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* 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
*/
#include <linux/config.h>
#include <linux/mm.h>
#include <linux/kernel_stat.h>
#include <linux/swap.h>
#include <linux/swapctl.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/bootmem.h>
#include <asm/dma.h>
#include <asm/uaccess.h> /* for copy_to/from_user */
#include <asm/pgtable.h>
int nr_swap_pages = 0;
int nr_free_pages = 0;
int nr_lru_pages;
LIST_HEAD(lru_cache);
/*
* Free area management
*
* The free_area_list arrays point to the queue heads of the free areas
* of different sizes
*/
#if CONFIG_AP1000
/* the AP+ needs to allocate 8MB contiguous, aligned chunks of ram
for the ring buffers */
#define NR_MEM_LISTS 12
#else
#define NR_MEM_LISTS 10
#endif
struct free_area_struct {
struct list_head free_list;
unsigned int * map;
unsigned long count;
};
#define MEM_TYPE_DMA 0
#define MEM_TYPE_NORMAL 1
#define MEM_TYPE_HIGH 2
static const char *mem_type_strs[] = {"DMA", "Normal", "High"};
#ifdef CONFIG_HIGHMEM
#define NR_MEM_TYPES 3
#else
#define NR_MEM_TYPES 2
#endif
static struct free_area_struct free_area[NR_MEM_TYPES][NR_MEM_LISTS];
/*
* 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.
*/
/*
* Buddy system. Hairy. You really aren't expected to understand this
*
* Hint: -mask = 1+~mask
*/
spinlock_t page_alloc_lock = SPIN_LOCK_UNLOCKED;
#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)
static inline void free_pages_ok(struct page *page, unsigned long map_nr, unsigned long order)
{
struct free_area_struct *area;
unsigned long index = map_nr >> (1 + order);
unsigned long mask = (~0UL) << order;
unsigned long flags;
struct page *buddy;
spin_lock_irqsave(&page_alloc_lock, flags);
#define list(x) (mem_map+(x))
#ifdef CONFIG_HIGHMEM
if (map_nr >= highmem_mapnr) {
area = free_area[MEM_TYPE_HIGH];
nr_free_highpages -= mask;
} else
#endif
if (PageDMA(page))
area = free_area[MEM_TYPE_DMA];
else
area = free_area[MEM_TYPE_NORMAL];
area += order;
map_nr &= mask;
nr_free_pages -= mask;
while (mask + (1 << (NR_MEM_LISTS-1))) {
if (!test_and_change_bit(index, area->map))
/*
* the buddy page is still allocated.
*/
break;
/*
* Move the buddy up one level.
*/
buddy = list(map_nr ^ -mask);
page = list(map_nr);
area->count--;
memlist_del(&buddy->list);
mask <<= 1;
area++;
index >>= 1;
map_nr &= mask;
}
area->count++;
memlist_add_head(&(list(map_nr))->list, &area->free_list);
#undef list
spin_unlock_irqrestore(&page_alloc_lock, flags);
}
/*
* Some ugly macros to speed up __get_free_pages()..
