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1 | /* | |
2 | * mm/mmap.c | |
3 | * | |
4 | * Written by obz. | |
5 | * | |
6 | * Address space accounting code <alan@lxorguk.ukuu.org.uk> | |
7 | */ | |
8 | ||
9 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
10 | ||
11 | #include <linux/kernel.h> | |
12 | #include <linux/slab.h> | |
13 | #include <linux/backing-dev.h> | |
14 | #include <linux/mm.h> | |
15 | #include <linux/vmacache.h> | |
16 | #include <linux/shm.h> | |
17 | #include <linux/mman.h> | |
18 | #include <linux/pagemap.h> | |
19 | #include <linux/swap.h> | |
20 | #include <linux/syscalls.h> | |
21 | #include <linux/capability.h> | |
22 | #include <linux/init.h> | |
23 | #include <linux/file.h> | |
24 | #include <linux/fs.h> | |
25 | #include <linux/personality.h> | |
26 | #include <linux/security.h> | |
27 | #include <linux/hugetlb.h> | |
28 | #include <linux/profile.h> | |
29 | #include <linux/export.h> | |
30 | #include <linux/mount.h> | |
31 | #include <linux/mempolicy.h> | |
32 | #include <linux/rmap.h> | |
33 | #include <linux/mmu_notifier.h> | |
34 | #include <linux/mmdebug.h> | |
35 | #include <linux/perf_event.h> | |
36 | #include <linux/audit.h> | |
37 | #include <linux/khugepaged.h> | |
38 | #include <linux/uprobes.h> | |
39 | #include <linux/rbtree_augmented.h> | |
40 | #include <linux/sched/sysctl.h> | |
41 | #include <linux/notifier.h> | |
42 | #include <linux/memory.h> | |
43 | #include <linux/printk.h> | |
44 | #include <linux/userfaultfd_k.h> | |
45 | #include <linux/moduleparam.h> | |
46 | ||
47 | #include <asm/uaccess.h> | |
48 | #include <asm/cacheflush.h> | |
49 | #include <asm/tlb.h> | |
50 | #include <asm/mmu_context.h> | |
51 | ||
52 | #include "internal.h" | |
53 | ||
54 | #ifndef arch_mmap_check | |
55 | #define arch_mmap_check(addr, len, flags) (0) | |
56 | #endif | |
57 | ||
58 | #ifndef arch_rebalance_pgtables | |
59 | #define arch_rebalance_pgtables(addr, len) (addr) | |
60 | #endif | |
61 | ||
62 | #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS | |
63 | const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN; | |
64 | const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX; | |
65 | int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS; | |
66 | #endif | |
67 | #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS | |
68 | const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN; | |
69 | const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX; | |
70 | int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS; | |
71 | #endif | |
72 | ||
73 | static bool ignore_rlimit_data = true; | |
74 | core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644); | |
75 | ||
76 | static void unmap_region(struct mm_struct *mm, | |
77 | struct vm_area_struct *vma, struct vm_area_struct *prev, | |
78 | unsigned long start, unsigned long end); | |
79 | ||
80 | /* description of effects of mapping type and prot in current implementation. | |
81 | * this is due to the limited x86 page protection hardware. The expected | |
82 | * behavior is in parens: | |
83 | * | |
84 | * map_type prot | |
85 | * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC | |
86 | * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes | |
87 | * w: (no) no w: (no) no w: (yes) yes w: (no) no | |
88 | * x: (no) no x: (no) yes x: (no) yes x: (yes) yes | |
89 | * | |
90 | * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes | |
91 | * w: (no) no w: (no) no w: (copy) copy w: (no) no | |
92 | * x: (no) no x: (no) yes x: (no) yes x: (yes) yes | |
93 | * | |
94 | */ | |
95 | pgprot_t protection_map[16] = { | |
96 | __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, | |
97 | __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 | |
98 | }; | |
99 | ||
100 | pgprot_t vm_get_page_prot(unsigned long vm_flags) | |
101 | { | |
102 | return __pgprot(pgprot_val(protection_map[vm_flags & | |
103 | (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) | | |
104 | pgprot_val(arch_vm_get_page_prot(vm_flags))); | |
105 | } | |
106 | EXPORT_SYMBOL(vm_get_page_prot); | |
107 | ||
108 | static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags) | |
109 | { | |
110 | return pgprot_modify(oldprot, vm_get_page_prot(vm_flags)); | |
111 | } | |
112 | ||
113 | /* Update vma->vm_page_prot to reflect vma->vm_flags. */ | |
114 | void vma_set_page_prot(struct vm_area_struct *vma) | |
115 | { | |
116 | unsigned long vm_flags = vma->vm_flags; | |
117 | ||
118 | vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags); | |
119 | if (vma_wants_writenotify(vma)) { | |
120 | vm_flags &= ~VM_SHARED; | |
121 | vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, | |
122 | vm_flags); | |
123 | } | |
124 | } | |
125 | ||
126 | ||
127 | int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; /* heuristic overcommit */ | |
128 | int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */ | |
129 | unsigned long sysctl_overcommit_kbytes __read_mostly; | |
130 | int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; | |
131 | unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */ | |
132 | unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */ | |
133 | /* | |
134 | * Make sure vm_committed_as in one cacheline and not cacheline shared with | |
135 | * other variables. It can be updated by several CPUs frequently. | |
136 | */ | |
137 | struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp; | |
138 | ||
139 | /* | |
140 | * The global memory commitment made in the system can be a metric | |
141 | * that can be used to drive ballooning decisions when Linux is hosted | |
