On 09/05/2012 05:25 PM, [email protected] wrote:
> From: Yasuaki Ishimatsu <[email protected]>
>
> All pages of virtual mapping in removed memory cannot be freed, since some pages
> used as PGD/PUD includes not only removed memory but also other memory. So the
> patch checks whether page can be freed or not.
>
> How to check whether page can be freed or not?
> 1. When removing memory, the page structs of the revmoved memory are filled
> with 0FD.
> 2. All page structs are filled with 0xFD on PT/PMD, PT/PMD can be cleared.
> In this case, the page used as PT/PMD can be freed.
>
> Applying patch, __remove_section() of CONFIG_SPARSEMEM_VMEMMAP is integrated
> into one. So __remove_section() of CONFIG_SPARSEMEM_VMEMMAP is deleted.
>
> Note: vmemmap_kfree() and vmemmap_free_bootmem() are not implemented for ia64,
> ppc, s390, and sparc.
>
> CC: David Rientjes <[email protected]>
> CC: Jiang Liu <[email protected]>
> CC: Len Brown <[email protected]>
> CC: Benjamin Herrenschmidt <[email protected]>
> CC: Paul Mackerras <[email protected]>
> CC: Christoph Lameter <[email protected]>
> Cc: Minchan Kim <[email protected]>
> CC: Andrew Morton <[email protected]>
> CC: KOSAKI Motohiro <[email protected]>
> CC: Wen Congyang <[email protected]>
> Signed-off-by: Yasuaki Ishimatsu <[email protected]>
> ---
> arch/ia64/mm/discontig.c | 8 +++
> arch/powerpc/mm/init_64.c | 8 +++
> arch/s390/mm/vmem.c | 8 +++
> arch/sparc/mm/init_64.c | 8 +++
> arch/x86/mm/init_64.c | 119 +++++++++++++++++++++++++++++++++++++++++++++
> include/linux/mm.h | 2 +
> mm/memory_hotplug.c | 17 +------
> mm/sparse.c | 5 +-
> 8 files changed, 158 insertions(+), 17 deletions(-)
>
> diff --git a/arch/ia64/mm/discontig.c b/arch/ia64/mm/discontig.c
> index 33943db..0d23b69 100644
> --- a/arch/ia64/mm/discontig.c
> +++ b/arch/ia64/mm/discontig.c
> @@ -823,6 +823,14 @@ int __meminit vmemmap_populate(struct page *start_page,
> return vmemmap_populate_basepages(start_page, size, node);
> }
>
> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages)
> +{
> +}
> +
> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages)
> +{
> +}
> +
> void register_page_bootmem_memmap(unsigned long section_nr,
> struct page *start_page, unsigned long size)
> {
> diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
> index 3690c44..835a2b3 100644
> --- a/arch/powerpc/mm/init_64.c
> +++ b/arch/powerpc/mm/init_64.c
> @@ -299,6 +299,14 @@ int __meminit vmemmap_populate(struct page *start_page,
> return 0;
> }
>
> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages)
> +{
> +}
> +
> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages)
> +{
> +}
> +
> void register_page_bootmem_memmap(unsigned long section_nr,
> struct page *start_page, unsigned long size)
> {
> diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
> index eda55cd..4b42b0b 100644
> --- a/arch/s390/mm/vmem.c
> +++ b/arch/s390/mm/vmem.c
> @@ -227,6 +227,14 @@ out:
> return ret;
> }
>
> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages)
> +{
> +}
> +
> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages)
> +{
> +}
> +
> void register_page_bootmem_memmap(unsigned long section_nr,
> struct page *start_page, unsigned long size)
> {
> diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
> index add1cc7..1384826 100644
> --- a/arch/sparc/mm/init_64.c
> +++ b/arch/sparc/mm/init_64.c
> @@ -2078,6 +2078,14 @@ void __meminit vmemmap_populate_print_last(void)
> }
> }
>
> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages)
> +{
> +}
> +
> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages)
> +{
> +}
> +
> void register_page_bootmem_memmap(unsigned long section_nr,
> struct page *start_page, unsigned long size)
> {
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index 0075592..4e8f8a4 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -1138,6 +1138,125 @@ vmemmap_populate(struct page *start_page, unsigned long size, int node)
> return 0;
> }
>
> +#define PAGE_INUSE 0xFD
> +
> +unsigned long find_and_clear_pte_page(unsigned long addr, unsigned long end,
> + struct page **pp, int *page_size)
> +{
> + pgd_t *pgd;
> + pud_t *pud;
> + pmd_t *pmd;
> + pte_t *pte;
> + void *page_addr;
> + unsigned long next;
> +
> + *pp = NULL;
> +
> + pgd = pgd_offset_k(addr);
> + if (pgd_none(*pgd))
> + return pgd_addr_end(addr, end);
> +
> + pud = pud_offset(pgd, addr);
> + if (pud_none(*pud))
> + return pud_addr_end(addr, end);
> +
> + if (!cpu_has_pse) {
> + next = (addr + PAGE_SIZE) & PAGE_MASK;
> + pmd = pmd_offset(pud, addr);
> + if (pmd_none(*pmd))
> + return next;
> +
> + pte = pte_offset_kernel(pmd, addr);
> + if (pte_none(*pte))
> + return next;
> +
> + *page_size = PAGE_SIZE;
> + *pp = pte_page(*pte);
> + } else {
> + next = pmd_addr_end(addr, end);
> +
> + pmd = pmd_offset(pud, addr);
> + if (pmd_none(*pmd))
> + return next;
> +
> + *page_size = PMD_SIZE;
> + *pp = pmd_page(*pmd);
> + }
> +
> + /*
> + * Removed page structs are filled with 0xFD.
