From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx157.postini.com [74.125.245.157]) by kanga.kvack.org (Postfix) with SMTP id 2B1316B005C for ; Thu, 19 Jul 2012 05:55:08 -0400 (EDT) Received: from m1.gw.fujitsu.co.jp (unknown [10.0.50.71]) by fgwmail5.fujitsu.co.jp (Postfix) with ESMTP id BE2CC3EE0BD for ; Thu, 19 Jul 2012 18:55:06 +0900 (JST) Received: from smail (m1 [127.0.0.1]) by outgoing.m1.gw.fujitsu.co.jp (Postfix) with ESMTP id 9C55145DE5D for ; Thu, 19 Jul 2012 18:55:06 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (s1.gw.fujitsu.co.jp [10.0.50.91]) by m1.gw.fujitsu.co.jp (Postfix) with ESMTP id 7E26445DE54 for ; Thu, 19 Jul 2012 18:55:06 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id 6F50A1DB8052 for ; Thu, 19 Jul 2012 18:55:06 +0900 (JST) Received: from g01jpexchkw04.g01.fujitsu.local (g01jpexchkw04.g01.fujitsu.local [10.0.194.43]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id 1D1461DB804E for ; Thu, 19 Jul 2012 18:55:06 +0900 (JST) Message-ID: <5007D963.6010902@jp.fujitsu.com> Date: Thu, 19 Jul 2012 18:54:43 +0900 From: Yasuaki Ishimatsu MIME-Version: 1.0 Subject: Re: [RFC PATCH v4 11/13] memory-hotplug : free memmap of sparse-vmemmap References: <50068974.1070409@jp.fujitsu.com> <50068D09.1050704@jp.fujitsu.com> <5007D722.1030807@cn.fujitsu.com> In-Reply-To: <5007D722.1030807@cn.fujitsu.com> Content-Type: text/plain; charset="ISO-2022-JP" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Wen Congyang Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@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 Hi Wen, 2012/07/19 18:45, Wen Congyang wrote: > At 07/18/2012 06:16 PM, Yasuaki Ishimatsu Wrote: >> 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. >> >> 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/x86/mm/init_64.c | 121 ++++++++++++++++++++++++++++++++++++++++++++++++++ >> include/linux/mm.h | 2 >> mm/memory_hotplug.c | 19 ------- >> mm/sparse.c | 5 +- >> 4 files changed, 128 insertions(+), 19 deletions(-) >> >> Index: linux-3.5-rc6/include/linux/mm.h >> =================================================================== >> --- linux-3.5-rc6.orig/include/linux/mm.h 2012-07-18 18:01:28.000000000 +0900 >> +++ linux-3.5-rc6/include/linux/mm.h 2012-07-18 18:03:05.551168773 +0900 >> @@ -1588,6 +1588,8 @@ int vmemmap_populate(struct page *start_ >> 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, >> Index: linux-3.5-rc6/mm/sparse.c >> =================================================================== >> --- linux-3.5-rc6.orig/mm/sparse.c 2012-07-18 17:59:25.000000000 +0900 >> +++ linux-3.5-rc6/mm/sparse.c 2012-07-18 18:03:05.553168749 +0900 >> @@ -614,12 +614,13 @@ static inline struct page *kmalloc_secti >> /* 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) >> Index: linux-3.5-rc6/arch/x86/mm/init_64.c >> =================================================================== >> --- linux-3.5-rc6.orig/arch/x86/mm/init_64.c 2012-07-18 18:01:28.000000000 +0900 >> +++ linux-3.5-rc6/arch/x86/mm/init_64.c 2012-07-18 18:03:05.564168611 +0900 >> @@ -978,6 +978,127 @@ vmemmap_populate(struct page *start_page >> 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; >> + } >> + >> + 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((unsigned long)page_address(page)); > > I think you want to free the memory to store struct page. > So why you free page_address(page)? Ths page is PT/PMD page and it has stored struct pages. So I free the page. Thanks, Yasuaki Ishimatsu > Thanks > Wen Congyang > >> + } >> + >> +} >> + >> +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) >> { >> Index: linux-3.5-rc6/mm/memory_hotplug.c >> =================================================================== >> --- linux-3.5-rc6.orig/mm/memory_hotplug.c 2012-07-18 18:01:28.000000000 +0900 >> +++ linux-3.5-rc6/mm/memory_hotplug.c 2012-07-18 18:25:11.036597977 +0900 >> @@ -300,7 +300,6 @@ static int __meminit __add_section(int n >> 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; >> @@ -309,29 +308,15 @@ static int __remove_section(struct zone >> return ret; >> >> ret = unregister_memory_section(ms); >> - >> - return ret; >> -} >> -#else >> -static int __remove_section(struct zone *zone, struct mem_section *ms) >> -{ >> - unsigned long flags; >> - struct pglist_data *pgdat = zone->zone_pgdat; >> - int ret = -EINVAL; >> - >> - if (!valid_section(ms)) >> - return ret; >> - >> - ret = unregister_memory_section(ms); >> if (ret) >> return ret; >> >> 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 >> >> -- >> 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/ >> > -- 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