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

From: jencce zhou
Date: Tue Jul 31 2012 - 22:44:41 EST

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In reply to: Wen Congyang: "Re: [RFC PATCH v5 12/19] memory-hotplug: introduce new function arch_remove_memory()"
Next in thread: Wen Congyang: "[RFC PATCH v5 13/19] memory-hotplug: check page type in get_page_bootmem"
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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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Next message: Larry Woodman: "Re: [PATCH -alternative] mm: hugetlbfs: Close race during teardownof hugetlbfs shared page tables V2 (resend)"
Previous message: Ben Hutchings: "Re: [ 28/73] ARM: OMAP2+: OPP: Fix to ensure check of right oppdefafter bad one"
In reply to: Wen Congyang: "Re: [RFC PATCH v5 12/19] memory-hotplug: introduce new function arch_remove_memory()"
Next in thread: Wen Congyang: "[RFC PATCH v5 13/19] memory-hotplug: check page type in get_page_bootmem"
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