udldrmfb: udl_get_edid: drop unneeded i--
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / mm / mremap.c
blobe1031e1f6a61b68ba5055a162ea0d9161b510ba2
1 /*
2 * mm/mremap.c
4 * (C) Copyright 1996 Linus Torvalds
6 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
7 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
8 */
10 #include <linux/mm.h>
11 #include <linux/hugetlb.h>
12 #include <linux/shm.h>
13 #include <linux/ksm.h>
14 #include <linux/mman.h>
15 #include <linux/swap.h>
16 #include <linux/capability.h>
17 #include <linux/fs.h>
18 #include <linux/highmem.h>
19 #include <linux/security.h>
20 #include <linux/syscalls.h>
21 #include <linux/mmu_notifier.h>
23 #include <asm/uaccess.h>
24 #include <asm/cacheflush.h>
25 #include <asm/tlbflush.h>
27 #include "internal.h"
29 static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
31 pgd_t *pgd;
32 pud_t *pud;
33 pmd_t *pmd;
35 pgd = pgd_offset(mm, addr);
36 if (pgd_none_or_clear_bad(pgd))
37 return NULL;
39 pud = pud_offset(pgd, addr);
40 if (pud_none_or_clear_bad(pud))
41 return NULL;
43 pmd = pmd_offset(pud, addr);
44 if (pmd_none(*pmd))
45 return NULL;
47 return pmd;
50 static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
51 unsigned long addr)
53 pgd_t *pgd;
54 pud_t *pud;
55 pmd_t *pmd;
57 pgd = pgd_offset(mm, addr);
58 pud = pud_alloc(mm, pgd, addr);
59 if (!pud)
60 return NULL;
62 pmd = pmd_alloc(mm, pud, addr);
63 if (!pmd)
64 return NULL;
66 VM_BUG_ON(pmd_trans_huge(*pmd));
68 return pmd;
71 static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
72 unsigned long old_addr, unsigned long old_end,
73 struct vm_area_struct *new_vma, pmd_t *new_pmd,
74 unsigned long new_addr, bool need_rmap_locks)
76 struct address_space *mapping = NULL;
77 struct anon_vma *anon_vma = NULL;
78 struct mm_struct *mm = vma->vm_mm;
79 pte_t *old_pte, *new_pte, pte;
80 spinlock_t *old_ptl, *new_ptl;
83 * When need_rmap_locks is true, we take the i_mmap_mutex and anon_vma
84 * locks to ensure that rmap will always observe either the old or the
85 * new ptes. This is the easiest way to avoid races with
86 * truncate_pagecache(), page migration, etc...
88 * When need_rmap_locks is false, we use other ways to avoid
89 * such races:
91 * - During exec() shift_arg_pages(), we use a specially tagged vma
92 * which rmap call sites look for using is_vma_temporary_stack().
94 * - During mremap(), new_vma is often known to be placed after vma
95 * in rmap traversal order. This ensures rmap will always observe
96 * either the old pte, or the new pte, or both (the page table locks
97 * serialize access to individual ptes, but only rmap traversal
98 * order guarantees that we won't miss both the old and new ptes).
100 if (need_rmap_locks) {
101 if (vma->vm_file) {
102 mapping = vma->vm_file->f_mapping;
103 mutex_lock(&mapping->i_mmap_mutex);
105 if (vma->anon_vma) {
106 anon_vma = vma->anon_vma;
107 anon_vma_lock_write(anon_vma);
112 * We don't have to worry about the ordering of src and dst
113 * pte locks because exclusive mmap_sem prevents deadlock.
