Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/mm/mremap.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 10812 byte(s)
Tag kernel26-2.6.12-alx-r9
1 | /* |
2 | * mm/mremap.c |
3 | * |
4 | * (C) Copyright 1996 Linus Torvalds |
5 | * |
6 | * Address space accounting code <alan@redhat.com> |
7 | * (C) Copyright 2002 Red Hat Inc, All Rights Reserved |
8 | */ |
9 | |
10 | #include <linux/mm.h> |
11 | #include <linux/hugetlb.h> |
12 | #include <linux/slab.h> |
13 | #include <linux/shm.h> |
14 | #include <linux/mman.h> |
15 | #include <linux/swap.h> |
16 | #include <linux/fs.h> |
17 | #include <linux/highmem.h> |
18 | #include <linux/security.h> |
19 | #include <linux/syscalls.h> |
20 | |
21 | #include <asm/uaccess.h> |
22 | #include <asm/cacheflush.h> |
23 | #include <asm/tlbflush.h> |
24 | |
25 | static pte_t *get_one_pte_map_nested(struct mm_struct *mm, unsigned long addr) |
26 | { |
27 | pgd_t *pgd; |
28 | pud_t *pud; |
29 | pmd_t *pmd; |
30 | pte_t *pte = NULL; |
31 | |
32 | pgd = pgd_offset(mm, addr); |
33 | if (pgd_none_or_clear_bad(pgd)) |
34 | goto end; |
35 | |
36 | pud = pud_offset(pgd, addr); |
37 | if (pud_none_or_clear_bad(pud)) |
38 | goto end; |
39 | |
40 | pmd = pmd_offset(pud, addr); |
41 | if (pmd_none_or_clear_bad(pmd)) |
42 | goto end; |
43 | |
44 | pte = pte_offset_map_nested(pmd, addr); |
45 | if (pte_none(*pte)) { |
46 | pte_unmap_nested(pte); |
47 | pte = NULL; |
48 | } |
49 | end: |
50 | return pte; |
51 | } |
52 | |
53 | static pte_t *get_one_pte_map(struct mm_struct *mm, unsigned long addr) |
54 | { |
55 | pgd_t *pgd; |
56 | pud_t *pud; |
57 | pmd_t *pmd; |
58 | |
59 | pgd = pgd_offset(mm, addr); |
60 | if (pgd_none_or_clear_bad(pgd)) |
61 | return NULL; |
62 | |
63 | pud = pud_offset(pgd, addr); |
64 | if (pud_none_or_clear_bad(pud)) |
65 | return NULL; |
66 | |
67 | pmd = pmd_offset(pud, addr); |
68 | if (pmd_none_or_clear_bad(pmd)) |
69 | return NULL; |
70 | |
71 | return pte_offset_map(pmd, addr); |
72 | } |
73 | |
74 | static inline pte_t *alloc_one_pte_map(struct mm_struct *mm, unsigned long addr) |
75 | { |
76 | pgd_t *pgd; |
77 | pud_t *pud; |
78 | pmd_t *pmd; |
79 | pte_t *pte = NULL; |
80 | |
81 | pgd = pgd_offset(mm, addr); |
82 | |
83 | pud = pud_alloc(mm, pgd, addr); |
84 | if (!pud) |
85 | return NULL; |
86 | pmd = pmd_alloc(mm, pud, addr); |
87 | if (pmd) |
88 | pte = pte_alloc_map(mm, pmd, addr); |
89 | return pte; |
90 | } |
91 | |
92 | static int |
93 | move_one_page(struct vm_area_struct *vma, unsigned long old_addr, |
94 | struct vm_area_struct *new_vma, unsigned long new_addr) |
95 | { |
96 | struct address_space *mapping = NULL; |
97 | struct mm_struct *mm = vma->vm_mm; |
98 | int error = 0; |
99 | pte_t *src, *dst; |
100 | |
101 | if (vma->vm_file) { |
102 | /* |
103 | * Subtle point from Rajesh Venkatasubramanian: before |
104 | * moving file-based ptes, we must lock vmtruncate out, |
105 | * since it might clean the dst vma before the src vma, |
106 | * and we propagate stale pages into the dst afterward. |
107 | */ |
108 | mapping = vma->vm_file->f_mapping; |
109 | spin_lock(&mapping->i_mmap_lock); |
110 | if (new_vma->vm_truncate_count && |
111 | new_vma->vm_truncate_count != vma->vm_truncate_count) |
112 | new_vma->vm_truncate_count = 0; |
113 | } |
114 | spin_lock(&mm->page_table_lock); |
115 | |
116 | src = get_one_pte_map_nested(mm, old_addr); |
117 | if (src) { |
