2 #include <linux/mmzone.h>
3 #include <linux/bootmem.h>
4 #include <linux/page_ext.h>
5 #include <linux/memory.h>
6 #include <linux/vmalloc.h>
7 #include <linux/kmemleak.h>
8 #include <linux/page_owner.h>
9 #include <linux/page_idle.h>
12 * struct page extension
14 * This is the feature to manage memory for extended data per page.
16 * Until now, we must modify struct page itself to store extra data per page.
17 * This requires rebuilding the kernel and it is really time consuming process.
18 * And, sometimes, rebuild is impossible due to third party module dependency.
19 * At last, enlarging struct page could cause un-wanted system behaviour change.
21 * This feature is intended to overcome above mentioned problems. This feature
22 * allocates memory for extended data per page in certain place rather than
23 * the struct page itself. This memory can be accessed by the accessor
24 * functions provided by this code. During the boot process, it checks whether
25 * allocation of huge chunk of memory is needed or not. If not, it avoids
26 * allocating memory at all. With this advantage, we can include this feature
27 * into the kernel in default and can avoid rebuild and solve related problems.
29 * To help these things to work well, there are two callbacks for clients. One
30 * is the need callback which is mandatory if user wants to avoid useless
31 * memory allocation at boot-time. The other is optional, init callback, which
32 * is used to do proper initialization after memory is allocated.
34 * The need callback is used to decide whether extended memory allocation is
35 * needed or not. Sometimes users want to deactivate some features in this
36 * boot and extra memory would be unneccessary. In this case, to avoid
37 * allocating huge chunk of memory, each clients represent their need of
38 * extra memory through the need callback. If one of the need callbacks
39 * returns true, it means that someone needs extra memory so that
40 * page extension core should allocates memory for page extension. If
41 * none of need callbacks return true, memory isn't needed at all in this boot
42 * and page extension core can skip to allocate memory. As result,
43 * none of memory is wasted.
45 * The init callback is used to do proper initialization after page extension
46 * is completely initialized. In sparse memory system, extra memory is
47 * allocated some time later than memmap is allocated. In other words, lifetime
48 * of memory for page extension isn't same with memmap for struct page.
49 * Therefore, clients can't store extra data until page extension is
50 * initialized, even if pages are allocated and used freely. This could
51 * cause inadequate state of extra data per page, so, to prevent it, client
52 * can utilize this callback to initialize the state of it correctly.
55 static struct page_ext_operations
*page_ext_ops
[] = {
57 #ifdef CONFIG_PAGE_POISONING
60 #ifdef CONFIG_PAGE_OWNER
63 #if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
68 static unsigned long total_usage
;
70 static bool __init
invoke_need_callbacks(void)
73 int entries
= ARRAY_SIZE(page_ext_ops
);
75 for (i
= 0; i
< entries
; i
++) {
76 if (page_ext_ops
[i
]->need
&& page_ext_ops
[i
]->need())
83 static void __init
invoke_init_callbacks(void)
86 int entries
= ARRAY_SIZE(page_ext_ops
);
88 for (i
= 0; i
< entries
; i
++) {
89 if (page_ext_ops
[i
]->init
)
90 page_ext_ops
[i
]->init();
94 #if !defined(CONFIG_SPARSEMEM)
97 void __meminit
pgdat_page_ext_init(struct pglist_data
*pgdat
)
99 pgdat
->node_page_ext
= NULL
;
102 struct page_ext
*lookup_page_ext(struct page
*page
)
104 unsigned long pfn
= page_to_pfn(page
);
106 struct page_ext
*base
;
108 base
= NODE_DATA(page_to_nid(page
))->node_page_ext
;
109 #if defined(CONFIG_DEBUG_VM) || defined(CONFIG_PAGE_POISONING)
111 * The sanity checks the page allocator does upon freeing a
112 * page can reach here before the page_ext arrays are
113 * allocated when feeding a range of pages to the allocator
114 * for the first time during bootup or memory hotplug.
