/* * linux/mm/page_alloc.c * * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds * Swap reorganised 29.12.95, Stephen Tweedie * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999 * Reshaped it to be a zoned allocator, Ingo Molnar, Red Hat, 1999 * Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999 * Zone balancing, Kanoj Sarcar, SGI, Jan 2000 */ #include #include #include #include #include #include #include #include #include #include int nr_swap_pages; int nr_active_pages; int nr_inactive_pages; struct list_head inactive_list; struct list_head active_list; pg_data_t *pgdat_list; static char *zone_names[MAX_NR_ZONES] = { "DMA", "Normal", "HighMem" }; static int zone_balance_ratio[MAX_NR_ZONES] __initdata = { 128, 128, 128, }; static int zone_balance_min[MAX_NR_ZONES] __initdata = { 20 , 20, 20, }; static int zone_balance_max[MAX_NR_ZONES] __initdata = { 255 , 255, 255, }; /* * Free_page() adds the page to the free lists. This is optimized for * fast normal cases (no error jumps taken normally). * * The way to optimize jumps for gcc-2.2.2 is to: * - select the "normal" case and put it inside the if () { XXX } * - no else-statements if you can avoid them * * With the above two rules, you get a straight-line execution path * for the normal case, giving better asm-code. */ #define memlist_init(x) INIT_LIST_HEAD(x) #define memlist_add_head list_add #define memlist_add_tail list_add_tail #define memlist_del list_del #define memlist_entry list_entry #define memlist_next(x) ((x)->next) #define memlist_prev(x) ((x)->prev) /* * Temporary debugging check. */ #define BAD_RANGE(zone,x) (((zone) != (x)->zone) || (((x)-mem_map) < (zone)->zone_start_mapnr) || (((x)-mem_map) >= (zone)->zone_start_mapnr+(zone)->size)) /* * Buddy system. Hairy. You really aren't expected to understand this * * Hint: -mask = 1+~mask */ static void FASTCALL(__free_pages_ok (struct page *page, unsigned int order)); static void __free_pages_ok (struct page *page, unsigned int order) { unsigned long index, page_idx, mask, flags; free_area_t *area; struct page *base; zone_t *zone; if (page->buffers) BUG(); if (page->mapping) BUG(); if (!VALID_PAGE(page)) BUG(); if (PageSwapCache(page)) BUG(); if (PageLocked(page)) BUG(); if (PageLRU(page)) BUG(); if (PageActive(page)) BUG(); TRACE_MEMORY(TRACE_EV_MEMORY_PAGE_FREE, order); page->flags &= ~((1<flags & PF_FREE_PAGES) goto local_freelist; back_local_freelist: zone = page->zone; mask = (~0UL) << order; base = zone->zone_mem_map; page_idx = page - base; if (page_idx & ~mask) BUG(); index = page_idx >> (1 + order); area = zone->free_area + order; spin_lock_irqsave(&zone->lock, flags); zone->free_pages -= mask; while (mask + (1 << (MAX_ORDER-1))) { struct page *buddy1, *buddy2; if (area >= zone->free_area + MAX_ORDER) BUG(); if (!__test_and_change_bit(index, area->map)) /* * the buddy page is still allocated. */ break; /* * Move the buddy up one level. */ buddy1 = base + (page_idx ^ -mask); buddy2 = base + page_idx; if (BAD_RANGE(zone,buddy1)) BUG(); if (BAD_RANGE(zone,buddy2)) BUG(); memlist_del(&buddy1->list); mask <<= 1; area++; index >>= 1; page_idx &= mask; } memlist_add_head(&(base + page_idx)->list, &area->free_list); spin_unlock_irqrestore(&zone->lock, flags); return; local_freelist: if (current->nr_local_pages) goto back_local_freelist; if (in_interrupt()) goto back_local_freelist; list_add(&page->list, ¤t->local_pages); page->index = order; current->nr_local_pages++; } #define