ia64/linux-2.6.18-xen.hg

view mm/mremap.c @ 452:c7ed6fe5dca0

kexec: dont initialise regions in reserve_memory()

There is no need to initialise efi_memmap_res and boot_param_res in
reserve_memory() for the initial xen domain as it is done in
machine_kexec_setup_resources() using values from the kexec hypercall.

Signed-off-by: Simon Horman <horms@verge.net.au>
author Keir Fraser <keir.fraser@citrix.com>
date Thu Feb 28 10:55:18 2008 +0000 (2008-02-28)
parents 831230e53067
children
line source
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 */
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/capability.h>
17 #include <linux/fs.h>
18 #include <linux/highmem.h>
19 #include <linux/security.h>
20 #include <linux/syscalls.h>
22 #include <asm/uaccess.h>
23 #include <asm/cacheflush.h>
24 #include <asm/tlbflush.h>
26 static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
27 {
28 pgd_t *pgd;
29 pud_t *pud;
30 pmd_t *pmd;
32 pgd = pgd_offset(mm, addr);
33 if (pgd_none_or_clear_bad(pgd))
34 return NULL;
36 pud = pud_offset(pgd, addr);
37 if (pud_none_or_clear_bad(pud))
38 return NULL;
40 pmd = pmd_offset(pud, addr);
41 if (pmd_none_or_clear_bad(pmd))
42 return NULL;
44 return pmd;
45 }
47 static pmd_t *alloc_new_pmd(struct mm_struct *mm, unsigned long addr)
48 {
49 pgd_t *pgd;
50 pud_t *pud;
51 pmd_t *pmd;
53 pgd = pgd_offset(mm, addr);
54 pud = pud_alloc(mm, pgd, addr);
55 if (!pud)
56 return NULL;
58 pmd = pmd_alloc(mm, pud, addr);
59 if (!pmd)
60 return NULL;
62 if (!pmd_present(*pmd) && __pte_alloc(mm, pmd, addr))
63 return NULL;
65 return pmd;
66 }
68 static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
69 unsigned long old_addr, unsigned long old_end,
70 struct vm_area_struct *new_vma, pmd_t *new_pmd,
71 unsigned long new_addr)
72 {
73 struct address_space *mapping = NULL;
74 struct mm_struct *mm = vma->vm_mm;
75 pte_t *old_pte, *new_pte, pte;
76 spinlock_t *old_ptl, *new_ptl;
78 if (vma->vm_file) {
79 /*
80 * Subtle point from Rajesh Venkatasubramanian: before
81 * moving file-based ptes, we must lock vmtruncate out,
82 * since it might clean the dst vma before the src vma,
83 * and we propagate stale pages into the dst afterward.
84 */
85 mapping = vma->vm_file->f_mapping;
86 spin_lock(&mapping->i_mmap_lock);
87 if (new_vma->vm_truncate_count &&
88 new_vma->vm_truncate_count != vma->vm_truncate_count)
89 new_vma->vm_truncate_count = 0;
90 }
92 /*
93 * We don't have to worry about the ordering of src and dst
94 * pte locks because exclusive mmap_sem prevents deadlock.
95 */
96 old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
97 new_pte = pte_offset_map_nested(new_pmd, new_addr);
98 new_ptl = pte_lockptr(mm, new_pmd);
99 if (new_ptl != old_ptl)
100 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
102 for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
103 new_pte++, new_addr += PAGE_SIZE) {
104 if (pte_none(*old_pte))
105 continue;
106 pte = ptep_clear_flush(vma, old_addr, old_pte);
107 /* ZERO_PAGE can be dependant on virtual addr */
108 pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
109 set_pte_at(mm, new_addr, new_pte, pte);
110 }
112 if (new_ptl != old_ptl)
113 spin_unlock(new_ptl);
114 pte_unmap_nested(new_pte - 1);
115 pte_unmap_unlock(old_pte - 1, old_ptl);
116 if (mapping)
117 spin_unlock(&mapping->i_mmap_lock);
118 }
120 #define LATENCY_LIMIT (64 * PAGE_SIZE)
122 static unsigned long move_page_tables(struct vm_area_struct *vma,
123 unsigned long old_addr, struct vm_area_struct *new_vma,
124 unsigned long new_addr, unsigned long len)
125 {
126 unsigned long extent, next, old_end;
127 pmd_t *old_pmd, *new_pmd;
129 old_end = old_addr + len;
130 flush_cache_range(vma, old_addr, old_end);
132 for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
133 cond_resched();
134 next = (old_addr + PMD_SIZE) & PMD_MASK;
135 if (next - 1 > old_end)
136 next = old_end;
137 extent = next - old_addr;
138 old_pmd = get_old_pmd(vma->vm_mm, old_addr);
139 if (!old_pmd)
140 continue;
141 new_pmd = alloc_new_pmd(vma->vm_mm, new_addr);
142 if (!new_pmd)
143 break;
144 next = (new_addr + PMD_SIZE) & PMD_MASK;
145 if (extent > next - new_addr)
146 extent = next - new_addr;
147 if (extent > LATENCY_LIMIT)
148 extent = LATENCY_LIMIT;
149 move_ptes(vma, old_pmd, old_addr, old_addr + extent,
150 new_vma, new_pmd, new_addr);
151 }
153 return len + old_addr - old_end; /* how much done */
154 }
156 static unsigned long move_vma(struct vm_area_struct *vma,
157 unsigned long old_addr, unsigned long old_len,
158 unsigned long new_len, unsigned long new_addr)
159 {
160 struct mm_struct *mm = vma->vm_mm;
161 struct vm_area_struct *new_vma;
162 unsigned long vm_flags = vma->vm_flags;
163 unsigned long new_pgoff;
164 unsigned long moved_len;
165 unsigned long excess = 0;
166 unsigned long hiwater_vm;
167 int split = 0;
169 /*
170 * We'd prefer to avoid failure later on in do_munmap:
171 * which may split one vma into three before unmapping.