> + */
> + memset((void *)addr, PAGE_INUSE, next - addr);
> +
> + page_addr = page_address(*pp);
> +
> + /*
> + * Check the page is filled with 0xFD or not.
> + * memchr_inv() returns the address. In this case, we cannot
> + * clear PTE/PUD entry, since the page is used by other.
> + * So we cannot also free the page.
> + *
> + * memchr_inv() returns NULL. In this case, we can clear
> + * PTE/PUD entry, since the page is not used by other.
> + * So we can also free the page.
> + */
> + if (memchr_inv(page_addr, PAGE_INUSE, *page_size)) {
> + *pp = NULL;
> + return next;
> + }
> +
Hi Yasuaki,
why call memchr_inv check after memset, this time the page can always be
filled with 0xFD.
> + if (!cpu_has_pse)
> + pte_clear(&init_mm, addr, pte);
> + else
> + pmd_clear(pmd);
> +
> + return next;
> +}
> +
> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages)
> +{
> + unsigned long addr = (unsigned long)memmap;
> + unsigned long end = (unsigned long)(memmap + nr_pages);
> + unsigned long next;
> + struct page *page;
> + int page_size;
> +
> + for (; addr < end; addr = next) {
> + page = NULL;
> + page_size = 0;
> + next = find_and_clear_pte_page(addr, end, &page, &page_size);
> + if (!page)
> + continue;
> +
> + free_pages((unsigned long)page_address(page),
> + get_order(page_size));
> + __flush_tlb_one(addr);
> + }
> +}
> +
> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages)
> +{
> + unsigned long addr = (unsigned long)memmap;
> + unsigned long end = (unsigned long)(memmap + nr_pages);
> + unsigned long next;
> + struct page *page;
> + int page_size;
> + unsigned long magic;
> +
> + for (; addr < end; addr = next) {
> + page = NULL;
> + page_size = 0;
> + next = find_and_clear_pte_page(addr, end, &page, &page_size);
> + if (!page)
> + continue;
> +
> + magic = (unsigned long) page->lru.next;
> + if (magic == SECTION_INFO)
> + put_page_bootmem(page);
> + flush_tlb_kernel_range(addr, end);
> + }
> +}
> +
> void register_page_bootmem_memmap(unsigned long section_nr,
> struct page *start_page, unsigned long size)
> {
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index c607913..fb0d1fc 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1620,6 +1620,8 @@ int vmemmap_populate(struct page *start_page, unsigned long pages, int node);
> void vmemmap_populate_print_last(void);
> void register_page_bootmem_memmap(unsigned long section_nr, struct page *map,
> unsigned long size);
> +void vmemmap_kfree(struct page *memmpa, unsigned long nr_pages);
> +void vmemmap_free_bootmem(struct page *memmpa, unsigned long nr_pages);
>
> enum mf_flags {
> MF_COUNT_INCREASED = 1 << 0,
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 647a7f2..c54922c 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -308,19 +308,6 @@ static int __meminit __add_section(int nid, struct zone *zone,
> return register_new_memory(nid, __pfn_to_section(phys_start_pfn));
> }
>
> -#ifdef CONFIG_SPARSEMEM_VMEMMAP
> -static int __remove_section(struct zone *zone, struct mem_section *ms)
> -{
> - int ret = -EINVAL;
> -
> - if (!valid_section(ms))
> - return ret;
> -
> - ret = unregister_memory_section(ms);
> -
> - return ret;
> -}
> -#else
> static int __remove_section(struct zone *zone, struct mem_section *ms)
> {
> unsigned long flags;
> @@ -337,9 +324,9 @@ static int __remove_section(struct zone *zone, struct mem_section *ms)
> pgdat_resize_lock(pgdat, &flags);
> sparse_remove_one_section(zone, ms);
> pgdat_resize_unlock(pgdat, &flags);
> - return 0;
> +