115 old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
116 new_pte = pte_offset_map(new_pmd, new_addr);
117 new_ptl = pte_lockptr(mm, new_pmd);
118 if (new_ptl != old_ptl)
119 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
120 arch_enter_lazy_mmu_mode();
122 for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
123 new_pte++, new_addr += PAGE_SIZE) {
124 if (pte_none(*old_pte))
125 continue;
126 pte = ptep_get_and_clear(mm, old_addr, old_pte);
127 pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
128 set_pte_at(mm, new_addr, new_pte, pte);
131 arch_leave_lazy_mmu_mode();
132 if (new_ptl != old_ptl)
133 spin_unlock(new_ptl);
134 pte_unmap(new_pte - 1);
135 pte_unmap_unlock(old_pte - 1, old_ptl);
136 if (anon_vma)
137 anon_vma_unlock(anon_vma);
138 if (mapping)
139 mutex_unlock(&mapping->i_mmap_mutex);
142 #define LATENCY_LIMIT (64 * PAGE_SIZE)
144 unsigned long move_page_tables(struct vm_area_struct *vma,
145 unsigned long old_addr, struct vm_area_struct *new_vma,
146 unsigned long new_addr, unsigned long len,
147 bool need_rmap_locks)
149 unsigned long extent, next, old_end;
150 pmd_t *old_pmd, *new_pmd;
151 bool need_flush = false;
152 unsigned long mmun_start; /* For mmu_notifiers */
153 unsigned long mmun_end; /* For mmu_notifiers */
155 old_end = old_addr + len;
156 flush_cache_range(vma, old_addr, old_end);
158 mmun_start = old_addr;
159 mmun_end = old_end;
160 mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
162 for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
163 cond_resched();
164 next = (old_addr + PMD_SIZE) & PMD_MASK;
165 /* even if next overflowed, extent below will be ok */
166 extent = next - old_addr;
167 if (extent > old_end - old_addr)
168 extent = old_end - old_addr;
169 old_pmd = get_old_pmd(vma->vm_mm, old_addr);
170 if (!old_pmd)
171 continue;
172 new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
173 if (!new_pmd)
174 break;
175 if (pmd_trans_huge(*old_pmd)) {
176 int err = 0;
177 if (extent == HPAGE_PMD_SIZE)
178 err = move_huge_pmd(vma, new_vma, old_addr,
179 new_addr, old_end,
180 old_pmd, new_pmd);
181 if (err > 0) {
182 need_flush = true;
183 continue;
184 } else if (!err) {
185 split_huge_page_pmd(vma, old_addr, old_pmd);
187 VM_BUG_ON(pmd_trans_huge(*old_pmd));
189 if (pmd_none(*new_pmd) && __pte_alloc(new_vma->vm_mm, new_vma,
190 new_pmd, new_addr))
191 break;
192 next = (new_addr + PMD_SIZE) & PMD_MASK;
193 if (extent > next - new_addr)
194 extent = next - new_addr;
195 if (extent > LATENCY_LIMIT)
196 extent = LATENCY_LIMIT;
197 move_ptes(vma, old_pmd, old_addr, old_addr + extent,
198 new_vma, new_pmd, new_addr, need_rmap_locks);
199 need_flush = true;
201 if (likely(need_flush))
202 flush_tlb_range(vma, old_end-len, old_addr);
204 mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
206 return len + old_addr - old_end; /* how much done */
209 static unsigned long move_vma(struct vm_area_struct *vma,
210 unsigned long old_addr, unsigned long old_len,
211 unsigned long new_len, unsigned long new_addr)
213 struct mm_struct *mm = vma->vm_mm;
214 struct vm_area_struct *new_vma;
215 unsigned long vm_flags = vma->vm_flags;
216 unsigned long new_pgoff;
217 unsigned long moved_len;
218 unsigned long excess = 0;
219 unsigned long hiwater_vm;
220 int split = 0;
221 int err;
222 bool need_rmap_locks;
225 * We'd prefer to avoid failure later on in do_munmap:
226 * which may split one vma into three before unmapping.
228 if (mm->map_count >= sysctl_max_map_count - 3)
229 return -ENOMEM;
232 * Advise KSM to break any KSM pages in the area to be moved:
233 * it would be confusing if they were to turn up at the new
234 * location, where they happen to coincide with different KSM
235 * pages recently unmapped. But leave vma->vm_flags as it was,
236 * so KSM can come around to merge on vma and new_vma afterwards.
238 err = ksm_madvise(vma, old_addr, old_addr + old_len,
239 MADV_UNMERGEABLE, &vm_flags);
240 if (err)
241 return err;
243 new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
244 new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff,
245 &need_rmap_locks);
246 if (!new_vma)
247 return -ENOMEM;
249 moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len,
250 need_rmap_locks);
251 if (moved_len < old_len) {
253 * On error, move entries back from new area to old,
254 * which will succeed since page tables still there,
255 * and then proceed to unmap new area instead of old.
