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Message-ID: <20190503084603.GE15740@linux>
Date: Fri, 3 May 2019 10:46:03 +0200
From: Oscar Salvador <osalvador@...e.de>
To: Dan Williams <dan.j.williams@...el.com>
Cc: akpm@...ux-foundation.org, Michal Hocko <mhocko@...e.com>,
David Hildenbrand <david@...hat.com>,
Logan Gunthorpe <logang@...tatee.com>,
linux-nvdimm@...ts.01.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 05/12] mm/sparsemem: Convert kmalloc_section_memmap()
to populate_section_memmap()
On Wed, May 01, 2019 at 10:55:48PM -0700, Dan Williams wrote:
> Allow sub-section sized ranges to be added to the memmap.
> populate_section_memmap() takes an explict pfn range rather than
> assuming a full section, and those parameters are plumbed all the way
> through to vmmemap_populate(). There should be no sub-section usage in
> current deployments. New warnings are added to clarify which memmap
> allocation paths are sub-section capable.
>
> Cc: Michal Hocko <mhocko@...e.com>
> Cc: David Hildenbrand <david@...hat.com>
> Cc: Logan Gunthorpe <logang@...tatee.com>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
> arch/x86/mm/init_64.c | 4 ++-
> include/linux/mm.h | 4 ++-
> mm/sparse-vmemmap.c | 21 +++++++++++------
> mm/sparse.c | 61 +++++++++++++++++++++++++++++++------------------
> 4 files changed, 57 insertions(+), 33 deletions(-)
>
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index 20d14254b686..bb018d09d2dc 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -1457,7 +1457,9 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
> {
> int err;
>
> - if (boot_cpu_has(X86_FEATURE_PSE))
> + if (end - start < PAGES_PER_SECTION * sizeof(struct page))
maybe just:
if (PHYS_PFN(end) - PHYS_PFN(start) < PAGES_PER_SECTION) ?
> + err = vmemmap_populate_basepages(start, end, node);
> + else if (boot_cpu_has(X86_FEATURE_PSE))
> err = vmemmap_populate_hugepages(start, end, node, altmap);
> else if (altmap) {
> pr_err_once("%s: no cpu support for altmap allocations\n",
Although the following looks more clear to me:
int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
struct vmem_altmap *altmap)
{
int err;
bool partial_section = (PHYS_PFN(end) - PFN_PHYS(start)) < PAGES_PER_SECTION;
if (partial_section || !boot_cpu_has(X86_FEATURE_PSE))
err = vmemmap_populate_basepages(start, end, node);
else if (boot_cpu_has(X86_FEATURE_PSE))
err = vmemmap_populate_hugepages(start, end, node, altmap);
else if (altmap) {
pr_err_once("%s: no cpu support for altmap allocations\n",
__func__);
err = -ENOMEM;
}
if (!err)
sync_global_pgds(start, end - 1);
return err;
}
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 0e8834ac32b7..5360a0e4051d 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2748,8 +2748,8 @@ const char * arch_vma_name(struct vm_area_struct *vma);
> void print_vma_addr(char *prefix, unsigned long rip);
>
> void *sparse_buffer_alloc(unsigned long size);
> -struct page *sparse_mem_map_populate(unsigned long pnum, int nid,
> - struct vmem_altmap *altmap);
> +struct page * __populate_section_memmap(unsigned long pfn,
> + unsigned long nr_pages, int nid, struct vmem_altmap *altmap);
> pgd_t *vmemmap_pgd_populate(unsigned long addr, int node);
> p4d_t *vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node);
> pud_t *vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node);
> diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
> index 7fec05796796..dcb023aa23d1 100644
> --- a/mm/sparse-vmemmap.c
> +++ b/mm/sparse-vmemmap.c
> @@ -245,19 +245,26 @@ int __meminit vmemmap_populate_basepages(unsigned long start,
> return 0;
> }
>
> -struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid,
> - struct vmem_altmap *altmap)
> +struct page * __meminit __populate_section_memmap(unsigned long pfn,
> + unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
> {
> unsigned long start;
> unsigned long end;
> - struct page *map;
>
> - map = pfn_to_page(pnum * PAGES_PER_SECTION);
> - start = (unsigned long)map;
> - end = (unsigned long)(map + PAGES_PER_SECTION);
> + /*
> + * The minimum granularity of memmap extensions is
> + * SECTION_ACTIVE_SIZE as allocations are tracked in the
> + * 'map_active' bitmap of the section.
