mm/vma: drop incorrect comment from vms_gather_munmap_vmas()

The comment has been outdated since 6b73cff2 ("mm: change munmap
splitting order and move_vma()").  The move_vma() was altered to fix the
fragile state of the accounting since then.

Link: https://lkml.kernel.org/r/20240830040101.822209-21-Liam.Howlett@oracle.comSigned-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Bert Karwatzki <spasswolf@web.de>
Cc: Jeff Xu <jeffxu@chromium.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vma.c

@@ -755,13 +755,8 @@ int vms_gather_munmap_vmas(struct vma_munmap_struct *vms,
 
 	/*
 	 * If we need to split any vma, do it now to save pain later.
-	 *
-	 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
-	 * unmapped vm_area_struct will remain in use: so lower split_vma
-	 * places tmp vma above, and higher split_vma places tmp vma below.
+	 * Does it split the first one?
 	 */
-
-	/* Does it split the first one? */
 	if (vms->start > vms->vma->vm_start) {
 
 		/*