Re: [PATCH v3] mm/page_ext: Do not allocate space for page_ext->flags if not needed

[David Hildenbrand]

On 16.01.23 11:51, Vlastimil Babka wrote:
> On 1/13/23 16:42, Pasha Tatashin wrote:
> > There is 8 byte page_ext->flags field allocated per page whenever
> > CONFIG_PAGE_EXTENSION is enabled. However, not every user of page_ext
> > uses flags. Therefore, check whether flags is needed at least by one
> > user and if so allocate space for it.
> >
> > For example when page_table_check is enabled, on a machine with 128G
> > of memory before the fix:
> >
> > [    2.244288] allocated 536870912 bytes of page_ext
> > after the fix:
> > [    2.160154] allocated 268435456 bytes of page_ext
> >
> > Also, add a comment before page_ext_operations that describes the
> > field, and remove check if need() is set, as that is now a required
> > field.
> >
> > Signed-off-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
>
> Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
>
> Mike's comments look reasonable to me.

Seconded

Acked-by: David Hildenbrand <david@xxxxxxxxxx>

--
Thanks,

David / dhildenb