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 <rientjes@xxxxxxxxxx> > CC: Jiang Liu <liuj97@xxxxxxxxx> > CC: Len Brown <len.brown@xxxxxxxxx> > CC: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> > CC: Paul Mackerras <paulus@xxxxxxxxx> > CC: Christoph Lameter <cl@xxxxxxxxx> > Cc: Minchan Kim <minchan.kim@xxxxxxxxx> > CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > CC: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > CC: Wen Congyang <wency@xxxxxxxxxxxxxx> > Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx> > > --- > 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)); > + } > + > +} > + > +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; This two line should not be removed. Otherwise, we can not build the kernel. Thanks Wen Congyang > - 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@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html