On Wed 26-07-17 10:33:31, Michal Hocko wrote:
[...]
> @@ -312,7 +324,7 @@ int __ref __add_pages(int nid, unsigned long phys_start_pfn,
> }
>
> for (i = start_sec; i <= end_sec; i++) {
> - err = __add_section(nid, section_nr_to_pfn(i), want_memblock);
> + err = __add_section(nid, section_nr_to_pfn(i), want_memblock, altmap);
>
> /*
> * EEXIST is finally dealt with by ioresource collision
[...]
> diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
> index 483ba270d522..42d6721cfb71 100644
> --- a/mm/sparse-vmemmap.c
> +++ b/mm/sparse-vmemmap.c
> @@ -794,8 +798,20 @@ int __meminit sparse_add_one_section(struct pglist_data *pgdat, unsigned long st
> goto out;
> }
>
> + /*
> + * TODO get rid of this somehow - we want to postpone the full
> + * initialization until memmap_init_zone.
> + */
> memset(memmap, 0, sizeof(struct page) * PAGES_PER_SECTION);
>
> + /*
> + * now that we have a valid vmemmap mapping we can use
> + * pfn_to_page and flush struct pages which back the
> + * memmap
> + */
> + if (altmap && altmap->flush_alloc_pfns)
> + altmap->flush_alloc_pfns(altmap);
> +
> section_mark_present(ms);
>
> ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
I have only now realized that flush_alloc_pfns would go over the same
range of pfns for each section again and again. I haven't noticed that
because my memblock has one section but larger memblocks (2GB on x86
with a lot of memory) would see that issue. So I will fold the following
into the patch.
---
commit 2658f448af25aa2d2ff7fea12e60a8fe78966f9b
Author: Michal Hocko <mhocko@xxxxxxxx>
Date: Fri Jul 28 19:45:25 2017 +0200
fold me "mm, memory_hotplug: allocate memmap from the added memory range for sparse-vmemmap"
- rewind base pfn of the vmem_altmap when flushing one section
(mark_vmemmap_pages) because we do not want to flush the same range
all over again when memblock has more than one section
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 7aec9272fe4d..55f82c652d51 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -18,7 +18,7 @@ struct device;
* is mapped to the vmemmap - see mark_vmemmap_pages
*/
struct vmem_altmap {
- const unsigned long base_pfn;
+ unsigned long base_pfn;
const unsigned long reserve;
unsigned long free;
unsigned long align;
@@ -48,6 +48,9 @@ static inline void mark_vmemmap_pages(struct vmem_altmap *self)
struct page *page = pfn_to_page(pfn);
__SetPageVmemmap(page);
}
+
+ self->alloc = 0;
+ self->base_pfn += nr_pages + self->reserve;
}
/**
* struct dev_pagemap - metadata for ZONE_DEVICE mappings
--
Michal Hocko
SUSE Labs
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