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Linux/mm/percpu-vm.c

  1 /*
  2  * mm/percpu-vm.c - vmalloc area based chunk allocation
  3  *
  4  * Copyright (C) 2010           SUSE Linux Products GmbH
  5  * Copyright (C) 2010           Tejun Heo <tj@kernel.org>
  6  *
  7  * This file is released under the GPLv2.
  8  *
  9  * Chunks are mapped into vmalloc areas and populated page by page.
 10  * This is the default chunk allocator.
 11  */
 12 
 13 static struct page *pcpu_chunk_page(struct pcpu_chunk *chunk,
 14                                     unsigned int cpu, int page_idx)
 15 {
 16         /* must not be used on pre-mapped chunk */
 17         WARN_ON(chunk->immutable);
 18 
 19         return vmalloc_to_page((void *)pcpu_chunk_addr(chunk, cpu, page_idx));
 20 }
 21 
 22 /**
 23  * pcpu_get_pages - get temp pages array
 24  * @chunk: chunk of interest
 25  *
 26  * Returns pointer to array of pointers to struct page which can be indexed
 27  * with pcpu_page_idx().  Note that there is only one array and accesses
 28  * should be serialized by pcpu_alloc_mutex.
 29  *
 30  * RETURNS:
 31  * Pointer to temp pages array on success.
 32  */
 33 static struct page **pcpu_get_pages(struct pcpu_chunk *chunk_alloc)
 34 {
 35         static struct page **pages;
 36         size_t pages_size = pcpu_nr_units * pcpu_unit_pages * sizeof(pages[0]);
 37 
 38         lockdep_assert_held(&pcpu_alloc_mutex);
 39 
 40         if (!pages)
 41                 pages = pcpu_mem_zalloc(pages_size);
 42         return pages;
 43 }
 44 
 45 /**
 46  * pcpu_free_pages - free pages which were allocated for @chunk
 47  * @chunk: chunk pages were allocated for
 48  * @pages: array of pages to be freed, indexed by pcpu_page_idx()
 49  * @page_start: page index of the first page to be freed
 50  * @page_end: page index of the last page to be freed + 1
 51  *
 52  * Free pages [@page_start and @page_end) in @pages for all units.
 53  * The pages were allocated for @chunk.
 54  */
 55 static void pcpu_free_pages(struct pcpu_chunk *chunk,
 56                             struct page **pages, int page_start, int page_end)
 57 {
 58         unsigned int cpu;
 59         int i;
 60 
 61         for_each_possible_cpu(cpu) {
 62                 for (i = page_start; i < page_end; i++) {
 63                         struct page *page = pages[pcpu_page_idx(cpu, i)];
 64 
 65                         if (page)
 66                                 __free_page(page);
 67                 }
 68         }
 69 }
 70 
 71 /**
 72  * pcpu_alloc_pages - allocates pages for @chunk
 73  * @chunk: target chunk
 74  * @pages: array to put the allocated pages into, indexed by pcpu_page_idx()
 75  * @page_start: page index of the first page to be allocated
 76  * @page_end: page index of the last page to be allocated + 1
 77  *
 78  * Allocate pages [@page_start,@page_end) into @pages for all units.
 79  * The allocation is for @chunk.  Percpu core doesn't care about the
 80  * content of @pages and will pass it verbatim to pcpu_map_pages().
 81  */
 82 static int pcpu_alloc_pages(struct pcpu_chunk *chunk,
 83                             struct page **pages, int page_start, int page_end)
 84 {
 85         const gfp_t gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_COLD;
 86         unsigned int cpu, tcpu;
 87         int i;
 88 
 89         for_each_possible_cpu(cpu) {
 90                 for (i = page_start; i < page_end; i++) {
 91                         struct page **pagep = &pages[pcpu_page_idx(cpu, i)];
 92 
 93                         *pagep = alloc_pages_node(cpu_to_node(cpu), gfp, 0);
 94                         if (!*pagep)
 95                                 goto err;
 96                 }
 97         }
 98         return 0;
 99 
100 err:
101         while (--i >= page_start)
102                 __free_page(pages[pcpu_page_idx(cpu, i)]);
103 
104         for_each_possible_cpu(tcpu) {
105                 if (tcpu == cpu)
106                         break;
107                 for (i = page_start; i < page_end; i++)
108                         __free_page(pages[pcpu_page_idx(tcpu, i)]);
109         }
110         return -ENOMEM;
111 }
112 
113 /**
114  * pcpu_pre_unmap_flush - flush cache prior to unmapping
115  * @chunk: chunk the regions to be flushed belongs to
116  * @page_start: page index of the first page to be flushed
117  * @page_end: page index of the last page to be flushed + 1
118  *
119  * Pages in [@page_start,@page_end) of @chunk are about to be
120  * unmapped.  Flush cache.  As each flushing trial can be very
121  * expensive, issue flush on the whole region at once rather than
122  * doing it for each cpu.  This could be an overkill but is more
123  * scalable.
