2 * linux/mm/page_alloc.c
4 * Manages the free list, the system allocates free pages here.
5 * Note that kmalloc() lives in slab.c
7 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
8 * Swap reorganised 29.12.95, Stephen Tweedie
9 * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
10 * Reshaped it to be a zoned allocator, Ingo Molnar, Red Hat, 1999
11 * Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
12 * Zone balancing, Kanoj Sarcar, SGI, Jan 2000
13 * Per cpu hot/cold page lists, bulk allocation, Martin J. Bligh, Sept 2002
14 * (lots of bits borrowed from Ingo Molnar & Andrew Morton)
17 #include <linux/stddef.h>
19 #include <linux/swap.h>
20 #include <linux/interrupt.h>
21 #include <linux/pagemap.h>
22 #include <linux/bootmem.h>
23 #include <linux/compiler.h>
24 #include <linux/kernel.h>
25 #include <linux/module.h>
26 #include <linux/suspend.h>
27 #include <linux/pagevec.h>
28 #include <linux/blkdev.h>
29 #include <linux/slab.h>
30 #include <linux/notifier.h>
31 #include <linux/topology.h>
32 #include <linux/sysctl.h>
33 #include <linux/cpu.h>
34 #include <linux/cpuset.h>
35 #include <linux/memory_hotplug.h>
36 #include <linux/nodemask.h>
37 #include <linux/vmalloc.h>
38 #include <linux/mempolicy.h>
39 #include <linux/stop_machine.h>
41 #include <asm/tlbflush.h>
42 #include <asm/div64.h>
46 * MCD - HACK: Find somewhere to initialize this EARLY, or make this
49 nodemask_t node_online_map __read_mostly
= { { [0] = 1UL } };
50 EXPORT_SYMBOL(node_online_map
);
51 nodemask_t node_possible_map __read_mostly
= NODE_MASK_ALL
;
52 EXPORT_SYMBOL(node_possible_map
);
53 unsigned long totalram_pages __read_mostly
;
54 unsigned long totalreserve_pages __read_mostly
;
56 int percpu_pagelist_fraction
;
58 static void __free_pages_ok(struct page
*page
, unsigned int order
);
61 * results with 256, 32 in the lowmem_reserve sysctl:
62 * 1G machine -> (16M dma, 800M-16M normal, 1G-800M high)
63 * 1G machine -> (16M dma, 784M normal, 224M high)
64 * NORMAL allocation will leave 784M/256 of ram reserved in the ZONE_DMA
65 * HIGHMEM allocation will leave 224M/32 of ram reserved in ZONE_NORMAL
66 * HIGHMEM allocation will (224M+784M)/256 of ram reserved in ZONE_DMA
68 * TBD: should special case ZONE_DMA32 machines here - in those we normally
69 * don't need any ZONE_NORMAL reservation
71 int sysctl_lowmem_reserve_ratio
[MAX_NR_ZONES
-1] = {
73 #ifdef CONFIG_ZONE_DMA32
81 EXPORT_SYMBOL(totalram_pages
);
84 * Used by page_zone() to look up the address of the struct zone whose
85 * id is encoded in the upper bits of page->flags
87 struct zone
*zone_table
[1 << ZONETABLE_SHIFT
] __read_mostly
;
88 EXPORT_SYMBOL(zone_table
);
90 static char *zone_names
[MAX_NR_ZONES
] = {
92 #ifdef CONFIG_ZONE_DMA32
101 int min_free_kbytes
= 1024;
103 unsigned long __meminitdata nr_kernel_pages
;
104 unsigned long __meminitdata nr_all_pages
;
106 #ifdef CONFIG_DEBUG_VM
107 static int page_outside_zone_boundaries(struct zone
*zone
, struct page
*page
)
111 unsigned long pfn
= page_to_pfn(page
);
114 seq
= zone_span_seqbegin(zone
);
115 if (pfn
>= zone
->zone_start_pfn
+ zone
->spanned_pages
)
117 else if (pfn
< zone
->zone_start_pfn
)
119 } while (zone_span_seqretry(zone
, seq
));
124 static int page_is_consistent(struct zone
*zone
, struct page
*page
)
126 #ifdef CONFIG_HOLES_IN_ZONE
127 if (!pfn_valid(page_to_pfn(page
)))
130 if (zone
!= page_zone(page
))
136 * Temporary debugging check for pages not lying within a given zone.
138 static int bad_range(struct zone
*zone
, struct page
*page
)
140 if (page_outside_zone_boundaries(zone
, page
))
142 if (!page_is_consistent(zone
, page
))
148 static inline int bad_range(struct zone
*zone
, struct page
*page
)
154 static void bad_page(struct page
*page
)
156 printk(KERN_EMERG
"Bad page state in process '%s'\n"
157 KERN_EMERG
"page:%p flags:0x%0*lx mapping:%p mapcount:%d count:%d\n"
158 KERN_EMERG
"Trying to fix it up, but a reboot is needed\n"
159 KERN_EMERG
"Backtrace:\n",
160 current
->comm
, page
, (int)(2*sizeof(unsigned long)),
161 (unsigned long)page
->flags
, page
->mapping
,
162 page_mapcount(page
), page_count(page
));
164 page
->flags
&= ~(1 << PG_lru
|
174 set_page_count(page
, 0);
175 reset_page_mapcount(page
);
176 page
->mapping
= NULL
;
177 add_taint(TAINT_BAD_PAGE
);
181 * Higher-order pages are called "compound pages". They are structured thusly:
183 * The first PAGE_SIZE page is called the "head page".
185 * The remaining PAGE_SIZE pages are called "tail pages".
187 * All pages have PG_compound set. All pages have their ->private pointing at
188 * the head page (even the head page has this).
190 * The first tail page's ->lru.next holds the address of the compound page's
191 * put_page() function. Its ->lru.prev holds the order of allocation.
192 * This usage means that zero-order pages may not be compound.
195 static void free_compound_page(struct page
*page
)
197 __free_pages_ok(page
, (unsigned long)page
[1].lru
.prev
);
200 static void prep_compound_page(struct page
*page
, unsigned long order
)
203 int nr_pages
= 1 << order
;
205 page
[1].lru
.next
= (void *)free_compound_page
; /* set dtor */
206 page
[1].lru
.prev
= (void *)order
;
207 for (i
= 0; i
< nr_pages
; i
++) {
208 struct page
*p
= page
+ i
;
210 __SetPageCompound(p
);
211 set_page_private(p
, (unsigned long)page
);
215 static void destroy_compound_page(struct page
*page
, unsigned long order
)
218 int nr_pages
= 1 << order
;
220 if (unlikely((unsigned long)page
[1].lru
.prev
!= order
))
223 for (i
= 0; i
< nr_pages
; i
++) {
224 struct page
*p
= page
+ i
;
226 if (unlikely(!PageCompound(p
) |
227 (page_private(p
) != (unsigned long)page
)))
229 __ClearPageCompound(p
);
233 static inline void prep_zero_page(struct page
*page
, int order
, gfp_t gfp_flags
)
237 VM_BUG_ON((gfp_flags
& (__GFP_WAIT
| __GFP_HIGHMEM
)) == __GFP_HIGHMEM
);
239 * clear_highpage() will use KM_USER0, so it's a bug to use __GFP_ZERO
240 * and __GFP_HIGHMEM from hard or soft interrupt context.
242 VM_BUG_ON((gfp_flags
& __GFP_HIGHMEM
) && in_interrupt());
243 for (i
= 0; i
< (1 << order
); i
++)
244 clear_highpage(page
+ i
);
248 * function for dealing with page's order in buddy system.
249 * zone->lock is already acquired when we use these.
250 * So, we don't need atomic page->flags operations here.
252 static inline unsigned long page_order(struct page
*page
)
254 return page_private(page
);
257 static inline void set_page_order(struct page
*page
, int order
)
259 set_page_private(page
, order
);
260 __SetPageBuddy(page
);
263 static inline void rmv_page_order(struct page
*page
)
265 __ClearPageBuddy(page
);
266 set_page_private(page
, 0);
270 * Locate the struct page for both the matching buddy in our
271 * pair (buddy1) and the combined O(n+1) page they form (page).
273 * 1) Any buddy B1 will have an order O twin B2 which satisfies
274 * the following equation:
276 * For example, if the starting buddy (buddy2) is #8 its order
278 * B2 = 8 ^ (1 << 1) = 8 ^ 2 = 10
280 * 2) Any buddy B will have an order O+1 parent P which
281 * satisfies the following equation:
284 * Assumption: *_mem_map is contiguous at least up to MAX_ORDER
286 static inline struct page
*
287 __page_find_buddy(struct page
*page
, unsigned long page_idx
, unsigned int order
)
289 unsigned long buddy_idx
= page_idx
^ (1 << order
);
291 return page
+ (buddy_idx
- page_idx
);
294 static inline unsigned long
295 __find_combined_index(unsigned long page_idx
, unsigned int order
)
297 return (page_idx
& ~(1 << order
));
301 * This function checks whether a page is free && is the buddy
302 * we can do coalesce a page and its buddy if
303 * (a) the buddy is not in a hole &&
304 * (b) the buddy is in the buddy system &&
305 * (c) a page and its buddy have the same order &&
306 * (d) a page and its buddy are in the same zone.
308 * For recording whether a page is in the buddy system, we use PG_buddy.
309 * Setting, clearing, and testing PG_buddy is serialized by zone->lock.
311 * For recording page's order, we use page_private(page).
