Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756822Ab2JDG1c (ORCPT ); Thu, 4 Oct 2012 02:27:32 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:34977 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756095Ab2JDG13 (ORCPT ); Thu, 4 Oct 2012 02:27:29 -0400 X-SecurityPolicyCheck: OK by SHieldMailChecker v1.7.4 Message-ID: <506D2C1C.5060706@jp.fujitsu.com> Date: Thu, 4 Oct 2012 15:26:36 +0900 From: Yasuaki Ishimatsu User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:15.0) Gecko/20120907 Thunderbird/15.0.1 MIME-Version: 1.0 To: Ni zhan Chen CC: , , , , , , , , , , , , , , , , , , , Wen Congyang Subject: Re: [RFC v9 PATCH 16/21] memory-hotplug: free memmap of sparse-vmemmap References: <1346837155-534-1-git-send-email-wency@cn.fujitsu.com> <1346837155-534-17-git-send-email-wency@cn.fujitsu.com> <506A6BDC.3010400@gmail.com> In-Reply-To: <506A6BDC.3010400@gmail.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 11323 Lines: 335 Hi Chen, Sorry for late reply. 2012/10/02 13:21, Ni zhan Chen wrote: > On 09/05/2012 05:25 PM, wency@cn.fujitsu.com wrote: >> From: Yasuaki Ishimatsu >> >> 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 >> CC: Jiang Liu >> CC: Len Brown >> CC: Benjamin Herrenschmidt >> CC: Paul Mackerras >> CC: Christoph Lameter >> Cc: Minchan Kim >> CC: Andrew Morton >> CC: KOSAKI Motohiro >> CC: Wen Congyang >> Signed-off-by: Yasuaki Ishimatsu >> --- >> 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) > -- 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/