124  */
125 static void pcpu_pre_unmap_flush(struct pcpu_chunk *chunk,
126                                  int page_start, int page_end)
127 {
128         flush_cache_vunmap(
129                 pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
130                 pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
131 }
132 
133 static void __pcpu_unmap_pages(unsigned long addr, int nr_pages)
134 {
135         unmap_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT);
136 }
137 
138 /**
139  * pcpu_unmap_pages - unmap pages out of a pcpu_chunk
140  * @chunk: chunk of interest
141  * @pages: pages array which can be used to pass information to free
142  * @page_start: page index of the first page to unmap
143  * @page_end: page index of the last page to unmap + 1
144  *
145  * For each cpu, unmap pages [@page_start,@page_end) out of @chunk.
146  * Corresponding elements in @pages were cleared by the caller and can
147  * be used to carry information to pcpu_free_pages() which will be
148  * called after all unmaps are finished.  The caller should call
149  * proper pre/post flush functions.
150  */
151 static void pcpu_unmap_pages(struct pcpu_chunk *chunk,
152                              struct page **pages, int page_start, int page_end)
153 {
154         unsigned int cpu;
155         int i;
156 
157         for_each_possible_cpu(cpu) {
158                 for (i = page_start; i < page_end; i++) {
159                         struct page *page;
160 
161                         page = pcpu_chunk_page(chunk, cpu, i);
162                         WARN_ON(!page);
163                         pages[pcpu_page_idx(cpu, i)] = page;
164                 }
165                 __pcpu_unmap_pages(pcpu_chunk_addr(chunk, cpu, page_start),
166                                    page_end - page_start);
167         }
168 }
169 
170 /**
171  * pcpu_post_unmap_tlb_flush - flush TLB after unmapping
172  * @chunk: pcpu_chunk the regions to be flushed belong to
173  * @page_start: page index of the first page to be flushed
174  * @page_end: page index of the last page to be flushed + 1
175  *
176  * Pages [@page_start,@page_end) of @chunk have been unmapped.  Flush
177  * TLB for the regions.  This can be skipped if the area is to be
178  * returned to vmalloc as vmalloc will handle TLB flushing lazily.
179  *
180  * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
181  * for the whole region.
182  */
183 static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk,
184                                       int page_start, int page_end)
185 {
186         flush_tlb_kernel_range(
187                 pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
188                 pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
189 }
190 
191 static int __pcpu_map_pages(unsigned long addr, struct page **pages,
192                             int nr_pages)
193 {
194         return map_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT,
195                                         PAGE_KERNEL, pages);
196 }
197 
198 /**
199  * pcpu_map_pages - map pages into a pcpu_chunk
200  * @chunk: chunk of interest
201  * @pages: pages array containing pages to be mapped
202  * @page_start: page index of the first page to map
203  * @page_end: page index of the last page to map + 1
204  *
205  * For each cpu, map pages [@page_start,@page_end) into @chunk.  The
206  * caller is responsible for calling pcpu_post_map_flush() after all
207  * mappings are complete.
208  *
209  * This function is responsible for setting up whatever is necessary for
210  * reverse lookup (addr -> chunk).