142 | * as a guest. On Hyper-V, the host implements a policy engine for dynamically | |
143 | * balancing memory across competing virtual machines that are hosted. | |
144 | * Several metrics drive this policy engine including the guest reported | |
145 | * memory commitment. | |
146 | */ | |
147 | unsigned long vm_memory_committed(void) | |
148 | { | |
149 | return percpu_counter_read_positive(&vm_committed_as); | |
150 | } | |
151 | EXPORT_SYMBOL_GPL(vm_memory_committed); | |
152 | ||
153 | /* | |
154 | * Check that a process has enough memory to allocate a new virtual | |
155 | * mapping. 0 means there is enough memory for the allocation to | |
156 | * succeed and -ENOMEM implies there is not. | |
157 | * | |
158 | * We currently support three overcommit policies, which are set via the | |
159 | * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting | |
160 | * | |
161 | * Strict overcommit modes added 2002 Feb 26 by Alan Cox. | |
162 | * Additional code 2002 Jul 20 by Robert Love. | |
163 | * | |
164 | * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. | |
165 | * | |
166 | * Note this is a helper function intended to be used by LSMs which | |
167 | * wish to use this logic. | |
168 | */ | |
169 | int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) | |
170 | { | |
171 | long free, allowed, reserve; | |
172 | ||
173 | VM_WARN_ONCE(percpu_counter_read(&vm_committed_as) < | |
174 | -(s64)vm_committed_as_batch * num_online_cpus(), | |
175 | "memory commitment underflow"); | |
176 | ||
177 | vm_acct_memory(pages); | |
178 | ||
179 | /* | |
180 | * Sometimes we want to use more memory than we have | |
181 | */ | |
182 | if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) | |
183 | return 0; | |
184 | ||
185 | if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { | |
186 | free = global_page_state(NR_FREE_PAGES); | |
187 | free += global_page_state(NR_FILE_PAGES); | |
188 | ||
189 | /* | |
190 | * shmem pages shouldn't be counted as free in this | |
191 | * case, they can't be purged, only swapped out, and | |
192 | * that won't affect the overall amount of available | |
193 | * memory in the system. | |
194 | */ | |
195 | free -= global_page_state(NR_SHMEM); | |
196 | ||
197 | free += get_nr_swap_pages(); | |
198 | ||
199 | /* | |
200 | * Any slabs which are created with the | |
201 | * SLAB_RECLAIM_ACCOUNT flag claim to have contents | |
202 | * which are reclaimable, under pressure. The dentry | |
203 | * cache and most inode caches should fall into this | |
204 | */ | |
205 | free += global_page_state(NR_SLAB_RECLAIMABLE); | |
206 | ||
207 | /* | |
208 | * Leave reserved pages. The pages are not for anonymous pages. | |
209 | */ | |
210 | if (free <= totalreserve_pages) | |
211 | goto error; | |
212 | else | |
213 | free -= totalreserve_pages; | |
214 | ||
215 | /* | |
216 | * Reserve some for root | |
217 | */ | |
218 | if (!cap_sys_admin) | |
219 | free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); | |
220 | ||
221 | if (free > pages) | |
222 | return 0; | |
223 | ||
224 | goto error; | |
225 | } | |
226 | ||
227 | allowed = vm_commit_limit(); | |
228 | /* | |
229 | * Reserve some for root | |
230 | */ | |
231 | if (!cap_sys_admin) | |
232 | allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); | |
233 | ||
234 | /* | |
235 | * Don't let a single process grow so big a user can't recover | |
236 | */ | |
237 | if (mm) { | |
238 | reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10); | |
239 | allowed -= min_t(long, mm->total_vm / 32, reserve); | |
240 | } | |
241 | ||
242 | if (percpu_counter_read_positive(&vm_committed_as) < allowed) | |
243 | return 0; | |
244 | error: | |
245 | vm_unacct_memory(pages); | |
246 | ||
247 | return -ENOMEM; | |
248 | } | |
249 | ||
250 | /* | |
251 | * Requires inode->i_mapping->i_mmap_rwsem | |
252 | */ | |
253 | static void __remove_shared_vm_struct(struct vm_area_struct *vma, | |
254 | struct file *file, struct address_space *mapping) | |
255 | { | |
256 | if (vma->vm_flags & VM_DENYWRITE) | |
257 | atomic_inc(&file_inode(file)->i_writecount); | |
258 | if (vma->vm_flags & VM_SHARED) | |
259 | mapping_unmap_writable(mapping); | |
260 | ||
261 | flush_dcache_mmap_lock(mapping); | |
262 | vma_interval_tree_remove(vma, &mapping->i_mmap); | |
263 | flush_dcache_mmap_unlock(mapping); | |
264 | } | |
265 | ||
266 | /* | |
267 | * Unlink a file-based vm structure from its interval tree, to hide | |
268 | * vma from rmap and vmtruncate before freeing its page tables. | |
269 | */ | |
270 | void unlink_file_vma(struct vm_area_struct *vma) | |
271 | { | |
272 | struct file *file = vma->vm_file; | |
273 | ||
274 | if (file) { | |
275 | struct address_space *mapping = file->f_mapping; | |
276 | i_mmap_lock_write(mapping); | |
277 | __remove_shared_vm_struct(vma, file, mapping); | |
278 | i_mmap_unlock_write(mapping); | |
279 | } | |
280 | } | |
281 | ||
282 | /* | |
283 | * Close a vm structure and free it, returning the next. | |
284 | */ | |
285 | static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) | |
286 | { | |
287 | struct vm_area_struct *next = vma->vm_next; | |
288 | ||
289 | might_sleep(); | |
290 | if (vma->vm_ops && vma->vm_ops->close) | |
291 | vma->vm_ops->close(vma); | |
292 | if (vma->vm_file) | |
293 | fput(vma->vm_file); | |
294 | mpol_put(vma_policy(vma)); | |
295 | kmem_cache_free(vm_area_cachep, vma); | |
296 | return next; | |
297 | } | |
298 | ||
299 | static unsigned long do_brk(unsigned long addr, unsigned long len); | |
300 | ||
301 | SYSCALL_DEFINE1(brk, unsigned long, brk) | |
302 | { | |
