Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756705Ab2JWHJs (ORCPT ); Tue, 23 Oct 2012 03:09:48 -0400 Received: from mail-pa0-f46.google.com ([209.85.220.46]:52191 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756477Ab2JWHJo (ORCPT ); Tue, 23 Oct 2012 03:09:44 -0400 Message-ID: <50864297.9010708@gmail.com> Date: Tue, 23 Oct 2012 15:09:11 +0800 From: wujianguo User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:14.0) Gecko/20120713 Thunderbird/14.0 MIME-Version: 1.0 To: Wen Congyang CC: Yasuaki Ishimatsu , x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-ia64@vger.kernel.org, cmetcalf@tilera.com, sparclinux@vger.kernel.org, rientjes@google.com, liuj97@gmail.com, len.brown@intel.com, cl@linux.com, minchan.kim@gmail.com, akpm@linux-foundation.org, kosaki.motohiro@jp.fujitsu.com, wujianguo@huawei.com, qiuxishi@huawei.com, jiang.liu@huawei.com Subject: Re: [PATCH 8/10] memory-hotplug : remove page table of x86_64 architecture References: <506E43E0.70507@jp.fujitsu.com> <506E4799.30407@jp.fujitsu.com> <5073DFC0.3010400@gmail.com> <5084F195.6030908@cn.fujitsu.com> In-Reply-To: <5084F195.6030908@cn.fujitsu.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 16143 Lines: 562 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 >> >> Signed-off-by: Jianguo Wu >> Signed-off-by: Jiang Liu >> --- >> 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++; } } > >> +} >> + >> +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? > >> + 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 >>> >>> 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 >>> CC: Jiang Liu >>> CC: Len Brown >>> CC: Christoph Lameter >>> Cc: Minchan Kim >>> CC: Andrew Morton >>> CC: KOSAKI Motohiro >>> CC: Yasuaki Ishimatsu >>> Signed-off-by: Wen Congyang >>> --- >>> 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@kvack.org. For more info on Linux MM, >>> see: http://www.linux-mm.org/ . >>> Don't email: email@kvack.org >>> >> >> > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/