Re: [PATCH v10 08/13] mm/sparsemem: Prepare for sub-section ranges

David Hildenbrand
2019-06-20T10:31:21Z

On 19.06.19 07:52, Dan Williams wrote:
> Prepare the memory hot-{add,remove} paths for handling sub-section
> ranges by plumbing the starting page frame and number of pages being
> handled through arch_{add,remove}_memory() to
> sparse_{add,remove}_one_section().
>
> This is simply plumbing, small cleanups, and some identifier renames. No
> intended functional changes.
>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Logan Gunthorpe <logang@deltatee.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
> include/linux/memory_hotplug.h | 5 +-
> mm/memory_hotplug.c | 114 +++++++++++++++++++++++++---------------
> mm/sparse.c | 16 ++----
> 3 files changed, 81 insertions(+), 54 deletions(-)
>
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index 79e0add6a597..3ab0282b4fe5 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -348,9 +348,10 @@ extern int add_memory_resource(int nid, struct resource *resource);
> extern void move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
> unsigned long nr_pages, struct vmem_altmap *altmap);
> extern bool is_memblock_offlined(struct memory_block *mem);
> -extern int sparse_add_one_section(int nid, unsigned long start_pfn,
> - struct vmem_altmap *altmap);
> +extern int sparse_add_section(int nid, unsigned long pfn,
> + unsigned long nr_pages, struct vmem_altmap *altmap);
> extern void sparse_remove_one_section(struct mem_section *ms,
> + unsigned long pfn, unsigned long nr_pages,
> unsigned long map_offset, struct vmem_altmap *altmap);
> extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,
> unsigned long pnum);
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 4b882c57781a..399bf78bccc5 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -252,51 +252,84 @@ void __init register_page_bootmem_info_node(struct pglist_data *pgdat)
> }
> #endif /* CONFIG_HAVE_BOOTMEM_INFO_NODE */
>
> -static int __meminit __add_section(int nid, unsigned long phys_start_pfn,
> - struct vmem_altmap *altmap)
> +static int __meminit __add_section(int nid, unsigned long pfn,
> + unsigned long nr_pages, struct vmem_altmap *altmap)
> {
> int ret;
>
> - if (pfn_valid(phys_start_pfn))
> + if (pfn_valid(pfn))
> return -EEXIST;
>
> - ret = sparse_add_one_section(nid, phys_start_pfn, altmap);
> + ret = sparse_add_section(nid, pfn, nr_pages, altmap);
> return ret < 0 ? ret : 0;
> }
>
> +static int check_pfn_span(unsigned long pfn, unsigned long nr_pages,
> + const char *reason)
> +{
> + /*
> + * Disallow all operations smaller than a sub-section and only
> + * allow operations smaller than a section for
> + * SPARSEMEM_VMEMMAP. Note that check_hotplug_memory_range()
> + * enforces a larger memory_block_size_bytes() granularity for
> + * memory that will be marked online, so this check should only
> + * fire for direct arch_{add,remove}_memory() users outside of
> + * add_memory_resource().
> + */
> + unsigned long min_align;
> +
> + if (IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP))
> + min_align = PAGES_PER_SUBSECTION;
> + else
> + min_align = PAGES_PER_SECTION;
> + if (!IS_ALIGNED(pfn, min_align)
> + || !IS_ALIGNED(nr_pages, min_align)) {
> + WARN(1, "Misaligned __%s_pages start: %#lx end: #%lx\n",
> + reason, pfn, pfn + nr_pages - 1);
> + return -EINVAL;
> + }
> + return 0;
> +}
> +
> /*
> * Reasonably generic function for adding memory. It is
> * expected that archs that support memory hotplug will
> * call this function after deciding the zone to which to
> * add the new pages.
> */
> -int __ref __add_pages(int nid, unsigned long phys_start_pfn,
> - unsigned long nr_pages, struct mhp_restrictions *restrictions)
> +int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
> + struct mhp_restrictions *restrictions)