303 | unsigned long retval; | |
304 | unsigned long newbrk, oldbrk; | |
305 | struct mm_struct *mm = current->mm; | |
306 | unsigned long min_brk; | |
307 | bool populate; | |
308 | ||
309 | down_write(&mm->mmap_sem); | |
310 | ||
311 | #ifdef CONFIG_COMPAT_BRK | |
312 | /* | |
313 | * CONFIG_COMPAT_BRK can still be overridden by setting | |
314 | * randomize_va_space to 2, which will still cause mm->start_brk | |
315 | * to be arbitrarily shifted | |
316 | */ | |
317 | if (current->brk_randomized) | |
318 | min_brk = mm->start_brk; | |
319 | else | |
320 | min_brk = mm->end_data; | |
321 | #else | |
322 | min_brk = mm->start_brk; | |
323 | #endif | |
324 | if (brk < min_brk) | |
325 | goto out; | |
326 | ||
327 | /* | |
328 | * Check against rlimit here. If this check is done later after the test | |
329 | * of oldbrk with newbrk then it can escape the test and let the data | |
330 | * segment grow beyond its set limit the in case where the limit is | |
331 | * not page aligned -Ram Gupta | |
332 | */ | |
333 | if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk, | |
334 | mm->end_data, mm->start_data)) | |
335 | goto out; | |
336 | ||
337 | newbrk = PAGE_ALIGN(brk); | |
338 | oldbrk = PAGE_ALIGN(mm->brk); | |
339 | if (oldbrk == newbrk) | |
340 | goto set_brk; | |
341 | ||
342 | /* Always allow shrinking brk. */ | |
343 | if (brk <= mm->brk) { | |
344 | if (!do_munmap(mm, newbrk, oldbrk-newbrk)) | |
345 | goto set_brk; | |
346 | goto out; | |
347 | } | |
348 | ||
349 | /* Check against existing mmap mappings. */ | |
350 | if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) | |
351 | goto out; | |
352 | ||
353 | /* Ok, looks good - let it rip. */ | |
354 | if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) | |
355 | goto out; | |
356 | ||
357 | set_brk: | |
358 | mm->brk = brk; | |
359 | populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0; | |
360 | up_write(&mm->mmap_sem); | |
361 | if (populate) | |
362 | mm_populate(oldbrk, newbrk - oldbrk); | |
363 | return brk; | |
364 | ||
365 | out: | |
366 | retval = mm->brk; | |
367 | up_write(&mm->mmap_sem); | |
368 | return retval; | |
369 | } | |
370 | ||
371 | static long vma_compute_subtree_gap(struct vm_area_struct *vma) | |
372 | { | |
373 | unsigned long max, subtree_gap; | |
374 | max = vma->vm_start; | |
375 | if (vma->vm_prev) | |
376 | max -= vma->vm_prev->vm_end; | |
377 | if (vma->vm_rb.rb_left) { | |
378 | subtree_gap = rb_entry(vma->vm_rb.rb_left, | |
379 | struct vm_area_struct, vm_rb)->rb_subtree_gap; | |
380 | if (subtree_gap > max) | |
381 | max = subtree_gap; | |
382 | } | |
383 | if (vma->vm_rb.rb_right) { | |
384 | subtree_gap = rb_entry(vma->vm_rb.rb_right, | |
385 | struct vm_area_struct, vm_rb)->rb_subtree_gap; | |
386 | if (subtree_gap > max) | |
387 | max = subtree_gap; | |
388 | } | |
389 | return max; | |
390 | } | |
391 | ||
392 | #ifdef CONFIG_DEBUG_VM_RB | |
393 | static int browse_rb(struct mm_struct *mm) | |
394 | { | |
395 | struct rb_root *root = &mm->mm_rb; | |
396 | int i = 0, j, bug = 0; | |
397 | struct rb_node *nd, *pn = NULL; | |
398 | unsigned long prev = 0, pend = 0; | |
399 | ||
400 | for (nd = rb_first(root); nd; nd = rb_next(nd)) { | |
401 | struct vm_area_struct *vma; | |
402 | vma = rb_entry(nd, struct vm_area_struct, vm_rb); | |
403 | if (vma->vm_start < prev) { | |
404 | pr_emerg("vm_start %lx < prev %lx\n", | |
405 | vma->vm_start, prev); | |
406 | bug = 1; | |
407 | } | |
408 | if (vma->vm_start < pend) { | |
409 | pr_emerg("vm_start %lx < pend %lx\n", | |
410 | vma->vm_start, pend); | |
411 | bug = 1; | |
412 | } | |
413 | if (vma->vm_start > vma->vm_end) { | |
414 | pr_emerg("vm_start %lx > vm_end %lx\n", | |
415 | vma->vm_start, vma->vm_end); | |
416 | bug = 1; | |
417 | } | |
418 | spin_lock(&mm->page_table_lock); | |
419 | if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) { | |
420 | pr_emerg("free gap %lx, correct %lx\n", | |
421 | vma->rb_subtree_gap, | |
422 | vma_compute_subtree_gap(vma)); | |
423 | bug = 1; | |
424 | } | |
425 | spin_unlock(&mm->page_table_lock); | |
426 | i++; | |
427 | pn = nd; | |
428 | prev = vma->vm_start; | |
429 | pend = vma->vm_end; | |
430 | } | |
431 | j = 0; | |
432 | for (nd = pn; nd; nd = rb_prev(nd)) | |
433 | j++; | |
434 | if (i != j) { | |
435 | pr_emerg("backwards %d, forwards %d\n", j, i); | |
436 | bug = 1; | |
437 | } | |
438 | return bug ? -1 : i; | |
439 | } | |
440 | ||
441 | static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore) | |
442 | { | |
443 | struct rb_node *nd; | |
444 | ||
445 | for (nd = rb_first(root); nd; nd = rb_next(nd)) { | |
446 | struct vm_area_struct *vma; | |
447 | vma = rb_entry(nd, struct vm_area_struct, vm_rb); | |
448 | VM_BUG_ON_VMA(vma != ignore && | |
449 | vma->rb_subtree_gap != vma_compute_subtree_gap(vma), | |
450 | vma); | |
451 | } | |
452 | } | |
453 | ||
454 | static void validate_mm(struct mm_struct *mm) | |
455 | { | |
456 | int bug = 0; | |
457 | int i = 0; | |
458 | unsigned long highest_address = 0; | |
459 | struct vm_area_struct *vma = mm->mmap; | |
460 | ||
461 | while (vma) { | |
462 | struct anon_vma_chain *avc; | |
463 | ||
464 | vma_lock_anon_vma(vma); | |
465 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) | |
466 | anon_vma_interval_tree_verify(avc); | |
467 | vma_unlock_anon_vma(vma); | |
468 | highest_address = vma->vm_end; | |
469 | vma = vma->vm_next; | |
470 | i++; | |
471 | } | |
472 | if (i != mm->map_count) { | |
473 | pr_emerg("map_count %d vm_next %d\n", mm->map_count, i); | |
474 | bug = 1; | |
475 | } | |
476 | if (highest_address != mm->highest_vm_end) { | |