MARK_USED(index, order, area) \ __change_bit((index) >> (1+(order)), (area)->map) static inline struct page * expand (zone_t *zone, struct page *page, unsigned long index, int low, int high, free_area_t * area) { unsigned long size = 1 << high; while (high > low) { if (BAD_RANGE(zone,page)) BUG(); area--; high--; size >>= 1; memlist_add_head(&(page)->list, &(area)->free_list); MARK_USED(index, high, area); index += size; page += size; } if (BAD_RANGE(zone,page)) BUG(); return page; } static FASTCALL(struct page * rmqueue(zone_t *zone, unsigned int order)); static struct page * rmqueue(zone_t *zone, unsigned int order) { free_area_t * area = zone->free_area + order; unsigned int curr_order = order; struct list_head *head, *curr; unsigned long flags; struct page *page; spin_lock_irqsave(&zone->lock, flags); do { head = &area->free_list; curr = memlist_next(head); if (curr != head) { unsigned int index; page = memlist_entry(curr, struct page, list); if (BAD_RANGE(zone,page)) BUG(); memlist_del(curr); index = page - zone->zone_mem_map; if (curr_order != MAX_ORDER-1) MARK_USED(index, curr_order, area); zone->free_pages -= 1UL << order; page = expand(zone, page, index, order, curr_order, area); spin_unlock_irqrestore(&zone->lock, flags); set_page_count(page, 1); if (BAD_RANGE(zone,page)) BUG(); if (PageLRU(page)) BUG(); if (PageActive(page)) BUG(); return page; } curr_order++; area++; } while (curr_order < MAX_ORDER); spin_unlock_irqrestore(&zone->lock, flags); return NULL; } #ifndef CONFIG_DISCONTIGMEM struct page *_alloc_pages(unsigned int gfp_mask, unsigned int order) { return __alloc_pages(gfp_mask, order, contig_page_data.node_zonelists+(gfp_mask & GFP_ZONEMASK)); } #endif static struct page * FASTCALL(balance_classzone(zone_t *, unsigned int, unsigned int, int *)); static struct page * balance_classzone(zone_t * classzone, unsigned int gfp_mask, unsigned int order, int * freed) { struct page * page = NULL; int __freed = 0; if (!(gfp_mask & __GFP_WAIT)) goto out; if (in_interrupt()) BUG(); current->allocation_order = order; current->flags |= PF_MEMALLOC | PF_FREE_PAGES; __freed = try_to_free_pages(classzone, gfp_mask, order); current->flags &= ~(PF_MEMALLOC | PF_FREE_PAGES); if (current->nr_local_pages) { struct list_head * entry, * local_pages; struct page * tmp; int nr_pages; local_pages = ¤t->local_pages; if (likely(__freed)) { /* pick from the last inserted so we're lifo */ entry = local_pages->next; do { tmp = list_entry(entry, struct page, list); if (tmp->index == order && memclass(tmp->zone, classzone)) { list_del(entry); current->nr_local_pages--; set_page_count(tmp, 1); page = tmp; if (page->buffers) BUG(); if (page->mapping) BUG(); if (!VALID_PAGE(page)) BUG(); if (PageSwapCache(page)) BUG(); if (PageLocked(page)) BUG(); if (PageLRU(page)) BUG(); if (PageActive(page)) BUG(); if (PageDirty(page)) BUG(); break; } } while ((entry = entry->next) != local_pages); } nr_pages = current->nr_local_pages; /* free in reverse order so that the global order will be lifo */ while ((entry = local_pages->prev) != local_pages) { list_del(entry); tmp = list_entry(entry, struct page, list); __free_pages_ok(tmp, tmp->index); if (!nr_pages--) BUG(); } current->nr_local_pages = 0; } out: *freed = __freed; return page; } /* * This is the 'heart' of the zoned buddy allocator: */ struct page * __alloc_pages(unsigned int gfp_mask, unsigned int order, zonelist_t *zonelist) { unsigned long min; zone_t **zone, * classzone; struct page * page; int freed; zone = zonelist->zones; classzone = *zone; min = 1UL << order; for (;;) { zone_t *z = *(zone++); if (!z) break; min += z->pages_low; if (z->free_pages > min) { page = rmqueue(z, order); if (page) return page; } } classzone->need_balance = 1; mb(); if (waitqueue_active(&kswapd_wait)) wake_up_interruptible(&kswapd_wait); zone = zonelist->zones; min = 1UL << order; for (;;) { unsigned long local_min; zone_t *z = *(zone++); if (!z) break; local_min = z->pages_min; if (!(gfp_mask & __GFP_WAIT)) local_min >>= 2; min += local_min; if (z->free_pages > min) { page = rmqueue(z, order); if (page) return page; } } /* here we're in the low on memory slow path */ rebalance: if (current->flags & (PF_MEMALLOC | PF_MEMDIE)) { zone = zonelist->zones; for (;;) { zone_t *z = *(zone++); if (!z) break; page = rmqueue(z, order); if (page) return page; } return NULL; } /* Atomic allocations - we can't balance anything */ if (!(gfp_mask & __GFP_WAIT)) return NULL; page = balance_classzone(classzone, gfp_mask, order, &freed); if (page) return page; zone = zonelist->zones; min = 1UL << order; for (;;) { zone_t *z = *(zone++); if (!z) break; min += z->pages_min; if (z->free_pages > min) { page = rmqueue(z, order); if (page) return page; } } /* Don't let big-order allocations loop */ if (order > 3) return NULL; /* Yield for kswapd, and try again */ current->policy |= SCHED_YIELD; __set_current_state(TASK_RUNNING); schedule(); goto rebalance; } /* * Common helper functions. */ unsigned long __get_free_pages(unsigned int gfp_mask, unsigned int order) { struct page * page; page = alloc_pages(gfp_mask, order); if (!page) return 0; TRACE_MEMORY(TRACE_EV_MEMORY_PAGE_ALLOC, order); return (unsigned long) page_address(page); } unsigned long get_zeroed_page(unsigned int gfp_mask) { struct page * page; page = alloc_pages(gfp_mask, 0); if (page) { void *address = page_address(page); clear_page(address); return (unsigned long) address; } return 0; } void page_cache_release(struct page *page) { if (!PageReserved(page) && put_page_testzero(page)) { if (PageLRU(page)) lru_cache_del(page); __free_pages_ok(page, 0); } } void __free_pages(struct page *page, unsigned int order) { if (!PageReserved(page) && put_page_testzero(page)) __free_pages_ok(page, order); } void free_pages(unsigned long addr, unsigned int order) { if (addr != 0) __free_pages(virt_to_page(addr), order); } /* * Total amount of free (allocatable) RAM: */ unsigned int nr_free_pages (void) { unsigned int sum; zone_t *zone; pg_data_t *pgdat = pgdat_list; sum = 0; while (pgdat) { for (zone = pgdat->node_zones; zone < pgdat->node_zones + MAX_NR_ZONES; zone++) sum += zone->free_pages; pgdat = pgdat->node_next; } return sum; } /* * Amount of free RAM allocatable as buffer memory: */ unsigned int nr_free_buffer_pages (void) { pg_data_t *pgdat = pgdat_list; unsigned int sum = 0; do { zonelist_t *zonelist = pgdat->node_zonelists + (GFP_USER & GFP_ZONEMASK); zone_t **zonep = zonelist->zones; zone_t *zone; for (zone = *zonep++; zone; zone = *zonep++) { unsigned long size = zone->size; unsigned long high = zone->pages_high; if (size > high) sum += size - high; } pgdat = pgdat->node_next; } while (pgdat); return sum; } #if CONFIG_HIGHMEM unsigned int nr_free_highpages (void) { pg_data_t *pgdat = pgdat_list; unsigned int pages = 0; while (pgdat) { pages += pgdat->node_zones[ZONE_HIGHMEM].free_pages; pgdat = pgdat->node_next; } return