			if (error)
				return error;
		}
	}
again:
	vma_adjust_trans_huge(orig_vma, start, end, adjust_next);

	if (file) {
		mapping = file->f_mapping;
		root = &mapping->i_mmap;
		uprobe_munmap(vma, vma->vm_start, vma->vm_end);

		if (adjust_next)
			uprobe_munmap(next, next->vm_start, next->vm_end);

		i_mmap_lock_write(mapping);
		if (insert) {
			/*
			 * Put into interval tree now, so instantiated pages
			 * are visible to arm/parisc __flush_dcache_page
			 * throughout; but we cannot insert into address
			 * space until vma start or end is updated.
			 */
			__vma_link_file(insert);
		}
	}

	anon_vma = vma->anon_vma;
	if (!anon_vma && adjust_next)
		anon_vma = next->anon_vma;
	if (anon_vma) {
		VM_WARN_ON(adjust_next && next->anon_vma &&
			   anon_vma != next->anon_vma);
		anon_vma_lock_write(anon_vma);
		anon_vma_interval_tree_pre_update_vma(vma);
		if (adjust_next)
			anon_vma_interval_tree_pre_update_vma(next);
	}

	if (root) {
		flush_dcache_mmap_lock(mapping);
		vma_interval_tree_remove(vma, root);
		if (adjust_next)
			vma_interval_tree_remove(next, root);
	}

	if (start != vma->vm_start) {
		vma->vm_start = start;
		start_changed = true;
	}
	if (end != vma->vm_end) {
		vma->vm_end = end;
		end_changed = true;
	}
	vma->vm_pgoff = pgoff;
	if (adjust_next) {
		next->vm_start += adjust_next << PAGE_SHIFT;
		next->vm_pgoff += adjust_next;
	}

	if (root) {
		if (adjust_next)
			vma_interval_tree_insert(next, root);
		vma_interval_tree_insert(vma, root);
		flush_dcache_mmap_unlock(mapping);
	}

	if (remove_next) {
		/*
		 * vma_merge has merged next into vma, and needs
		 * us to remove next before dropping the locks.
		 */
		if (remove_next != 3)
			__vma_unlink_prev(mm, next, vma);
		else
			/*
			 * vma is not before next if they've been
			 * swapped.
			 *
			 * pre-swap() next->vm_start was reduced so
			 * tell validate_mm_rb to ignore pre-swap()
			 * "next" (which is stored in post-swap()
			 * "vma").
			 */
			__vma_unlink_common(mm, next, NULL, false, vma);
		if (file)
			__remove_shared_vm_struct(next, file, mapping);
	} else if (insert) {
		/*
		 * split_vma has split insert from vma, and needs
		 * us to insert it before dropping the locks
		 * (it may either follow vma or precede it).
		 */
		__insert_vm_struct(mm, insert);
	} else {
		if (start_changed)
			vma_gap_update(vma);
		if (end_changed) {
			if (!next)
				mm->highest_vm_end = vm_end_gap(vma);
			else if (!adjust_next)
				vma_gap_update(next);
		}
	}

	if (anon_vma) {
		anon_vma_interval_tree_post_update_vma(vma);
		if (adjust_next)
			anon_vma_interval_tree_post_update_vma(next);
		anon_vma_unlock_write(anon_vma);
	}
	if (mapping)
		i_mmap_unlock_write(mapping);

	if (root) {
		uprobe_mmap(vma);

		if (adjust_next)
			uprobe_mmap(next);
	}

	if (remove_next) {
		if (file) {
			uprobe_munmap(next, next->vm_start, next->vm_end);
			fput(file);
		}
		if (next->anon_vma)
			anon_vma_merge(vma, next);
		mm->map_count--;
		mpol_put(vma_policy(next));
		kmem_cache_free(vm_area_cachep, next);
		/*
		 * In mprotect's case 6 (see comments on vma_merge),
		 * we must remove another next too. It would clutter
		 * up the code too much to do both in one go.
		 */
		if (remove_next != 3) {
			/*
			 * If "next" was removed and vma->vm_end was
			 * expanded (up) over it, in turn
			 * "next->vm_prev->vm_end" changed and the
			 * "vma->vm_next" gap must be updated.
			 */
			next = vma->vm_next;
		} else {
			/*
			 * For the scope of the comment "next" and
			 * "vma" considered pre-swap(): if "vma" was
			 * removed, next->vm_start was expanded (down)
			 * over it and the "next" gap must be updated.
			 * Because of the swap() the post-swap() "vma"
			 * actually points to pre-swap() "next"
			 * (post-swap() "next" as opposed is now a
			 * dangling pointer).
			 */
			next = vma;
		}
		if (remove_next == 2) {
			remove_next = 1;
			end = next->vm_end;
			goto again;
		}
		else if (next)
			vma_gap_update(next);
		else {
			/*
			 * If remove_next == 2 we obviously can't
			 * reach this path.
			 *
			 * If remove_next == 3 we can't reach this
			 * path because pre-swap() next is always not
			 * NULL. pre-swap() "next" is not being
			 * removed and its next->vm_end is not altered
			 * (and furthermore "end" already matches
			 * next->vm_end in remove_next == 3).
			 *
			 * We reach this only in the remove_next == 1
			 * case if the "next" vma that was removed was
			 * the highest vma of the mm. However in such
			 * case next->vm_end == "end" and the extended
			 * "vma" has vma->vm_end == next->vm_end so
			 * mm->highest_vm_end doesn't need any update
			 * in remove_next == 1 case.
			 */
			VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
		}
	}
	if (insert && file)
		uprobe_mmap(insert);

	validate_mm(mm);

	return 0;
}