477 | pr_emerg("mm->highest_vm_end %lx, found %lx\n", | |
478 | mm->highest_vm_end, highest_address); | |
479 | bug = 1; | |
480 | } | |
481 | i = browse_rb(mm); | |
482 | if (i != mm->map_count) { | |
483 | if (i != -1) | |
484 | pr_emerg("map_count %d rb %d\n", mm->map_count, i); | |
485 | bug = 1; | |
486 | } | |
487 | VM_BUG_ON_MM(bug, mm); | |
488 | } | |
489 | #else | |
490 | #define validate_mm_rb(root, ignore) do { } while (0) | |
491 | #define validate_mm(mm) do { } while (0) | |
492 | #endif | |
493 | ||
494 | RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb, | |
495 | unsigned long, rb_subtree_gap, vma_compute_subtree_gap) | |
496 | ||
497 | /* | |
498 | * Update augmented rbtree rb_subtree_gap values after vma->vm_start or | |
499 | * vma->vm_prev->vm_end values changed, without modifying the vma's position | |
500 | * in the rbtree. | |
501 | */ | |
502 | static void vma_gap_update(struct vm_area_struct *vma) | |
503 | { | |
504 | /* | |
505 | * As it turns out, RB_DECLARE_CALLBACKS() already created a callback | |
506 | * function that does exacltly what we want. | |
507 | */ | |
508 | vma_gap_callbacks_propagate(&vma->vm_rb, NULL); | |
509 | } | |
510 | ||
511 | static inline void vma_rb_insert(struct vm_area_struct *vma, | |
512 | struct rb_root *root) | |
513 | { | |
514 | /* All rb_subtree_gap values must be consistent prior to insertion */ | |
515 | validate_mm_rb(root, NULL); | |
516 | ||
517 | rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks); | |
518 | } | |
519 | ||
520 | static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root) | |
521 | { | |
522 | /* | |
523 | * All rb_subtree_gap values must be consistent prior to erase, | |
524 | * with the possible exception of the vma being erased. | |
525 | */ | |
526 | validate_mm_rb(root, vma); | |
527 | ||
528 | /* | |
529 | * Note rb_erase_augmented is a fairly large inline function, | |
530 | * so make sure we instantiate it only once with our desired | |
531 | * augmented rbtree callbacks. | |
532 | */ | |
533 | rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks); | |
534 | } | |
535 | ||
536 | /* | |
537 | * vma has some anon_vma assigned, and is already inserted on that | |
538 | * anon_vma's interval trees. | |
539 | * | |
540 | * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the | |
541 | * vma must be removed from the anon_vma's interval trees using | |
542 | * anon_vma_interval_tree_pre_update_vma(). | |
543 | * | |
544 | * After the update, the vma will be reinserted using | |
545 | * anon_vma_interval_tree_post_update_vma(). | |
546 | * | |
547 | * The entire update must be protected by exclusive mmap_sem and by | |
548 | * the root anon_vma's mutex. | |
549 | */ | |
550 | static inline void | |
551 | anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma) | |
552 | { | |
553 | struct anon_vma_chain *avc; | |
554 | ||
555 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) | |
556 | anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root); | |
557 | } | |
558 | ||
559 | static inline void | |
560 | anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma) | |
561 | { | |
562 | struct anon_vma_chain *avc; | |
563 | ||
564 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) | |
565 | anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root); | |
566 | } | |
567 | ||
568 | static int find_vma_links(struct mm_struct *mm, unsigned long addr, | |
569 | unsigned long end, struct vm_area_struct **pprev, | |
570 | struct rb_node ***rb_link, struct rb_node **rb_parent) | |
571 | { | |
572 | struct rb_node **__rb_link, *__rb_parent, *rb_prev; | |
573 | ||
574 | __rb_link = &mm->mm_rb.rb_node; | |
575 | rb_prev = __rb_parent = NULL; | |
576 | ||
577 | while (*__rb_link) { | |
578 | struct vm_area_struct *vma_tmp; | |
579 | ||
580 | __rb_parent = *__rb_link; | |
581 | vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); | |
582 | ||
583 | if (vma_tmp->vm_end > addr) { | |
584 | /* Fail if an existing vma overlaps the area */ | |
585 | if (vma_tmp->vm_start < end) | |
586 | return -ENOMEM; | |
587 | __rb_link = &__rb_parent->rb_left; | |
588 | } else { | |
589 | rb_prev = __rb_parent; | |
590 | __rb_link = &__rb_parent->rb_right; | |
591 | } | |
592 | } | |
593 | ||
594 | *pprev = NULL; | |
595 | if (rb_prev) | |
596 | *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); | |
597 | *rb_link = __rb_link; | |
598 | *rb_parent = __rb_parent; | |
599 | return 0; | |
600 | } | |
601 | ||
602 | static unsigned long count_vma_pages_range(struct mm_struct *mm, | |
603 | unsigned long addr, unsigned long end) | |
604 | { | |
605 | unsigned long nr_pages = 0; | |
606 | struct vm_area_struct *vma; | |
607 | ||
608 | /* Find first overlaping mapping */ | |
609 | vma = find_vma_intersection(mm, addr, end); | |
610 | if (!vma) | |
611 | return 0; | |
612 | ||
613 | nr_pages = (min(end, vma->vm_end) - | |
614 | max(addr, vma->vm_start)) >> PAGE_SHIFT; | |
615 | ||
616 | /* Iterate over the rest of the overlaps */ | |
617 | for (vma = vma->vm_next; vma; vma = vma->vm_next) { | |
618 | unsigned long overlap_len; | |
619 | ||
620 | if (vma->vm_start > end) | |
621 | break; | |
622 | ||
623 | overlap_len = min(end, vma->vm_end) - vma->vm_start; | |
624 | nr_pages += overlap_len >> PAGE_SHIFT; | |
625 | } | |
626 | ||
627 | return nr_pages; | |
628 | } | |
629 | ||
630 | void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, | |
631 | struct rb_node **rb_link, struct rb_node *rb_parent) | |
632 | { | |
633 | /* Update tracking information for the gap following the new vma. */ | |