> + return ret;
> }
> -#endif
>
> /*
> * Reasonably generic function for adding memory. It is
> diff --git a/mm/sparse.c b/mm/sparse.c
> index fac95f2..ab9d755 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -613,12 +613,13 @@ static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
> /* This will make the necessary allocations eventually. */
> return sparse_mem_map_populate(pnum, nid);
> }
> -static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
> +static void __kfree_section_memmap(struct page *page, unsigned long nr_pages)
> {
> - return; /* XXX: Not implemented yet */
> + vmemmap_kfree(page, nr_pages);
> }
> static void free_map_bootmem(struct page *page, unsigned long nr_pages)
> {
> + vmemmap_free_bootmem(page, nr_pages);
> }
> #else
> static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
Hi Chen,
Sorry for late reply.
2012/10/02 13:21, Ni zhan Chen wrote:
> On 09/05/2012 05:25 PM, [email protected] wrote:
>> From: Yasuaki Ishimatsu <[email protected]>
>>
>> All pages of virtual mapping in removed memory cannot be freed, since some pages
>> used as PGD/PUD includes not only removed memory but also other memory. So the
>> patch checks whether page can be freed or not.
>>
>> How to check whether page can be freed or not?
>> 1. When removing memory, the page structs of the revmoved memory are filled
>> with 0FD.
>> 2. All page structs are filled with 0xFD on PT/PMD, PT/PMD can be cleared.
>> In this case, the page used as PT/PMD can be freed.
>>
>> Applying patch, __remove_section() of CONFIG_SPARSEMEM_VMEMMAP is integrated
>> into one. So __remove_section() of CONFIG_SPARSEMEM_VMEMMAP is deleted.
>>
>> Note: vmemmap_kfree() and vmemmap_free_bootmem() are not implemented for ia64,
>> ppc, s390, and sparc.
>>
>> CC: David Rientjes <[email protected]>
>> CC: Jiang Liu <[email protected]>
>> CC: Len Brown <[email protected]>
>> CC: Benjamin Herrenschmidt <[email protected]>
>> CC: Paul Mackerras <[email protected]>
>> CC: Christoph Lameter <[email protected]>
>> Cc: Minchan Kim <[email protected]>
>> CC: Andrew Morton <[email protected]>
>> CC: KOSAKI Motohiro <[email protected]>
>> CC: Wen Congyang <[email protected]>
>> Signed-off-by: Yasuaki Ishimatsu <[email protected]>
>> ---
>> arch/ia64/mm/discontig.c | 8 +++
>> arch/powerpc/mm/init_64.c | 8 +++
>> arch/s390/mm/vmem.c | 8 +++
>> arch/sparc/mm/init_64.c | 8 +++
>> arch/x86/mm/init_64.c | 119 +++++++++++++++++++++++++++++++++++++++++++++
>> include/linux/mm.h | 2 +
>> mm/memory_hotplug.c | 17 +------
>> mm/sparse.c | 5 +-
>> 8 files changed, 158 insertions(+), 17 deletions(-)
>>
>> diff --git a/arch/ia64/mm/discontig.c b/arch/ia64/mm/discontig.c
>> index 33943db..0d23b69 100644
>> --- a/arch/ia64/mm/discontig.c
>> +++ b/arch/ia64/mm/discontig.c
>> @@ -823,6 +823,14 @@ int __meminit vmemmap_populate(struct page *start_page,
>> return vmemmap_populate_basepages(start_page, size, node);
>> }
>> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages)
>> +{
>> +}
>> +
>> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages)
>> +{
>> +}
>> +
>> void register_page_bootmem_memmap(unsigned long section_nr,
>> struct page *start_page, unsigned long size)
>> {
>> diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
>> index 3690c44..835a2b3 100644
>> --- a/arch/powerpc/mm/init_64.c
>> +++ b/arch/powerpc/mm/init_64.c
>> @@ -299,6 +299,14 @@ int __meminit vmemmap_populate(struct page *start_page,
>> return 0;
>> }
>> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages)
