[PATCH v2 09/12] memory-hotplug: remove page table of x86_64 architecture

wency
2012-10-23T10:26:55Z

From: Wen Congyang <wency@cn.fujitsu.com>

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 <rientjes@google.com>
CC: Jiang Liu <liuj97@gmail.com>
CC: Len Brown <len.brown@intel.com>
CC: Christoph Lameter <cl@linux.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Jianguo Wu <wujianguo@huawei.com>
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
---
arch/x86/include/asm/pgtable_types.h | 1 +
arch/x86/mm/init_64.c | 223 ++++++++++++++++++++++++++++++++++
arch/x86/mm/pageattr.c | 47 ++++----
3 files changed, 249 insertions(+), 22 deletions(-)

diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index ec8a1fc..fb0c24d 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -332,6 +332,7 @@ static inline void update_page_count(int level, unsigned long pages) { }
* 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__ */

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 73b1b6a..4809a9f 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -675,6 +675,227 @@ 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;
+ 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))
+ return;
+ }
+
+ /* free a pte talbe */
+ free_pagetable(pmd_page(*pmd));
+ 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))
+ return;
+ }
+
+ /* free a pmd talbe */
+ 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))
+ return;
+ }
+
+ /* free a pud table */
+ free_pagetable(pgd_page(*pgd));
+ pgd_clear(pgd);
+}
+
+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 && addr < end; i++, addr = next) {
+ unsigned long pte_phys;
+ pmd_t *pmd = pmd_page + pmd_index(addr);
+ pte_t *pte;
+
+ next = pmd_addr_end(addr, end);
+
+ if (!pmd_present(*pmd))
+ continue;
+
+ if (pmd_large(*pmd)) {
+ if (IS_ALIGNED(addr, PMD_SIZE) &&
+ IS_ALIGNED(next, PMD_SIZE)) {
+ 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);
+ BUG_ON(!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));
+ spin_unlock(&init_mm.page_table_lock);
+
+ /* Do a global flush tlb after splitting a large page */
+ flush_tlb_all();
+ }
+
+ spin_lock(&init_mm.page_table_lock);
+ pte = map_low_page((pte_t *)pmd_page_vaddr(*pmd));
+ phys_pte_remove(pte, addr, next);
+ free_pte_table(pte, pmd);
+ 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 && addr < end; i++, addr = next) {
+ unsigned long pmd_phys;
+ pud_t *pud = pud_page + pud_index(addr);
+ pmd_t *pmd;
+
+ next = pud_addr_end(addr, end);
+
+ if (!pud_present(*pud))
+ continue;
+
+ if (pud_large(*pud)) {
+ if (IS_ALIGNED(addr, PUD_SIZE) &&
+ IS_ALIGNED(next, PUD_SIZE)) {
+ 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);
+ BUG_ON(!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);
+
+ /* Do a global flush tlb after splitting a large page */
+ flush_tlb_all();
+ }
+
+ pmd = map_low_page((pmd_t *)pud_page_vaddr(*pud));
+ phys_pmd_remove(pmd, addr, next);
+ free_pmd_table(pmd, pud);
+ unmap_low_page(pmd);
+ }
+
+ 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 = 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(next));
+ free_pud_table(pud, pgd);
+ unmap_low_page(pud);
+ }
+
+ flush_tlb_all();
+}
+
#ifdef CONFIG_MEMORY_HOTREMOVE
int __ref arch_remove_memory(u64 start, u64 size)
{
@@ -687,6 +908,8 @@ int __ref arch_remove_memory(u64 start, u64 size)
ret = __remove_pages(zone, start_pfn, nr_pages);
WARN_ON_ONCE(ret);

+ kernel_physical_mapping_remove(start, start + size);
+
return ret;
}
#endif
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index a718e0d..7dcb6f9 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -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, unsigned long address)
* 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, unsigned long address)
* 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;
}
--
1.7.1