Re: [RFC PATCH v5 12/19] memory-hotplug: introduce new function arch_remove_memory()

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2012/7/27 Wen Congyang <wency@xxxxxxxxxxxxxx>:
> We don't call __add_pages() directly in the function add_memory()
> because some other architecture related things need to be done
> before or after calling __add_pages(). So we should introduce
> a new function arch_remove_memory() to revert the things
> done in arch_add_memory().
>
> Note: the function for s390 is not implemented(I don't know how to
> implement it for s390).
>
> CC: David Rientjes <rientjes@xxxxxxxxxx>
> CC: Jiang Liu <liuj97@xxxxxxxxx>
> CC: Len Brown <len.brown@xxxxxxxxx>
> CC: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> CC: Paul Mackerras <paulus@xxxxxxxxx>
> CC: Christoph Lameter <cl@xxxxxxxxx>
> Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
> CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> CC: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> CC: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
> Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
> ---
>  arch/ia64/mm/init.c                  |   16 ++++
>  arch/powerpc/mm/mem.c                |   14 +++
>  arch/s390/mm/init.c                  |    8 ++
>  arch/sh/mm/init.c                    |   15 +++
>  arch/tile/mm/init.c                  |    8 ++
>  arch/x86/include/asm/pgtable_types.h |    1 +
>  arch/x86/mm/init_32.c                |   10 ++
>  arch/x86/mm/init_64.c                |  160 ++++++++++++++++++++++++++++++++++
>  arch/x86/mm/pageattr.c               |   47 +++++-----
>  include/linux/memory_hotplug.h       |    1 +
>  mm/memory_hotplug.c                  |    1 +
>  11 files changed, 259 insertions(+), 22 deletions(-)
>
> diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
> index 0eab454..1e345ed 100644
> --- a/arch/ia64/mm/init.c
> +++ b/arch/ia64/mm/init.c
> @@ -688,6 +688,22 @@ int arch_add_memory(int nid, u64 start, u64 size)
>
>         return ret;
>  }
> +
> +#ifdef CONFIG_MEMORY_HOTREMOVE
> +int arch_remove_memory(u64 start, u64 size)
> +{
> +       unsigned long start_pfn = start >> PAGE_SHIFT;
> +       unsigned long nr_pages = size >> PAGE_SHIFT;
> +       int ret;
> +
> +       ret = __remove_pages(start_pfn, nr_pages);
> +       if (ret)
> +               pr_warn("%s: Problem encountered in __remove_pages() as"
> +                       " ret=%d\n", __func__,  ret);
> +
> +       return ret;
> +}
> +#endif
>  #endif
>

in 3.5 ia64 implementation did not call __remove_pages at all. so why?


>  /*
> diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
> index baaafde..249cef4 100644
> --- a/arch/powerpc/mm/mem.c
> +++ b/arch/powerpc/mm/mem.c
> @@ -133,6 +133,20 @@ int arch_add_memory(int nid, u64 start, u64 size)
>
>         return __add_pages(nid, zone, start_pfn, nr_pages);
>  }
> +
> +#ifdef CONFIG_MEMORY_HOTREMOVE
> +int arch_remove_memory(u64 start, u64 size)
> +{
> +       unsigned long start_pfn = start >> PAGE_SHIFT;
> +       unsigned long nr_pages = size >> PAGE_SHIFT;
> +
> +       start = (unsigned long)__va(start);
> +       if (remove_section_mapping(start, start + size))
> +               return -EINVAL;
> +
> +       return __remove_pages(start_pfn, nr_pages);
> +}
> +#endif
>  #endif /* CONFIG_MEMORY_HOTPLUG */
>
>  /*
> diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
> index 6adbc08..ca4bc46 100644
> --- a/arch/s390/mm/init.c
> +++ b/arch/s390/mm/init.c
> @@ -257,4 +257,12 @@ int arch_add_memory(int nid, u64 start, u64 size)
>                 vmem_remove_mapping(start, size);
>         return rc;
>  }
> +
> +#ifdef CONFIG_MEMORY_HOTREMOVE
> +int arch_remove_memory(u64 start, u64 size)
> +{
> +       /* TODO */
> +       return -EBUSY;
> +}
> +#endif
>  #endif /* CONFIG_MEMORY_HOTPLUG */
> diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
> index 82cc576..fc84491 100644
> --- a/arch/sh/mm/init.c
> +++ b/arch/sh/mm/init.c
> @@ -558,4 +558,19 @@ int memory_add_physaddr_to_nid(u64 addr)