>> +{
>> +}
>> +
>> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages)
>> +{
>> +}
>> +
>> void register_page_bootmem_memmap(unsigned long section_nr,
>> struct page *start_page, unsigned long size)
>> {
>> diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
>> index eda55cd..4b42b0b 100644
>> --- a/arch/s390/mm/vmem.c
>> +++ b/arch/s390/mm/vmem.c
>> @@ -227,6 +227,14 @@ out:
>> return ret;
>> }
>> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages)
>> +{
>> +}
>> +
>> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages)
>> +{
>> +}
>> +
>> void register_page_bootmem_memmap(unsigned long section_nr,
>> struct page *start_page, unsigned long size)
>> {
>> diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
>> index add1cc7..1384826 100644
>> --- a/arch/sparc/mm/init_64.c
>> +++ b/arch/sparc/mm/init_64.c
>> @@ -2078,6 +2078,14 @@ void __meminit vmemmap_populate_print_last(void)
>> }
>> }
>> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages)
>> +{
>> +}
>> +
>> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages)
>> +{
>> +}
>> +
>> void register_page_bootmem_memmap(unsigned long section_nr,
>> struct page *start_page, unsigned long size)
>> {
>> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
>> index 0075592..4e8f8a4 100644
>> --- a/arch/x86/mm/init_64.c
>> +++ b/arch/x86/mm/init_64.c
>> @@ -1138,6 +1138,125 @@ vmemmap_populate(struct page *start_page, unsigned long size, int node)
>> return 0;
>> }
>> +#define PAGE_INUSE 0xFD
>> +
>> +unsigned long find_and_clear_pte_page(unsigned long addr, unsigned long end,
>> + struct page **pp, int *page_size)
>> +{
>> + pgd_t *pgd;
>> + pud_t *pud;
>> + pmd_t *pmd;
>> + pte_t *pte;
>> + void *page_addr;
>> + unsigned long next;
>> +
>> + *pp = NULL;
>> +
>> + pgd = pgd_offset_k(addr);
>> + if (pgd_none(*pgd))
>> + return pgd_addr_end(addr, end);
>> +
>> + pud = pud_offset(pgd, addr);
>> + if (pud_none(*pud))
>> + return pud_addr_end(addr, end);
>> +
>> + if (!cpu_has_pse) {
>> + next = (addr + PAGE_SIZE) & PAGE_MASK;
>> + pmd = pmd_offset(pud, addr);
>> + if (pmd_none(*pmd))
>> + return next;
>> +
>> + pte = pte_offset_kernel(pmd, addr);
>> + if (pte_none(*pte))
>> + return next;
>> +
>> + *page_size = PAGE_SIZE;
>> + *pp = pte_page(*pte);
>> + } else {
>> + next = pmd_addr_end(addr, end);
>> +
>> + pmd = pmd_offset(pud, addr);
>> + if (pmd_none(*pmd))
>> + return next;
>> +
>> + *page_size = PMD_SIZE;
>> + *pp = pmd_page(*pmd);
>> + }
>> +
>> + /*
>> + * Removed page structs are filled with 0xFD.
>> + */
>> + memset((void *)addr, PAGE_INUSE, next - addr);
>> +
>> + page_addr = page_address(*pp);
>> +
>> + /*
>> + * Check the page is filled with 0xFD or not.
>> + * memchr_inv() returns the address. In this case, we cannot
>> + * clear PTE/PUD entry, since the page is used by other.
>> + * So we cannot also free the page.
>> + *
>> + * memchr_inv() returns NULL. In this case, we can clear
>> + * PTE/PUD entry, since the page is not used by other.
>> + * So we can also free the page.
>> + */
>> + if (memchr_inv(page_addr, PAGE_INUSE, *page_size)) {
>> + *pp = NULL;
>> + return next;
>> + }
>> +
>
> Hi Yasuaki,
>
> why call memchr_inv check after memset, this time the page can always be filled with 0xFD.
The page is not always filled with 0xFD. find_and_clear_pte_page()
is calld in each section. So the function fills the page
section size/sizeof(page) byte with 0xFD one time. Thus if section size is
small, the page is filled with 0xFD.
