From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752063Ab2JBEWM (ORCPT ); Tue, 2 Oct 2012 00:22:12 -0400 Received: from mail-ie0-f174.google.com ([209.85.223.174]:44464 "EHLO mail-ie0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751295Ab2JBEWG (ORCPT ); Tue, 2 Oct 2012 00:22:06 -0400 Message-ID: <506A6BDC.3010400@gmail.com> Date: Tue, 02 Oct 2012 12:21:48 +0800 From: Ni zhan Chen User-Agent: Mozilla/5.0 (X11; Linux i686; rv:15.0) Gecko/20120827 Thunderbird/15.0 MIME-Version: 1.0 To: isimatu.yasuaki@jp.fujitsu.com CC: 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, benh@kernel.crashing.org, paulus@samba.org, cl@linux.com, minchan.kim@gmail.com, akpm@linux-foundation.org, kosaki.motohiro@jp.fujitsu.com, 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> In-Reply-To: <1346837155-534-17-git-send-email-wency@cn.fujitsu.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 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. > + 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)