ARM: S3C64XX: Fix missing header error with CONFIG_CPU_IDLE enabled
[linux-2.6.git] / mm / bootmem.c
blob1324cd74faec45dc2b0ba4f0b3fb0659640e9f25
1 /*
2 * bootmem - A boot-time physical memory allocator and configurator
4 * Copyright (C) 1999 Ingo Molnar
5 * 1999 Kanoj Sarcar, SGI
6 * 2008 Johannes Weiner
8 * Access to this subsystem has to be serialized externally (which is true
9 * for the boot process anyway).
11 #include <linux/init.h>
12 #include <linux/pfn.h>
13 #include <linux/slab.h>
14 #include <linux/bootmem.h>
15 #include <linux/export.h>
16 #include <linux/kmemleak.h>
17 #include <linux/range.h>
18 #include <linux/memblock.h>
20 #include <asm/bug.h>
21 #include <asm/io.h>
22 #include <asm/processor.h>
24 #include "internal.h"
26 #ifndef CONFIG_NEED_MULTIPLE_NODES
27 struct pglist_data __refdata contig_page_data = {
28 .bdata = &bootmem_node_data[0]
30 EXPORT_SYMBOL(contig_page_data);
31 #endif
33 unsigned long max_low_pfn;
34 unsigned long min_low_pfn;
35 unsigned long max_pfn;
37 bootmem_data_t bootmem_node_data[MAX_NUMNODES] __initdata;
39 static struct list_head bdata_list __initdata = LIST_HEAD_INIT(bdata_list);
41 static int bootmem_debug;
43 static int __init bootmem_debug_setup(char *buf)
45 bootmem_debug = 1;
46 return 0;
48 early_param("bootmem_debug", bootmem_debug_setup);
50 #define bdebug(fmt, args...) ({ \
51 if (unlikely(bootmem_debug)) \
52 printk(KERN_INFO \
53 "bootmem::%s " fmt, \
54 __func__, ## args); \
57 static unsigned long __init bootmap_bytes(unsigned long pages)
59 unsigned long bytes = DIV_ROUND_UP(pages, 8);
61 return ALIGN(bytes, sizeof(long));
64 /**
65 * bootmem_bootmap_pages - calculate bitmap size in pages
66 * @pages: number of pages the bitmap has to represent
68 unsigned long __init bootmem_bootmap_pages(unsigned long pages)
70 unsigned long bytes = bootmap_bytes(pages);
72 return PAGE_ALIGN(bytes) >> PAGE_SHIFT;
76 * link bdata in order
78 static void __init link_bootmem(bootmem_data_t *bdata)
80 bootmem_data_t *ent;
82 list_for_each_entry(ent, &bdata_list, list) {
83 if (bdata->node_min_pfn < ent->node_min_pfn) {
84 list_add_tail(&bdata->list, &ent->list);
85 return;
89 list_add_tail(&bdata->list, &bdata_list);
93 * Called once to set up the allocator itself.
95 static unsigned long __init init_bootmem_core(bootmem_data_t *bdata,
96 unsigned long mapstart, unsigned long start, unsigned long end)
98 unsigned long mapsize;
100 mminit_validate_memmodel_limits(&start, &end);
101 bdata->node_bootmem_map = phys_to_virt(PFN_PHYS(mapstart));
102 bdata->node_min_pfn = start;
103 bdata->node_low_pfn = end;
104 link_bootmem(bdata);
107 * Initially all pages are reserved - setup_arch() has to
108 * register free RAM areas explicitly.
110 mapsize = bootmap_bytes(end - start);
111 memset(bdata->node_bootmem_map, 0xff, mapsize);
113 bdebug("nid=%td start=%lx map=%lx end=%lx mapsize=%lx\n",
114 bdata - bootmem_node_data, start, mapstart, end, mapsize);
116 return mapsize;
120 * init_bootmem_node - register a node as boot memory
121 * @pgdat: node to register
122 * @freepfn: pfn where the bitmap for this node is to be placed
123 * @startpfn: first pfn on the node
124 * @endpfn: first pfn after the node
126 * Returns the number of bytes needed to hold the bitmap for this node.
