At 10/23/2012 03:09 PM, wujianguo Wrote: > On 2012-10-22 15:11, Wen Congyang wrote: >> Hi, Wu >> >> Sorry for late reply. >> >> At 10/09/2012 04:26 PM, wujianguo Wrote: >>> Hi Congyang, >>> I think we should also free pages which are used by page tables after removing >>> page tables of the memory. >> >> It is OK to do it. >> >>> >>> From: Jianguo Wu <wujianguo@xxxxxxxxxx> >>> >>> Signed-off-by: Jianguo Wu <wujianguo@xxxxxxxxxx> >>> Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx> >>> --- >>> arch/x86/mm/init_64.c | 110 +++++++++++++++++++++++++++++++++++++++--------- >>> 1 files changed, 89 insertions(+), 21 deletions(-) >>> >>> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c >>> index 5596dfa..81f9c3b 100644 >>> --- a/arch/x86/mm/init_64.c >>> +++ b/arch/x86/mm/init_64.c >>> @@ -675,6 +675,74 @@ int arch_add_memory(int nid, u64 start, u64 size) >>> } >>> EXPORT_SYMBOL_GPL(arch_add_memory); >>> >>> +static inline void free_pagetable(struct page *page) >>> +{ >>> + struct zone *zone; >>> + >>> + __ClearPageReserved(page); >>> + __free_page(page); >>> + >>> + zone = page_zone(page); >>> + zone_span_writelock(zone); >>> + zone->present_pages++; >>> + zone_span_writeunlock(zone); >>> + totalram_pages++; >> >> Why do you update zone and totalram_pages here? > Sorry, I made a mistake here. Only if the page was allocated at booting, we should update > zone and totalram_pages(zone->present_pages and totalram_pages mean pages which are > managed by buddy system). > > How about: > static inline void free_pagetable(struct page *page) > { > struct zone *zone; > bool bootmem = false; > > /* bootmem page has reserved flag */ > if (PageReserved(page)) { > __ClearPageReserved(page); > bootmem = true; > } > > __free_page(page); > > if (bootmem) { > zone = page_zone(page); > zone_span_writelock(zone); > zone->present_pages++; > zone_span_writeunlock(zone); > totalram_pages++; > } > } This verson looks fine to me. > >> >>> +} >>> + >>> +static void free_pte_table(pte_t *pte_start, pmd_t *pmd) >>> +{ >>> + pte_t *pte; >>> + int i; >>> + >>> + for (i = 0; i < PTRS_PER_PTE; i++) { >>> + pte = pte_start + i; >>> + if (pte_val(*pte)) >>> + break; >>> + } >>> + >>> + /* free a pte talbe */ >>> + if (i == PTRS_PER_PTE) { >>> + free_pagetable(pmd_page(*pmd)); >> >> The memory may be allocated at booting. So it is very dangerous to >> free it without any check. > The page is only used by page table, so is safe to free it when all the page table > entries have been cleared, right? Yes, but I guess we need to do more. For example, all boot memory are in memblock.reserved, and you don't update memblock here. Thanks Wen Congyang > >> >>> + pmd_clear(pmd); >>> + } >>> +} >>> + >>> +static void free_pmd_table(pmd_t *pmd_start, pud_t *pud) >>> +{ >>> + pmd_t *pmd; >>> + int i; >>> + >>> + for (i = 0; i < PTRS_PER_PMD; i++) { >>> + pmd = pmd_start + i; >>> + if (pmd_val(*pmd)) >>> + break; >>> + } >>> + >>> + /* free a pmd talbe */ >>> + if (i == PTRS_PER_PMD) { >>> + free_pagetable(pud_page(*pud)); >>> + pud_clear(pud); >>> + } >>> +} >>> + >>> +static void free_pud_table(pud_t *pud_start, pgd_t *pgd) >>> +{ >>> + pud_t *pud; >>> + int i; >>> + >>> + for (i = 0; i < PTRS_PER_PUD; i++) { >>> + pud = pud_start + i; >>> + if (pud_val(*pud)) >>> + break; >>> + } >>> + >>> + /* free a pud table */ >>> + if (i == PTRS_PER_PUD) { >>> + free_pagetable(pgd_page(*pgd)); >>> + pgd_clear(pgd); >>> + } >>> +} >>> + >>> static void __meminit >>> phys_pte_remove(pte_t *pte_page, unsigned long addr, unsigned long end) >>> { >>> @@ -704,21 +772,19 @@ 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) { >>> + for (; i < PTRS_PER_PMD && addr < end; 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; >>> + next = pmd_addr_end(addr, end); >>> >>> if (!pmd_present(*pmd)) >>> continue; >>> >>> if (pmd_large(*pmd)) { >>> - if ((addr & ~PMD_MASK) == 0 && next <= end) { >>> + if (IS_ALIGNED(addr, PMD_SIZE) && >>> + IS_ALIGNED(next, PMD_SIZE)) { >>> set_pmd(pmd, __pmd(0)); >>> pages++; >>> continue; >>> @@ -729,7 +795,8 @@ phys_pmd_remove(pmd_t *pmd_page, unsigned long addr, unsigned long end) >>> * so split 2M page to 4K page. >>> */ >>> pte = alloc_low_page(&pte_phys); >>> - __split_large_page((pte_t *)pmd, addr, pte); >>> + __split_large_page((pte_t *)pmd, >>> + (unsigned long)__va(addr), pte); >>> >>> spin_lock(&init_mm.page_table_lock); >>> pmd_populate_kernel(&init_mm, pmd, __va(pte_phys)); >>> @@ -738,7 +805,8 @@ phys_pmd_remove(pmd_t *pmd_page, unsigned long addr, unsigned long end) >>> >>> spin_lock(&init_mm.page_table_lock); >>> pte = map_low_page((pte_t *)pmd_page_vaddr(*pmd)); >>> - phys_pte_remove(pte, addr, end); >>> + phys_pte_remove(pte, addr, next); >>> + free_pte_table(pte, pmd); >>> unmap_low_page(pte); >>> spin_unlock(&init_mm.page_table_lock); >>> } >>> @@ -751,21 +819,19 @@ 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) { >>> + for (; i < PTRS_PER_PUD && addr < end; 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; >>> + next = pud_addr_end(addr, end); >>> >>> if (!pud_present(*pud)) >>> continue; >>> >>> if (pud_large(*pud)) { >>> - if ((addr & ~PUD_MASK) == 0 && next <= end) { >>> + if (IS_ALIGNED(addr, PUD_SIZE) && >>> + IS_ALIGNED(next, PUD_SIZE)) { >>> set_pud(pud, __pud(0)); >>> pages++; >>> continue; >>> @@ -776,15 +842,18 @@ phys_pud_remove(pud_t *pud_page, unsigned long addr, unsigned long end) >>> * so split 1G page to 2M page. >>> */ >>> pmd = alloc_low_page(&pmd_phys); >>> - __split_large_page((pte_t *)pud, addr, (pte_t *)pmd); >>> + __split_large_page((pte_t *)pud, >>> + (unsigned long)__va(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); >>> + pmd = map_low_page((pmd_t *)pud_page_vaddr(*pud)); >> >> Hmm, pmd_offset(pud, 0) is equal to (pmd_t *)pud_page_vaddr(*pud). >> >> Is it OK to merge your patch into my patch? >> > Yes, sure. > > Thanks, > Jianguo Wu > >> Thanks >> Wen Congyang >> >>> + phys_pmd_remove(pmd, addr, next); >>> + free_pmd_table(pmd, pud); >>> unmap_low_page(pmd); >>> __flush_tlb_all(); >>> } >>> @@ -805,15 +874,14 @@ kernel_physical_mapping_remove(unsigned long start, unsigned long end) >>> pgd_t *pgd = pgd_offset_k(start); >>> pud_t *pud; >>> >>> - next = (start + PGDIR_SIZE) & PGDIR_MASK; >>> - if (next > end) >>> - next = end; >>> + next = pgd_addr_end(start, end); >>> >>> if (!pgd_present(*pgd)) >>> continue; >>> >>> pud = map_low_page((pud_t *)pgd_page_vaddr(*pgd)); >>> - phys_pud_remove(pud, __pa(start), __pa(end)); >>> + phys_pud_remove(pud, __pa(start), __pa(next)); >>> + free_pud_table(pud, pgd); >>> unmap_low_page(pud); >>> } >>> >>> -- 1.7.6.1 . >>> >>> >>> On 2012-10-5 10:36, Yasuaki Ishimatsu wrote: >>>> From: Wen Congyang <wency@xxxxxxxxxxxxxx> >>>> >>>> For hot removing memory, we sholud remove page table about the memory. >>>> So the patch searches a page table about the removed memory, and clear >>>> page table. >>>> >>>> CC: David Rientjes <rientjes@xxxxxxxxxx> >>>> CC: Jiang Liu <liuj97@xxxxxxxxx> >>>> CC: Len Brown <len.brown@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/x86/include/asm/pgtable_types.h | 1 >>>> arch/x86/mm/init_64.c | 147 +++++++++++++++++++++++++++++++++++ >>>> arch/x86/mm/pageattr.c | 47 +++++------ >>>> 3 files changed, 173 insertions(+), 22 deletions(-) >>>> >>>> Index: linux-3.6/arch/x86/mm/init_64.c >>>> =================================================================== >>>> --- linux-3.6.orig/arch/x86/mm/init_64.c 2012-10-04 18:30:21.171698416 +0900 >>>> +++ linux-3.6/arch/x86/mm/init_64.c 2012-10-04 18:30:27.317704652 +0900 >>>> @@ -675,6 +675,151 @@ int arch_add_memory(int nid, u64 start, >>>> } >>>> 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(u64 start, u64 size) >>>> { >>>> @@ -687,6 +832,8 @@ int __ref arch_remove_memory(u64 start, >>>> ret = __remove_pages(zone, start_pfn, nr_pages); >>>> WARN_ON_ONCE(ret); >>>> >>>> + kernel_physical_mapping_remove(start, start + size); >>>> + >>>> return ret; >>>> } >>>> #endif >>>> Index: linux-3.6/arch/x86/include/asm/pgtable_types.h >>>> =================================================================== >>>> --- linux-3.6.orig/arch/x86/include/asm/pgtable_types.h 2012-10-04 18:26:51.925486954 +0900 >>>> +++ linux-3.6/arch/x86/include/asm/pgtable_types.h 2012-10-04 18:30:27.322704656 +0900 >>>> @@ -334,6 +334,7 @@ static inline void update_page_count(int >>>> * 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__ */ >>>> >>>> Index: linux-3.6/arch/x86/mm/pageattr.c >>>> =================================================================== >>>> --- linux-3.6.orig/arch/x86/mm/pageattr.c 2012-10-04 18:26:51.923486952 +0900 >>>> +++ linux-3.6/arch/x86/mm/pageattr.c 2012-10-04 18:30:27.328704662 +0900 >>>> @@ -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, >>>> * 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, >>>> * 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; >>>> } >>>> >>>> -- >>>> To unsubscribe, send a message with 'unsubscribe linux-mm' in >>>> the body to majordomo@xxxxxxxxx. For more info on Linux MM, >>>> see: http://www.linux-mm.org/ . >>>> Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a> >>>> >>> >>> >> >> > > -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html