313 static inline int page_is_buddy(struct page
*page
, struct page
*buddy
,
316 #ifdef CONFIG_HOLES_IN_ZONE
317 if (!pfn_valid(page_to_pfn(buddy
)))
321 if (page_zone_id(page
) != page_zone_id(buddy
))
324 if (PageBuddy(buddy
) && page_order(buddy
) == order
) {
325 BUG_ON(page_count(buddy
) != 0);
332 * Freeing function for a buddy system allocator.
334 * The concept of a buddy system is to maintain direct-mapped table
335 * (containing bit values) for memory blocks of various "orders".
336 * The bottom level table contains the map for the smallest allocatable
337 * units of memory (here, pages), and each level above it describes
338 * pairs of units from the levels below, hence, "buddies".
339 * At a high level, all that happens here is marking the table entry
340 * at the bottom level available, and propagating the changes upward
341 * as necessary, plus some accounting needed to play nicely with other
342 * parts of the VM system.
343 * At each level, we keep a list of pages, which are heads of continuous
344 * free pages of length of (1 << order) and marked with PG_buddy. Page's
345 * order is recorded in page_private(page) field.
346 * So when we are allocating or freeing one, we can derive the state of the
347 * other. That is, if we allocate a small block, and both were
348 * free, the remainder of the region must be split into blocks.
349 * If a block is freed, and its buddy is also free, then this
350 * triggers coalescing into a block of larger size.
355 static inline void __free_one_page(struct page
*page
,
356 struct zone
*zone
, unsigned int order
)
358 unsigned long page_idx
;
359 int order_size
= 1 << order
;
361 if (unlikely(PageCompound(page
)))
362 destroy_compound_page(page
, order
);
364 page_idx
= page_to_pfn(page
) & ((1 << MAX_ORDER
) - 1);
366 VM_BUG_ON(page_idx
& (order_size
- 1));
367 VM_BUG_ON(bad_range(zone
, page
));
369 zone
->free_pages
+= order_size
;
370 while (order
< MAX_ORDER
-1) {
371 unsigned long combined_idx
;
372 struct free_area
*area
;
375 buddy
= __page_find_buddy(page
, page_idx
, order
);
376 if (!page_is_buddy(page
, buddy
, order
))
377 break; /* Move the buddy up one level. */
379 list_del(&buddy
->lru
);
380 area
= zone
->free_area
+ order
;
382 rmv_page_order(buddy
);
383 combined_idx
= __find_combined_index(page_idx
, order
);
384 page
= page
+ (combined_idx
- page_idx
);
385 page_idx
= combined_idx
;
388 set_page_order(page
, order
);
389 list_add(&page
->lru
, &zone
->free_area
[order
].free_list
);
390 zone
->free_area
[order
].nr_free
++;
393 static inline int free_pages_check(struct page
*page
)
395 if (unlikely(page_mapcount(page
) |
396 (page
->mapping
!= NULL
) |
397 (page_count(page
) != 0) |
411 __ClearPageDirty(page
);
413 * For now, we report if PG_reserved was found set, but do not
414 * clear it, and do not free the page. But we shall soon need
415 * to do more, for when the ZERO_PAGE count wraps negative.
417 return PageReserved(page
);
421 * Frees a list of pages.
422 * Assumes all pages on list are in same zone, and of same order.
423 * count is the number of pages to free.
425 * If the zone was previously in an "all pages pinned" state then look to
426 * see if this freeing clears that state.
428 * And clear the zone's pages_scanned counter, to hold off the "all pages are
429 * pinned" detection logic.
431 static void free_pages_bulk(struct zone
*zone
, int count
,
432 struct list_head
*list
, int order
)
434 spin_lock(&zone
->lock
);
435 zone
->all_unreclaimable
= 0;
436 zone
->pages_scanned
= 0;
440 VM_BUG_ON(list_empty(list
));
441 page
= list_entry(list
->prev
, struct page
, lru
);
442 /* have to delete it as __free_one_page list manipulates */
443 list_del(&page
->lru
);
444 __free_one_page(page
, zone
, order
);
446 spin_unlock(&zone
->lock
);
449 static void free_one_page(struct zone
*zone
, struct page
*page
, int order
)
451 spin_lock(&zone
->lock
);
452 zone
->all_unreclaimable
= 0;
453 zone
->pages_scanned
= 0;
454 __free_one_page(page
, zone
,order
);
455 spin_unlock(&zone
->lock
);
458 static void __free_pages_ok(struct page
*page
, unsigned int order
)
464 arch_free_page(page
, order
);
465 if (!PageHighMem(page
))
466 debug_check_no_locks_freed(page_address(page
),
469 for (i
= 0 ; i
< (1 << order
) ; ++i
)
470 reserved
+= free_pages_check(page
+ i
);
474 kernel_map_pages(page
, 1 << order
, 0);
475 local_irq_save(flags
);
476 __count_vm_events(PGFREE
, 1 << order
);
477 free_one_page(page_zone(page
), page
, order
);
478 local_irq_restore(flags
);
482 * permit the bootmem allocator to evade page validation on high-order frees
484 void fastcall __init
__free_pages_bootmem(struct page
*page
, unsigned int order
)
487 __ClearPageReserved(page
);
488 set_page_count(page
, 0);
489 set_page_refcounted(page
);
495 for (loop
= 0; loop
< BITS_PER_LONG
; loop
++) {
496 struct page
*p
= &page
[loop
];
498 if (loop
+ 1 < BITS_PER_LONG
)
500 __ClearPageReserved(p
);
501 set_page_count(p
, 0);
504 set_page_refcounted(page
);
505 __free_pages(page
, order
);
511 * The order of subdivision here is critical for the IO subsystem.
512 * Please do not alter this order without good reasons and regression
513 * testing. Specifically, as large blocks of memory are subdivided,
514 * the order in which smaller blocks are delivered depends on the order
515 * they're subdivided in this function. This is the primary factor
516 * influencing the order in which pages are delivered to the IO
517 * subsystem according to empirical testing, and this is also justified
518 * by considering the behavior of a buddy system containing a single
519 * large block of memory acted on by a series of small allocations.
520 * This behavior is a critical factor in sglist merging's success.
524 static inline void expand(struct zone
*zone
, struct page
*page
,
525 int low
, int high
, struct free_area
*area
)
527 unsigned long size
= 1 << high
;
533 VM_BUG_ON(bad_range(zone
, &page
[size
]));
534 list_add(&page
[size
].lru
, &area
->free_list
);
536 set_page_order(&page
[size
], high
);
541 * This page is about to be returned from the page allocator
543 static int prep_new_page(struct page
*page
, int order
, gfp_t gfp_flags
)
545 if (unlikely(page_mapcount(page
) |
546 (page
->mapping
!= NULL
) |
547 (page_count(page
) != 0) |
563 * For now, we report if PG_reserved was found set, but do not
564 * clear it, and do not allocate the page: as a safety net.
566 if (PageReserved(page
))
569 page
->flags
&= ~(1 << PG_uptodate
| 1 << PG_error
|
570 1 << PG_referenced
| 1 << PG_arch_1
|
571 1 << PG_checked
| 1 << PG_mappedtodisk
);
572 set_page_private(page
, 0);
573 set_page_refcounted(page
);
574 kernel_map_pages(page
, 1 << order
, 1);
576 if (gfp_flags
& __GFP_ZERO
)
577 prep_zero_page(page
, order
, gfp_flags
);
579 if (order
&& (gfp_flags
& __GFP_COMP
))
580 prep_compound_page(page
, order
);
586 * Do the hard work of removing an element from the buddy allocator.
587 * Call me with the zone->lock already held.
589 static struct page
*__rmqueue(struct zone
*zone
, unsigned int order
)
591 struct free_area
* area
;
592 unsigned int current_order
;
595 for (current_order
= order
; current_order
< MAX_ORDER
; ++current_order
) {
596 area
= zone
->free_area
+ current_order
;
597 if (list_empty(&area
->free_list
))
600 page
= list_entry(area
->free_list
.next
, struct page
, lru
);
601 list_del(&page
->lru
);
602 rmv_page_order(page
);
604 zone
->free_pages
-= 1UL << order
;
605 expand(zone
, page
, order
, current_order
, area
);
613 * Obtain a specified number of elements from the buddy allocator, all under
614 * a single hold of the lock, for efficiency. Add them to the supplied list.
615 * Returns the number of new pages which were placed at *list.
617 static int rmqueue_bulk(struct zone
*zone
, unsigned int order
,
618 unsigned long count
, struct list_head
*list
)
622 spin_lock(&zone
->lock
);
623 for (i
= 0; i
< count
; ++i
) {
624 struct page
*page
= __rmqueue(zone
, order
);
625 if (unlikely(page
== NULL
))
627 list_add_tail(&page
->lru
, list
);
629 spin_unlock(&zone
->lock
);
635 * Called from the slab reaper to drain pagesets on a particular node that
636 * belongs to the currently executing processor.
637 * Note that this function must be called with the thread pinned to
638 * a single processor.