>  EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
>  #endif
>
> +#ifdef CONFIG_MEMORY_HOTREMOVE
> +int arch_remove_memory(u64 start, u64 size)
> +{
> +       unsigned long start_pfn = start >> PAGE_SHIFT;
> +       unsigned long nr_pages = size >> PAGE_SHIFT;
> +       int ret;
> +
> +       ret = __remove_pages(start_pfn, nr_pages);
> +       if (unlikely(ret))
> +               pr_warn("%s: Failed, __remove_pages() == %d\n", __func__,
> +                       ret);
> +
> +       return ret;
> +}
> +#endif
>  #endif /* CONFIG_MEMORY_HOTPLUG */
> diff --git a/arch/tile/mm/init.c b/arch/tile/mm/init.c
> index ef29d6c..2749515 100644
> --- a/arch/tile/mm/init.c
> +++ b/arch/tile/mm/init.c
> @@ -935,6 +935,14 @@ int remove_memory(u64 start, u64 size)
>  {
>         return -EINVAL;
>  }
> +
> +#ifdef CONFIG_MEMORY_HOTREMOVE
> +int arch_remove_memory(u64 start, u64 size)
> +{
> +       /* TODO */
> +       return -EBUSY;
> +}
> +#endif
>  #endif
>
>  struct kmem_cache *pgd_cache;
> diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
> index 013286a..b725af2 100644
> --- a/arch/x86/include/asm/pgtable_types.h
> +++ b/arch/x86/include/asm/pgtable_types.h
> @@ -334,6 +334,7 @@ static inline void update_page_count(int level, unsigned long pages) { }
>   * as a pte too.
>   */
>  extern pte_t *lookup_address(unsigned long address, unsigned int *level);
> +extern int __split_large_page(pte_t *kpte, unsigned long address, pte_t *pbase);
>
>  #endif /* !__ASSEMBLY__ */
>
> diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
> index 575d86f..a690153 100644
> --- a/arch/x86/mm/init_32.c
> +++ b/arch/x86/mm/init_32.c
> @@ -842,6 +842,16 @@ int arch_add_memory(int nid, u64 start, u64 size)
>
>         return __add_pages(nid, zone, start_pfn, nr_pages);
>  }
> +
> +#ifdef CONFIG_MEMORY_HOTREMOVE
> +int arch_remove_memory(unsigned long start, unsigned long size)
> +{
> +       unsigned long start_pfn = start >> PAGE_SHIFT;
> +       unsigned long nr_pages = size >> PAGE_SHIFT;
> +
> +       return __remove_pages(start_pfn, nr_pages);
> +}
> +#endif
>  #endif
>
>  /*
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index 2b6b4a3..f1554a9 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -675,6 +675,166 @@ int arch_add_memory(int nid, u64 start, u64 size)
>  }
>  EXPORT_SYMBOL_GPL(arch_add_memory);
>
> +static void __meminit
> +phys_pte_remove(pte_t *pte_page, unsigned long addr, unsigned long end)
> +{
> +       unsigned pages = 0;
> +       int i = pte_index(addr);
> +
> +       pte_t *pte = pte_page + pte_index(addr);
> +
> +       for (; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE, pte++) {
> +
> +               if (addr >= end)
> +                       break;
> +
> +               if (!pte_present(*pte))
> +                       continue;
> +
> +               pages++;
> +               set_pte(pte, __pte(0));
> +       }
> +
> +       update_page_count(PG_LEVEL_4K, -pages);
> +}
> +
> +static void __meminit
> +phys_pmd_remove(pmd_t *pmd_page, unsigned long addr, unsigned long end)
> +{
> +       unsigned long pages = 0, next;
> +       int i = pmd_index(addr);
> +
> +       for (; i < PTRS_PER_PMD; i++, addr = next) {
> +               unsigned long pte_phys;
> +               pmd_t *pmd = pmd_page + pmd_index(addr);
> +               pte_t *pte;
> +
> +               if (addr >= end)
> +                       break;
> +
> +               next = (addr & PMD_MASK) + PMD_SIZE;
> +
> +               if (!pmd_present(*pmd))
> +                       continue;
> +
> +               if (pmd_large(*pmd)) {
> +                       if ((addr & ~PMD_MASK) == 0 && next <= end) {
> +                               set_pmd(pmd, __pmd(0));
> +                               pages++;
> +                               continue;
> +                       }
> +
> +                       /*
> +                        * We use 2M page, but we need to remove part of them,
> +                        * so split 2M page to 4K page.