172 */
173 if (mm->map_count >= sysctl_max_map_count - 3)
174 return -ENOMEM;
176 new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
177 new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff);
178 if (!new_vma)
179 return -ENOMEM;
181 moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len);
182 if (moved_len < old_len) {
183 /*
184 * On error, move entries back from new area to old,
185 * which will succeed since page tables still there,
186 * and then proceed to unmap new area instead of old.
187 */
188 move_page_tables(new_vma, new_addr, vma, old_addr, moved_len);
189 vma = new_vma;
190 old_len = new_len;
191 old_addr = new_addr;
192 new_addr = -ENOMEM;
193 }
195 /* Conceal VM_ACCOUNT so old reservation is not undone */
196 if (vm_flags & VM_ACCOUNT) {
197 vma->vm_flags &= ~VM_ACCOUNT;
198 excess = vma->vm_end - vma->vm_start - old_len;
199 if (old_addr > vma->vm_start &&
200 old_addr + old_len < vma->vm_end)
201 split = 1;
202 }
204 /*
205 * If we failed to move page tables we still do total_vm increment
206 * since do_munmap() will decrement it by old_len == new_len.
207 *
208 * Since total_vm is about to be raised artificially high for a
209 * moment, we need to restore high watermark afterwards: if stats
210 * are taken meanwhile, total_vm and hiwater_vm appear too high.
211 * If this were a serious issue, we'd add a flag to do_munmap().
212 */
213 hiwater_vm = mm->hiwater_vm;
214 mm->total_vm += new_len >> PAGE_SHIFT;
215 vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
217 if (do_munmap(mm, old_addr, old_len) < 0) {
218 /* OOM: unable to split vma, just get accounts right */
219 vm_unacct_memory(excess >> PAGE_SHIFT);
220 excess = 0;
221 }
222 mm->hiwater_vm = hiwater_vm;
224 /* Restore VM_ACCOUNT if one or two pieces of vma left */
225 if (excess) {
226 vma->vm_flags |= VM_ACCOUNT;
227 if (split)
228 vma->vm_next->vm_flags |= VM_ACCOUNT;
229 }
231 if (vm_flags & VM_LOCKED) {
232 mm->locked_vm += new_len >> PAGE_SHIFT;
233 if (new_len > old_len)
234 make_pages_present(new_addr + old_len,
235 new_addr + new_len);
236 }
238 return new_addr;
239 }
241 /*
242 * Expand (or shrink) an existing mapping, potentially moving it at the
243 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
244 *
245 * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
246 * This option implies MREMAP_MAYMOVE.
247 */
248 unsigned long do_mremap(unsigned long addr,
249 unsigned long old_len, unsigned long new_len,
250 unsigned long flags, unsigned long new_addr)
251 {
252 struct mm_struct *mm = current->mm;
253 struct vm_area_struct *vma;
254 unsigned long ret = -EINVAL;
255 unsigned long charged = 0;
257 if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
258 goto out;
260 if (addr & ~PAGE_MASK)
261 goto out;
263 old_len = PAGE_ALIGN(old_len);
264 new_len = PAGE_ALIGN(new_len);
266 /*
267 * We allow a zero old-len as a special case
268 * for DOS-emu "duplicate shm area" thing. But
269 * a zero new-len is nonsensical.