640 void drain_node_pages(int nodeid
)
646 for (z
= 0; z
< MAX_NR_ZONES
; z
++) {
647 struct zone
*zone
= NODE_DATA(nodeid
)->node_zones
+ z
;
648 struct per_cpu_pageset
*pset
;
650 if (!populated_zone(zone
))
653 pset
= zone_pcp(zone
, smp_processor_id());
654 for (i
= 0; i
< ARRAY_SIZE(pset
->pcp
); i
++) {
655 struct per_cpu_pages
*pcp
;
659 local_irq_save(flags
);
660 free_pages_bulk(zone
, pcp
->count
, &pcp
->list
, 0);
662 local_irq_restore(flags
);
669 #if defined(CONFIG_PM) || defined(CONFIG_HOTPLUG_CPU)
670 static void __drain_pages(unsigned int cpu
)
676 for_each_zone(zone
) {
677 struct per_cpu_pageset
*pset
;
679 pset
= zone_pcp(zone
, cpu
);
680 for (i
= 0; i
< ARRAY_SIZE(pset
->pcp
); i
++) {
681 struct per_cpu_pages
*pcp
;
684 local_irq_save(flags
);
685 free_pages_bulk(zone
, pcp
->count
, &pcp
->list
, 0);
687 local_irq_restore(flags
);
691 #endif /* CONFIG_PM || CONFIG_HOTPLUG_CPU */
695 void mark_free_pages(struct zone
*zone
)
697 unsigned long zone_pfn
, flags
;
699 struct list_head
*curr
;
701 if (!zone
->spanned_pages
)
704 spin_lock_irqsave(&zone
->lock
, flags
);
705 for (zone_pfn
= 0; zone_pfn
< zone
->spanned_pages
; ++zone_pfn
)
706 ClearPageNosaveFree(pfn_to_page(zone_pfn
+ zone
->zone_start_pfn
));
708 for (order
= MAX_ORDER
- 1; order
>= 0; --order
)
709 list_for_each(curr
, &zone
->free_area
[order
].free_list
) {
710 unsigned long start_pfn
, i
;
712 start_pfn
= page_to_pfn(list_entry(curr
, struct page
, lru
));
714 for (i
=0; i
< (1<<order
); i
++)
715 SetPageNosaveFree(pfn_to_page(start_pfn
+i
));
717 spin_unlock_irqrestore(&zone
->lock
, flags
);
721 * Spill all of this CPU's per-cpu pages back into the buddy allocator.
723 void drain_local_pages(void)
727 local_irq_save(flags
);
728 __drain_pages(smp_processor_id());
729 local_irq_restore(flags
);
731 #endif /* CONFIG_PM */
734 * Free a 0-order page
736 static void fastcall
free_hot_cold_page(struct page
*page
, int cold
)
738 struct zone
*zone
= page_zone(page
);
739 struct per_cpu_pages
*pcp
;
742 arch_free_page(page
, 0);
745 page
->mapping
= NULL
;
746 if (free_pages_check(page
))
749 kernel_map_pages(page
, 1, 0);
751 pcp
= &zone_pcp(zone
, get_cpu())->pcp
[cold
];
752 local_irq_save(flags
);
753 __count_vm_event(PGFREE
);
754 list_add(&page
->lru
, &pcp
->list
);
756 if (pcp
->count
>= pcp
->high
) {
757 free_pages_bulk(zone
, pcp
->batch
, &pcp
->list
, 0);
758 pcp
->count
-= pcp
->batch
;
760 local_irq_restore(flags
);
764 void fastcall
free_hot_page(struct page
*page
)
766 free_hot_cold_page(page
, 0);
769 void fastcall
free_cold_page(struct page
*page
)
771 free_hot_cold_page(page
, 1);
775 * split_page takes a non-compound higher-order page, and splits it into
776 * n (1<<order) sub-pages: page[0..n]
777 * Each sub-page must be freed individually.
779 * Note: this is probably too low level an operation for use in drivers.
780 * Please consult with lkml before using this in your driver.
782 void split_page(struct page
*page
, unsigned int order
)
786 VM_BUG_ON(PageCompound(page
));
787 VM_BUG_ON(!page_count(page
));
788 for (i
= 1; i
< (1 << order
); i
++)
789 set_page_refcounted(page
+ i
);
793 * Really, prep_compound_page() should be called from __rmqueue_bulk(). But
794 * we cheat by calling it from here, in the order > 0 path. Saves a branch
797 static struct page
*buffered_rmqueue(struct zonelist
*zonelist
,
798 struct zone
*zone
, int order
, gfp_t gfp_flags
)
802 int cold
= !!(gfp_flags
& __GFP_COLD
);
807 if (likely(order
== 0)) {
808 struct per_cpu_pages
*pcp
;
810 pcp
= &zone_pcp(zone
, cpu
)->pcp
[cold
];
811 local_irq_save(flags
);
813 pcp
->count
+= rmqueue_bulk(zone
, 0,
814 pcp
->batch
, &pcp
->list
);
815 if (unlikely(!pcp
->count
))
818 page
= list_entry(pcp
->list
.next
, struct page
, lru
);
819 list_del(&page
->lru
);
822 spin_lock_irqsave(&zone
->lock
, flags
);
823 page
= __rmqueue(zone
, order
);
824 spin_unlock(&zone
->lock
);
829 __count_zone_vm_events(PGALLOC
, zone
, 1 << order
);
830 zone_statistics(zonelist
, zone
);
831 local_irq_restore(flags
);
834 VM_BUG_ON(bad_range(zone
, page
));
835 if (prep_new_page(page
, order
, gfp_flags
))
840 local_irq_restore(flags
);
845 #define ALLOC_NO_WATERMARKS 0x01 /* don't check watermarks at all */
846 #define ALLOC_WMARK_MIN 0x02 /* use pages_min watermark */
847 #define ALLOC_WMARK_LOW 0x04 /* use pages_low watermark */
848 #define ALLOC_WMARK_HIGH 0x08 /* use pages_high watermark */
849 #define ALLOC_HARDER 0x10 /* try to alloc harder */
850 #define ALLOC_HIGH 0x20 /* __GFP_HIGH set */
851 #define ALLOC_CPUSET 0x40 /* check for correct cpuset */
854 * Return 1 if free pages are above 'mark'. This takes into account the order
857 int zone_watermark_ok(struct zone
*z
, int order
, unsigned long mark
,
858 int classzone_idx
, int alloc_flags
)
860 /* free_pages my go negative - that's OK */
861 long min
= mark
, free_pages
= z
->free_pages
- (1 << order
) + 1;
864 if (alloc_flags
& ALLOC_HIGH
)
866 if (alloc_flags
& ALLOC_HARDER
)
869 if (free_pages
<= min
+ z
->lowmem_reserve
[classzone_idx
])
871 for (o
= 0; o
< order
; o
++) {
872 /* At the next order, this order's pages become unavailable */
873 free_pages
-= z
->free_area
[o
].nr_free
<< o
;
875 /* Require fewer higher order pages to be free */
878 if (free_pages
<= min
)
885 * get_page_from_freeliest goes through the zonelist trying to allocate
889 get_page_from_freelist(gfp_t gfp_mask
, unsigned int order
,
890 struct zonelist
*zonelist
, int alloc_flags
)
892 struct zone
**z
= zonelist
->zones
;
893 struct page
*page
= NULL
;
894 int classzone_idx
= zone_idx(*z
);
898 * Go through the zonelist once, looking for a zone with enough free.
899 * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
903 if (unlikely((gfp_mask
& __GFP_THISNODE
) &&
904 zone
->zone_pgdat
!= zonelist
->zones
[0]->zone_pgdat
))
906 if ((alloc_flags
& ALLOC_CPUSET
) &&
907 !cpuset_zone_allowed(zone
, gfp_mask
))
910 if (!(alloc_flags
& ALLOC_NO_WATERMARKS
)) {
912 if (alloc_flags
& ALLOC_WMARK_MIN
)
913 mark
= zone
->pages_min
;
914 else if (alloc_flags
& ALLOC_WMARK_LOW
)
915 mark
= zone
->pages_low
;
917 mark
= zone
->pages_high
;
918 if (!zone_watermark_ok(zone
, order
, mark
,
919 classzone_idx
, alloc_flags
))
920 if (!zone_reclaim_mode
||
921 !zone_reclaim(zone
, gfp_mask
, order
))
925 page
= buffered_rmqueue(zonelist
, zone
, order
, gfp_mask
);
929 } while (*(++z
) != NULL
);
934 * This is the 'heart' of the zoned buddy allocator.
936 struct page
* fastcall
937 __alloc_pages(gfp_t gfp_mask
, unsigned int order
,
938 struct zonelist
*zonelist
)
940 const gfp_t wait
= gfp_mask
& __GFP_WAIT
;
943 struct reclaim_state reclaim_state
;
944 struct task_struct
*p
= current
;
947 int did_some_progress
;
949 might_sleep_if(wait
);
952 z
= zonelist
->zones
; /* the list of zones suitable for gfp_mask */
954 if (unlikely(*z
== NULL
)) {
955 /* Should this ever happen?? */
959 page
= get_page_from_freelist(gfp_mask
|__GFP_HARDWALL
, order
,
960 zonelist
, ALLOC_WMARK_LOW
|ALLOC_CPUSET
);
965 wakeup_kswapd(*z
, order
);
969 * OK, we're below the kswapd watermark and have kicked background
970 * reclaim. Now things get more complex, so set up alloc_flags according
971 * to how we want to proceed.
973 * The caller may dip into page reserves a bit more if the caller
974 * cannot run direct reclaim, or if the caller has realtime scheduling
975 * policy or is asking for __GFP_HIGH memory. GFP_ATOMIC requests will
976 * set both ALLOC_HARDER (!wait) and ALLOC_HIGH (__GFP_HIGH).