257 move_page_tables(new_vma, new_addr, vma, old_addr, moved_len,
258 true);
259 vma = new_vma;
260 old_len = new_len;
261 old_addr = new_addr;
262 new_addr = -ENOMEM;
265 /* Conceal VM_ACCOUNT so old reservation is not undone */
266 if (vm_flags & VM_ACCOUNT) {
267 vma->vm_flags &= ~VM_ACCOUNT;
268 excess = vma->vm_end - vma->vm_start - old_len;
269 if (old_addr > vma->vm_start &&
270 old_addr + old_len < vma->vm_end)
271 split = 1;
275 * If we failed to move page tables we still do total_vm increment
276 * since do_munmap() will decrement it by old_len == new_len.
278 * Since total_vm is about to be raised artificially high for a
279 * moment, we need to restore high watermark afterwards: if stats
280 * are taken meanwhile, total_vm and hiwater_vm appear too high.
281 * If this were a serious issue, we'd add a flag to do_munmap().
283 hiwater_vm = mm->hiwater_vm;
284 vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
286 if (do_munmap(mm, old_addr, old_len) < 0) {
287 /* OOM: unable to split vma, just get accounts right */
288 vm_unacct_memory(excess >> PAGE_SHIFT);
289 excess = 0;
291 mm->hiwater_vm = hiwater_vm;
293 /* Restore VM_ACCOUNT if one or two pieces of vma left */
294 if (excess) {
295 vma->vm_flags |= VM_ACCOUNT;
296 if (split)
297 vma->vm_next->vm_flags |= VM_ACCOUNT;
300 if (vm_flags & VM_LOCKED) {
301 mm->locked_vm += new_len >> PAGE_SHIFT;
302 if (new_len > old_len)
303 mlock_vma_pages_range(new_vma, new_addr + old_len,
304 new_addr + new_len);
307 return new_addr;
310 static struct vm_area_struct *vma_to_resize(unsigned long addr,
311 unsigned long old_len, unsigned long new_len, unsigned long *p)
313 struct mm_struct *mm = current->mm;
314 struct vm_area_struct *vma = find_vma(mm, addr);
316 if (!vma || vma->vm_start > addr)
317 goto Efault;
319 if (is_vm_hugetlb_page(vma))
320 goto Einval;
322 /* We can't remap across vm area boundaries */
323 if (old_len > vma->vm_end - addr)
324 goto Efault;
326 /* Need to be careful about a growing mapping */
327 if (new_len > old_len) {
328 unsigned long pgoff;
330 if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
331 goto Efault;
332 pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
333 pgoff += vma->vm_pgoff;
334 if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
335 goto Einval;
338 if (vma->vm_flags & VM_LOCKED) {
339 unsigned long locked, lock_limit;
340 locked = mm->locked_vm << PAGE_SHIFT;
341 lock_limit = rlimit(RLIMIT_MEMLOCK);
342 locked += new_len - old_len;
343 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
344 goto Eagain;
347 if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT))
348 goto Enomem;
350 if (vma->vm_flags & VM_ACCOUNT) {
351 unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;
352 if (security_vm_enough_memory_mm(mm, charged))
353 goto Efault;
354 *p = charged;
357 return vma;
359 Efault: /* very odd choice for most of the cases, but... */
360 return ERR_PTR(-EFAULT);
361 Einval:
362 return ERR_PTR(-EINVAL);
363 Enomem:
364 return ERR_PTR(-ENOMEM);
365 Eagain:
366 return ERR_PTR(-EAGAIN);
369 static unsigned long mremap_to(unsigned long addr,
370 unsigned long old_len, unsigned long new_addr,
371 unsigned long new_len)
373 struct mm_struct *mm = current->mm;
374 struct vm_area_struct *vma;
375 unsigned long ret = -EINVAL;
376 unsigned long charged = 0;
377 unsigned long map_flags;
379 if (new_addr & ~PAGE_MASK)
380 goto out;
382 if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
383 goto out;
385 /* Check if the location we're moving into overlaps the
386 * old location at all, and fail if it does.