*/
#define MARK_USED(index, order, area) \
change_bit((index) >> (1+(order)), (area)->map)
#define CAN_DMA(x) (PageDMA(x))
#define ADDRESS(x) (PAGE_OFFSET + ((x) << PAGE_SHIFT))
int __free_page(struct page *page)
{
if (!PageReserved(page) && put_page_testzero(page)) {
if (PageSwapCache(page))
PAGE_BUG(page);
if (PageLocked(page))
PAGE_BUG(page);
free_pages_ok(page, page-mem_map, 0);
return 1;
}
return 0;
}
int free_pages(unsigned long addr, unsigned long order)
{
unsigned long map_nr = MAP_NR(addr);
if (map_nr < max_mapnr) {
mem_map_t * map = mem_map + map_nr;
if (!PageReserved(map) && put_page_testzero(map)) {
if (PageSwapCache(map))
PAGE_BUG(map);
if (PageLocked(map))
PAGE_BUG(map);
free_pages_ok(map, map_nr, order);
return 1;
}
}
return 0;
}
static inline unsigned long EXPAND (struct page *map, unsigned long index,
int low, int high, struct free_area_struct * area)
{
unsigned long size = 1 << high;
while (high > low) {
area--;
high--;
size >>= 1;
area->count++;
memlist_add_head(&(map)->list, &(area)->free_list);
MARK_USED(index, high, area);
index += size;
map += size;
}
set_page_count(map, 1);
return index;
}
static inline struct page * rmqueue (int order, unsigned type)
{
struct free_area_struct * area = free_area[type]+order;
unsigned long curr_order = order, map_nr;
struct page *page;
struct list_head *head, *curr;
do {
head = &area->free_list;
curr = memlist_next(head);
if (curr != head) {
page = memlist_entry(curr, struct page, list);
memlist_del(curr);
area->count--;
map_nr = page - mem_map;
MARK_USED(map_nr, curr_order, area);
nr_free_pages -= 1 << order;
map_nr = EXPAND(page, map_nr, order, curr_order, area);
page = mem_map + map_nr;
return page;
}
curr_order++;
area++;
} while (curr_order < NR_MEM_LISTS);
return NULL;
}
static inline int balance_lowmemory (int gfp_mask)
{
int freed;
static int low_on_memory = 0;
#ifndef CONFIG_HIGHMEM
if (nr_free_pages > freepages.min) {
if (!low_on_memory)
return 1;
if (nr_free_pages >= freepages.high) {
low_on_memory = 0;
return 1;
}
}
low_on_memory = 1;
#else
static int low_on_highmemory = 0;
if (gfp_mask & __GFP_HIGHMEM)
{
if (nr_free_pages > freepages.min) {
if (!low_on_highmemory) {
return 1;
}
if (nr_free_pages >= freepages.high) {
low_on_highmemory = 0;
return 1;
}
}
low_on_highmemory = 1;
} else {
if (nr_free_pages+nr_free_highpages > freepages.min) {
if (!low_on_memory) {
return 1;
}
if (nr_free_pages+nr_free_highpages >= freepages.high) {
low_on_memory = 0;
return 1;
}
}
low_on_memory = 1;
}
#endif
current->flags |= PF_MEMALLOC;
freed = try_to_free_pages(gfp_mask);
current->flags &= ~PF_MEMALLOC;
if (!freed && !(gfp_mask & (__GFP_MED | __GFP_HIGH)))
return 0;
return 1;
}
struct page * __get_pages(int gfp_mask, unsigned long order)
{
unsigned long flags;
struct page *page;
unsigned type;
if (order >= NR_MEM_LISTS)
goto nopage;
/*
* If anyone calls gfp from interrupts nonatomically then it
* will sooner or later tripped up by a schedule().
*/
/*
* If this is a recursive call, we'd better
* do our best to just allocate things without
* further thought.
*/
if (!(current->flags & PF_MEMALLOC))
goto lowmemory;
ok_to_allocate:
#ifdef CONFIG_HIGHMEM
if (gfp_mask & __GFP_HIGHMEM)
type = MEM_TYPE_HIGH;
else
#endif
if (gfp_mask & __GFP_DMA)
type = MEM_TYPE_DMA;
else
type = MEM_TYPE_NORMAL;
spin_lock_irqsave(&page_alloc_lock, flags);
do {
page = rmqueue(order, type);
if (page) {
spin_unlock_irqrestore(&page_alloc_lock, flags);
return page;
}
} while (type-- > 0) ;
spin_unlock_irqrestore(&page_alloc_lock, flags);
/*
* If we can schedule, do so, and make sure to yield.
* We may be a real-time process, and if kswapd is
* waiting for us we need to allow it to run a bit.