978 alloc_flags
= ALLOC_WMARK_MIN
;
979 if ((unlikely(rt_task(p
)) && !in_interrupt()) || !wait
)
980 alloc_flags
|= ALLOC_HARDER
;
981 if (gfp_mask
& __GFP_HIGH
)
982 alloc_flags
|= ALLOC_HIGH
;
984 alloc_flags
|= ALLOC_CPUSET
;
987 * Go through the zonelist again. Let __GFP_HIGH and allocations
988 * coming from realtime tasks go deeper into reserves.
990 * This is the last chance, in general, before the goto nopage.
991 * Ignore cpuset if GFP_ATOMIC (!wait) rather than fail alloc.
992 * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
994 page
= get_page_from_freelist(gfp_mask
, order
, zonelist
, alloc_flags
);
998 /* This allocation should allow future memory freeing. */
1000 if (((p
->flags
& PF_MEMALLOC
) || unlikely(test_thread_flag(TIF_MEMDIE
)))
1001 && !in_interrupt()) {
1002 if (!(gfp_mask
& __GFP_NOMEMALLOC
)) {
1004 /* go through the zonelist yet again, ignoring mins */
1005 page
= get_page_from_freelist(gfp_mask
, order
,
1006 zonelist
, ALLOC_NO_WATERMARKS
);
1009 if (gfp_mask
& __GFP_NOFAIL
) {
1010 blk_congestion_wait(WRITE
, HZ
/50);
1017 /* Atomic allocations - we can't balance anything */
1024 /* We now go into synchronous reclaim */
1025 cpuset_memory_pressure_bump();
1026 p
->flags
|= PF_MEMALLOC
;
1027 reclaim_state
.reclaimed_slab
= 0;
1028 p
->reclaim_state
= &reclaim_state
;
1030 did_some_progress
= try_to_free_pages(zonelist
->zones
, gfp_mask
);
1032 p
->reclaim_state
= NULL
;
1033 p
->flags
&= ~PF_MEMALLOC
;
1037 if (likely(did_some_progress
)) {
1038 page
= get_page_from_freelist(gfp_mask
, order
,
1039 zonelist
, alloc_flags
);
1042 } else if ((gfp_mask
& __GFP_FS
) && !(gfp_mask
& __GFP_NORETRY
)) {
1044 * Go through the zonelist yet one more time, keep
1045 * very high watermark here, this is only to catch
1046 * a parallel oom killing, we must fail if we're still
1047 * under heavy pressure.
1049 page
= get_page_from_freelist(gfp_mask
|__GFP_HARDWALL
, order
,
1050 zonelist
, ALLOC_WMARK_HIGH
|ALLOC_CPUSET
);
1054 out_of_memory(zonelist
, gfp_mask
, order
);
1059 * Don't let big-order allocations loop unless the caller explicitly
1060 * requests that. Wait for some write requests to complete then retry.
1062 * In this implementation, __GFP_REPEAT means __GFP_NOFAIL for order
1063 * <= 3, but that may not be true in other implementations.
1066 if (!(gfp_mask
& __GFP_NORETRY
)) {
1067 if ((order
<= 3) || (gfp_mask
& __GFP_REPEAT
))
1069 if (gfp_mask
& __GFP_NOFAIL
)
1073 blk_congestion_wait(WRITE
, HZ
/50);
1078 if (!(gfp_mask
& __GFP_NOWARN
) && printk_ratelimit()) {
1079 printk(KERN_WARNING
"%s: page allocation failure."
1080 " order:%d, mode:0x%x\n",
1081 p
->comm
, order
, gfp_mask
);
1089 EXPORT_SYMBOL(__alloc_pages
);
1092 * Common helper functions.
1094 fastcall
unsigned long __get_free_pages(gfp_t gfp_mask
, unsigned int order
)
1097 page
= alloc_pages(gfp_mask
, order
);
1100 return (unsigned long) page_address(page
);
1103 EXPORT_SYMBOL(__get_free_pages
);
1105 fastcall
unsigned long get_zeroed_page(gfp_t gfp_mask
)
1110 * get_zeroed_page() returns a 32-bit address, which cannot represent
1113 VM_BUG_ON((gfp_mask
& __GFP_HIGHMEM
) != 0);
1115 page
= alloc_pages(gfp_mask
| __GFP_ZERO
, 0);
1117 return (unsigned long) page_address(page
);
1121 EXPORT_SYMBOL(get_zeroed_page
);
1123 void __pagevec_free(struct pagevec
*pvec
)
1125 int i
= pagevec_count(pvec
);
1128 free_hot_cold_page(pvec
->pages
[i
], pvec
->cold
);
1131 fastcall
void __free_pages(struct page
*page
, unsigned int order
)
1133 if (put_page_testzero(page
)) {
1135 free_hot_page(page
);
1137 __free_pages_ok(page
, order
);
1141 EXPORT_SYMBOL(__free_pages
);
1143 fastcall
void free_pages(unsigned long addr
, unsigned int order
)
1146 VM_BUG_ON(!virt_addr_valid((void *)addr
));
1147 __free_pages(virt_to_page((void *)addr
), order
);
1151 EXPORT_SYMBOL(free_pages
);
1154 * Total amount of free (allocatable) RAM:
1156 unsigned int nr_free_pages(void)
1158 unsigned int sum
= 0;
1162 sum
+= zone
->free_pages
;
1167 EXPORT_SYMBOL(nr_free_pages
);
1170 unsigned int nr_free_pages_pgdat(pg_data_t
*pgdat
)
1172 unsigned int sum
= 0;
1175 for (i
= 0; i
< MAX_NR_ZONES
; i
++)
1176 sum
+= pgdat
->node_zones
[i
].free_pages
;
1182 static unsigned int nr_free_zone_pages(int offset
)
1184 /* Just pick one node, since fallback list is circular */
1185 pg_data_t
*pgdat
= NODE_DATA(numa_node_id());
1186 unsigned int sum
= 0;
1188 struct zonelist
*zonelist
= pgdat
->node_zonelists
+ offset
;
1189 struct zone
**zonep
= zonelist
->zones
;
1192 for (zone
= *zonep
++; zone
; zone
= *zonep
++) {
1193 unsigned long size
= zone
->present_pages
;
1194 unsigned long high
= zone
->pages_high
;
1203 * Amount of free RAM allocatable within ZONE_DMA and ZONE_NORMAL
1205 unsigned int nr_free_buffer_pages(void)
1207 return nr_free_zone_pages(gfp_zone(GFP_USER
));
1211 * Amount of free RAM allocatable within all zones
1213 unsigned int nr_free_pagecache_pages(void)
1215 return nr_free_zone_pages(gfp_zone(GFP_HIGHUSER
));
1218 static void show_node(struct zone
*zone
)
1220 printk("Node %d ", zone
->zone_pgdat
->node_id
);
1223 #define show_node(zone) do { } while (0)
1226 void si_meminfo(struct sysinfo
*val
)
1228 val
->totalram
= totalram_pages
;
1230 val
->freeram
= nr_free_pages();
1231 val
->bufferram
= nr_blockdev_pages();
1232 val
->totalhigh
= totalhigh_pages
;
1233 val
->freehigh
= nr_free_highpages();
1234 val
->mem_unit
= PAGE_SIZE
;
1237 EXPORT_SYMBOL(si_meminfo
);
1240 void si_meminfo_node(struct sysinfo
*val
, int nid
)
1242 pg_data_t
*pgdat
= NODE_DATA(nid
);
1244 val
->totalram
= pgdat
->node_present_pages
;
1245 val
->freeram
= nr_free_pages_pgdat(pgdat
);
1246 #ifdef CONFIG_HIGHMEM
1247 val
->totalhigh
= pgdat
->node_zones
[ZONE_HIGHMEM
].present_pages
;
1248 val
->freehigh
= pgdat
->node_zones
[ZONE_HIGHMEM
].free_pages
;
1253 val
->mem_unit
= PAGE_SIZE
;
1257 #define K(x) ((x) << (PAGE_SHIFT-10))
1260 * Show free area list (used inside shift_scroll-lock stuff)
1261 * We also calculate the percentage fragmentation. We do this by counting the
1262 * memory on each free list with the exception of the first item on the list.
