Re: [PATCH v4] mm: fix is_pinnable_page against on cma page

John Hubbard
2022-05-12T04:47:54Z

On 5/11/22 20:44, Minchan Kim wrote:
> Thanks for checking, John.
>
> I don't want to have the READ_ONCE in __get_pfnblock_flags_mask
> atm even though it's an extra memory dereference for specific
> architecutre and specific compiler unless other callsites *do*
> need it.
>
> We choose the choice(i.e., having __READ_ONCE in is_pinanble_
> page) for *potential* cases(e.g., aggressive LTO for future)
> and if it's an extra memory dereference atm, it would be multiple
> instructions *potentailly* as having more change or different
> compiler and/or arches now or later. It's out of scope in
> this patch.

Agreed!

thanks,
--
John Hubbard
NVIDIA