Re: [patch] mm, page_alloc: set num_movable in move_freepages()

[Andrew Morton]

On Fri, 5 Oct 2018 13:56:39 -0700 (PDT) David Rientjes <rient...@google.com> 
wrote:

> If move_freepages() returns 0 because zone_spans_pfn(), *num_movable can

     move_free_pages_block()?           !zone_spans_pfn()?

> hold the value from the stack because it does not get initialized in
> move_freepages().
> 
> Move the initialization to move_freepages_block() to guarantee the value
> actually makes sense.
> 
> This currently doesn't affect its only caller where num_movable != NULL,
> so no bug fix, but just more robust.
> 
> ...