1264 void show_free_areas(void)
1266 int cpu
, temperature
;
1267 unsigned long active
;
1268 unsigned long inactive
;
1272 for_each_zone(zone
) {
1274 printk("%s per-cpu:", zone
->name
);
1276 if (!populated_zone(zone
)) {
1282 for_each_online_cpu(cpu
) {
1283 struct per_cpu_pageset
*pageset
;
1285 pageset
= zone_pcp(zone
, cpu
);
1287 for (temperature
= 0; temperature
< 2; temperature
++)
1288 printk("cpu %d %s: high %d, batch %d used:%d\n",
1290 temperature
? "cold" : "hot",
1291 pageset
->pcp
[temperature
].high
,
1292 pageset
->pcp
[temperature
].batch
,
1293 pageset
->pcp
[temperature
].count
);
1297 get_zone_counts(&active
, &inactive
, &free
);
1299 printk("Active:%lu inactive:%lu dirty:%lu writeback:%lu "
1300 "unstable:%lu free:%u slab:%lu mapped:%lu pagetables:%lu\n",
1303 global_page_state(NR_FILE_DIRTY
),
1304 global_page_state(NR_WRITEBACK
),
1305 global_page_state(NR_UNSTABLE_NFS
),
1307 global_page_state(NR_SLAB
),
1308 global_page_state(NR_FILE_MAPPED
),
1309 global_page_state(NR_PAGETABLE
));
1311 for_each_zone(zone
) {
1323 " pages_scanned:%lu"
1324 " all_unreclaimable? %s"
1327 K(zone
->free_pages
),
1330 K(zone
->pages_high
),
1332 K(zone
->nr_inactive
),
1333 K(zone
->present_pages
),
1334 zone
->pages_scanned
,
1335 (zone
->all_unreclaimable
? "yes" : "no")
1337 printk("lowmem_reserve[]:");
1338 for (i
= 0; i
< MAX_NR_ZONES
; i
++)
1339 printk(" %lu", zone
->lowmem_reserve
[i
]);
1343 for_each_zone(zone
) {
1344 unsigned long nr
[MAX_ORDER
], flags
, order
, total
= 0;
1347 printk("%s: ", zone
->name
);
1348 if (!populated_zone(zone
)) {
1353 spin_lock_irqsave(&zone
->lock
, flags
);
1354 for (order
= 0; order
< MAX_ORDER
; order
++) {
1355 nr
[order
] = zone
->free_area
[order
].nr_free
;
1356 total
+= nr
[order
] << order
;
1358 spin_unlock_irqrestore(&zone
->lock
, flags
);
1359 for (order
= 0; order
< MAX_ORDER
; order
++)
1360 printk("%lu*%lukB ", nr
[order
], K(1UL) << order
);
1361 printk("= %lukB\n", K(total
));
1364 show_swap_cache_info();
1368 * Builds allocation fallback zone lists.
1370 * Add all populated zones of a node to the zonelist.
1372 static int __meminit
build_zonelists_node(pg_data_t
*pgdat
,
1373 struct zonelist
*zonelist
, int nr_zones
, enum zone_type zone_type
)
1377 BUG_ON(zone_type
>= MAX_NR_ZONES
);
1382 zone
= pgdat
->node_zones
+ zone_type
;
1383 if (populated_zone(zone
)) {
1384 zonelist
->zones
[nr_zones
++] = zone
;
1385 check_highest_zone(zone_type
);
1388 } while (zone_type
);
1393 #define MAX_NODE_LOAD (num_online_nodes())
1394 static int __meminitdata node_load
[MAX_NUMNODES
];
1396 * find_next_best_node - find the next node that should appear in a given node's fallback list
1397 * @node: node whose fallback list we're appending
1398 * @used_node_mask: nodemask_t of already used nodes
1400 * We use a number of factors to determine which is the next node that should
1401 * appear on a given node's fallback list. The node should not have appeared
1402 * already in @node's fallback list, and it should be the next closest node
1403 * according to the distance array (which contains arbitrary distance values
1404 * from each node to each node in the system), and should also prefer nodes
1405 * with no CPUs, since presumably they'll have very little allocation pressure
1406 * on them otherwise.
1407 * It returns -1 if no node is found.
1409 static int __meminit
find_next_best_node(int node
, nodemask_t
*used_node_mask
)
1412 int min_val
= INT_MAX
;
1415 /* Use the local node if we haven't already */
1416 if (!node_isset(node
, *used_node_mask
)) {
1417 node_set(node
, *used_node_mask
);
1421 for_each_online_node(n
) {
1424 /* Don't want a node to appear more than once */
1425 if (node_isset(n
, *used_node_mask
))
1428 /* Use the distance array to find the distance */
1429 val
= node_distance(node
, n
);
1431 /* Penalize nodes under us ("prefer the next node") */
1434 /* Give preference to headless and unused nodes */
1435 tmp
= node_to_cpumask(n
);
1436 if (!cpus_empty(tmp
))
1437 val
+= PENALTY_FOR_NODE_WITH_CPUS
;
1439 /* Slight preference for less loaded node */
1440 val
*= (MAX_NODE_LOAD
*MAX_NUMNODES
);
1441 val
+= node_load
[n
];
1443 if (val
< min_val
) {
1450 node_set(best_node
, *used_node_mask
);
1455 static void __meminit
build_zonelists(pg_data_t
*pgdat
)
1457 int j
, node
, local_node
;
1459 int prev_node
, load
;
1460 struct zonelist
*zonelist
;
1461 nodemask_t used_mask
;
1463 /* initialize zonelists */
1464 for (i
= 0; i
< MAX_NR_ZONES
; i
++) {
1465 zonelist
= pgdat
->node_zonelists
+ i
;
1466 zonelist
->zones
[0] = NULL
;
1469 /* NUMA-aware ordering of nodes */
1470 local_node
= pgdat
->node_id
;
1471 load
= num_online_nodes();
1472 prev_node
= local_node
;
1473 nodes_clear(used_mask
);
1474 while ((node
= find_next_best_node(local_node
, &used_mask
)) >= 0) {
1475 int distance
= node_distance(local_node
, node
);
1478 * If another node is sufficiently far away then it is better
1479 * to reclaim pages in a zone before going off node.
1481 if (distance
> RECLAIM_DISTANCE
)
1482 zone_reclaim_mode
= 1;
1485 * We don't want to pressure a particular node.
1486 * So adding penalty to the first node in same
1487 * distance group to make it round-robin.
1490 if (distance
!= node_distance(local_node
, prev_node
))
1491 node_load
[node
] += load
;
1494 for (i
= 0; i
< MAX_NR_ZONES
; i
++) {
1495 zonelist
= pgdat
->node_zonelists
+ i
;
1496 for (j
= 0; zonelist
->zones
[j
] != NULL
; j
++);
1498 j
= build_zonelists_node(NODE_DATA(node
), zonelist
, j
, i
);
1499 zonelist
->zones
[j
] = NULL
;
1504 #else /* CONFIG_NUMA */
1506 static void __meminit
build_zonelists(pg_data_t
*pgdat
)
1508 int node
, local_node
;
1511 local_node
= pgdat
->node_id
;
1512 for (i
= 0; i
< MAX_NR_ZONES
; i
++) {
1513 struct zonelist
*zonelist
;
1515 zonelist
= pgdat
->node_zonelists
+ i
;
1517 j
= build_zonelists_node(pgdat
, zonelist
, 0, i
);
1519 * Now we build the zonelist so that it contains the zones
1520 * of all the other nodes.
1521 * We don't want to pressure a particular node, so when
1522 * building the zones for node N, we make sure that the
1523 * zones coming right after the local ones are those from
1524 * node N+1 (modulo N)
1526 for (node
= local_node
+ 1; node
< MAX_NUMNODES
; node
++) {
1527 if (!node_online(node
))
1529 j
= build_zonelists_node(NODE_DATA(node
), zonelist
, j
, i
);
1531 for (node
= 0; node
< local_node
; node
++) {
1532 if (!node_online(node
))
1534 j
= build_zonelists_node(NODE_DATA(node
), zonelist
, j
, i
);
1537 zonelist
->zones
[j
] = NULL
;
1541 #endif /* CONFIG_NUMA */
1543 /* return values int ....just for stop_machine_run() */
1544 static int __meminit
__build_all_zonelists(void *dummy
)
1547 for_each_online_node(nid
)
1548 build_zonelists(NODE_DATA(nid
));
1552 void __meminit
build_all_zonelists(void)
1554 if (system_state
== SYSTEM_BOOTING
) {
1555 __build_all_zonelists(0);
1556 cpuset_init_current_mems_allowed();
1558 /* we have to stop all cpus to guaranntee there is no user
1560 stop_machine_run(__build_all_zonelists
, NULL
, NR_CPUS
);
1561 /* cpuset refresh routine should be here */
1563 vm_total_pages
= nr_free_pagecache_pages();
1564 printk("Built %i zonelists. Total pages: %ld\n",
1565 num_online_nodes(), vm_total_pages
);
1569 * Helper functions to size the waitqueue hash table.
1570 * Essentially these want to choose hash table sizes sufficiently
1571 * large so that collisions trying to wait on pages are rare.
1572 * But in fact, the number of active page waitqueues on typical
1573 * systems is ridiculously low, less than 200. So this is even
1574 * conservative, even though it seems large.
1576 * The constant PAGES_PER_WAITQUEUE specifies the ratio of pages to
1577 * waitqueues, i.e. the size of the waitq table given the number of pages.
1579 #define PAGES_PER_WAITQUEUE 256
1581 #ifndef CONFIG_MEMORY_HOTPLUG
1582 static inline unsigned long wait_table_hash_nr_entries(unsigned long pages
)
1584 unsigned long size
= 1;
1586 pages
/= PAGES_PER_WAITQUEUE
;
1588 while (size
< pages
)
1592 * Once we have dozens or even hundreds of threads sleeping
1593 * on IO we've got bigger problems than wait queue collision.
1594 * Limit the size of the wait table to a reasonable size.
1596 size
= min(size
, 4096UL);
1598 return max(size
, 4UL);
1602 * A zone's size might be changed by hot-add, so it is not possible to determine
1603 * a suitable size for its wait_table. So we use the maximum size now.
1605 * The max wait table size = 4096 x sizeof(wait_queue_head_t). ie:
1607 * i386 (preemption config) : 4096 x 16 = 64Kbyte.
1608 * ia64, x86-64 (no preemption): 4096 x 20 = 80Kbyte.
1609 * ia64, x86-64 (preemption) : 4096 x 24 = 96Kbyte.
1611 * The maximum entries are prepared when a zone's memory is (512K + 256) pages
1612 * or more by the traditional way. (See above). It equals:
1614 * i386, x86-64, powerpc(4K page size) : = ( 2G + 1M)byte.