128 unsigned long __init init_bootmem_node(pg_data_t *pgdat, unsigned long freepfn,
129 unsigned long startpfn, unsigned long endpfn)
131 return init_bootmem_core(pgdat->bdata, freepfn, startpfn, endpfn);
135 * init_bootmem - register boot memory
136 * @start: pfn where the bitmap is to be placed
137 * @pages: number of available physical pages
139 * Returns the number of bytes needed to hold the bitmap.
141 unsigned long __init init_bootmem(unsigned long start, unsigned long pages)
143 max_low_pfn = pages;
144 min_low_pfn = start;
145 return init_bootmem_core(NODE_DATA(0)->bdata, start, 0, pages);
149 * free_bootmem_late - free bootmem pages directly to page allocator
150 * @addr: starting physical address of the range
151 * @size: size of the range in bytes
153 * This is only useful when the bootmem allocator has already been torn
154 * down, but we are still initializing the system. Pages are given directly
155 * to the page allocator, no bootmem metadata is updated because it is gone.
157 void __init free_bootmem_late(unsigned long physaddr, unsigned long size)
159 unsigned long cursor, end;
161 kmemleak_free_part(__va(physaddr), size);
163 cursor = PFN_UP(physaddr);
164 end = PFN_DOWN(physaddr + size);
166 for (; cursor < end; cursor++) {
167 __free_pages_bootmem(pfn_to_page(cursor), 0);
168 totalram_pages++;
172 static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
174 struct page *page;
175 unsigned long start, end, pages, count = 0;
177 if (!bdata->node_bootmem_map)
178 return 0;
180 start = bdata->node_min_pfn;
181 end = bdata->node_low_pfn;
183 bdebug("nid=%td start=%lx end=%lx\n",
184 bdata - bootmem_node_data, start, end);
186 while (start < end) {
187 unsigned long *map, idx, vec;
189 map = bdata->node_bootmem_map;
190 idx = start - bdata->node_min_pfn;
191 vec = ~map[idx / BITS_PER_LONG];
193 * If we have a properly aligned and fully unreserved
194 * BITS_PER_LONG block of pages in front of us, free
195 * it in one go.
197 if (IS_ALIGNED(start, BITS_PER_LONG) && vec == ~0UL) {
198 int order = ilog2(BITS_PER_LONG);
200 __free_pages_bootmem(pfn_to_page(start), order);
201 count += BITS_PER_LONG;
202 start += BITS_PER_LONG;
203 } else {
204 unsigned long off = 0;
206 vec >>= start & (BITS_PER_LONG - 1);
207 while (vec) {
208 if (vec & 1) {
209 page = pfn_to_page(start + off);
210 __free_pages_bootmem(page, 0);
211 count++;
213 vec >>= 1;
214 off++;
216 start = ALIGN(start + 1, BITS_PER_LONG);
220 page = virt_to_page(bdata->node_bootmem_map);
221 pages = bdata->node_low_pfn - bdata->node_min_pfn;
222 pages = bootmem_bootmap_pages(pages);
223 count += pages;
224 while (pages--)
225 __free_pages_bootmem(page++, 0);
227 bdebug("nid=%td released=%lx\n", bdata - bootmem_node_data, count);
229 return count;
232 static void reset_node_lowmem_managed_pages(pg_data_t *pgdat)
234 struct zone *z;
237 * In free_area_init_core(), highmem zone's managed_pages is set to
238 * present_pages, and bootmem allocator doesn't allocate from highmem
239 * zones. So there's no need to recalculate managed_pages because all
240 * highmem pages will be managed by the buddy system. Here highmem
241 * zone also includes highmem movable zone.
243 for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
244 if (!is_highmem(z))
245 z->managed_pages = 0;
249 * free_all_bootmem_node - release a node's free pages to the buddy allocator
250 * @pgdat: node to be released
252 * Returns the number of pages actually released.
254 unsigned long __init free_all_bootmem_node(pg_data_t *pgdat)
256 register_page_bootmem_info_node(pgdat);
257 reset_node_lowmem_managed_pages(pgdat);
258 return free_all_bootmem_core(pgdat->bdata);
262 * free_all_bootmem - release free pages to the buddy allocator
264 * Returns the number of pages actually released.
