On Tue, Dec 07, 2021 at 01:50:30PM -0800, Suren Baghdasaryan wrote:

- Added a comment for vm_operations_struct::close, documenting restriction for
taking mmap_lock in the callback, per Michal Hocko and Matthew Wilcox

This should be a separate patch because it stands alone, but ...

 struct vm_operations_struct {
 	void (*open)(struct vm_area_struct * area);
+    /*
+     * Called with mmap_lock lock held for write from __split_vma and
+     * remove_vma, therefore should never take that lock.
+     */

Your whitespace indentation is weird.  And it'd be nice to make this a
kernel-doc comment (I know none of the others are, but that should be
fixed too).  And naming the functions that call it is wrong too.

	/**
	 * @close: Called when the VMA is being removed from the MM.
	 * Context: Caller holds mmap_lock.
	 */