116 * This check is also necessary for ensuring page poisoning
117 * works as expected when enabled
122 index
= pfn
- round_down(node_start_pfn(page_to_nid(page
)),
127 static int __init
alloc_node_page_ext(int nid
)
129 struct page_ext
*base
;
130 unsigned long table_size
;
131 unsigned long nr_pages
;
133 nr_pages
= NODE_DATA(nid
)->node_spanned_pages
;
138 * Need extra space if node range is not aligned with
139 * MAX_ORDER_NR_PAGES. When page allocator's buddy algorithm
140 * checks buddy's status, range could be out of exact node range.
142 if (!IS_ALIGNED(node_start_pfn(nid
), MAX_ORDER_NR_PAGES
) ||
143 !IS_ALIGNED(node_end_pfn(nid
), MAX_ORDER_NR_PAGES
))
144 nr_pages
+= MAX_ORDER_NR_PAGES
;
146 table_size
= sizeof(struct page_ext
) * nr_pages
;
148 base
= memblock_virt_alloc_try_nid_nopanic(
149 table_size
, PAGE_SIZE
, __pa(MAX_DMA_ADDRESS
),
150 BOOTMEM_ALLOC_ACCESSIBLE
, nid
);
153 NODE_DATA(nid
)->node_page_ext
= base
;
154 total_usage
+= table_size
;
158 void __init
page_ext_init_flatmem(void)
163 if (!invoke_need_callbacks())
166 for_each_online_node(nid
) {
167 fail
= alloc_node_page_ext(nid
);
171 pr_info("allocated %ld bytes of page_ext\n", total_usage
);
172 invoke_init_callbacks();
176 pr_crit("allocation of page_ext failed.\n");
177 panic("Out of memory");
180 #else /* CONFIG_FLAT_NODE_MEM_MAP */
182 struct page_ext
*lookup_page_ext(struct page
*page
)
184 unsigned long pfn
= page_to_pfn(page
);
185 struct mem_section
*section
= __pfn_to_section(pfn
);
186 #if defined(CONFIG_DEBUG_VM) || defined(CONFIG_PAGE_POISONING)
188 * The sanity checks the page allocator does upon freeing a
189 * page can reach here before the page_ext arrays are
190 * allocated when feeding a range of pages to the allocator
191 * for the first time during bootup or memory hotplug.
193 * This check is also necessary for ensuring page poisoning
194 * works as expected when enabled
196 if (!section
->page_ext
)
199 return section
->page_ext
+ pfn
;
202 static void *__meminit
alloc_page_ext(size_t size
, int nid
)
204 gfp_t flags
= GFP_KERNEL
| __GFP_ZERO
| __GFP_NOWARN
;
207 addr
= alloc_pages_exact_nid(nid
, size
, flags
);
209 kmemleak_alloc(addr
, size
, 1, flags
);
213 if (node_state(nid
, N_HIGH_MEMORY
))
214 addr
= vzalloc_node(size
, nid
);
216 addr
= vzalloc(size
);
221 static int __meminit
init_section_page_ext(unsigned long pfn
, int nid
)
223 struct mem_section
*section
;
224 struct page_ext
*base
;
225 unsigned long table_size
;
227 section
= __pfn_to_section(pfn
);
229 if (section
->page_ext
)
232 table_size
= sizeof(struct page_ext
) * PAGES_PER_SECTION
;
233 base
= alloc_page_ext(table_size
, nid
);
236 * The value stored in section->page_ext is (base - pfn)
237 * and it does not point to the memory block allocated above,
238 * causing kmemleak false positives.
240 kmemleak_not_leak(base
);
243 pr_err("page ext allocation failure\n");
248 * The passed "pfn" may not be aligned to SECTION. For the calculation
249 * we need to apply a mask.