118 | /* |
119 | * Look to see whether alloc_one_pte_map needs to perform a |
120 | * memory allocation. If it does then we need to drop the |
121 | * atomic kmap |
122 | */ |
123 | dst = get_one_pte_map(mm, new_addr); |
124 | if (unlikely(!dst)) { |
125 | pte_unmap_nested(src); |
126 | if (mapping) |
127 | spin_unlock(&mapping->i_mmap_lock); |
128 | dst = alloc_one_pte_map(mm, new_addr); |
129 | if (mapping && !spin_trylock(&mapping->i_mmap_lock)) { |
130 | spin_unlock(&mm->page_table_lock); |
131 | spin_lock(&mapping->i_mmap_lock); |
132 | spin_lock(&mm->page_table_lock); |
133 | } |
134 | src = get_one_pte_map_nested(mm, old_addr); |
135 | } |
136 | /* |
137 | * Since alloc_one_pte_map can drop and re-acquire |
138 | * page_table_lock, we should re-check the src entry... |
139 | */ |
140 | if (src) { |
141 | if (dst) { |
142 | pte_t pte; |
143 | pte = ptep_clear_flush(vma, old_addr, src); |
144 | set_pte_at(mm, new_addr, dst, pte); |
145 | } else |
146 | error = -ENOMEM; |
147 | pte_unmap_nested(src); |
148 | } |
149 | if (dst) |
150 | pte_unmap(dst); |
151 | } |
152 | spin_unlock(&mm->page_table_lock); |
153 | if (mapping) |
154 | spin_unlock(&mapping->i_mmap_lock); |
155 | return error; |
156 | } |
157 | |
158 | static unsigned long move_page_tables(struct vm_area_struct *vma, |
159 | unsigned long old_addr, struct vm_area_struct *new_vma, |
160 | unsigned long new_addr, unsigned long len) |
161 | { |
162 | unsigned long offset; |
163 | |
164 | flush_cache_range(vma, old_addr, old_addr + len); |
165 | |
166 | /* |
167 | * This is not the clever way to do this, but we're taking the |
168 | * easy way out on the assumption that most remappings will be |
169 | * only a few pages.. This also makes error recovery easier. |
170 | */ |
171 | for (offset = 0; offset < len; offset += PAGE_SIZE) { |
172 | if (move_one_page(vma, old_addr + offset, |
173 | new_vma, new_addr + offset) < 0) |
174 | break; |
175 | cond_resched(); |
176 | } |
177 | return offset; |
178 | } |
179 | |
180 | static unsigned long move_vma(struct vm_area_struct *vma, |
181 | unsigned long old_addr, unsigned long old_len, |
182 | unsigned long new_len, unsigned long new_addr) |
183 | { |
184 | struct mm_struct *mm = vma->vm_mm; |
185 | struct vm_area_struct *new_vma; |
186 | unsigned long vm_flags = vma->vm_flags; |
187 | unsigned long new_pgoff; |
188 | unsigned long moved_len; |
189 | unsigned long excess = 0; |
190 | int split = 0; |
191 | |
192 | /* |
193 | * We'd prefer to avoid failure later on in do_munmap: |
194 | * which may split one vma into three before unmapping. |
195 | */ |
196 | if (mm->map_count >= sysctl_max_map_count - 3) |
197 | return -ENOMEM; |
198 | |
199 | new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT); |
200 | new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff); |
201 | if (!new_vma) |
202 | return -ENOMEM; |
203 | |
204 | moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len); |
205 | if (moved_len < old_len) { |
206 | /* |
207 | * On error, move entries back from new area to old, |
208 | * which will succeed since page tables still there, |
209 | * and then proceed to unmap new area instead of old. |
210 | */ |
211 | move_page_tables(new_vma, new_addr, vma, old_addr, moved_len); |
212 | vma = new_vma; |
213 | old_len = new_len; |
214 | old_addr = new_addr; |
215 | new_addr = -ENOMEM; |
216 | } |
217 | |