634 | if (vma->vm_next) | |
635 | vma_gap_update(vma->vm_next); | |
636 | else | |
637 | mm->highest_vm_end = vma->vm_end; | |
638 | ||
639 | /* | |
640 | * vma->vm_prev wasn't known when we followed the rbtree to find the | |
641 | * correct insertion point for that vma. As a result, we could not | |
642 | * update the vma vm_rb parents rb_subtree_gap values on the way down. | |
643 | * So, we first insert the vma with a zero rb_subtree_gap value | |
644 | * (to be consistent with what we did on the way down), and then | |
645 | * immediately update the gap to the correct value. Finally we | |
646 | * rebalance the rbtree after all augmented values have been set. | |
647 | */ | |
648 | rb_link_node(&vma->vm_rb, rb_parent, rb_link); | |
649 | vma->rb_subtree_gap = 0; | |
650 | vma_gap_update(vma); | |
651 | vma_rb_insert(vma, &mm->mm_rb); | |
652 | } | |
653 | ||
654 | static void __vma_link_file(struct vm_area_struct *vma) | |
655 | { | |
656 | struct file *file; | |
657 | ||
658 | file = vma->vm_file; | |
659 | if (file) { | |
660 | struct address_space *mapping = file->f_mapping; | |
661 | ||
662 | if (vma->vm_flags & VM_DENYWRITE) | |
663 | atomic_dec(&file_inode(file)->i_writecount); | |
664 | if (vma->vm_flags & VM_SHARED) | |
665 | atomic_inc(&mapping->i_mmap_writable); | |
666 | ||
667 | flush_dcache_mmap_lock(mapping); | |
668 | vma_interval_tree_insert(vma, &mapping->i_mmap); | |
669 | flush_dcache_mmap_unlock(mapping); | |
670 | } | |
671 | } | |
672 | ||
673 | static void | |
674 | __vma_link(struct mm_struct *mm, struct vm_area_struct *vma, | |
675 | struct vm_area_struct *prev, struct rb_node **rb_link, | |
676 | struct rb_node *rb_parent) | |
677 | { | |
678 | __vma_link_list(mm, vma, prev, rb_parent); | |
679 | __vma_link_rb(mm, vma, rb_link, rb_parent); | |
680 | } | |
681 | ||
682 | static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, | |
683 | struct vm_area_struct *prev, struct rb_node **rb_link, | |
684 | struct rb_node *rb_parent) | |
685 | { | |
686 | struct address_space *mapping = NULL; | |
687 | ||
688 | if (vma->vm_file) { | |
689 | mapping = vma->vm_file->f_mapping; | |
690 | i_mmap_lock_write(mapping); | |
691 | } | |
692 | ||
693 | __vma_link(mm, vma, prev, rb_link, rb_parent); | |
694 | __vma_link_file(vma); | |
695 | ||
696 | if (mapping) | |
697 | i_mmap_unlock_write(mapping); | |
698 | ||
699 | mm->map_count++; | |
700 | validate_mm(mm); | |
701 | } | |
702 | ||
703 | /* | |
704 | * Helper for vma_adjust() in the split_vma insert case: insert a vma into the | |
705 | * mm's list and rbtree. It has already been inserted into the interval tree. | |
706 | */ | |
707 | static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) | |
708 | { | |
709 | struct vm_area_struct *prev; | |
710 | struct rb_node **rb_link, *rb_parent; | |
711 | ||
712 | if (find_vma_links(mm, vma->vm_start, vma->vm_end, | |
713 | &prev, &rb_link, &rb_parent)) | |
714 | BUG(); | |
715 | __vma_link(mm, vma, prev, rb_link, rb_parent); | |
716 | mm->map_count++; | |
717 | } | |
718 | ||
719 | static inline void | |
720 | __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, | |
721 | struct vm_area_struct *prev) | |
722 | { | |
723 | struct vm_area_struct *next; | |
724 | ||
725 | vma_rb_erase(vma, &mm->mm_rb); | |
726 | prev->vm_next = next = vma->vm_next; | |
727 | if (next) | |
728 | next->vm_prev = prev; | |
729 | ||
730 | /* Kill the cache */ | |
731 | vmacache_invalidate(mm); | |
732 | } | |
733 | ||
734 | /* | |
735 | * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that | |
736 | * is already present in an i_mmap tree without adjusting the tree. | |
737 | * The following helper function should be used when such adjustments | |
738 | * are necessary. The "insert" vma (if any) is to be inserted | |
739 | * before we drop the necessary locks. | |
740 | */ | |
741 | int vma_adjust(struct vm_area_struct *vma, unsigned long start, | |
742 | unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert) | |
743 | { | |
744 | struct mm_struct *mm = vma->vm_mm; | |
745 | struct vm_area_struct *next = vma->vm_next; | |
746 | struct vm_area_struct *importer = NULL; | |
747 | struct address_space *mapping = NULL; | |
748 | struct rb_root *root = NULL; | |
749 | struct anon_vma *anon_vma = NULL; | |
750 | struct file *file = vma->vm_file; | |
751 | bool start_changed = false, end_changed = false; | |
752 | long adjust_next = 0; | |
753 | int remove_next = 0; | |
754 | ||
755 | if (next && !insert) { | |
756 | struct vm_area_struct *exporter = NULL; | |
757 | ||
758 | if (end >= next->vm_end) { | |
759 | /* | |
760 | * vma expands, overlapping all the next, and | |
761 | * perhaps the one after too (mprotect case 6). | |
762 | */ | |
763 | again: remove_next = 1 + (end > next->vm_end); | |
764 | end = next->vm_end; | |
765 | exporter = next; | |
766 | importer = vma; | |
767 | } else if (end > next->vm_start) { | |
768 | /* | |
769 | * vma expands, overlapping part of the next: | |
770 | * mprotect case 5 shifting the boundary up. | |
771 | */ | |
772 | adjust_next = (end - next->vm_start) >> PAGE_SHIFT; | |
773 | exporter = next; | |
774 | importer = vma; | |
775 | } else if (end < vma->vm_end) { | |
776 | /* | |
777 | * vma shrinks, and !insert tells it's not | |
778 | * split_vma inserting another: so it must be | |
779 | * mprotect case 4 shifting the boundary down. | |
780 | */ | |
781 | adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT); | |
782 | exporter = vma; | |
783 | importer = next; | |
784 | } | |
785 | ||
786 | /* | |
787 | * Easily overlooked: when mprotect shifts the boundary, | |