266 unsigned long __init free_all_bootmem(void)
268 unsigned long total_pages = 0;
269 bootmem_data_t *bdata;
270 struct pglist_data *pgdat;
272 for_each_online_pgdat(pgdat)
273 reset_node_lowmem_managed_pages(pgdat);
275 list_for_each_entry(bdata, &bdata_list, list)
276 total_pages += free_all_bootmem_core(bdata);
278 return total_pages;
281 static void __init __free(bootmem_data_t *bdata,
282 unsigned long sidx, unsigned long eidx)
284 unsigned long idx;
286 bdebug("nid=%td start=%lx end=%lx\n", bdata - bootmem_node_data,
287 sidx + bdata->node_min_pfn,
288 eidx + bdata->node_min_pfn);
290 if (bdata->hint_idx > sidx)
291 bdata->hint_idx = sidx;
293 for (idx = sidx; idx < eidx; idx++)
294 if (!test_and_clear_bit(idx, bdata->node_bootmem_map))
295 BUG();
298 static int __init __reserve(bootmem_data_t *bdata, unsigned long sidx,
299 unsigned long eidx, int flags)
301 unsigned long idx;
302 int exclusive = flags & BOOTMEM_EXCLUSIVE;
304 bdebug("nid=%td start=%lx end=%lx flags=%x\n",
305 bdata - bootmem_node_data,
306 sidx + bdata->node_min_pfn,
307 eidx + bdata->node_min_pfn,
308 flags);
310 for (idx = sidx; idx < eidx; idx++)
311 if (test_and_set_bit(idx, bdata->node_bootmem_map)) {
312 if (exclusive) {
313 __free(bdata, sidx, idx);
314 return -EBUSY;
316 bdebug("silent double reserve of PFN %lx\n",
317 idx + bdata->node_min_pfn);
319 return 0;
322 static int __init mark_bootmem_node(bootmem_data_t *bdata,
323 unsigned long start, unsigned long end,
324 int reserve, int flags)
326 unsigned long sidx, eidx;
328 bdebug("nid=%td start=%lx end=%lx reserve=%d flags=%x\n",
329 bdata - bootmem_node_data, start, end, reserve, flags);
331 BUG_ON(start < bdata->node_min_pfn);
332 BUG_ON(end > bdata->node_low_pfn);
334 sidx = start - bdata->node_min_pfn;
335 eidx = end - bdata->node_min_pfn;
337 if (reserve)
338 return __reserve(bdata, sidx, eidx, flags);
339 else
340 __free(bdata, sidx, eidx);
341 return 0;
344 static int __init mark_bootmem(unsigned long start, unsigned long end,
345 int reserve, int flags)
347 unsigned long pos;
348 bootmem_data_t *bdata;
350 pos = start;
351 list_for_each_entry(bdata, &bdata_list, list) {
352 int err;
353 unsigned long max;
355 if (pos < bdata->node_min_pfn ||
356 pos >= bdata->node_low_pfn) {
357 BUG_ON(pos != start);
358 continue;
361 max = min(bdata->node_low_pfn, end);
363 err = mark_bootmem_node(bdata, pos, max, reserve, flags);
364 if (reserve && err) {
365 mark_bootmem(start, pos, 0, 0);
366 return err;
369 if (max == end)
370 return 0;
371 pos = bdata->node_low_pfn;
373 BUG();
377 * free_bootmem_node - mark a page range as usable
378 * @pgdat: node the range resides on
379 * @physaddr: starting address of the range
380 * @size: size of the range in bytes
382 * Partial pages will be considered reserved and left as they are.
384 * The range must reside completely on the specified node.
386 void __init free_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
387 unsigned long size)
389 unsigned long start, end;
391 kmemleak_free_part(__va(physaddr), size);
393 start = PFN_UP(physaddr);
394 end = PFN_DOWN(physaddr + size);
396 mark_bootmem_node(pgdat->bdata, start, end, 0, 0);
400 * free_bootmem - mark a page range as usable
401 * @addr: starting physical address of the range
402 * @size: size of the range in bytes
404 * Partial pages will be considered reserved and left as they are.
406 * The range must be contiguous but may span node boundaries.