Thanks,
Yasuaki Ishimatsu
>> + if (!cpu_has_pse)
>> + pte_clear(&init_mm, addr, pte);
>> + else
>> + pmd_clear(pmd);
>> +
>> + return next;
>> +}
>> +
>> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages)
>> +{
>> + unsigned long addr = (unsigned long)memmap;
>> + unsigned long end = (unsigned long)(memmap + nr_pages);
>> + unsigned long next;
>> + struct page *page;
>> + int page_size;
>> +
>> + for (; addr < end; addr = next) {
>> + page = NULL;
>> + page_size = 0;
>> + next = find_and_clear_pte_page(addr, end, &page, &page_size);
>> + if (!page)
>> + continue;
>> +
>> + free_pages((unsigned long)page_address(page),
>> + get_order(page_size));
>> + __flush_tlb_one(addr);
>> + }
>> +}
>> +
>> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages)
>> +{
>> + unsigned long addr = (unsigned long)memmap;
>> + unsigned long end = (unsigned long)(memmap + nr_pages);
>> + unsigned long next;
>> + struct page *page;
>> + int page_size;
>> + unsigned long magic;
>> +
>> + for (; addr < end; addr = next) {
>> + page = NULL;
>> + page_size = 0;
>> + next = find_and_clear_pte_page(addr, end, &page, &page_size);
>> + if (!page)
>> + continue;
>> +
>> + magic = (unsigned long) page->lru.next;
>> + if (magic == SECTION_INFO)
>> + put_page_bootmem(page);
>> + flush_tlb_kernel_range(addr, end);
>> + }
>> +}
>> +
>> void register_page_bootmem_memmap(unsigned long section_nr,
>> struct page *start_page, unsigned long size)
>> {
>> diff --git a/include/linux/mm.h b/include/linux/mm.h
>> index c607913..fb0d1fc 100644
>> --- a/include/linux/mm.h
>> +++ b/include/linux/mm.h
>> @@ -1620,6 +1620,8 @@ int vmemmap_populate(struct page *start_page, unsigned long pages, int node);
>> void vmemmap_populate_print_last(void);
>> void register_page_bootmem_memmap(unsigned long section_nr, struct page *map,
>> unsigned long size);
>> +void vmemmap_kfree(struct page *memmpa, unsigned long nr_pages);
>> +void vmemmap_free_bootmem(struct page *memmpa, unsigned long nr_pages);
>> enum mf_flags {
>> MF_COUNT_INCREASED = 1 << 0,
>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>> index 647a7f2..c54922c 100644
>> --- a/mm/memory_hotplug.c
>> +++ b/mm/memory_hotplug.c
>> @@ -308,19 +308,6 @@ static int __meminit __add_section(int nid, struct zone *zone,
>> return register_new_memory(nid, __pfn_to_section(phys_start_pfn));
>> }
>> -#ifdef CONFIG_SPARSEMEM_VMEMMAP
>> -static int __remove_section(struct zone *zone, struct mem_section *ms)
>> -{
>> - int ret = -EINVAL;
>> -
>> - if (!valid_section(ms))
>> - return ret;
>> -
>> - ret = unregister_memory_section(ms);
>> -
>> - return ret;
>> -}
>> -#else
>> static int __remove_section(struct zone *zone, struct mem_section *ms)
>> {
>> unsigned long flags;
>> @@ -337,9 +324,9 @@ static int __remove_section(struct zone *zone, struct mem_section *ms)
>> pgdat_resize_lock(pgdat, &flags);
>> sparse_remove_one_section(zone, ms);
>> pgdat_resize_unlock(pgdat, &flags);
>> - return 0;
>> +
>> + return ret;
>> }
>> -#endif
>> /*
>> * Reasonably generic function for adding memory. It is
>> diff --git a/mm/sparse.c b/mm/sparse.c
>> index fac95f2..ab9d755 100644
>> --- a/mm/sparse.c
>> +++ b/mm/sparse.c
>> @@ -613,12 +613,13 @@ static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
>> /* This will make the necessary allocations eventually. */
>> return sparse_mem_map_populate(pnum, nid);
>> }
>> -static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
>> +static void __kfree_section_memmap(struct page *page, unsigned long nr_pages)
>> {
>> - return; /* XXX: Not implemented yet */
>> + vmemmap_kfree(page, nr_pages);
>> }
>> static void free_map_bootmem(struct page *page, unsigned long nr_pages)
>> {
>> + vmemmap_free_bootmem(page, nr_pages);
>> }
>> #else
>> static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
>
On 10/04/2012 02:26 PM, Yasuaki Ishimatsu wrote:
> Hi Chen,
>
> Sorry for late reply.