788 | * make sure the expanding vma has anon_vma set if the | |
789 | * shrinking vma had, to cover any anon pages imported. | |
790 | */ | |
791 | if (exporter && exporter->anon_vma && !importer->anon_vma) { | |
792 | int error; | |
793 | ||
794 | importer->anon_vma = exporter->anon_vma; | |
795 | error = anon_vma_clone(importer, exporter); | |
796 | if (error) | |
797 | return error; | |
798 | } | |
799 | } | |
800 | ||
801 | if (file) { | |
802 | mapping = file->f_mapping; | |
803 | root = &mapping->i_mmap; | |
804 | uprobe_munmap(vma, vma->vm_start, vma->vm_end); | |
805 | ||
806 | if (adjust_next) | |
807 | uprobe_munmap(next, next->vm_start, next->vm_end); | |
808 | ||
809 | i_mmap_lock_write(mapping); | |
810 | if (insert) { | |
811 | /* | |
812 | * Put into interval tree now, so instantiated pages | |
813 | * are visible to arm/parisc __flush_dcache_page | |
814 | * throughout; but we cannot insert into address | |
815 | * space until vma start or end is updated. | |
816 | */ | |
817 | __vma_link_file(insert); | |
818 | } | |
819 | } | |
820 | ||
821 | vma_adjust_trans_huge(vma, start, end, adjust_next); | |
822 | ||
823 | anon_vma = vma->anon_vma; | |
824 | if (!anon_vma && adjust_next) | |
825 | anon_vma = next->anon_vma; | |
826 | if (anon_vma) { | |
827 | VM_BUG_ON_VMA(adjust_next && next->anon_vma && | |
828 | anon_vma != next->anon_vma, next); | |
829 | anon_vma_lock_write(anon_vma); | |
830 | anon_vma_interval_tree_pre_update_vma(vma); | |
831 | if (adjust_next) | |
832 | anon_vma_interval_tree_pre_update_vma(next); | |
833 | } | |
834 | ||
835 | if (root) { | |
836 | flush_dcache_mmap_lock(mapping); | |
837 | vma_interval_tree_remove(vma, root); | |
838 | if (adjust_next) | |
839 | vma_interval_tree_remove(next, root); | |
840 | } | |
841 | ||
842 | if (start != vma->vm_start) { | |
843 | vma->vm_start = start; | |
844 | start_changed = true; | |
845 | } | |
846 | if (end != vma->vm_end) { | |
847 | vma->vm_end = end; | |
848 | end_changed = true; | |
849 | } | |
850 | vma->vm_pgoff = pgoff; | |
851 | if (adjust_next) { | |
852 | next->vm_start += adjust_next << PAGE_SHIFT; | |
853 | next->vm_pgoff += adjust_next; | |
854 | } | |
855 | ||
856 | if (root) { | |
857 | if (adjust_next) | |
858 | vma_interval_tree_insert(next, root); | |
859 | vma_interval_tree_insert(vma, root); | |
860 | flush_dcache_mmap_unlock(mapping); | |
861 | } | |
862 | ||
863 | if (remove_next) { | |
864 | /* | |
865 | * vma_merge has merged next into vma, and needs | |
866 | * us to remove next before dropping the locks. | |
867 | */ | |
868 | __vma_unlink(mm, next, vma); | |
869 | if (file) | |
870 | __remove_shared_vm_struct(next, file, mapping); | |
871 | } else if (insert) { | |
872 | /* | |
873 | * split_vma has split insert from vma, and needs | |
874 | * us to insert it before dropping the locks | |
875 | * (it may either follow vma or precede it). | |
876 | */ | |
877 | __insert_vm_struct(mm, insert); | |
878 | } else { | |
879 | if (start_changed) | |
880 | vma_gap_update(vma); | |
881 | if (end_changed) { | |
882 | if (!next) | |
883 | mm->highest_vm_end = end; | |
884 | else if (!adjust_next) | |
885 | vma_gap_update(next); | |
886 | } | |
887 | } | |
888 | ||
889 | if (anon_vma) { | |
890 | anon_vma_interval_tree_post_update_vma(vma); | |
891 | if (adjust_next) | |
892 | anon_vma_interval_tree_post_update_vma(next); | |
893 | anon_vma_unlock_write(anon_vma); | |
894 | } | |
895 | if (mapping) | |
896 | i_mmap_unlock_write(mapping); | |
897 | ||
898 | if (root) { | |
899 | uprobe_mmap(vma); | |
900 | ||
901 | if (adjust_next) | |
902 | uprobe_mmap(next); | |
903 | } | |
904 | ||
905 | if (remove_next) { | |
906 | if (file) { | |
907 | uprobe_munmap(next, next->vm_start, next->vm_end); | |
908 | fput(file); | |
909 | } | |
910 | if (next->anon_vma) | |
911 | anon_vma_merge(vma, next); | |
912 | mm->map_count--; | |
913 | mpol_put(vma_policy(next)); | |
914 | kmem_cache_free(vm_area_cachep, next); | |
915 | /* | |
916 | * In mprotect's case 6 (see comments on vma_merge), | |
917 | * we must remove another next too. It would clutter | |
918 | * up the code too much to do both in one go. | |
919 | */ | |
920 | next = vma->vm_next; | |
921 | if (remove_next == 2) | |
922 | goto again; | |
923 | else if (next) | |
924 | vma_gap_update(next); | |
925 | else | |
926 | mm->highest_vm_end = end; | |
927 | } | |
928 | if (insert && file) | |
929 | uprobe_mmap(insert); | |
930 | ||
931 | validate_mm(mm); | |
932 | ||
933 | return 0; | |
934 | } | |
935 | ||
936 | /* | |
937 | * If the vma has a ->close operation then the driver probably needs to release | |
938 | * per-vma resources, so we don't attempt to merge those. | |
939 | */ | |
940 | static inline int is_mergeable_vma(struct vm_area_struct *vma, | |
941 | struct file *file, unsigned long vm_flags, | |
942 | struct vm_userfaultfd_ctx vm_userfaultfd_ctx) | |
943 | { | |
944 | /* | |
945 | * VM_SOFTDIRTY should not prevent from VMA merging, if we | |
946 | * match the flags but dirty bit -- the caller should mark | |
947 | * merged VMA as dirty. If dirty bit won't be excluded from | |
948 | * comparison, we increase pressue on the memory system forcing | |
949 | * the kernel to generate new VMAs when old one could be | |
950 | * extended instead. | |
951 | */ | |
952 | if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY) | |
953 | return 0; | |
954 | if (vma->vm_file != file) | |
955 | return 0; | |
956 | if (vma->vm_ops && vma->vm_ops->close) | |
957 | return 0; | |
958 | if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx)) | |
959 | return 0; | |