*/
if (gfp_mask & __GFP_WAIT) {
current->policy |= SCHED_YIELD;
schedule();
}
nopage:
return NULL;
lowmemory:
if (balance_lowmemory(gfp_mask))
goto ok_to_allocate;
goto nopage;
}
unsigned long __get_free_pages(int gfp_mask, unsigned long order)
{
struct page *page;
page = __get_pages(gfp_mask, order);
if (!page)
return 0;
return page_address(page);
}
struct page * get_free_highpage(int gfp_mask)
{
return __get_pages(gfp_mask, 0);
}
/*
* 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(void)
{
unsigned long order, flags;
unsigned type;
spin_lock_irqsave(&page_alloc_lock, flags);
printk("Free pages: %6dkB (%6ldkB HighMem)\n",
nr_free_pages<<(PAGE_SHIFT-10),
nr_free_highpages<<(PAGE_SHIFT-10));
printk("( Free: %d, lru_cache: %d (%d %d %d) )\n",
nr_free_pages,
nr_lru_pages,
freepages.min,
freepages.low,
freepages.high);
for (type = 0; type < NR_MEM_TYPES; type++) {
unsigned long total = 0;
printk(" %s: ", mem_type_strs[type]);
for (order = 0; order < NR_MEM_LISTS; order++) {
unsigned long nr = free_area[type][order].count;
total += nr * ((PAGE_SIZE>>10) << order);
printk("%lu*%lukB ", nr, (unsigned long)((PAGE_SIZE>>10) << order));
}
printk("= %lukB)\n", total);
}
spin_unlock_irqrestore(&page_alloc_lock, flags);
#ifdef SWAP_CACHE_INFO
show_swap_cache_info();
#endif
}
#define LONG_ALIGN(x) (((x)+(sizeof(long))-1)&~((sizeof(long))-1))
/*
* set up the free-area data structures:
* - mark all pages reserved
* - mark all memory queues empty
* - clear the memory bitmaps
*/
volatile int data;
void __init free_area_init(unsigned long end_mem_pages)
{
mem_map_t * p;
unsigned long i, j;
unsigned long map_size;
/*
* Select nr of pages we try to keep free for important stuff
* with a minimum of 10 pages and a maximum of 256 pages, so
* that we don't waste too much memory on large systems.
* This is fairly arbitrary, but based on some behaviour
* analysis.
*/
i = end_mem_pages >> 7;
if (i < 10)
i = 10;
if (i > 256)
i = 256;
freepages.min = i;
freepages.low = i * 2;
freepages.high = i * 3;
/*
* Most architectures just pick 'start_mem'. Some architectures
* (with lots of mem and discontinous memory maps) have to search
* for a good area.
*/
map_size = end_mem_pages*sizeof(struct page);
mem_map = (struct page *) alloc_bootmem(map_size);
memset(mem_map, 0, map_size);
/*
* Initially all pages are reserved - free ones are freed
* up by free_all_bootmem() once the early boot process is
* done.
*/
for (p = mem_map; p < mem_map + end_mem_pages; p++) {
set_page_count(p, 0);
p->flags = (1 << PG_DMA);
SetPageReserved(p);
init_waitqueue_head(&p->wait);
memlist_init(&p->list);
}
for (j = 0 ; j < NR_MEM_TYPES ; j++) {
unsigned long mask = -1;
for (i = 0 ; i < NR_MEM_LISTS ; i++) {
unsigned long bitmap_size;
unsigned int * map;
memlist_init(&free_area[j][i].free_list);
mask += mask;
end_mem_pages = (end_mem_pages + ~mask) & mask;
bitmap_size = end_mem_pages >> i;
bitmap_size = (bitmap_size + 7) >> 3;
bitmap_size = LONG_ALIGN(bitmap_size);
map = (unsigned int *) alloc_bootmem(bitmap_size);
free_area[j][i].map = map;
memset((void *) map, 0, bitmap_size);
}
}
}
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