> {
> unsigned long i;
> - int err = 0;
> - int start_sec, end_sec;
> + int start_sec, end_sec, err;
> struct vmem_altmap *altmap = restrictions->altmap;
>
> - /* during initialize mem_map, align hot-added range to section */
> - start_sec = pfn_to_section_nr(phys_start_pfn);
> - end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
> -
> if (altmap) {
> /*
> * Validate altmap is within bounds of the total request
> */
> - if (altmap->base_pfn != phys_start_pfn
> + if (altmap->base_pfn != pfn
> || vmem_altmap_offset(altmap) > nr_pages) {
> pr_warn_once("memory add fail, invalid altmap\n");
> - err = -EINVAL;
> - goto out;
> + return -EINVAL;
> }
> altmap->alloc = 0;
> }
>
> + err = check_pfn_span(pfn, nr_pages, "add");
> + if (err)
> + return err;
> +
> + start_sec = pfn_to_section_nr(pfn);
> + end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
> for (i = start_sec; i <= end_sec; i++) {
> - err = __add_section(nid, section_nr_to_pfn(i), altmap);
> + unsigned long pfns;
> +
> + pfns = min(nr_pages, PAGES_PER_SECTION
> + - (pfn & ~PAGE_SECTION_MASK));
> + err = __add_section(nid, pfn, pfns, altmap);
> + pfn += pfns;
> + nr_pages -= pfns;
>
> /*
> * EEXIST is finally dealt with by ioresource collision
> @@ -309,7 +342,6 @@ int __ref __add_pages(int nid, unsigned long phys_start_pfn,
> cond_resched();
> }
> vmemmap_populate_print_last();
> -out:
> return err;
> }
>
> @@ -487,10 +519,10 @@ static void shrink_pgdat_span(struct pglist_data *pgdat,
> pgdat->node_spanned_pages = 0;
> }
>
> -static void __remove_zone(struct zone *zone, unsigned long start_pfn)
> +static void __remove_zone(struct zone *zone, unsigned long start_pfn,
> + unsigned long nr_pages)
> {
> struct pglist_data *pgdat = zone->zone_pgdat;
> - int nr_pages = PAGES_PER_SECTION;
> unsigned long flags;
>
> pgdat_resize_lock(zone->zone_pgdat, &flags);
> @@ -499,27 +531,23 @@ static void __remove_zone(struct zone *zone, unsigned long start_pfn)
> pgdat_resize_unlock(zone->zone_pgdat, &flags);
> }
>
> -static void __remove_section(struct zone *zone, struct mem_section *ms,
> - unsigned long map_offset,
> - struct vmem_altmap *altmap)
> +static void __remove_section(struct zone *zone, unsigned long pfn,
> + unsigned long nr_pages, unsigned long map_offset,
> + struct vmem_altmap *altmap)
> {
> - unsigned long start_pfn;
> - int scn_nr;
> + struct mem_section *ms = __nr_to_section(pfn_to_section_nr(pfn));
>
> if (WARN_ON_ONCE(!valid_section(ms)))
> return;
>
> - scn_nr = __section_nr(ms);
> - start_pfn = section_nr_to_pfn((unsigned long)scn_nr);
> - __remove_zone(zone, start_pfn);
> -
> - sparse_remove_one_section(ms, map_offset, altmap);
> + __remove_zone(zone, pfn, nr_pages);
> + sparse_remove_one_section(ms, pfn, nr_pages, map_offset, altmap);
> }
>
> /**
> * __remove_pages() - remove sections of pages from a zone
> * @zone: zone from which pages need to be removed
> - * @phys_start_pfn: starting pageframe (must be aligned to start of a section)
> + * @pfn: starting pageframe (must be aligned to start of a section)
> * @nr_pages: number of pages to remove (must be multiple of section size)
> * @altmap: alternative device page map or %NULL if default memmap is used
> *
> @@ -528,31 +556,31 @@ static void __remove_section(struct zone *zone, struct mem_section *ms,
> * sure that pages are marked reserved and zones are adjust properly by
> * calling offline_pages().
> */
> -void __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
> +void __remove_pages(struct zone *zone, unsigned long pfn,
> unsigned long nr_pages, struct vmem_altmap *altmap)
> {
> - unsigned long i;
> unsigned long map_offset = 0;
> - int sections_to_remove;
> + int i, start_sec, end_sec;

As mentioned in v9, use "unsigned long" for start_sec and end_sec please.

--

Thanks,

David / dhildenb