1615 * ia64(16K page size) : = ( 8G + 4M)byte.
1616 * powerpc (64K page size) : = (32G +16M)byte.
1618 static inline unsigned long wait_table_hash_nr_entries(unsigned long pages
)
1625 * This is an integer logarithm so that shifts can be used later
1626 * to extract the more random high bits from the multiplicative
1627 * hash function before the remainder is taken.
1629 static inline unsigned long wait_table_bits(unsigned long size
)
1634 #define LONG_ALIGN(x) (((x)+(sizeof(long))-1)&~((sizeof(long))-1))
1636 static void __init
calculate_zone_totalpages(struct pglist_data
*pgdat
,
1637 unsigned long *zones_size
, unsigned long *zholes_size
)
1639 unsigned long realtotalpages
, totalpages
= 0;
1642 for (i
= 0; i
< MAX_NR_ZONES
; i
++)
1643 totalpages
+= zones_size
[i
];
1644 pgdat
->node_spanned_pages
= totalpages
;
1646 realtotalpages
= totalpages
;
1648 for (i
= 0; i
< MAX_NR_ZONES
; i
++)
1649 realtotalpages
-= zholes_size
[i
];
1650 pgdat
->node_present_pages
= realtotalpages
;
1651 printk(KERN_DEBUG
"On node %d totalpages: %lu\n", pgdat
->node_id
, realtotalpages
);
1656 * Initially all pages are reserved - free ones are freed
1657 * up by free_all_bootmem() once the early boot process is
1658 * done. Non-atomic initialization, single-pass.
1660 void __meminit
memmap_init_zone(unsigned long size
, int nid
, unsigned long zone
,
1661 unsigned long start_pfn
)
1664 unsigned long end_pfn
= start_pfn
+ size
;
1667 for (pfn
= start_pfn
; pfn
< end_pfn
; pfn
++) {
1668 if (!early_pfn_valid(pfn
))
1670 page
= pfn_to_page(pfn
);
1671 set_page_links(page
, zone
, nid
, pfn
);
1672 init_page_count(page
);
1673 reset_page_mapcount(page
);
1674 SetPageReserved(page
);
1675 INIT_LIST_HEAD(&page
->lru
);
1676 #ifdef WANT_PAGE_VIRTUAL
1677 /* The shift won't overflow because ZONE_NORMAL is below 4G. */
1678 if (!is_highmem_idx(zone
))
1679 set_page_address(page
, __va(pfn
<< PAGE_SHIFT
));
1684 void zone_init_free_lists(struct pglist_data
*pgdat
, struct zone
*zone
,
1688 for (order
= 0; order
< MAX_ORDER
; order
++) {
1689 INIT_LIST_HEAD(&zone
->free_area
[order
].free_list
);
1690 zone
->free_area
[order
].nr_free
= 0;
1694 #define ZONETABLE_INDEX(x, zone_nr) ((x << ZONES_SHIFT) | zone_nr)
1695 void zonetable_add(struct zone
*zone
, int nid
, enum zone_type zid
,
1696 unsigned long pfn
, unsigned long size
)
1698 unsigned long snum
= pfn_to_section_nr(pfn
);
1699 unsigned long end
= pfn_to_section_nr(pfn
+ size
);
1702 zone_table
[ZONETABLE_INDEX(nid
, zid
)] = zone
;
1704 for (; snum
<= end
; snum
++)
1705 zone_table
[ZONETABLE_INDEX(snum
, zid
)] = zone
;
1708 #ifndef __HAVE_ARCH_MEMMAP_INIT
1709 #define memmap_init(size, nid, zone, start_pfn) \
1710 memmap_init_zone((size), (nid), (zone), (start_pfn))
1713 static int __cpuinit
zone_batchsize(struct zone
*zone
)
1718 * The per-cpu-pages pools are set to around 1000th of the
1719 * size of the zone. But no more than 1/2 of a meg.
1721 * OK, so we don't know how big the cache is. So guess.
1723 batch
= zone
->present_pages
/ 1024;
1724 if (batch
* PAGE_SIZE
> 512 * 1024)
1725 batch
= (512 * 1024) / PAGE_SIZE
;
1726 batch
/= 4; /* We effectively *= 4 below */
1731 * Clamp the batch to a 2^n - 1 value. Having a power
1732 * of 2 value was found to be more likely to have
1733 * suboptimal cache aliasing properties in some cases.
1735 * For example if 2 tasks are alternately allocating
1736 * batches of pages, one task can end up with a lot
1737 * of pages of one half of the possible page colors
1738 * and the other with pages of the other colors.
1740 batch
= (1 << (fls(batch
+ batch
/2)-1)) - 1;
1745 inline void setup_pageset(struct per_cpu_pageset
*p
, unsigned long batch
)
1747 struct per_cpu_pages
*pcp
;
1749 memset(p
, 0, sizeof(*p
));
1751 pcp
= &p
->pcp
[0]; /* hot */
1753 pcp
->high
= 6 * batch
;
1754 pcp
->batch
= max(1UL, 1 * batch
);
1755 INIT_LIST_HEAD(&pcp
->list
);
1757 pcp
= &p
->pcp
[1]; /* cold*/
1759 pcp
->high
= 2 * batch
;
1760 pcp
->batch
= max(1UL, batch
/2);
1761 INIT_LIST_HEAD(&pcp
->list
);
1765 * setup_pagelist_highmark() sets the high water mark for hot per_cpu_pagelist
1766 * to the value high for the pageset p.
1769 static void setup_pagelist_highmark(struct per_cpu_pageset
*p
,
1772 struct per_cpu_pages
*pcp
;
1774 pcp
= &p
->pcp
[0]; /* hot list */
1776 pcp
->batch
= max(1UL, high
/4);
1777 if ((high
/4) > (PAGE_SHIFT
* 8))
1778 pcp
->batch
= PAGE_SHIFT
* 8;
1784 * Boot pageset table. One per cpu which is going to be used for all
1785 * zones and all nodes. The parameters will be set in such a way
1786 * that an item put on a list will immediately be handed over to
1787 * the buddy list. This is safe since pageset manipulation is done
1788 * with interrupts disabled.
1790 * Some NUMA counter updates may also be caught by the boot pagesets.
1792 * The boot_pagesets must be kept even after bootup is complete for
1793 * unused processors and/or zones. They do play a role for bootstrapping
1794 * hotplugged processors.
1796 * zoneinfo_show() and maybe other functions do
1797 * not check if the processor is online before following the pageset pointer.
1798 * Other parts of the kernel may not check if the zone is available.
1800 static struct per_cpu_pageset boot_pageset
[NR_CPUS
];
1803 * Dynamically allocate memory for the
1804 * per cpu pageset array in struct zone.
1806 static int __cpuinit
process_zones(int cpu
)
1808 struct zone
*zone
, *dzone
;
1810 for_each_zone(zone
) {
1812 zone_pcp(zone
, cpu
) = kmalloc_node(sizeof(struct per_cpu_pageset
),
1813 GFP_KERNEL
, cpu_to_node(cpu
));
1814 if (!zone_pcp(zone
, cpu
))
1817 setup_pageset(zone_pcp(zone
, cpu
), zone_batchsize(zone
));
1819 if (percpu_pagelist_fraction
)
1820 setup_pagelist_highmark(zone_pcp(zone
, cpu
),
1821 (zone
->present_pages
/ percpu_pagelist_fraction
));
1826 for_each_zone(dzone
) {
1829 kfree(zone_pcp(dzone
, cpu
));
1830 zone_pcp(dzone
, cpu
) = NULL
;
1835 static inline void free_zone_pagesets(int cpu
)
1839 for_each_zone(zone
) {
1840 struct per_cpu_pageset
*pset
= zone_pcp(zone
, cpu
);
1842 /* Free per_cpu_pageset if it is slab allocated */
1843 if (pset
!= &boot_pageset
[cpu
])
1845 zone_pcp(zone
, cpu
) = NULL
;
1849 static int __cpuinit
pageset_cpuup_callback(struct notifier_block
*nfb
,
1850 unsigned long action
,
1853 int cpu
= (long)hcpu
;
1854 int ret
= NOTIFY_OK
;
1857 case CPU_UP_PREPARE
:
1858 if (process_zones(cpu
))
1861 case CPU_UP_CANCELED
:
1863 free_zone_pagesets(cpu
);
1871 static struct notifier_block __cpuinitdata pageset_notifier
=
1872 { &pageset_cpuup_callback
, NULL
, 0 };
1874 void __init
setup_per_cpu_pageset(void)
1878 /* Initialize per_cpu_pageset for cpu 0.
1879 * A cpuup callback will do this for every cpu
1880 * as it comes online
1882 err
= process_zones(smp_processor_id());
1884 register_cpu_notifier(&pageset_notifier
);
1890 int zone_wait_table_init(struct zone
*zone
, unsigned long zone_size_pages
)
1893 struct pglist_data
*pgdat
= zone
->zone_pgdat
;
1897 * The per-page waitqueue mechanism uses hashed waitqueues
1900 zone
->wait_table_hash_nr_entries
=
1901 wait_table_hash_nr_entries(zone_size_pages
);
1902 zone
->wait_table_bits
=
1903 wait_table_bits(zone
->wait_table_hash_nr_entries
);
1904 alloc_size
= zone
->wait_table_hash_nr_entries
1905 * sizeof(wait_queue_head_t
);
1907 if (system_state
== SYSTEM_BOOTING
) {
1908 zone
->wait_table
= (wait_queue_head_t
*)
1909 alloc_bootmem_node(pgdat
, alloc_size
);
1912 * This case means that a zone whose size was 0 gets new memory
1913 * via memory hot-add.