270 */
271 if (!new_len)
272 goto out;
274 /* new_addr is only valid if MREMAP_FIXED is specified */
275 if (flags & MREMAP_FIXED) {
276 if (new_addr & ~PAGE_MASK)
277 goto out;
278 if (!(flags & MREMAP_MAYMOVE))
279 goto out;
281 if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
282 goto out;
284 /* Check if the location we're moving into overlaps the
285 * old location at all, and fail if it does.
286 */
287 if ((new_addr <= addr) && (new_addr+new_len) > addr)
288 goto out;
290 if ((addr <= new_addr) && (addr+old_len) > new_addr)
291 goto out;
293 ret = do_munmap(mm, new_addr, new_len);
294 if (ret)
295 goto out;
296 }
298 /*
299 * Always allow a shrinking remap: that just unmaps
300 * the unnecessary pages..
301 * do_munmap does all the needed commit accounting
302 */
303 if (old_len >= new_len) {
304 ret = do_munmap(mm, addr+new_len, old_len - new_len);
305 if (ret && old_len != new_len)
306 goto out;
307 ret = addr;
308 if (!(flags & MREMAP_FIXED) || (new_addr == addr))
309 goto out;
310 old_len = new_len;
311 }
313 /*
314 * Ok, we need to grow.. or relocate.
315 */
316 ret = -EFAULT;
317 vma = find_vma(mm, addr);
318 if (!vma || vma->vm_start > addr)
319 goto out;
320 if (is_vm_hugetlb_page(vma)) {
321 ret = -EINVAL;
322 goto out;
323 }
324 /* We can't remap across vm area boundaries */
325 if (old_len > vma->vm_end - addr)
326 goto out;
327 if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) {
328 if (new_len > old_len)
329 goto out;
330 }
331 if (vma->vm_flags & VM_LOCKED) {
332 unsigned long locked, lock_limit;
333 locked = mm->locked_vm << PAGE_SHIFT;
334 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
335 locked += new_len - old_len;
336 ret = -EAGAIN;
337 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
338 goto out;
339 }
340 if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) {
341 ret = -ENOMEM;
342 goto out;
343 }
345 if (vma->vm_flags & VM_ACCOUNT) {
346 charged = (new_len - old_len) >> PAGE_SHIFT;
347 if (security_vm_enough_memory(charged))
348 goto out_nc;
349 }
351 /* old_len exactly to the end of the area..
352 * And we're not relocating the area.
353 */
354 if (old_len == vma->vm_end - addr &&
355 !((flags & MREMAP_FIXED) && (addr != new_addr)) &&
356 (old_len != new_len || !(flags & MREMAP_MAYMOVE))) {
357 unsigned long max_addr = TASK_SIZE;
358 if (vma->vm_next)
359 max_addr = vma->vm_next->vm_start;
360 /* can we just expand the current mapping? */
361 if (max_addr - addr >= new_len) {
362 int pages = (new_len - old_len) >> PAGE_SHIFT;
364 vma_adjust(vma, vma->vm_start,
365 addr + new_len, vma->vm_pgoff, NULL);
367 mm->total_vm += pages;
368 vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
369 if (vma->vm_flags & VM_LOCKED) {
370 mm->locked_vm += pages;
371 make_pages_present(addr + old_len,
372 addr + new_len);
373 }
374 ret = addr;
375 goto out;
376 }
377 }
379 /*
380 * We weren't able to just expand or shrink the area,
381 * we need to create a new one and move it..
382 */
383 ret = -ENOMEM;
384 if (flags & MREMAP_MAYMOVE) {
385 if (!(flags & MREMAP_FIXED)) {
386 unsigned long map_flags = 0;
387 if (vma->vm_flags & VM_MAYSHARE)
388 map_flags |= MAP_SHARED;
390 new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
391 vma->vm_pgoff, map_flags);
392 ret = new_addr;
393 if (new_addr & ~PAGE_MASK)
394 goto out;
395 }
396 ret = move_vma(vma, addr, old_len, new_len, new_addr);
397 }
398 out:
399 if (ret & ~PAGE_MASK)
400 vm_unacct_memory(charged);
401 out_nc:
402 return ret;
403 }
405 asmlinkage unsigned long sys_mremap(unsigned long addr,
406 unsigned long old_len, unsigned long new_len,
407 unsigned long flags, unsigned long new_addr)
408 {
409 unsigned long ret;
411 down_write(&current->mm->mmap_sem);
412 ret = do_mremap(addr, old_len, new_len, flags, new_addr);
413 up_write(&current->mm->mmap_sem);
414 return ret;
415 }