Oddities in do_read_cache_page()

[Hannes Reinecke]

Hey Matt,

I've stumbled across this code in do_read_cache_page():

        struct folio *folio;

        folio = do_read_cache_folio(mapping, index, filler, file, gfp);
        if (IS_ERR(folio))
                return &folio->page;
        return folio_file_page(folio, index);

Following 'do_read_cache_folio()' I see that it does things like

                folio = filemap_alloc_folio(gfp, 0);
                if (!folio)
                        return ERR_PTR(-ENOMEM);

Now I freely admit that my knowledge of folios is hazy at best, but 
dereferencing an error pointer is something I would seriously frown upon 
 if I were to review the code.
Care to explain?
Or is it, indeed, simply a bug?

Cheers,

Hannes
--
Dr. Hannes Reinecke		           Kernel Storage Architect
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