211  */
212 static int pcpu_map_pages(struct pcpu_chunk *chunk,
213                           struct page **pages, int page_start, int page_end)
214 {
215         unsigned int cpu, tcpu;
216         int i, err;
217 
218         for_each_possible_cpu(cpu) {
219                 err = __pcpu_map_pages(pcpu_chunk_addr(chunk, cpu, page_start),
220                                        &pages[pcpu_page_idx(cpu, page_start)],
221                                        page_end - page_start);
222                 if (err < 0)
223                         goto err;
224 
225                 for (i = page_start; i < page_end; i++)
226                         pcpu_set_page_chunk(pages[pcpu_page_idx(cpu, i)],
227                                             chunk);
228         }
229         return 0;
230 err:
231         for_each_possible_cpu(tcpu) {
232                 if (tcpu == cpu)
233                         break;
234                 __pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start),
235                                    page_end - page_start);
236         }
237         pcpu_post_unmap_tlb_flush(chunk, page_start, page_end);
238         return err;
239 }
240 
241 /**
242  * pcpu_post_map_flush - flush cache after mapping
243  * @chunk: pcpu_chunk the regions to be flushed belong to
244  * @page_start: page index of the first page to be flushed
245  * @page_end: page index of the last page to be flushed + 1
246  *
247  * Pages [@page_start,@page_end) of @chunk have been mapped.  Flush
248  * cache.
249  *
250  * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
251  * for the whole region.
252  */
253 static void pcpu_post_map_flush(struct pcpu_chunk *chunk,
254                                 int page_start, int page_end)
255 {
256         flush_cache_vmap(
257                 pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
258                 pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
259 }
260 
261 /**
262  * pcpu_populate_chunk - populate and map an area of a pcpu_chunk
263  * @chunk: chunk of interest
264  * @page_start: the start page
265  * @page_end: the end page
266  *
267  * For each cpu, populate and map pages [@page_start,@page_end) into
268  * @chunk.
269  *
270  * CONTEXT:
271  * pcpu_alloc_mutex, does GFP_KERNEL allocation.
272  */
273 static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
274                                int page_start, int page_end)
275 {
276         struct page **pages;
277 
278         pages = pcpu_get_pages(chunk);
279         if (!pages)
280                 return -ENOMEM;
281 
282         if (pcpu_alloc_pages(chunk, pages, page_start, page_end))
283                 return -ENOMEM;
284 
285         if (pcpu_map_pages(chunk, pages, page_start, page_end)) {
286                 pcpu_free_pages(chunk, pages, page_start, page_end);
287                 return -ENOMEM;
288         }
289         pcpu_post_map_flush(chunk, page_start, page_end);
290 
291         return 0;
292 }
293 
294 /**
295  * pcpu_depopulate_chunk - depopulate and unmap an area of a pcpu_chunk
296  * @chunk: chunk to depopulate
297  * @page_start: the start page
298  * @page_end: the end page
299  *
300  * For each cpu, depopulate and unmap pages [@page_start,@page_end)
301  * from @chunk.
302  *
303  * CONTEXT:
304  * pcpu_alloc_mutex.
305  */
306 static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
307                                   int page_start, int page_end)
308 {
309         struct page **pages;
310 
311         /*
312          * If control reaches here, there must have been at least one
313          * successful population attempt so the temp pages array must
314          * be available now.
315          */
316         pages = pcpu_get_pages(chunk);
317         BUG_ON(!pages);
318 
319         /* unmap and free */
320         pcpu_pre_unmap_flush(chunk, page_start, page_end);
321 
322         pcpu_unmap_pages(chunk, pages, page_start, page_end);
323 
324         /* no need to flush tlb, vmalloc will handle it lazily */
325 
326         pcpu_free_pages(chunk, pages, page_start, page_end);
327 }
328 
329 static struct pcpu_chunk *pcpu_create_chunk(void)
330 {
331         struct pcpu_chunk *chunk;
332         struct vm_struct **vms;
333 
334         chunk = pcpu_alloc_chunk();
335         if (!chunk)
336                 return NULL;
337 
338         vms = pcpu_get_vm_areas(pcpu_group_offsets, pcpu_group_sizes,
339                                 pcpu_nr_groups, pcpu_atom_size);
340         if (!vms) {
341                 pcpu_free_chunk(chunk);
342                 return NULL;
343         }
344 
345         chunk->data = vms;
346         chunk->base_addr = vms[0]->addr - pcpu_group_offsets[0];
347         return chunk;
348 }
349 
350 static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
351 {
352         if (chunk && chunk->data)
353                 pcpu_free_vm_areas(chunk->data, pcpu_nr_groups);
354         pcpu_free_chunk(chunk);
355 }
356 
357 static struct page *pcpu_addr_to_page(void *addr)
358 {
359         return vmalloc_to_page(addr);
360 }
361 
362 static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
363 {
364         /* no extra restriction */
365         return 0;
366 }
367 

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