1914 * But it may be the case that a new node was hot-added. In
1915 * this case vmalloc() will not be able to use this new node's
1916 * memory - this wait_table must be initialized to use this new
1917 * node itself as well.
1918 * To use this new node's memory, further consideration will be
1921 zone
->wait_table
= (wait_queue_head_t
*)vmalloc(alloc_size
);
1923 if (!zone
->wait_table
)
1926 for(i
= 0; i
< zone
->wait_table_hash_nr_entries
; ++i
)
1927 init_waitqueue_head(zone
->wait_table
+ i
);
1932 static __meminit
void zone_pcp_init(struct zone
*zone
)
1935 unsigned long batch
= zone_batchsize(zone
);
1937 for (cpu
= 0; cpu
< NR_CPUS
; cpu
++) {
1939 /* Early boot. Slab allocator not functional yet */
1940 zone_pcp(zone
, cpu
) = &boot_pageset
[cpu
];
1941 setup_pageset(&boot_pageset
[cpu
],0);
1943 setup_pageset(zone_pcp(zone
,cpu
), batch
);
1946 if (zone
->present_pages
)
1947 printk(KERN_DEBUG
" %s zone: %lu pages, LIFO batch:%lu\n",
1948 zone
->name
, zone
->present_pages
, batch
);
1951 __meminit
int init_currently_empty_zone(struct zone
*zone
,
1952 unsigned long zone_start_pfn
,
1955 struct pglist_data
*pgdat
= zone
->zone_pgdat
;
1957 ret
= zone_wait_table_init(zone
, size
);
1960 pgdat
->nr_zones
= zone_idx(zone
) + 1;
1962 zone
->zone_start_pfn
= zone_start_pfn
;
1964 memmap_init(size
, pgdat
->node_id
, zone_idx(zone
), zone_start_pfn
);
1966 zone_init_free_lists(pgdat
, zone
, zone
->spanned_pages
);
1972 * Set up the zone data structures:
1973 * - mark all pages reserved
1974 * - mark all memory queues empty
1975 * - clear the memory bitmaps
1977 static void __meminit
free_area_init_core(struct pglist_data
*pgdat
,
1978 unsigned long *zones_size
, unsigned long *zholes_size
)
1981 int nid
= pgdat
->node_id
;
1982 unsigned long zone_start_pfn
= pgdat
->node_start_pfn
;
1985 pgdat_resize_init(pgdat
);
1986 pgdat
->nr_zones
= 0;
1987 init_waitqueue_head(&pgdat
->kswapd_wait
);
1988 pgdat
->kswapd_max_order
= 0;
1990 for (j
= 0; j
< MAX_NR_ZONES
; j
++) {
1991 struct zone
*zone
= pgdat
->node_zones
+ j
;
1992 unsigned long size
, realsize
;
1994 realsize
= size
= zones_size
[j
];
1996 realsize
-= zholes_size
[j
];
1998 if (!is_highmem_idx(j
))
1999 nr_kernel_pages
+= realsize
;
2000 nr_all_pages
+= realsize
;
2002 zone
->spanned_pages
= size
;
2003 zone
->present_pages
= realsize
;
2005 zone
->min_unmapped_pages
= (realsize
*sysctl_min_unmapped_ratio
)
2008 zone
->name
= zone_names
[j
];
2009 spin_lock_init(&zone
->lock
);
2010 spin_lock_init(&zone
->lru_lock
);
2011 zone_seqlock_init(zone
);
2012 zone
->zone_pgdat
= pgdat
;
2013 zone
->free_pages
= 0;
2015 zone
->temp_priority
= zone
->prev_priority
= DEF_PRIORITY
;
2017 zone_pcp_init(zone
);
2018 INIT_LIST_HEAD(&zone
->active_list
);
2019 INIT_LIST_HEAD(&zone
->inactive_list
);
2020 zone
->nr_scan_active
= 0;
2021 zone
->nr_scan_inactive
= 0;
2022 zone
->nr_active
= 0;
2023 zone
->nr_inactive
= 0;
2024 zap_zone_vm_stats(zone
);
2025 atomic_set(&zone
->reclaim_in_progress
, 0);
2029 zonetable_add(zone
, nid
, j
, zone_start_pfn
, size
);
2030 ret
= init_currently_empty_zone(zone
, zone_start_pfn
, size
);
2032 zone_start_pfn
+= size
;
2036 static void __init
alloc_node_mem_map(struct pglist_data
*pgdat
)
2038 /* Skip empty nodes */
2039 if (!pgdat
->node_spanned_pages
)
2042 #ifdef CONFIG_FLAT_NODE_MEM_MAP
2043 /* ia64 gets its own node_mem_map, before this, without bootmem */
2044 if (!pgdat
->node_mem_map
) {
2045 unsigned long size
, start
, end
;
2049 * The zone's endpoints aren't required to be MAX_ORDER
2050 * aligned but the node_mem_map endpoints must be in order
2051 * for the buddy allocator to function correctly.
2053 start
= pgdat
->node_start_pfn
& ~(MAX_ORDER_NR_PAGES
- 1);
2054 end
= pgdat
->node_start_pfn
+ pgdat
->node_spanned_pages
;
2055 end
= ALIGN(end
, MAX_ORDER_NR_PAGES
);
2056 size
= (end
- start
) * sizeof(struct page
);
2057 map
= alloc_remap(pgdat
->node_id
, size
);
2059 map
= alloc_bootmem_node(pgdat
, size
);
2060 pgdat
->node_mem_map
= map
+ (pgdat
->node_start_pfn
- start
);
2062 #ifdef CONFIG_FLATMEM
2064 * With no DISCONTIG, the global mem_map is just set as node 0's
2066 if (pgdat
== NODE_DATA(0))
2067 mem_map
= NODE_DATA(0)->node_mem_map
;
2069 #endif /* CONFIG_FLAT_NODE_MEM_MAP */
2072 void __meminit
free_area_init_node(int nid
, struct pglist_data
*pgdat
,
2073 unsigned long *zones_size
, unsigned long node_start_pfn
,
2074 unsigned long *zholes_size
)
2076 pgdat
->node_id
= nid
;
2077 pgdat
->node_start_pfn
= node_start_pfn
;
2078 calculate_zone_totalpages(pgdat
, zones_size
, zholes_size
);
2080 alloc_node_mem_map(pgdat
);
2082 free_area_init_core(pgdat
, zones_size
, zholes_size
);
2085 #ifndef CONFIG_NEED_MULTIPLE_NODES
2086 static bootmem_data_t contig_bootmem_data
;
2087 struct pglist_data contig_page_data
= { .bdata
= &contig_bootmem_data
};
2089 EXPORT_SYMBOL(contig_page_data
);
2092 void __init
free_area_init(unsigned long *zones_size
)
2094 free_area_init_node(0, NODE_DATA(0), zones_size
,
2095 __pa(PAGE_OFFSET
) >> PAGE_SHIFT
, NULL
);
2098 #ifdef CONFIG_HOTPLUG_CPU
2099 static int page_alloc_cpu_notify(struct notifier_block
*self
,
2100 unsigned long action
, void *hcpu
)
2102 int cpu
= (unsigned long)hcpu
;
2104 if (action
== CPU_DEAD
) {
2105 local_irq_disable();
2107 vm_events_fold_cpu(cpu
);
2109 refresh_cpu_vm_stats(cpu
);
2113 #endif /* CONFIG_HOTPLUG_CPU */
2115 void __init
page_alloc_init(void)
2117 hotcpu_notifier(page_alloc_cpu_notify
, 0);
2121 * calculate_totalreserve_pages - called when sysctl_lower_zone_reserve_ratio
2122 * or min_free_kbytes changes.
2124 static void calculate_totalreserve_pages(void)
2126 struct pglist_data
*pgdat
;
2127 unsigned long reserve_pages
= 0;
2128 enum zone_type i
, j
;
2130 for_each_online_pgdat(pgdat
) {
2131 for (i
= 0; i
< MAX_NR_ZONES
; i
++) {
2132 struct zone
*zone
= pgdat
->node_zones
+ i
;
2133 unsigned long max
= 0;
2135 /* Find valid and maximum lowmem_reserve in the zone */
2136 for (j
= i
; j
< MAX_NR_ZONES
; j
++) {
2137 if (zone
->lowmem_reserve
[j
] > max
)
2138 max
= zone
->lowmem_reserve
[j
];
2141 /* we treat pages_high as reserved pages. */
2142 max
+= zone
->pages_high
;
2144 if (max
> zone
->present_pages
)
2145 max
= zone
->present_pages
;
2146 reserve_pages
+= max
;
2149 totalreserve_pages
= reserve_pages
;
2153 * setup_per_zone_lowmem_reserve - called whenever
2154 * sysctl_lower_zone_reserve_ratio changes. Ensures that each zone
2155 * has a correct pages reserved value, so an adequate number of
2156 * pages are left in the zone after a successful __alloc_pages().