251 pfn
&= PAGE_SECTION_MASK
;
252 section
->page_ext
= base
- pfn
;
253 total_usage
+= table_size
;
256 #ifdef CONFIG_MEMORY_HOTPLUG
257 static void free_page_ext(void *addr
)
259 if (is_vmalloc_addr(addr
)) {
262 struct page
*page
= virt_to_page(addr
);
265 table_size
= sizeof(struct page_ext
) * PAGES_PER_SECTION
;
267 BUG_ON(PageReserved(page
));
268 free_pages_exact(addr
, table_size
);
272 static void __free_page_ext(unsigned long pfn
)
274 struct mem_section
*ms
;
275 struct page_ext
*base
;
277 ms
= __pfn_to_section(pfn
);
278 if (!ms
|| !ms
->page_ext
)
280 base
= ms
->page_ext
+ pfn
;
285 static int __meminit
online_page_ext(unsigned long start_pfn
,
286 unsigned long nr_pages
,
289 unsigned long start
, end
, pfn
;
292 start
= SECTION_ALIGN_DOWN(start_pfn
);
293 end
= SECTION_ALIGN_UP(start_pfn
+ nr_pages
);
297 * In this case, "nid" already exists and contains valid memory.
298 * "start_pfn" passed to us is a pfn which is an arg for
299 * online__pages(), and start_pfn should exist.
301 nid
= pfn_to_nid(start_pfn
);
302 VM_BUG_ON(!node_state(nid
, N_ONLINE
));
305 for (pfn
= start
; !fail
&& pfn
< end
; pfn
+= PAGES_PER_SECTION
) {
306 if (!pfn_present(pfn
))
308 fail
= init_section_page_ext(pfn
, nid
);
314 for (pfn
= start
; pfn
< end
; pfn
+= PAGES_PER_SECTION
)
315 __free_page_ext(pfn
);
320 static int __meminit
offline_page_ext(unsigned long start_pfn
,
321 unsigned long nr_pages
, int nid
)
323 unsigned long start
, end
, pfn
;
325 start
= SECTION_ALIGN_DOWN(start_pfn
);
326 end
= SECTION_ALIGN_UP(start_pfn
+ nr_pages
);
328 for (pfn
= start
; pfn
< end
; pfn
+= PAGES_PER_SECTION
)
329 __free_page_ext(pfn
);
334 static int __meminit
page_ext_callback(struct notifier_block
*self
,
335 unsigned long action
, void *arg
)
337 struct memory_notify
*mn
= arg
;
341 case MEM_GOING_ONLINE
:
342 ret
= online_page_ext(mn
->start_pfn
,
343 mn
->nr_pages
, mn
->status_change_nid
);
346 offline_page_ext(mn
->start_pfn
,
347 mn
->nr_pages
, mn
->status_change_nid
);
349 case MEM_CANCEL_ONLINE
:
350 offline_page_ext(mn
->start_pfn
,
351 mn
->nr_pages
, mn
->status_change_nid
);
353 case MEM_GOING_OFFLINE
:
356 case MEM_CANCEL_OFFLINE
:
360 return notifier_from_errno(ret
);
365 void __init
page_ext_init(void)
370 if (!invoke_need_callbacks())
373 for_each_node_state(nid
, N_MEMORY
) {
374 unsigned long start_pfn
, end_pfn
;
376 start_pfn
= node_start_pfn(nid
);
377 end_pfn
= node_end_pfn(nid
);
379 * start_pfn and end_pfn may not be aligned to SECTION and the
380 * page->flags of out of node pages are not initialized. So we
381 * scan [start_pfn, the biggest section's pfn < end_pfn) here.
383 for (pfn
= start_pfn
; pfn
< end_pfn
;
384 pfn
= ALIGN(pfn
+ 1, PAGES_PER_SECTION
)) {
389 * Nodes's pfns can be overlapping.
390 * We know some arch can have a nodes layout such as
391 * -------------pfn-------------->
392 * N0 | N1 | N2 | N0 | N1 | N2|....
394 * Take into account DEFERRED_STRUCT_PAGE_INIT.
396 if (early_pfn_to_nid(pfn
) != nid
)
398 if (init_section_page_ext(pfn
, nid
))
402 hotplug_memory_notifier(page_ext_callback
, 0);
403 pr_info("allocated %ld bytes of page_ext\n", total_usage
);
404 invoke_init_callbacks();
408 panic("Out of memory");
411 void __meminit
pgdat_page_ext_init(struct pglist_data
*pgdat
)