218 | /* Conceal VM_ACCOUNT so old reservation is not undone */ |
219 | if (vm_flags & VM_ACCOUNT) { |
220 | vma->vm_flags &= ~VM_ACCOUNT; |
221 | excess = vma->vm_end - vma->vm_start - old_len; |
222 | if (old_addr > vma->vm_start && |
223 | old_addr + old_len < vma->vm_end) |
224 | split = 1; |
225 | } |
226 | |
227 | /* |
228 | * if we failed to move page tables we still do total_vm increment |
229 | * since do_munmap() will decrement it by old_len == new_len |
230 | */ |
231 | mm->total_vm += new_len >> PAGE_SHIFT; |
232 | |
233 | if (do_munmap(mm, old_addr, old_len) < 0) { |
234 | /* OOM: unable to split vma, just get accounts right */ |
235 | vm_unacct_memory(excess >> PAGE_SHIFT); |
236 | excess = 0; |
237 | } |
238 | |
239 | /* Restore VM_ACCOUNT if one or two pieces of vma left */ |
240 | if (excess) { |
241 | vma->vm_flags |= VM_ACCOUNT; |
242 | if (split) |
243 | vma->vm_next->vm_flags |= VM_ACCOUNT; |
244 | } |
245 | |
246 | __vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT); |
247 | if (vm_flags & VM_LOCKED) { |
248 | mm->locked_vm += new_len >> PAGE_SHIFT; |
249 | if (new_len > old_len) |
250 | make_pages_present(new_addr + old_len, |
251 | new_addr + new_len); |
252 | } |
253 | |
254 | return new_addr; |
255 | } |
256 | |
257 | /* |
258 | * Expand (or shrink) an existing mapping, potentially moving it at the |
259 | * same time (controlled by the MREMAP_MAYMOVE flag and available VM space) |
260 | * |
261 | * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise |
262 | * This option implies MREMAP_MAYMOVE. |
263 | */ |
264 | unsigned long do_mremap(unsigned long addr, |
265 | unsigned long old_len, unsigned long new_len, |
266 | unsigned long flags, unsigned long new_addr) |
267 | { |
268 | struct vm_area_struct *vma; |
269 | unsigned long ret = -EINVAL; |
270 | unsigned long charged = 0; |
271 | |
272 | if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE)) |
273 | goto out; |
274 | |
275 | if (addr & ~PAGE_MASK) |
276 | goto out; |
277 | |
278 | old_len = PAGE_ALIGN(old_len); |
279 | new_len = PAGE_ALIGN(new_len); |
280 | |
281 | /* |
282 | * We allow a zero old-len as a special case |
283 | * for DOS-emu "duplicate shm area" thing. But |
284 | * a zero new-len is nonsensical. |
285 | */ |
286 | if (!new_len) |
287 | goto out; |
288 | |
289 | /* new_addr is only valid if MREMAP_FIXED is specified */ |
290 | if (flags & MREMAP_FIXED) { |
291 | if (new_addr & ~PAGE_MASK) |
292 | goto out; |
293 | if (!(flags & MREMAP_MAYMOVE)) |
294 | goto out; |
295 | |
296 | if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len) |
297 | goto out; |
298 | |
299 | /* Check if the location we're moving into overlaps the |
300 | * old location at all, and fail if it does. |
301 | */ |
302 | if ((new_addr <= addr) && (new_addr+new_len) > addr) |
303 | goto out; |
304 | |
305 | if ((addr <= new_addr) && (addr+old_len) > new_addr) |
306 | goto out; |
307 | |
308 | ret = do_munmap(current->mm, new_addr, new_len); |
309 | if (ret) |
310 | goto out; |
311 | } |
312 | |
313 | /* |
314 | * Always allow a shrinking remap: that just unmaps |
315 | * the unnecessary pages.. |
316 | * do_munmap does all the needed commit accounting |
317 | */ |
318 | if (old_len >= new_len) { |
319 | ret = do_munmap(current->mm, addr+new_len, old_len - new_len); |
320 | if (ret && old_len != new_len) |
321 | goto out; |
322 | ret = addr; |