> +                        */
> +                       pte = alloc_low_page(&pte_phys);
> +                       __split_large_page((pte_t *)pmd, addr, pte);
> +
> +                       spin_lock(&init_mm.page_table_lock);
> +                       pmd_populate_kernel(&init_mm, pmd, __va(pte_phys));
> +                       spin_unlock(&init_mm.page_table_lock);
> +               }
> +
> +               spin_lock(&init_mm.page_table_lock);
> +               pte = map_low_page((pte_t *)pmd_page_vaddr(*pmd));
> +               phys_pte_remove(pte, addr, end);
> +               unmap_low_page(pte);
> +               spin_unlock(&init_mm.page_table_lock);
> +       }
> +       update_page_count(PG_LEVEL_2M, -pages);
> +}
> +
> +static void __meminit
> +phys_pud_remove(pud_t *pud_page, unsigned long addr, unsigned long end)
> +{
> +       unsigned long pages = 0, next;
> +       int i = pud_index(addr);
> +
> +       for (; i < PTRS_PER_PUD; i++, addr = next) {
> +               unsigned long pmd_phys;
> +               pud_t *pud = pud_page + pud_index(addr);
> +               pmd_t *pmd;
> +
> +               if (addr >= end)
> +                       break;
> +
> +               next = (addr & PUD_MASK) + PUD_SIZE;
> +
> +               if (!pud_present(*pud))
> +                       continue;
> +
> +               if (pud_large(*pud)) {
> +                       if ((addr & ~PUD_MASK) == 0 && next <= end) {
> +                               set_pud(pud, __pud(0));
> +                               pages++;
> +                               continue;
> +                       }
> +
> +                       /*
> +                        * We use 1G page, but we need to remove part of them,
> +                        * so split 1G page to 2M page.
> +                        */
> +                       pmd = alloc_low_page(&pmd_phys);
> +                       __split_large_page((pte_t *)pud, addr, (pte_t *)pmd);
> +
> +                       spin_lock(&init_mm.page_table_lock);
> +                       pud_populate(&init_mm, pud, __va(pmd_phys));
> +                       spin_unlock(&init_mm.page_table_lock);
> +               }
> +
> +               pmd = map_low_page(pmd_offset(pud, 0));
> +               phys_pmd_remove(pmd, addr, end);
> +               unmap_low_page(pmd);
> +               __flush_tlb_all();
> +       }
> +       __flush_tlb_all();
> +
> +       update_page_count(PG_LEVEL_1G, -pages);
> +}
> +
> +void __meminit
> +kernel_physical_mapping_remove(unsigned long start, unsigned long end)
> +{
> +       unsigned long next;
> +
> +       start = (unsigned long)__va(start);
> +       end = (unsigned long)__va(end);
> +
> +       for (; start < end; start = next) {
> +               pgd_t *pgd = pgd_offset_k(start);
> +               pud_t *pud;
> +
> +               next = (start + PGDIR_SIZE) & PGDIR_MASK;
> +               if (next > end)
> +                       next = end;
> +
> +               if (!pgd_present(*pgd))
> +                       continue;
> +
> +               pud = map_low_page((pud_t *)pgd_page_vaddr(*pgd));
> +               phys_pud_remove(pud, __pa(start), __pa(end));
> +               unmap_low_page(pud);
> +       }
> +
> +       __flush_tlb_all();
> +}
> +
> +#ifdef CONFIG_MEMORY_HOTREMOVE
> +int __ref arch_remove_memory(unsigned long start, unsigned long size)
> +{
> +       unsigned long start_pfn = start >> PAGE_SHIFT;
> +       unsigned long nr_pages = size >> PAGE_SHIFT;
> +       int ret;
> +
> +       ret = __remove_pages(start_pfn, nr_pages);
> +       WARN_ON_ONCE(ret);
> +
> +       kernel_physical_mapping_remove(start, start + size);