408 void __init free_bootmem(unsigned long physaddr, unsigned long size)
410 unsigned long start, end;
412 kmemleak_free_part(__va(physaddr), size);
414 start = PFN_UP(physaddr);
415 end = PFN_DOWN(physaddr + size);
417 mark_bootmem(start, end, 0, 0);
421 * reserve_bootmem_node - mark a page range as reserved
422 * @pgdat: node the range resides on
423 * @physaddr: starting address of the range
424 * @size: size of the range in bytes
425 * @flags: reservation flags (see linux/bootmem.h)
427 * Partial pages will be reserved.
429 * The range must reside completely on the specified node.
431 int __init reserve_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
432 unsigned long size, int flags)
434 unsigned long start, end;
436 start = PFN_DOWN(physaddr);
437 end = PFN_UP(physaddr + size);
439 return mark_bootmem_node(pgdat->bdata, start, end, 1, flags);
443 * reserve_bootmem - mark a page range as reserved
444 * @addr: starting address of the range
445 * @size: size of the range in bytes
446 * @flags: reservation flags (see linux/bootmem.h)
448 * Partial pages will be reserved.
450 * The range must be contiguous but may span node boundaries.
452 int __init reserve_bootmem(unsigned long addr, unsigned long size,
453 int flags)
455 unsigned long start, end;
457 start = PFN_DOWN(addr);
458 end = PFN_UP(addr + size);
460 return mark_bootmem(start, end, 1, flags);
463 static unsigned long __init align_idx(struct bootmem_data *bdata,
464 unsigned long idx, unsigned long step)
466 unsigned long base = bdata->node_min_pfn;
469 * Align the index with respect to the node start so that the
470 * combination of both satisfies the requested alignment.
473 return ALIGN(base + idx, step) - base;
476 static unsigned long __init align_off(struct bootmem_data *bdata,
477 unsigned long off, unsigned long align)
479 unsigned long base = PFN_PHYS(bdata->node_min_pfn);
481 /* Same as align_idx for byte offsets */
483 return ALIGN(base + off, align) - base;
486 static void * __init alloc_bootmem_bdata(struct bootmem_data *bdata,
487 unsigned long size, unsigned long align,
488 unsigned long goal, unsigned long limit)
490 unsigned long fallback = 0;
491 unsigned long min, max, start, sidx, midx, step;
493 bdebug("nid=%td size=%lx [%lu pages] align=%lx goal=%lx limit=%lx\n",
494 bdata - bootmem_node_data, size, PAGE_ALIGN(size) >> PAGE_SHIFT,
495 align, goal, limit);
497 BUG_ON(!size);
498 BUG_ON(align & (align - 1));
499 BUG_ON(limit && goal + size > limit);
501 if (!bdata->node_bootmem_map)
502 return NULL;
504 min = bdata->node_min_pfn;
505 max = bdata->node_low_pfn;
507 goal >>= PAGE_SHIFT;
508 limit >>= PAGE_SHIFT;
510 if (limit && max > limit)
511 max = limit;
512 if (max <= min)
513 return NULL;
515 step = max(align >> PAGE_SHIFT, 1UL);
517 if (goal && min < goal && goal < max)
518 start = ALIGN(goal, step);
519 else
520 start = ALIGN(min, step);
522 sidx = start - bdata->node_min_pfn;
523 midx = max - bdata->node_min_pfn;
525 if (bdata->hint_idx > sidx) {
527 * Handle the valid case of sidx being zero and still
528 * catch the fallback below.
530 fallback = sidx + 1;
531 sidx = align_idx(bdata, bdata->hint_idx, step);
534 while (1) {
535 int merge;
536 void *region;
537 unsigned long eidx, i, start_off, end_off;
538 find_block:
539 sidx = find_next_zero_bit(bdata->node_bootmem_map, midx, sidx);
540 sidx = align_idx(bdata, sidx, step);
541 eidx = sidx + PFN_UP(size);
543 if (sidx >= midx || eidx > midx)
544 break;
546 for (i = sidx; i < eidx; i++)
547 if (test_bit(i, bdata->node_bootmem_map)) {
548 sidx = align_idx(bdata, i, step);
549 if (sidx == i)
550 sidx += step;
551 goto find_block;
554 if (bdata->last_end_off & (PAGE_SIZE - 1) &&
555 PFN_DOWN(bdata->last_end_off) + 1 == sidx)
556 start_off = align_off(bdata, bdata->last_end_off, align);
557 else
558 start_off = PFN_PHYS(sidx);
560 merge = PFN_DOWN(start_off) < sidx;
561 end_off = start_off + size;
563 bdata->last_end_off = end_off;
564 bdata->hint_idx = PFN_UP(end_off);
567 * Reserve the area now:
569 if (__reserve(bdata, PFN_DOWN(start_off) + merge,
570 PFN_UP(end_off), BOOTMEM_EXCLUSIVE))
571 BUG();
573 region = phys_to_virt(PFN_PHYS(bdata->node_min_pfn) +
574 start_off);
575 memset(region, 0, size);
577 * The min_count is set to 0 so that bootmem allocated blocks
578 * are never reported as leaks.