pages; } #endif #define K(x) ((x) << (PAGE_SHIFT-10)) /* * Show free area list (used inside shift_scroll-lock stuff) * We also calculate the percentage fragmentation. We do this by counting the * memory on each free list with the exception of the first item on the list. */ void show_free_areas_core(pg_data_t *pgdat) { unsigned int order; unsigned type; pg_data_t *tmpdat = pgdat; printk("Free pages: %6dkB (%6dkB HighMem)\n", K(nr_free_pages()), K(nr_free_highpages())); while (tmpdat) { zone_t *zone; for (zone = tmpdat->node_zones; zone < tmpdat->node_zones + MAX_NR_ZONES; zone++) printk("Zone:%s freepages:%6lukB min:%6lukB low:%6lukB " "high:%6lukB\n", zone->name, K(zone->free_pages), K(zone->pages_min), K(zone->pages_low), K(zone->pages_high)); tmpdat = tmpdat->node_next; } printk("( Active: %d, inactive: %d, free: %d )\n", nr_active_pages, nr_inactive_pages, nr_free_pages()); for (type = 0; type < MAX_NR_ZONES; type++) { struct list_head *head, *curr; zone_t *zone = pgdat->node_zones + type; unsigned long nr, total, flags; total = 0; if (zone->size) { spin_lock_irqsave(&zone->lock, flags); for (order = 0; order < MAX_ORDER; order++) { head = &(zone->free_area + order)->free_list; curr = head; nr = 0; for (;;) { curr = memlist_next(curr); if (curr == head) break; nr++; } total += nr * (1 << order); printk("%lu*%lukB ", nr, K(1UL) << order); } spin_unlock_irqrestore(&zone->lock, flags); } printk("= %lukB)\n", K(total)); } #ifdef SWAP_CACHE_INFO show_swap_cache_info(); #endif } void show_free_areas(void) { show_free_areas_core(pgdat_list); } /* * Builds allocation fallback zone lists. */ static inline void build_zonelists(pg_data_t *pgdat) { int i, j, k; for (i = 0; i <= GFP_ZONEMASK; i++) { zonelist_t *zonelist; zone_t *zone; zonelist = pgdat->node_zonelists + i; memset(zonelist, 0, sizeof(*zonelist)); j = 0; k = ZONE_NORMAL; if (i & __GFP_HIGHMEM) k = ZONE_HIGHMEM; if (i & __GFP_DMA) k = ZONE_DMA; switch (k) { default: BUG(); /* * fallthrough: */ case ZONE_HIGHMEM: zone = pgdat->node_zones + ZONE_HIGHMEM; if (zone->size) { #ifndef CONFIG_HIGHMEM BUG(); #endif zonelist->zones[j++] = zone; } case ZONE_NORMAL: zone = pgdat->node_zones + ZONE_NORMAL; if (zone->size) zonelist->zones[j++] = zone; case ZONE_DMA: zone = pgdat->node_zones + ZONE_DMA; if (zone->size) zonelist->zones[j++] = zone; } zonelist->zones[j++] = NULL; } } #define LONG_ALIGN(x) (((x)+(sizeof(long))-1)&~((sizeof(long))-1)) /* * Set up the zone data structures: * - mark all pages reserved * - mark all memory queues empty * - clear the memory bitmaps */ void __init free_area_init_core(int nid, pg_data_t *pgdat, struct page **gmap, unsigned long *zones_size, unsigned long zone_start_paddr, unsigned long *zholes_size, struct page *lmem_map) { struct page *p; unsigned long i, j; unsigned long map_size; unsigned long totalpages, offset, realtotalpages; const unsigned long zone_required_alignment = 1UL << (MAX_ORDER-1); if (zone_start_paddr & ~PAGE_MASK) BUG(); totalpages = 0; for (i = 0; i < MAX_NR_ZONES; i++) { unsigned long size = zones_size[i]; totalpages += size; } realtotalpages = totalpages; if (zholes_size) for (i = 0; i < MAX_NR_ZONES; i++) realtotalpages -= zholes_size[i]; printk("On node %d totalpages: %lu\n", nid, realtotalpages); INIT_LIST_HEAD(&active_list); INIT_LIST_HEAD(&inactive_list); /* * Some architectures (with lots of mem and discontinous memory * maps) have to search for a good mem_map area: * For discontigmem, the