On 02/07/20 at 07:16am, Wei Yang wrote:
> memmap should be the physical address to page struct instead of virtual
> address to pfn.
Maybe not, memmap stores a virtual address.
>
> Since we call this only for SPARSEMEM_VMEMMAP, pfn_to_page() is valid at
> this point.
>
> Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug")
> Signed-off-by: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
> CC: Dan Williams <dan.j.williams@xxxxxxxxx>
> ---
> mm/sparse.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/sparse.c b/mm/sparse.c
> index b5da121bdd6e..56816f653588 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -888,7 +888,7 @@ int __meminit sparse_add_section(int nid, unsigned long start_pfn,
> /* Align memmap to section boundary in the subsection case */
> if (IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP) &&
> section_nr_to_pfn(section_nr) != start_pfn)
> - memmap = pfn_to_kaddr(section_nr_to_pfn(section_nr));
> + memmap = pfn_to_page(section_nr_to_pfn(section_nr));
With Dan's confirmation, sub-section is only valid in vmemmap case. I
think the old if (section_nr_to_pfn(section_nr) != start_pfn) is enough
to filter out non vmemmap case. So only below code is good:
+ memmap = pfn_to_page(section_nr_to_pfn(section_nr));
> sparse_init_one_section(ms, section_nr, memmap, ms->usage, 0);
>
> return 0;
> --
> 2.17.1
>
