On Mon, Jan 21, 2019 at 04:27:47PM -0500, Qian Cai wrote:
> Fixes: 9f1eb38e0e11 ("mm, kmemleak: little optimization while scanning")
> Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> Signed-off-by: Qian Cai <cai@xxxxxx>
Heh, I guess that it comes in handy to have a machine with CONFIG_HOLES_IN_ZONE
enabled.
I totally missed the fact that systems with such configuration can have
uninitialized pages even if the section is online.
To be honest, I blindly thought that if a section was online, that means
that all its pages were initialized properly.
Thanks for fixing it:
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
> ---
>
> v3: change the "Fixes" line.
> v2: update the changelog; keep the bound check; use pfn_valid_within().
>
> include/linux/memory_hotplug.h | 17 +++++++++--------
> 1 file changed, 9 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index 07da5c6c5ba0..cdeecd9bd87e 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -21,14 +21,15 @@ struct vmem_altmap;
> * walkers which rely on the fully initialized page->flags and others
> * should use this rather than pfn_valid && pfn_to_page
> */
> -#define pfn_to_online_page(pfn) \
> -({ \
> - struct page *___page = NULL; \
> - unsigned long ___nr = pfn_to_section_nr(pfn); \
> - \
> - if (___nr < NR_MEM_SECTIONS && online_section_nr(___nr))\
> - ___page = pfn_to_page(pfn); \
> - ___page; \
> +#define pfn_to_online_page(pfn) \
> +({ \
> + struct page *___page = NULL; \
> + unsigned long ___nr = pfn_to_section_nr(pfn); \
> + \
> + if (___nr < NR_MEM_SECTIONS && online_section_nr(___nr) && \
> + pfn_valid_within(pfn)) \
> + ___page = pfn_to_page(pfn); \
> + ___page; \
> })
>
> /*
> --
> 2.17.2 (Apple Git-113)
>
--
Oscar Salvador
SUSE L3
