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git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/blob - mm/percpu-km.c
2 * mm/percpu-km.c - kernel memory based chunk allocation
4 * Copyright (C) 2010 SUSE Linux Products GmbH
5 * Copyright (C) 2010 Tejun Heo <tj@kernel.org>
7 * This file is released under the GPLv2.
9 * Chunks are allocated as a contiguous kernel memory using gfp
10 * allocation. This is to be used on nommu architectures.
14 * - define CONFIG_NEED_PER_CPU_KM from the arch Kconfig.
16 * - CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK must not be defined. It's
17 * not compatible with PER_CPU_KM. EMBED_FIRST_CHUNK should work
20 * - NUMA is not supported. When setting up the first chunk,
21 * @cpu_distance_fn should be NULL or report all CPUs to be nearer
22 * than or at LOCAL_DISTANCE.
24 * - It's best if the chunk size is power of two multiple of
25 * PAGE_SIZE. Because each chunk is allocated as a contiguous
26 * kernel memory block using alloc_pages(), memory will be wasted if
27 * chunk size is not aligned. percpu-km code will whine about it.
30 #if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
31 #error "contiguous percpu allocation is incompatible with paged first chunk"
34 #include <linux/log2.h>
36 static int pcpu_populate_chunk(struct pcpu_chunk
*chunk
,
37 int page_start
, int page_end
)
42 static void pcpu_depopulate_chunk(struct pcpu_chunk
*chunk
,
43 int page_start
, int page_end
)
48 static struct pcpu_chunk
*pcpu_create_chunk(void)
50 const int nr_pages
= pcpu_group_sizes
[0] >> PAGE_SHIFT
;
51 struct pcpu_chunk
*chunk
;
55 chunk
= pcpu_alloc_chunk();
59 pages
= alloc_pages(GFP_KERNEL
, order_base_2(nr_pages
));
61 pcpu_free_chunk(chunk
);
65 for (i
= 0; i
< nr_pages
; i
++)
66 pcpu_set_page_chunk(nth_page(pages
, i
), chunk
);
69 chunk
->base_addr
= page_address(pages
) - pcpu_group_offsets
[0];
71 spin_lock_irq(&pcpu_lock
);
72 pcpu_chunk_populated(chunk
, 0, nr_pages
);
73 spin_unlock_irq(&pcpu_lock
);
78 static void pcpu_destroy_chunk(struct pcpu_chunk
*chunk
)
80 const int nr_pages
= pcpu_group_sizes
[0] >> PAGE_SHIFT
;
82 if (chunk
&& chunk
->data
)
83 __free_pages(chunk
->data
, order_base_2(nr_pages
));
84 pcpu_free_chunk(chunk
);
87 static struct page
*pcpu_addr_to_page(void *addr
)
89 return virt_to_page(addr
);
92 static int __init
pcpu_verify_alloc_info(const struct pcpu_alloc_info
*ai
)
94 size_t nr_pages
, alloc_pages
;
96 /* all units must be in a single group */
97 if (ai
->nr_groups
!= 1) {
98 printk(KERN_CRIT
"percpu: can't handle more than one groups\n");
102 nr_pages
= (ai
->groups
[0].nr_units
* ai
->unit_size
) >> PAGE_SHIFT
;
103 alloc_pages
= roundup_pow_of_two(nr_pages
);
105 if (alloc_pages
> nr_pages
)
106 printk(KERN_WARNING
"percpu: wasting %zu pages per chunk\n",
107 alloc_pages
- nr_pages
);