conceptual mem map array starts from * PAGE_OFFSET, we need to align the actual array onto a mem map * boundary, so that MAP_NR works. */ map_size = (totalpages + 1)*sizeof(struct page); if (lmem_map == (struct page *)0) { lmem_map = (struct page *) alloc_bootmem_node(pgdat, map_size); lmem_map = (struct page *)(PAGE_OFFSET + MAP_ALIGN((unsigned long)lmem_map - PAGE_OFFSET)); } *gmap = pgdat->node_mem_map = lmem_map; pgdat->node_size = totalpages; pgdat->node_start_paddr = zone_start_paddr; pgdat->node_start_mapnr = (lmem_map - mem_map); pgdat->nr_zones = 0; /* * Initially all pages are reserved - free ones are freed * up by free_all_bootmem() once the early boot process is * done. */ for (p = lmem_map; p < lmem_map + totalpages; p++) { set_page_count(p, 0); SetPageReserved(p); init_waitqueue_head(&p->wait); memlist_init(&p->list); } offset = lmem_map - mem_map; for (j = 0; j < MAX_NR_ZONES; j++) { zone_t *zone = pgdat->node_zones + j; unsigned long mask; unsigned long size, realsize; realsize = size = zones_size[j]; if (zholes_size) realsize -= zholes_size[j]; printk("zone(%lu): %lu pages.\n", j, size); zone->size = size; zone->name = zone_names[j]; zone->lock = SPIN_LOCK_UNLOCKED; zone->zone_pgdat = pgdat; zone->free_pages = 0; zone->need_balance = 0; if (!size) continue; pgdat->nr_zones = j+1; mask = (realsize / zone_balance_ratio[j]); if (mask < zone_balance_min[j]) mask = zone_balance_min[j]; else if (mask > zone_balance_max[j]) mask = zone_balance_max[j]; zone->pages_min = mask; zone->pages_low = mask*2; zone->pages_high = mask*3; zone->zone_mem_map = mem_map + offset; zone->zone_start_mapnr = offset; zone->zone_start_paddr = zone_start_paddr; if ((zone_start_paddr >> PAGE_SHIFT) & (zone_required_alignment-1)) printk("BUG: wrong zone alignment, it will crash\n"); for (i = 0; i < size; i++) { struct page *page = mem_map + offset + i; page->zone = zone; if (j != ZONE_HIGHMEM) page->virtual = (void*)__va(zone_start_paddr); zone_start_paddr += PAGE_SIZE; } offset += size; for (i = 0; ; i++) { unsigned long bitmap_size; memlist_init(&zone->free_area[i].free_list); if (i == MAX_ORDER-1) { zone->free_area[i].map = NULL; break; } /* * Page buddy system uses "index >> (i+1)", * where "index" is at most "size-1". * * The extra "+3" is to round down to byte * size (8 bits per byte assumption). Thus * we get "(size-1) >> (i+4)" as the last byte * we can access. * * The "+1" is because we want to round the * byte allocation up rather than down. So * we should have had a "+7" before we shifted * down by three. Also, we have to add one as * we actually _use_ the last bit (it's [0,n] * inclusive, not [0,n[). * * So we actually had +7+1 before we shift * down by 3. But (n+8) >> 3 == (n >> 3) + 1 * (modulo overflows, which we do not have). * * Finally, we LONG_ALIGN because all bitmap * operations are on longs. */ bitmap_size = (size-1) >> (i+4); bitmap_size = LONG_ALIGN(bitmap_size+1); zone->free_area[i].map = (unsigned long *) alloc_bootmem_node(pgdat, bitmap_size); } } build_zonelists(pgdat); } void __init free_area_init(unsigned long *zones_size) { free_area_init_core(0, &contig_page_data, &mem_map, zones_size, 0, 0, 0); } static int __init setup_mem_frac(char *str) { int j = 0; while (get_option(&str, &zone_balance_ratio[j++]) == 2); printk("setup_mem_frac: "); for (j = 0; j < MAX_NR_ZONES; j++) printk("%d ", zone_balance_ratio[j]); printk("\n"); return 1; } __setup("memfrac=", setup_mem_frac);