580 kmemleak_alloc(region, size, 0, 0);
581 return region;
584 if (fallback) {
585 sidx = align_idx(bdata, fallback - 1, step);
586 fallback = 0;
587 goto find_block;
590 return NULL;
593 static void * __init alloc_bootmem_core(unsigned long size,
594 unsigned long align,
595 unsigned long goal,
596 unsigned long limit)
598 bootmem_data_t *bdata;
599 void *region;
601 if (WARN_ON_ONCE(slab_is_available()))
602 return kzalloc(size, GFP_NOWAIT);
604 list_for_each_entry(bdata, &bdata_list, list) {
605 if (goal && bdata->node_low_pfn <= PFN_DOWN(goal))
606 continue;
607 if (limit && bdata->node_min_pfn >= PFN_DOWN(limit))
608 break;
610 region = alloc_bootmem_bdata(bdata, size, align, goal, limit);
611 if (region)
612 return region;
615 return NULL;
618 static void * __init ___alloc_bootmem_nopanic(unsigned long size,
619 unsigned long align,
620 unsigned long goal,
621 unsigned long limit)
623 void *ptr;
625 restart:
626 ptr = alloc_bootmem_core(size, align, goal, limit);
627 if (ptr)
628 return ptr;
629 if (goal) {
630 goal = 0;
631 goto restart;
634 return NULL;
638 * __alloc_bootmem_nopanic - allocate boot memory without panicking
639 * @size: size of the request in bytes
640 * @align: alignment of the region
641 * @goal: preferred starting address of the region
643 * The goal is dropped if it can not be satisfied and the allocation will
644 * fall back to memory below @goal.
646 * Allocation may happen on any node in the system.
648 * Returns NULL on failure.
650 void * __init __alloc_bootmem_nopanic(unsigned long size, unsigned long align,
651 unsigned long goal)
653 unsigned long limit = 0;
655 return ___alloc_bootmem_nopanic(size, align, goal, limit);
658 static void * __init ___alloc_bootmem(unsigned long size, unsigned long align,
659 unsigned long goal, unsigned long limit)
661 void *mem = ___alloc_bootmem_nopanic(size, align, goal, limit);
663 if (mem)
664 return mem;
666 * Whoops, we cannot satisfy the allocation request.
668 printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);
669 panic("Out of memory");
670 return NULL;
674 * __alloc_bootmem - allocate boot memory
675 * @size: size of the request in bytes
676 * @align: alignment of the region
677 * @goal: preferred starting address of the region
679 * The goal is dropped if it can not be satisfied and the allocation will
680 * fall back to memory below @goal.
682 * Allocation may happen on any node in the system.
684 * The function panics if the request can not be satisfied.