323 | if (!(flags & MREMAP_FIXED) || (new_addr == addr)) |
324 | goto out; |
325 | old_len = new_len; |
326 | } |
327 | |
328 | /* |
329 | * Ok, we need to grow.. or relocate. |
330 | */ |
331 | ret = -EFAULT; |
332 | vma = find_vma(current->mm, addr); |
333 | if (!vma || vma->vm_start > addr) |
334 | goto out; |
335 | if (is_vm_hugetlb_page(vma)) { |
336 | ret = -EINVAL; |
337 | goto out; |
338 | } |
339 | /* We can't remap across vm area boundaries */ |
340 | if (old_len > vma->vm_end - addr) |
341 | goto out; |
342 | if (vma->vm_flags & VM_DONTEXPAND) { |
343 | if (new_len > old_len) |
344 | goto out; |
345 | } |
346 | if (vma->vm_flags & VM_LOCKED) { |
347 | unsigned long locked, lock_limit; |
348 | locked = current->mm->locked_vm << PAGE_SHIFT; |
349 | lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; |
350 | locked += new_len - old_len; |
351 | ret = -EAGAIN; |
352 | if (locked > lock_limit && !capable(CAP_IPC_LOCK)) |
353 | goto out; |
354 | } |
355 | if (!may_expand_vm(current->mm, (new_len - old_len) >> PAGE_SHIFT)) { |
356 | ret = -ENOMEM; |
357 | goto out; |
358 | } |
359 | |
360 | if (vma->vm_flags & VM_ACCOUNT) { |
361 | charged = (new_len - old_len) >> PAGE_SHIFT; |
362 | if (security_vm_enough_memory(charged)) |
363 | goto out_nc; |
364 | } |
365 | |
366 | /* old_len exactly to the end of the area.. |
367 | * And we're not relocating the area. |
368 | */ |
369 | if (old_len == vma->vm_end - addr && |
370 | !((flags & MREMAP_FIXED) && (addr != new_addr)) && |
371 | (old_len != new_len || !(flags & MREMAP_MAYMOVE))) { |
372 | unsigned long max_addr = TASK_SIZE; |
373 | if (vma->vm_next) |
374 | max_addr = vma->vm_next->vm_start; |
375 | /* can we just expand the current mapping? */ |
376 | if (max_addr - addr >= new_len) { |
377 | int pages = (new_len - old_len) >> PAGE_SHIFT; |
378 | |
379 | vma_adjust(vma, vma->vm_start, |
380 | addr + new_len, vma->vm_pgoff, NULL); |
381 | |
382 | current->mm->total_vm += pages; |
383 | __vm_stat_account(vma->vm_mm, vma->vm_flags, |
384 | vma->vm_file, pages); |
385 | if (vma->vm_flags & VM_LOCKED) { |
386 | current->mm->locked_vm += pages; |
387 | make_pages_present(addr + old_len, |
388 | addr + new_len); |
389 | } |
390 | ret = addr; |
391 | goto out; |
392 | } |
393 | } |
394 | |
395 | /* |
396 | * We weren't able to just expand or shrink the area, |
397 | * we need to create a new one and move it.. |
398 | */ |
399 | ret = -ENOMEM; |
400 | if (flags & MREMAP_MAYMOVE) { |
401 | if (!(flags & MREMAP_FIXED)) { |
402 | unsigned long map_flags = 0; |
403 | if (vma->vm_flags & VM_MAYSHARE) |
404 | map_flags |= MAP_SHARED; |
405 | |
406 | new_addr = get_unmapped_area(vma->vm_file, 0, new_len, |
407 | vma->vm_pgoff, map_flags); |
408 | ret = new_addr; |
409 | if (new_addr & ~PAGE_MASK) |
410 | goto out; |
411 | } |
412 | ret = move_vma(vma, addr, old_len, new_len, new_addr); |
413 | } |
414 | out: |
415 | if (ret & ~PAGE_MASK) |
416 | vm_unacct_memory(charged); |
417 | out_nc: |
418 | return ret; |
419 | } |
420 | |
421 | asmlinkage unsigned long sys_mremap(unsigned long addr, |
422 | unsigned long old_len, unsigned long new_len, |
423 | unsigned long flags, unsigned long new_addr) |
424 | { |
425 | unsigned long ret; |
426 | |
427 | down_write(¤t->mm->mmap_sem); |
428 | ret = do_mremap(addr, old_len, new_len, flags, new_addr); |
429 | up_write(¤t->mm->mmap_sem); |
430 | return ret; |
431 | } |