2158 static void setup_per_zone_lowmem_reserve(void)
2160 struct pglist_data
*pgdat
;
2161 enum zone_type j
, idx
;
2163 for_each_online_pgdat(pgdat
) {
2164 for (j
= 0; j
< MAX_NR_ZONES
; j
++) {
2165 struct zone
*zone
= pgdat
->node_zones
+ j
;
2166 unsigned long present_pages
= zone
->present_pages
;
2168 zone
->lowmem_reserve
[j
] = 0;
2172 struct zone
*lower_zone
;
2176 if (sysctl_lowmem_reserve_ratio
[idx
] < 1)
2177 sysctl_lowmem_reserve_ratio
[idx
] = 1;
2179 lower_zone
= pgdat
->node_zones
+ idx
;
2180 lower_zone
->lowmem_reserve
[j
] = present_pages
/
2181 sysctl_lowmem_reserve_ratio
[idx
];
2182 present_pages
+= lower_zone
->present_pages
;
2187 /* update totalreserve_pages */
2188 calculate_totalreserve_pages();
2192 * setup_per_zone_pages_min - called when min_free_kbytes changes. Ensures
2193 * that the pages_{min,low,high} values for each zone are set correctly
2194 * with respect to min_free_kbytes.
2196 void setup_per_zone_pages_min(void)
2198 unsigned long pages_min
= min_free_kbytes
>> (PAGE_SHIFT
- 10);
2199 unsigned long lowmem_pages
= 0;
2201 unsigned long flags
;
2203 /* Calculate total number of !ZONE_HIGHMEM pages */
2204 for_each_zone(zone
) {
2205 if (!is_highmem(zone
))
2206 lowmem_pages
+= zone
->present_pages
;
2209 for_each_zone(zone
) {
2212 spin_lock_irqsave(&zone
->lru_lock
, flags
);
2213 tmp
= (u64
)pages_min
* zone
->present_pages
;
2214 do_div(tmp
, lowmem_pages
);
2215 if (is_highmem(zone
)) {
2217 * __GFP_HIGH and PF_MEMALLOC allocations usually don't
2218 * need highmem pages, so cap pages_min to a small
2221 * The (pages_high-pages_low) and (pages_low-pages_min)
2222 * deltas controls asynch page reclaim, and so should
2223 * not be capped for highmem.
2227 min_pages
= zone
->present_pages
/ 1024;
2228 if (min_pages
< SWAP_CLUSTER_MAX
)
2229 min_pages
= SWAP_CLUSTER_MAX
;
2230 if (min_pages
> 128)
2232 zone
->pages_min
= min_pages
;
2235 * If it's a lowmem zone, reserve a number of pages
2236 * proportionate to the zone's size.
2238 zone
->pages_min
= tmp
;
2241 zone
->pages_low
= zone
->pages_min
+ (tmp
>> 2);
2242 zone
->pages_high
= zone
->pages_min
+ (tmp
>> 1);
2243 spin_unlock_irqrestore(&zone
->lru_lock
, flags
);
2246 /* update totalreserve_pages */
2247 calculate_totalreserve_pages();
2251 * Initialise min_free_kbytes.
2253 * For small machines we want it small (128k min). For large machines
2254 * we want it large (64MB max). But it is not linear, because network
2255 * bandwidth does not increase linearly with machine size. We use
2257 * min_free_kbytes = 4 * sqrt(lowmem_kbytes), for better accuracy:
2258 * min_free_kbytes = sqrt(lowmem_kbytes * 16)
2274 static int __init
init_per_zone_pages_min(void)
2276 unsigned long lowmem_kbytes
;
2278 lowmem_kbytes
= nr_free_buffer_pages() * (PAGE_SIZE
>> 10);
2280 min_free_kbytes
= int_sqrt(lowmem_kbytes
* 16);
2281 if (min_free_kbytes
< 128)
2282 min_free_kbytes
= 128;
2283 if (min_free_kbytes
> 65536)
2284 min_free_kbytes
= 65536;
2285 setup_per_zone_pages_min();
2286 setup_per_zone_lowmem_reserve();
2289 module_init(init_per_zone_pages_min
)
2292 * min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so
2293 * that we can call two helper functions whenever min_free_kbytes
2296 int min_free_kbytes_sysctl_handler(ctl_table
*table
, int write
,
2297 struct file
*file
, void __user
*buffer
, size_t *length
, loff_t
*ppos
)
2299 proc_dointvec(table
, write
, file
, buffer
, length
, ppos
);
2300 setup_per_zone_pages_min();
2305 int sysctl_min_unmapped_ratio_sysctl_handler(ctl_table
*table
, int write
,
2306 struct file
*file
, void __user
*buffer
, size_t *length
, loff_t
*ppos
)
2311 rc
= proc_dointvec_minmax(table
, write
, file
, buffer
, length
, ppos
);
2316 zone
->min_unmapped_pages
= (zone
->present_pages
*
2317 sysctl_min_unmapped_ratio
) / 100;
2323 * lowmem_reserve_ratio_sysctl_handler - just a wrapper around
2324 * proc_dointvec() so that we can call setup_per_zone_lowmem_reserve()
2325 * whenever sysctl_lowmem_reserve_ratio changes.
2327 * The reserve ratio obviously has absolutely no relation with the
2328 * pages_min watermarks. The lowmem reserve ratio can only make sense
2329 * if in function of the boot time zone sizes.
2331 int lowmem_reserve_ratio_sysctl_handler(ctl_table
*table
, int write
,
2332 struct file
*file
, void __user
*buffer
, size_t *length
, loff_t
*ppos
)
2334 proc_dointvec_minmax(table
, write
, file
, buffer
, length
, ppos
);
2335 setup_per_zone_lowmem_reserve();
2340 * percpu_pagelist_fraction - changes the pcp->high for each zone on each
2341 * cpu. It is the fraction of total pages in each zone that a hot per cpu pagelist
2342 * can have before it gets flushed back to buddy allocator.
2345 int percpu_pagelist_fraction_sysctl_handler(ctl_table
*table
, int write
,
2346 struct file
*file
, void __user
*buffer
, size_t *length
, loff_t
*ppos
)
2352 ret
= proc_dointvec_minmax(table
, write
, file
, buffer
, length
, ppos
);
2353 if (!write
|| (ret
== -EINVAL
))
2355 for_each_zone(zone
) {
2356 for_each_online_cpu(cpu
) {
2358 high
= zone
->present_pages
/ percpu_pagelist_fraction
;
2359 setup_pagelist_highmark(zone_pcp(zone
, cpu
), high
);
2365 int hashdist
= HASHDIST_DEFAULT
;
2368 static int __init
set_hashdist(char *str
)
2372 hashdist
= simple_strtoul(str
, &str
, 0);
2375 __setup("hashdist=", set_hashdist
);
2379 * allocate a large system hash table from bootmem
2380 * - it is assumed that the hash table must contain an exact power-of-2
2381 * quantity of entries
2382 * - limit is the number of hash buckets, not the total allocation size
2384 void *__init
alloc_large_system_hash(const char *tablename
,
2385 unsigned long bucketsize
,
2386 unsigned long numentries
,
2389 unsigned int *_hash_shift
,
2390 unsigned int *_hash_mask
,
2391 unsigned long limit
)
2393 unsigned long long max
= limit
;
2394 unsigned long log2qty
, size
;
2397 /* allow the kernel cmdline to have a say */
2399 /* round applicable memory size up to nearest megabyte */
2400 numentries
= (flags
& HASH_HIGHMEM
) ? nr_all_pages
: nr_kernel_pages
;
2401 numentries
+= (1UL << (20 - PAGE_SHIFT
)) - 1;
2402 numentries
>>= 20 - PAGE_SHIFT
;
2403 numentries
<<= 20 - PAGE_SHIFT
;
2405 /* limit to 1 bucket per 2^scale bytes of low memory */
2406 if (scale
> PAGE_SHIFT
)
2407 numentries
>>= (scale
- PAGE_SHIFT
);
2409 numentries
<<= (PAGE_SHIFT
- scale
);
2411 numentries
= roundup_pow_of_two(numentries
);
2413 /* limit allocation size to 1/16 total memory by default */
2415 max
= ((unsigned long long)nr_all_pages
<< PAGE_SHIFT
) >> 4;
2416 do_div(max
, bucketsize
);
2419 if (numentries
> max
)
2422 log2qty
= long_log2(numentries
);
2425 size
= bucketsize
<< log2qty
;
2426 if (flags
& HASH_EARLY
)
2427 table
= alloc_bootmem(size
);
2429 table
= __vmalloc(size
, GFP_ATOMIC
, PAGE_KERNEL
);
2431 unsigned long order
;
2432 for (order
= 0; ((1UL << order
) << PAGE_SHIFT
) < size
; order
++)
2434 table
= (void*) __get_free_pages(GFP_ATOMIC
, order
);
2436 } while (!table
&& size
> PAGE_SIZE
&& --log2qty
);
2439 panic("Failed to allocate %s hash table\n", tablename
);
2441 printk("%s hash table entries: %d (order: %d, %lu bytes)\n",
2444 long_log2(size
) - PAGE_SHIFT
,
2448 *_hash_shift
= log2qty
;
2450 *_hash_mask
= (1 << log2qty
) - 1;
2455 #ifdef CONFIG_OUT_OF_LINE_PFN_TO_PAGE
2456 struct page
*pfn_to_page(unsigned long pfn
)
2458 return __pfn_to_page(pfn
);
2460 unsigned long page_to_pfn(struct page
*page
)
2462 return __page_to_pfn(page
);
2464 EXPORT_SYMBOL(pfn_to_page
);
2465 EXPORT_SYMBOL(page_to_pfn
);
2466 #endif /* CONFIG_OUT_OF_LINE_PFN_TO_PAGE */