> + */
> + end = ALIGN(pfn + nr_pages, PHYS_PFN(SECTION_ACTIVE_SIZE));
I would use PAGES_PER_SUB_SECTION directly:
end = ALIGN(pfn + nr_pages, PAGES_PER_SUB_SECTION);
> + pfn &= PHYS_PFN(SECTION_ACTIVE_MASK);
pfn &= PAGE_SUB_SECTION_MASK ?
[...]
> -static struct page *__kmalloc_section_memmap(void)
> +struct page *populate_section_memmap(unsigned long pfn,
> + unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
> {
> struct page *page, *ret;
> unsigned long memmap_size = sizeof(struct page) * PAGES_PER_SECTION;
>
> + if ((pfn & ~PAGE_SECTION_MASK) || nr_pages != PAGES_PER_SECTION) {
> + WARN(1, "%s: called with section unaligned parameters\n",
> + __func__);
> + return NULL;
> + }
Can this actually happen? We need CONFIG_SPARSEMEM_VMEMMAP in order to use nvdimm,
right?
But I guess it is fine to have a safety net just in case.
> +
> page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));
> if (page)
> goto got_map_page;
> @@ -682,15 +692,17 @@ static struct page *__kmalloc_section_memmap(void)
> return ret;
> }
>
> -static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
> +static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
> struct vmem_altmap *altmap)
> {
> - return __kmalloc_section_memmap();
> -}
> + struct page *memmap = pfn_to_page(pfn);
> +
> + if ((pfn & ~PAGE_SECTION_MASK) || nr_pages != PAGES_PER_SECTION) {
> + WARN(1, "%s: called with section unaligned parameters\n",
> + __func__);
> + return;
> + }
>
> -static void __kfree_section_memmap(struct page *memmap,
> - struct vmem_altmap *altmap)
> -{
> if (is_vmalloc_addr(memmap))
> vfree(memmap);
> else
> @@ -761,12 +773,13 @@ int __meminit sparse_add_one_section(int nid, unsigned long start_pfn,
> if (ret < 0 && ret != -EEXIST)
> return ret;
> ret = 0;
> - memmap = kmalloc_section_memmap(section_nr, nid, altmap);
> + memmap = populate_section_memmap(start_pfn, PAGES_PER_SECTION, nid,
> + altmap);
> if (!memmap)
> return -ENOMEM;
> usage = kzalloc(mem_section_usage_size(), GFP_KERNEL);
> if (!usage) {
> - __kfree_section_memmap(memmap, altmap);
> + depopulate_section_memmap(start_pfn, PAGES_PER_SECTION, altmap);
> return -ENOMEM;
> }
>
> @@ -788,7 +801,7 @@ int __meminit sparse_add_one_section(int nid, unsigned long start_pfn,
> out:
> if (ret < 0) {
> kfree(usage);
> - __kfree_section_memmap(memmap, altmap);
> + depopulate_section_memmap(start_pfn, PAGES_PER_SECTION, altmap);
> }
> return ret;
> }
> @@ -825,7 +838,8 @@ static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
> #endif
>
> static void free_section_usage(struct page *memmap,
> - struct mem_section_usage *usage, struct vmem_altmap *altmap)
> + struct mem_section_usage *usage, unsigned long pfn,
> + unsigned long nr_pages, struct vmem_altmap *altmap)
> {
> struct page *usage_page;
>
> @@ -839,7 +853,7 @@ static void free_section_usage(struct page *memmap,
> if (PageSlab(usage_page) || PageCompound(usage_page)) {
> kfree(usage);
> if (memmap)
> - __kfree_section_memmap(memmap, altmap);
> + depopulate_section_memmap(pfn, nr_pages, altmap);
> return;
> }
>
> @@ -868,7 +882,8 @@ void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
>
> clear_hwpoisoned_pages(memmap + map_offset,
> PAGES_PER_SECTION - map_offset);
> - free_section_usage(memmap, usage, altmap);
> + free_section_usage(memmap, usage, section_nr_to_pfn(__section_nr(ms)),
> + PAGES_PER_SECTION, altmap);
> }
> #endif /* CONFIG_MEMORY_HOTREMOVE */
> #endif /* CONFIG_MEMORY_HOTPLUG */
>
--
Oscar Salvador
SUSE L3
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