>
> 2012/10/02 13:21, Ni zhan Chen wrote:
>> On 09/05/2012 05:25 PM, [email protected] wrote:
>>> From: Yasuaki Ishimatsu <[email protected]>
>>>
>>> All pages of virtual mapping in removed memory cannot be freed,
>>> since some pages
>>> used as PGD/PUD includes not only removed memory but also other
>>> memory. So the
>>> patch checks whether page can be freed or not.
>>>
>>> How to check whether page can be freed or not?
>>> 1. When removing memory, the page structs of the revmoved memory
>>> are filled
>>> with 0FD.
>>> 2. All page structs are filled with 0xFD on PT/PMD, PT/PMD can be
>>> cleared.
>>> In this case, the page used as PT/PMD can be freed.
>>>
>>> Applying patch, __remove_section() of CONFIG_SPARSEMEM_VMEMMAP is
>>> integrated
>>> into one. So __remove_section() of CONFIG_SPARSEMEM_VMEMMAP is deleted.
>>>
>>> Note: vmemmap_kfree() and vmemmap_free_bootmem() are not
>>> implemented for ia64,
>>> ppc, s390, and sparc.
>>>
>>> CC: David Rientjes <[email protected]>
>>> CC: Jiang Liu <[email protected]>
>>> CC: Len Brown <[email protected]>
>>> CC: Benjamin Herrenschmidt <[email protected]>
>>> CC: Paul Mackerras <[email protected]>
>>> CC: Christoph Lameter <[email protected]>
>>> Cc: Minchan Kim <[email protected]>
>>> CC: Andrew Morton <[email protected]>
>>> CC: KOSAKI Motohiro <[email protected]>
>>> CC: Wen Congyang <[email protected]>
>>> Signed-off-by: Yasuaki Ishimatsu <[email protected]>
>>> ---
>>> arch/ia64/mm/discontig.c | 8 +++
>>> arch/powerpc/mm/init_64.c | 8 +++
>>> arch/s390/mm/vmem.c | 8 +++
>>> arch/sparc/mm/init_64.c | 8 +++
>>> arch/x86/mm/init_64.c | 119
>>> +++++++++++++++++++++++++++++++++++++++++++++
>>> include/linux/mm.h | 2 +
>>> mm/memory_hotplug.c | 17 +------
>>> mm/sparse.c | 5 +-
>>> 8 files changed, 158 insertions(+), 17 deletions(-)
>>>
>>> diff --git a/arch/ia64/mm/discontig.c b/arch/ia64/mm/discontig.c
>>> index 33943db..0d23b69 100644
>>> --- a/arch/ia64/mm/discontig.c
>>> +++ b/arch/ia64/mm/discontig.c
>>> @@ -823,6 +823,14 @@ int __meminit vmemmap_populate(struct page
>>> *start_page,
>>> return vmemmap_populate_basepages(start_page, size, node);
>>> }
>>> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages)
>>> +{
>>> +}
>>> +
>>> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages)
>>> +{
>>> +}
>>> +
>>> void register_page_bootmem_memmap(unsigned long section_nr,
>>> struct page *start_page, unsigned long size)
>>> {
>>> diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
>>> index 3690c44..835a2b3 100644
>>> --- a/arch/powerpc/mm/init_64.c
>>> +++ b/arch/powerpc/mm/init_64.c
>>> @@ -299,6 +299,14 @@ int __meminit vmemmap_populate(struct page
>>> *start_page,
>>> return 0;
>>> }
>>> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages)
>>> +{
>>> +}
>>> +
>>> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages)
>>> +{
>>> +}
>>> +
>>> void register_page_bootmem_memmap(unsigned long section_nr,
>>> struct page *start_page, unsigned long size)
>>> {
>>> diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
>>> index eda55cd..4b42b0b 100644
>>> --- a/arch/s390/mm/vmem.c
>>> +++ b/arch/s390/mm/vmem.c
>>> @@ -227,6 +227,14 @@ out:
>>> return ret;
>>> }