686 void * __init __alloc_bootmem(unsigned long size, unsigned long align,
687 unsigned long goal)
689 unsigned long limit = 0;
691 return ___alloc_bootmem(size, align, goal, limit);
694 void * __init ___alloc_bootmem_node_nopanic(pg_data_t *pgdat,
695 unsigned long size, unsigned long align,
696 unsigned long goal, unsigned long limit)
698 void *ptr;
700 if (WARN_ON_ONCE(slab_is_available()))
701 return kzalloc(size, GFP_NOWAIT);
702 again:
704 /* do not panic in alloc_bootmem_bdata() */
705 if (limit && goal + size > limit)
706 limit = 0;
708 ptr = alloc_bootmem_bdata(pgdat->bdata, size, align, goal, limit);
709 if (ptr)
710 return ptr;
712 ptr = alloc_bootmem_core(size, align, goal, limit);
713 if (ptr)
714 return ptr;
716 if (goal) {
717 goal = 0;
718 goto again;
721 return NULL;
724 void * __init __alloc_bootmem_node_nopanic(pg_data_t *pgdat, unsigned long size,
725 unsigned long align, unsigned long goal)
727 if (WARN_ON_ONCE(slab_is_available()))
728 return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
730 return ___alloc_bootmem_node_nopanic(pgdat, size, align, goal, 0);
733 void * __init ___alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
734 unsigned long align, unsigned long goal,
735 unsigned long limit)
737 void *ptr;
739 ptr = ___alloc_bootmem_node_nopanic(pgdat, size, align, goal, 0);
740 if (ptr)
741 return ptr;
743 printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);
744 panic("Out of memory");
745 return NULL;
749 * __alloc_bootmem_node - allocate boot memory from a specific node
750 * @pgdat: node to allocate from
751 * @size: size of the request in bytes
752 * @align: alignment of the region
753 * @goal: preferred starting address of the region
755 * The goal is dropped if it can not be satisfied and the allocation will
756 * fall back to memory below @goal.
758 * Allocation may fall back to any node in the system if the specified node
759 * can not hold the requested memory.
761 * The function panics if the request can not be satisfied.
763 void * __init __alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
764 unsigned long align, unsigned long goal)
766 if (WARN_ON_ONCE(slab_is_available()))
767 return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
769 return ___alloc_bootmem_node(pgdat, size, align, goal, 0);
772 void * __init __alloc_bootmem_node_high(pg_data_t *pgdat, unsigned long size,
773 unsigned long align, unsigned long goal)
775 #ifdef MAX_DMA32_PFN
776 unsigned long end_pfn;
778 if (WARN_ON_ONCE(slab_is_available()))
779 return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
781 /* update goal according ...MAX_DMA32_PFN */
782 end_pfn = pgdat->node_start_pfn + pgdat->node_spanned_pages;
784 if (end_pfn > MAX_DMA32_PFN + (128 >> (20 - PAGE_SHIFT)) &&
785 (goal >> PAGE_SHIFT) < MAX_DMA32_PFN) {
786 void *ptr;
787 unsigned long new_goal;
789 new_goal = MAX_DMA32_PFN << PAGE_SHIFT;
790 ptr = alloc_bootmem_bdata(pgdat->bdata, size, align,
791 new_goal, 0);
792 if (ptr)
793 return ptr;
795 #endif
797 return __alloc_bootmem_node(pgdat, size, align, goal);
801 #ifndef ARCH_LOW_ADDRESS_LIMIT
802 #define ARCH_LOW_ADDRESS_LIMIT 0xffffffffUL
803 #endif
806 * __alloc_bootmem_low - allocate low boot memory
807 * @size: size of the request in bytes
808 * @align: alignment of the region
809 * @goal: preferred starting address of the region
811 * The goal is dropped if it can not be satisfied and the allocation will
812 * fall back to memory below @goal.
814 * Allocation may happen on any node in the system.
816 * The function panics if the request can not be satisfied.
818 void * __init __alloc_bootmem_low(unsigned long size, unsigned long align,
819 unsigned long goal)
821 return ___alloc_bootmem(size, align, goal, ARCH_LOW_ADDRESS_LIMIT);
825 * __alloc_bootmem_low_node - allocate low boot memory from a specific node
826 * @pgdat: node to allocate from
827 * @size: size of the request in bytes
828 * @align: alignment of the region
829 * @goal: preferred starting address of the region
831 * The goal is dropped if it can not be satisfied and the allocation will
832 * fall back to memory below @goal.
834 * Allocation may fall back to any node in the system if the specified node
835 * can not hold the requested memory.
837 * The function panics if the request can not be satisfied.
839 void * __init __alloc_bootmem_low_node(pg_data_t *pgdat, unsigned long size,
840 unsigned long align, unsigned long goal)
842 if (WARN_ON_ONCE(slab_is_available()))
843 return kzalloc_node(size, GFP_NOWAIT, pgdat->node_id);
845 return ___alloc_bootmem_node(pgdat, size, align,
846 goal, ARCH_LOW_ADDRESS_LIMIT);