ipc/shm: use the vma iterator for munmap calls

Pass through the vma iterator to do_vmi_munmap() to handle the iterator
state internally

Link: https://lkml.kernel.org/r/20230120162650.984577-16-Liam.Howlett@oracle.comSigned-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

ipc/shm.c

@@ -1786,8 +1786,8 @@ long ksys_shmdt(char __user *shmaddr)
 			 */
 			file = vma->vm_file;
 			size = i_size_read(file_inode(vma->vm_file));
-			do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
-			mas_pause(&vmi.mas);
+			do_vmi_munmap(&vmi, mm, vma->vm_start,
+			      vma->vm_end - vma->vm_start, NULL, false);
 			/*
 			 * We discovered the size of the shm segment, so
 			 * break out of here and fall through to the next
@@ -1810,10 +1810,9 @@ long ksys_shmdt(char __user *shmaddr)
 		/* finding a matching vma now does not alter retval */
 		if ((vma->vm_ops == &shm_vm_ops) &&
 		    ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) &&
-		    (vma->vm_file == file)) {
-			do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
-			mas_pause(&vmi.mas);
-		}
+		    (vma->vm_file == file))
+			do_vmi_munmap(&vmi, mm, vma->vm_start,
+			      vma->vm_end - vma->vm_start, NULL, false);
 
 		vma = vma_next(&vmi);
 	}