Re: [PATCH] mm: folio-compat: fix bug for pagecache_get_page

[Andrew Morton]

On Tue, 18 Oct 2022 15:39:39 +0100 Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:

> On Tue, Oct 18, 2022 at 10:36:39PM +0800, Tuo Cao wrote:
> > The folio returned from __filemap_get_folio may be a NULL, it will
> > causes the kernel crash when access folio->page.
> 
> This is not a bug.  &folio->page does not dereference folio but performs
> pointer arithmetic.

This is the third attempt to "fix" this.  So far.  I think we should
take the hint and make the check for a null pointer more explicit.