388 if ((new_addr <= addr) && (new_addr+new_len) > addr)
389 goto out;
391 if ((addr <= new_addr) && (addr+old_len) > new_addr)
392 goto out;
394 ret = do_munmap(mm, new_addr, new_len);
395 if (ret)
396 goto out;
398 if (old_len >= new_len) {
399 ret = do_munmap(mm, addr+new_len, old_len - new_len);
400 if (ret && old_len != new_len)
401 goto out;
402 old_len = new_len;
405 vma = vma_to_resize(addr, old_len, new_len, &charged);
406 if (IS_ERR(vma)) {
407 ret = PTR_ERR(vma);
408 goto out;
411 map_flags = MAP_FIXED;
412 if (vma->vm_flags & VM_MAYSHARE)
413 map_flags |= MAP_SHARED;
415 ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
416 ((addr - vma->vm_start) >> PAGE_SHIFT),
417 map_flags);
418 if (ret & ~PAGE_MASK)
419 goto out1;
421 ret = move_vma(vma, addr, old_len, new_len, new_addr);
422 if (!(ret & ~PAGE_MASK))
423 goto out;
424 out1:
425 vm_unacct_memory(charged);
427 out:
428 return ret;
431 static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
433 unsigned long end = vma->vm_end + delta;
434 if (end < vma->vm_end) /* overflow */
435 return 0;
436 if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */
437 return 0;
438 if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
439 0, MAP_FIXED) & ~PAGE_MASK)
440 return 0;
441 return 1;
445 * Expand (or shrink) an existing mapping, potentially moving it at the
446 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
448 * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
449 * This option implies MREMAP_MAYMOVE.
451 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
452 unsigned long, new_len, unsigned long, flags,
453 unsigned long, new_addr)
455 struct mm_struct *mm = current->mm;
456 struct vm_area_struct *vma;
457 unsigned long ret = -EINVAL;
458 unsigned long charged = 0;
460 down_write(&current->mm->mmap_sem);
462 if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
463 goto out;
465 if (addr & ~PAGE_MASK)
466 goto out;
468 old_len = PAGE_ALIGN(old_len);
469 new_len = PAGE_ALIGN(new_len);
472 * We allow a zero old-len as a special case
473 * for DOS-emu "duplicate shm area" thing. But
474 * a zero new-len is nonsensical.
476 if (!new_len)
477 goto out;
479 if (flags & MREMAP_FIXED) {
480 if (flags & MREMAP_MAYMOVE)
481 ret = mremap_to(addr, old_len, new_addr, new_len);
482 goto out;
486 * Always allow a shrinking remap: that just unmaps
487 * the unnecessary pages..
488 * do_munmap does all the needed commit accounting
490 if (old_len >= new_len) {
491 ret = do_munmap(mm, addr+new_len, old_len - new_len);
492 if (ret && old_len != new_len)
493 goto out;
494 ret = addr;
495 goto out;
499 * Ok, we need to grow..
501 vma = vma_to_resize(addr, old_len, new_len, &charged);
502 if (IS_ERR(vma)) {
503 ret = PTR_ERR(vma);
504 goto out;
507 /* old_len exactly to the end of the area..
509 if (old_len == vma->vm_end - addr) {
510 /* can we just expand the current mapping? */
511 if (vma_expandable(vma, new_len - old_len)) {
512 int pages = (new_len - old_len) >> PAGE_SHIFT;
514 if (vma_adjust(vma, vma->vm_start, addr + new_len,
515 vma->vm_pgoff, NULL)) {
516 ret = -ENOMEM;
517 goto out;
520 vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
521 if (vma->vm_flags & VM_LOCKED) {
522 mm->locked_vm += pages;
523 mlock_vma_pages_range(vma, addr + old_len,
524 addr + new_len);
526 ret = addr;
527 goto out;
532 * We weren't able to just expand or shrink the area,
533 * we need to create a new one and move it..
535 ret = -ENOMEM;
536 if (flags & MREMAP_MAYMOVE) {
537 unsigned long map_flags = 0;
538 if (vma->vm_flags & VM_MAYSHARE)
539 map_flags |= MAP_SHARED;
541 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
542 vma->vm_pgoff +
543 ((addr - vma->vm_start) >> PAGE_SHIFT),
544 map_flags);
545 if (new_addr & ~PAGE_MASK) {
546 ret = new_addr;
547 goto out;
550 ret = move_vma(vma, addr, old_len, new_len, new_addr);
552 out:
553 if (ret & ~PAGE_MASK)
554 vm_unacct_memory(charged);
555 up_write(&current->mm->mmap_sem);
556 return ret;