>>> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages)
>>> +{
>>> +}
>>> +
>>> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages)
>>> +{
>>> +}
>>> +
>>> void register_page_bootmem_memmap(unsigned long section_nr,
>>> struct page *start_page, unsigned long size)
>>> {
>>> diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
>>> index add1cc7..1384826 100644
>>> --- a/arch/sparc/mm/init_64.c
>>> +++ b/arch/sparc/mm/init_64.c
>>> @@ -2078,6 +2078,14 @@ void __meminit vmemmap_populate_print_last(void)
>>> }
>>> }
>>> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages)
>>> +{
>>> +}
>>> +
>>> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages)
>>> +{
>>> +}
>>> +
>>> void register_page_bootmem_memmap(unsigned long section_nr,
>>> struct page *start_page, unsigned long size)
>>> {
>>> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
>>> index 0075592..4e8f8a4 100644
>>> --- a/arch/x86/mm/init_64.c
>>> +++ b/arch/x86/mm/init_64.c
>>> @@ -1138,6 +1138,125 @@ vmemmap_populate(struct page *start_page,
>>> unsigned long size, int node)
>>> return 0;
>>> }
>>> +#define PAGE_INUSE 0xFD
>>> +
>>> +unsigned long find_and_clear_pte_page(unsigned long addr, unsigned
>>> long end,
>>> + struct page **pp, int *page_size)
>>> +{
>>> + pgd_t *pgd;
>>> + pud_t *pud;
>>> + pmd_t *pmd;
>>> + pte_t *pte;
>>> + void *page_addr;
>>> + unsigned long next;
>>> +
>>> + *pp = NULL;
>>> +
>>> + pgd = pgd_offset_k(addr);
>>> + if (pgd_none(*pgd))
>>> + return pgd_addr_end(addr, end);
>>> +
>>> + pud = pud_offset(pgd, addr);
>>> + if (pud_none(*pud))
>>> + return pud_addr_end(addr, end);
>>> +
>>> + if (!cpu_has_pse) {
>>> + next = (addr + PAGE_SIZE) & PAGE_MASK;
>>> + pmd = pmd_offset(pud, addr);
>>> + if (pmd_none(*pmd))
>>> + return next;
>>> +
>>> + pte = pte_offset_kernel(pmd, addr);
>>> + if (pte_none(*pte))
>>> + return next;
>>> +
>>> + *page_size = PAGE_SIZE;
>>> + *pp = pte_page(*pte);
>>> + } else {
>>> + next = pmd_addr_end(addr, end);
>>> +
>>> + pmd = pmd_offset(pud, addr);
>>> + if (pmd_none(*pmd))
>>> + return next;
>>> +
>>> + *page_size = PMD_SIZE;
>>> + *pp = pmd_page(*pmd);
>>> + }
>>> +
>>> + /*
>>> + * Removed page structs are filled with 0xFD.
>>> + */
>>> + memset((void *)addr, PAGE_INUSE, next - addr);
>>> +
>>> + page_addr = page_address(*pp);
>>> +
>>> + /*
>>> + * Check the page is filled with 0xFD or not.
>>> + * memchr_inv() returns the address. In this case, we cannot
>>> + * clear PTE/PUD entry, since the page is used by other.
>>> + * So we cannot also free the page.
>>> + *
>>> + * memchr_inv() returns NULL. In this case, we can clear
>>> + * PTE/PUD entry, since the page is not used by other.
>>> + * So we can also free the page.
>>> + */
>>> + if (memchr_inv(page_addr, PAGE_INUSE, *page_size)) {
>>> + *pp = NULL;
>>> + return next;
>>> + }
>>> +
>>
>> Hi Yasuaki,
>>
>> why call memchr_inv check after memset, this time the page can always
>> be filled with 0xFD.
>
> The page is not always filled with 0xFD. find_and_clear_pte_page()
> is calld in each section. So the function fills the page
> section size/sizeof(page) byte with 0xFD one time. Thus if section
> size is
> small, the page is filled with 0xFD.
Hi Yasuaki,
But when section size will be small?