960 | return 1; | |
961 | } | |
962 | ||
963 | static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, | |
964 | struct anon_vma *anon_vma2, | |
965 | struct vm_area_struct *vma) | |
966 | { | |
967 | /* | |
968 | * The list_is_singular() test is to avoid merging VMA cloned from | |
969 | * parents. This can improve scalability caused by anon_vma lock. | |
970 | */ | |
971 | if ((!anon_vma1 || !anon_vma2) && (!vma || | |
972 | list_is_singular(&vma->anon_vma_chain))) | |
973 | return 1; | |
974 | return anon_vma1 == anon_vma2; | |
975 | } | |
976 | ||
977 | /* | |
978 | * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) | |
979 | * in front of (at a lower virtual address and file offset than) the vma. | |
980 | * | |
981 | * We cannot merge two vmas if they have differently assigned (non-NULL) | |
982 | * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. | |
983 | * | |
984 | * We don't check here for the merged mmap wrapping around the end of pagecache | |
985 | * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which | |
986 | * wrap, nor mmaps which cover the final page at index -1UL. | |
987 | */ | |
988 | static int | |
989 | can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, | |
990 | struct anon_vma *anon_vma, struct file *file, | |
991 | pgoff_t vm_pgoff, | |
992 | struct vm_userfaultfd_ctx vm_userfaultfd_ctx) | |
993 | { | |
994 | if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) && | |
995 | is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { | |
996 | if (vma->vm_pgoff == vm_pgoff) | |
997 | return 1; | |
998 | } | |
999 | return 0; | |
1000 | } | |
1001 | ||
1002 | /* | |
1003 | * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) | |
1004 | * beyond (at a higher virtual address and file offset than) the vma. | |
1005 | * | |
1006 | * We cannot merge two vmas if they have differently assigned (non-NULL) | |
1007 | * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. | |
1008 | */ | |
1009 | static int | |
1010 | can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, | |
1011 | struct anon_vma *anon_vma, struct file *file, | |
1012 | pgoff_t vm_pgoff, | |
1013 | struct vm_userfaultfd_ctx vm_userfaultfd_ctx) | |
1014 | { | |
1015 | if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) && | |
1016 | is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { | |
1017 | pgoff_t vm_pglen; | |
1018 | vm_pglen = vma_pages(vma); | |
1019 | if (vma->vm_pgoff + vm_pglen == vm_pgoff) | |
1020 | return 1; | |
1021 | } | |
1022 | return 0; | |
1023 | } | |
1024 | ||
1025 | /* | |
1026 | * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out | |
1027 | * whether that can be merged with its predecessor or its successor. | |
1028 | * Or both (it neatly fills a hole). | |
1029 | * | |
1030 | * In most cases - when called for mmap, brk or mremap - [addr,end) is | |
1031 | * certain not to be mapped by the time vma_merge is called; but when | |
1032 | * called for mprotect, it is certain to be already mapped (either at | |
1033 | * an offset within prev, or at the start of next), and the flags of | |
1034 | * this area are about to be changed to vm_flags - and the no-change | |
1035 | * case has already been eliminated. | |
1036 | * | |
1037 | * The following mprotect cases have to be considered, where AAAA is | |
1038 | * the area passed down from mprotect_fixup, never extending beyond one | |
1039 | * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: | |
1040 | * | |
1041 | * AAAA AAAA AAAA AAAA | |
1042 | * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX | |
1043 | * cannot merge might become might become might become | |
1044 | * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or | |
1045 | * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or | |
1046 | * mremap move: PPPPNNNNNNNN 8 | |
1047 | * AAAA | |
1048 | * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN | |
1049 | * might become case 1 below case 2 below case 3 below | |
1050 | * | |
1051 | * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: | |
1052 | * mprotect_fixup updates vm_flags & vm_page_prot on successful return. | |
1053 | */ | |
1054 | struct vm_area_struct *vma_merge(struct mm_struct *mm, | |
1055 | struct vm_area_struct *prev, unsigned long addr, | |
1056 | unsigned long end, unsigned long vm_flags, | |
1057 | struct anon_vma *anon_vma, struct file *file, | |
1058 | pgoff_t pgoff, struct mempolicy *policy, | |
1059 | struct vm_userfaultfd_ctx vm_userfaultfd_ctx) | |
1060 | { | |
1061 | pgoff_t pglen = (end - addr) >> PAGE_SHIFT; | |
1062 | struct vm_area_struct *area, *next; | |
1063 | int err; | |
1064 | ||
1065 | /* | |
1066 | * We later require that vma->vm_flags == vm_flags, | |
1067 | * so this tests vma->vm_flags & VM_SPECIAL, too. | |
1068 | */ | |
1069 | if (vm_flags & VM_SPECIAL) | |
1070 | return NULL; | |
1071 | ||
1072 | if (prev) | |
1073 | next = prev->vm_next; | |
1074 | else | |
1075 | next = mm->mmap; | |
1076 | area = next; | |
1077 | if (next && next->vm_end == end) /* cases 6, 7, 8 */ | |
1078 | next = next->vm_next; | |
1079 | ||
1080 | /* | |
1081 | * Can it merge with the predecessor? | |
1082 | */ | |
1083 | if (prev && prev->vm_end == addr && | |
1084 | mpol_equal(vma_policy(prev), policy) && | |
1085 | can_vma_merge_after(prev, vm_flags, | |
1086 | anon_vma, file, pgoff, | |
1087 | vm_userfaultfd_ctx)) { | |
1088 | /* | |
1089 | * OK, it can. Can we now merge in the successor as well? | |
1090 | */ | |
1091 | if (next && end == next->vm_start && | |
1092 | mpol_equal(policy, vma_policy(next)) && | |
1093 | can_vma_merge_before(next, vm_flags, | |
