diff options
Diffstat (limited to 'mm/memory_hotplug.c')
| -rw-r--r-- | mm/memory_hotplug.c | 254 |
1 files changed, 254 insertions, 0 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 1cbe957..c4e1b95 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -23,6 +23,9 @@ #include <linux/vmalloc.h> #include <linux/ioport.h> #include <linux/cpuset.h> +#include <linux/delay.h> +#include <linux/migrate.h> +#include <linux/page-isolation.h> #include <asm/tlbflush.h> @@ -302,3 +305,254 @@ error: return ret; } EXPORT_SYMBOL_GPL(add_memory); + +#ifdef CONFIG_MEMORY_HOTREMOVE +/* + * Confirm all pages in a range [start, end) is belongs to the same zone. + */ +static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn) +{ + unsigned long pfn; + struct zone *zone = NULL; + struct page *page; + int i; + for (pfn = start_pfn; + pfn < end_pfn; + pfn += MAX_ORDER_NR_PAGES) { + i = 0; + /* This is just a CONFIG_HOLES_IN_ZONE check.*/ + while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i)) + i++; + if (i == MAX_ORDER_NR_PAGES) + continue; + page = pfn_to_page(pfn + i); + if (zone && page_zone(page) != zone) + return 0; + zone = page_zone(page); + } + return 1; +} + +/* + * Scanning pfn is much easier than scanning lru list. + * Scan pfn from start to end and Find LRU page. + */ +int scan_lru_pages(unsigned long start, unsigned long end) +{ + unsigned long pfn; + struct page *page; + for (pfn = start; pfn < end; pfn++) { + if (pfn_valid(pfn)) { + page = pfn_to_page(pfn); + if (PageLRU(page)) + return pfn; + } + } + return 0; +} + +static struct page * +hotremove_migrate_alloc(struct page *page, + unsigned long private, + int **x) +{ + /* This should be improoooooved!! */ + return alloc_page(GFP_HIGHUSER_PAGECACHE); +} + + +#define NR_OFFLINE_AT_ONCE_PAGES (256) +static int +do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) +{ + unsigned long pfn; + struct page *page; + int move_pages = NR_OFFLINE_AT_ONCE_PAGES; + int not_managed = 0; + int ret = 0; + LIST_HEAD(source); + + for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) { + if (!pfn_valid(pfn)) + continue; + page = pfn_to_page(pfn); + if (!page_count(page)) + continue; + /* + * We can skip free pages. And we can only deal with pages on + * LRU. + */ + ret = isolate_lru_page(page, &source); + if (!ret) { /* Success */ + move_pages--; + } else { + /* Becasue we don't have big zone->lock. we should + check this again here. */ + if (page_count(page)) + not_managed++; +#ifdef CONFIG_DEBUG_VM + printk(KERN_INFO "removing from LRU failed" + " %lx/%d/%lx\n", + pfn, page_count(page), page->flags); +#endif + } + } + ret = -EBUSY; + if (not_managed) { + if (!list_empty(&source)) + putback_lru_pages(&source); + goto out; + } + ret = 0; + if (list_empty(&source)) + goto out; + /* this function returns # of failed pages */ + ret = migrate_pages(&source, hotremove_migrate_alloc, 0); + +out: + return ret; +} + +/* + * remove from free_area[] and mark all as Reserved. + */ +static int +offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages, + void *data) +{ + __offline_isolated_pages(start, start + nr_pages); + return 0; +} + +static void +offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn) +{ + walk_memory_resource(start_pfn, end_pfn - start_pfn, NULL, + offline_isolated_pages_cb); +} + +/* + * Check all pages in range, recoreded as memory resource, are isolated. + */ +static int +check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages, + void *data) +{ + int ret; + long offlined = *(long *)data; + ret = test_pages_isolated(start_pfn, start_pfn + nr_pages); + offlined = nr_pages; + if (!ret) + *(long *)data += offlined; + return ret; +} + +static long +check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn) +{ + long offlined = 0; + int ret; + + ret = walk_memory_resource(start_pfn, end_pfn - start_pfn, &offlined, + check_pages_isolated_cb); + if (ret < 0) + offlined = (long)ret; + return offlined; +} + +extern void drain_all_local_pages(void); + +int offline_pages(unsigned long start_pfn, + unsigned long end_pfn, unsigned long timeout) +{ + unsigned long pfn, nr_pages, expire; + long offlined_pages; + int ret, drain, retry_max; + struct zone *zone; + + BUG_ON(start_pfn >= end_pfn); + /* at least, alignment against pageblock is necessary */ + if (!IS_ALIGNED(start_pfn, pageblock_nr_pages)) + return -EINVAL; + if (!IS_ALIGNED(end_pfn, pageblock_nr_pages)) + return -EINVAL; + /* This makes hotplug much easier...and readable. + we assume this for now. .*/ + if (!test_pages_in_a_zone(start_pfn, end_pfn)) + return -EINVAL; + /* set above range as isolated */ + ret = start_isolate_page_range(start_pfn, end_pfn); + if (ret) + return ret; + nr_pages = end_pfn - start_pfn; + pfn = start_pfn; + expire = jiffies + timeout; + drain = 0; + retry_max = 5; +repeat: + /* start memory hot removal */ + ret = -EAGAIN; + if (time_after(jiffies, expire)) + goto failed_removal; + ret = -EINTR; + if (signal_pending(current)) + goto failed_removal; + ret = 0; + if (drain) { + lru_add_drain_all(); + flush_scheduled_work(); + cond_resched(); + drain_all_local_pages(); + } + + pfn = scan_lru_pages(start_pfn, end_pfn); + if (pfn) { /* We have page on LRU */ + ret = do_migrate_range(pfn, end_pfn); + if (!ret) { + drain = 1; + goto repeat; + } else { + if (ret < 0) + if (--retry_max == 0) + goto failed_removal; + yield(); + drain = 1; + goto repeat; + } + } + /* drain all zone's lru pagevec, this is asyncronous... */ + lru_add_drain_all(); + flush_scheduled_work(); + yield(); + /* drain pcp pages , this is synchrouns. */ + drain_all_local_pages(); + /* check again */ + offlined_pages = check_pages_isolated(start_pfn, end_pfn); + if (offlined_pages < 0) { + ret = -EBUSY; + goto failed_removal; + } + printk(KERN_INFO "Offlined Pages %ld\n", offlined_pages); + /* Ok, all of our target is islaoted. + We cannot do rollback at this point. */ + offline_isolated_pages(start_pfn, end_pfn); + /* reset pagetype flags */ + start_isolate_page_range(start_pfn, end_pfn); + /* removal success */ + zone = page_zone(pfn_to_page(start_pfn)); + zone->present_pages -= offlined_pages; + zone->zone_pgdat->node_present_pages -= offlined_pages; + totalram_pages -= offlined_pages; + num_physpages -= offlined_pages; + vm_total_pages = nr_free_pagecache_pages(); + writeback_set_ratelimit(); + return 0; + +failed_removal: + printk(KERN_INFO "memory offlining %lx to %lx failed\n", + start_pfn, end_pfn); + /* pushback to free area */ + undo_isolate_page_range(start_pfn, end_pfn); + return ret; +} +#endif /* CONFIG_MEMORY_HOTREMOVE */ |