Regards,
Chen
>
> Thanks,
> Yasuaki Ishimatsu
>
>
>>> + if (!cpu_has_pse)
>>> + pte_clear(&init_mm, addr, pte);
>>> + else
>>> + pmd_clear(pmd);
>>> +
>>> + return next;
>>> +}
>>> +
>>> +void vmemmap_kfree(struct page *memmap, unsigned long nr_pages)
>>> +{
>>> + unsigned long addr = (unsigned long)memmap;
>>> + unsigned long end = (unsigned long)(memmap + nr_pages);
>>> + unsigned long next;
>>> + struct page *page;
>>> + int page_size;
>>> +
>>> + for (; addr < end; addr = next) {
>>> + page = NULL;
>>> + page_size = 0;
>>> + next = find_and_clear_pte_page(addr, end, &page, &page_size);
>>> + if (!page)
>>> + continue;
>>> +
>>> + free_pages((unsigned long)page_address(page),
>>> + get_order(page_size));
>>> + __flush_tlb_one(addr);
>>> + }
>>> +}
>>> +
>>> +void vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages)
>>> +{
>>> + unsigned long addr = (unsigned long)memmap;
>>> + unsigned long end = (unsigned long)(memmap + nr_pages);
>>> + unsigned long next;
>>> + struct page *page;
>>> + int page_size;
>>> + unsigned long magic;
>>> +
>>> + for (; addr < end; addr = next) {
>>> + page = NULL;
>>> + page_size = 0;
>>> + next = find_and_clear_pte_page(addr, end, &page, &page_size);
>>> + if (!page)
>>> + continue;
>>> +
>>> + magic = (unsigned long) page->lru.next;
>>> + if (magic == SECTION_INFO)
>>> + put_page_bootmem(page);
>>> + flush_tlb_kernel_range(addr, end);
>>> + }
>>> +}
>>> +
>>> void register_page_bootmem_memmap(unsigned long section_nr,
>>> struct page *start_page, unsigned long size)
>>> {
>>> diff --git a/include/linux/mm.h b/include/linux/mm.h
>>> index c607913..fb0d1fc 100644
>>> --- a/include/linux/mm.h
>>> +++ b/include/linux/mm.h
>>> @@ -1620,6 +1620,8 @@ int vmemmap_populate(struct page *start_page,
>>> unsigned long pages, int node);
>>> void vmemmap_populate_print_last(void);
>>> void register_page_bootmem_memmap(unsigned long section_nr, struct
>>> page *map,
>>> unsigned long size);
>>> +void vmemmap_kfree(struct page *memmpa, unsigned long nr_pages);
>>> +void vmemmap_free_bootmem(struct page *memmpa, unsigned long
>>> nr_pages);
>>> enum mf_flags {
>>> MF_COUNT_INCREASED = 1 << 0,
>>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>>> index 647a7f2..c54922c 100644
>>> --- a/mm/memory_hotplug.c
>>> +++ b/mm/memory_hotplug.c
>>> @@ -308,19 +308,6 @@ static int __meminit __add_section(int nid,
>>> struct zone *zone,
>>> return register_new_memory(nid,
>>> __pfn_to_section(phys_start_pfn));
>>> }
>>> -#ifdef CONFIG_SPARSEMEM_VMEMMAP
>>> -static int __remove_section(struct zone *zone, struct mem_section *ms)
>>> -{
>>> - int ret = -EINVAL;
>>> -
>>> - if (!valid_section(ms))
>>> - return ret;
>>> -
>>> - ret = unregister_memory_section(ms);
>>> -
>>> - return ret;
>>> -}
>>> -#else
>>> static int __remove_section(struct zone *zone, struct mem_section
>>> *ms)
>>> {
>>> unsigned long flags;
>>> @@ -337,9 +324,9 @@ static int __remove_section(struct zone *zone,
>>> struct mem_section *ms)
>>> pgdat_resize_lock(pgdat, &flags);
>>> sparse_remove_one_section(zone, ms);
>>> pgdat_resize_unlock(pgdat, &flags);
>>> - return 0;
>>> +
>>> + return ret;
>>> }
>>> -#endif
>>> /*
>>> * Reasonably generic function for adding memory. It is
>>> diff --git a/mm/sparse.c b/mm/sparse.c
>>> index fac95f2..ab9d755 100644
>>> --- a/mm/sparse.c
>>> +++ b/mm/sparse.c
>>> @@ -613,12 +613,13 @@ static inline struct page
>>> *kmalloc_section_memmap(unsigned long pnum, int nid,
>>> /* This will make the necessary allocations eventually. */
>>> return sparse_mem_map_populate(pnum, nid);
>>> }
>>> -static void __kfree_section_memmap(struct page *memmap, unsigned
>>> long nr_pages)
>>> +static void __kfree_section_memmap(struct page *page, unsigned long
>>> nr_pages)
>>> {
>>> - return; /* XXX: Not implemented yet */
>>> + vmemmap_kfree(page, nr_pages);
>>> }
>>> static void free_map_bootmem(struct page *page, unsigned long
>>> nr_pages)
>>> {
>>> + vmemmap_free_bootmem(page, nr_pages);
>>> }
>>> #else
>>> static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
>>
>
>
>