> +
> +       return ret;
> +}
> +#endif
>  #endif /* CONFIG_MEMORY_HOTPLUG */
>
>  static struct kcore_list kcore_vsyscall;
> diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
> index 931930a..c22963d 100644
> --- a/arch/x86/mm/pageattr.c
> +++ b/arch/x86/mm/pageattr.c
> @@ -501,21 +501,13 @@ out_unlock:
>         return do_split;
>  }
>
> -static int split_large_page(pte_t *kpte, unsigned long address)
> +int __split_large_page(pte_t *kpte, unsigned long address, pte_t *pbase)
>  {
>         unsigned long pfn, pfninc = 1;
>         unsigned int i, level;
> -       pte_t *pbase, *tmp;
> +       pte_t *tmp;
>         pgprot_t ref_prot;
> -       struct page *base;
> -
> -       if (!debug_pagealloc)
> -               spin_unlock(&cpa_lock);
> -       base = alloc_pages(GFP_KERNEL | __GFP_NOTRACK, 0);
> -       if (!debug_pagealloc)
> -               spin_lock(&cpa_lock);
> -       if (!base)
> -               return -ENOMEM;
> +       struct page *base = virt_to_page(pbase);
>
>         spin_lock(&pgd_lock);
>         /*
> @@ -523,10 +515,11 @@ static int split_large_page(pte_t *kpte, unsigned long address)
>          * up for us already:
>          */
>         tmp = lookup_address(address, &level);
> -       if (tmp != kpte)
> -               goto out_unlock;
> +       if (tmp != kpte) {
> +               spin_unlock(&pgd_lock);
> +               return 1;
> +       }
>
> -       pbase = (pte_t *)page_address(base);
>         paravirt_alloc_pte(&init_mm, page_to_pfn(base));
>         ref_prot = pte_pgprot(pte_clrhuge(*kpte));
>         /*
> @@ -579,17 +572,27 @@ static int split_large_page(pte_t *kpte, unsigned long address)
>          * going on.
>          */
>         __flush_tlb_all();
> +       spin_unlock(&pgd_lock);
>
> -       base = NULL;
> +       return 0;
> +}
>
> -out_unlock:
> -       /*
> -        * If we dropped out via the lookup_address check under
> -        * pgd_lock then stick the page back into the pool:
> -        */
> -       if (base)
> +static int split_large_page(pte_t *kpte, unsigned long address)
> +{
> +       pte_t *pbase;
> +       struct page *base;
> +
> +       if (!debug_pagealloc)
> +               spin_unlock(&cpa_lock);
> +       base = alloc_pages(GFP_KERNEL | __GFP_NOTRACK, 0);
> +       if (!debug_pagealloc)
> +               spin_lock(&cpa_lock);
> +       if (!base)
> +               return -ENOMEM;
> +
> +       pbase = (pte_t *)page_address(base);
> +       if (__split_large_page(kpte, address, pbase))
>                 __free_page(base);
> -       spin_unlock(&pgd_lock);
>
>         return 0;
>  }
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index 8bf820d..0d500be 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -85,6 +85,7 @@ extern void __online_page_free(struct page *page);
>
>  #ifdef CONFIG_MEMORY_HOTREMOVE
>  extern bool is_pageblock_removable_nolock(struct page *page);
> +extern int arch_remove_memory(unsigned long start, unsigned long size);
>  #endif /* CONFIG_MEMORY_HOTREMOVE */
>
>  /* reasonably generic interface to expand the physical pages in a zone  */
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index a9e1579..0c932e1 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1071,6 +1071,7 @@ int __ref remove_memory(int nid, u64 start, u64 size)

line 1071?  which version does this patch base on?  thanks a lot.


>         /* remove memmap entry */
>         firmware_map_remove(start, start + size, "System RAM");
>
> +       arch_remove_memory(start, size);
>  out:
>         unlock_memory_hotplug();
>         return ret;
> --
> 1.7.1
>
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