1094 | anon_vma, file, | |
1095 | pgoff+pglen, | |
1096 | vm_userfaultfd_ctx) && | |
1097 | is_mergeable_anon_vma(prev->anon_vma, | |
1098 | next->anon_vma, NULL)) { | |
1099 | /* cases 1, 6 */ | |
1100 | err = vma_adjust(prev, prev->vm_start, | |
1101 | next->vm_end, prev->vm_pgoff, NULL); | |
1102 | } else /* cases 2, 5, 7 */ | |
1103 | err = vma_adjust(prev, prev->vm_start, | |
1104 | end, prev->vm_pgoff, NULL); | |
1105 | if (err) | |
1106 | return NULL; | |
1107 | khugepaged_enter_vma_merge(prev, vm_flags); | |
1108 | return prev; | |
1109 | } | |
1110 | ||
1111 | /* | |
1112 | * Can this new request be merged in front of next? | |
1113 | */ | |
1114 | if (next && end == next->vm_start && | |
1115 | mpol_equal(policy, vma_policy(next)) && | |
1116 | can_vma_merge_before(next, vm_flags, | |
1117 | anon_vma, file, pgoff+pglen, | |
1118 | vm_userfaultfd_ctx)) { | |
1119 | if (prev && addr < prev->vm_end) /* case 4 */ | |
1120 | err = vma_adjust(prev, prev->vm_start, | |
1121 | addr, prev->vm_pgoff, NULL); | |
1122 | else /* cases 3, 8 */ | |
1123 | err = vma_adjust(area, addr, next->vm_end, | |
1124 | next->vm_pgoff - pglen, NULL); | |
1125 | if (err) | |
1126 | return NULL; | |
1127 | khugepaged_enter_vma_merge(area, vm_flags); | |
1128 | return area; | |
1129 | } | |
1130 | ||
1131 | return NULL; | |
1132 | } | |
1133 | ||
1134 | /* | |
1135 | * Rough compatbility check to quickly see if it's even worth looking | |
1136 | * at sharing an anon_vma. | |
1137 | * | |
1138 | * They need to have the same vm_file, and the flags can only differ | |
1139 | * in things that mprotect may change. | |
1140 | * | |
1141 | * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that | |
1142 | * we can merge the two vma's. For example, we refuse to merge a vma if | |
1143 | * there is a vm_ops->close() function, because that indicates that the | |
1144 | * driver is doing some kind of reference counting. But that doesn't | |
1145 | * really matter for the anon_vma sharing case. | |
1146 | */ | |
1147 | static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b) | |
1148 | { | |
1149 | return a->vm_end == b->vm_start && | |
1150 | mpol_equal(vma_policy(a), vma_policy(b)) && | |
1151 | a->vm_file == b->vm_file && | |
1152 | !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) && | |
1153 | b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT); | |
1154 | } | |
1155 | ||
1156 | /* | |
1157 | * Do some basic sanity checking to see if we can re-use the anon_vma | |
1158 | * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be | |
1159 | * the same as 'old', the other will be the new one that is trying | |
1160 | * to share the anon_vma. | |
1161 | * | |
1162 | * NOTE! This runs with mm_sem held for reading, so it is possible that | |
1163 | * the anon_vma of 'old' is concurrently in the process of being set up | |
1164 | * by another page fault trying to merge _that_. But that's ok: if it | |
1165 | * is being set up, that automatically means that it will be a singleton | |
1166 | * acceptable for merging, so we can do all of this optimistically. But | |
1167 | * we do that READ_ONCE() to make sure that we never re-load the pointer. | |
1168 | * | |
1169 | * IOW: that the "list_is_singular()" test on the anon_vma_chain only | |
1170 | * matters for the 'stable anon_vma' case (ie the thing we want to avoid | |
1171 | * is to return an anon_vma that is "complex" due to having gone through | |
1172 | * a fork). | |
1173 | * | |
1174 | * We also make sure that the two vma's are compatible (adjacent, | |
1175 | * and with the same memory policies). That's all stable, even with just | |
1176 | * a read lock on the mm_sem. | |
1177 | */ | |
1178 | static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b) | |
1179 | { | |
1180 | if (anon_vma_compatible(a, b)) { | |
1181 | struct anon_vma *anon_vma = READ_ONCE(old->anon_vma); | |
1182 | ||
1183 | if (anon_vma && list_is_singular(&old->anon_vma_chain)) | |
1184 | return anon_vma; | |
1185 | } | |
1186 | return NULL; | |
1187 | } | |
1188 | ||
1189 | /* | |
1190 | * find_mergeable_anon_vma is used by anon_vma_prepare, to check | |
1191 | * neighbouring vmas for a suitable anon_vma, before it goes off | |
1192 | * to allocate a new anon_vma. It checks because a repetitive | |
1193 | * sequence of mprotects and faults may otherwise lead to distinct | |
1194 | * anon_vmas being allocated, preventing vma merge in subsequent | |
1195 | * mprotect. | |
1196 | */ | |
1197 | struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) | |
1198 | { | |
1199 | struct anon_vma *anon_vma; | |
1200 | struct vm_area_struct *near; | |
1201 | ||
1202 | near = vma->vm_next; | |
1203 | if (!near) | |
1204 | goto try_prev; | |
1205 | ||
1206 | anon_vma = reusable_anon_vma(near, vma, near); | |
1207 | if (anon_vma) | |
1208 | return anon_vma; | |
1209 | try_prev: | |
1210 | near = vma->vm_prev; | |
1211 | if (!near) | |
1212 | goto none; | |
1213 | ||
1214 | anon_vma = reusable_anon_vma(near, near, vma); | |
1215 | if (anon_vma) | |
1216 | return anon_vma; | |
1217 | none: | |
1218 | /* | |
1219 | * There's no absolute need to look only at touching neighbours: | |
1220 | * we could search further afield for "compatible" anon_vmas. | |
1221 | * But it would probably just be a waste of time searching, | |
1222 | * or lead to too many vmas hanging off the same anon_vma. | |
1223 | * We're trying to allow mprotect remerging later on, | |
1224 | * not trying to minimize memory used for anon_vmas. | |
1225 | */ | |
1226 | return NULL; | |
1227 | } | |
1228 | ||
1229 | /* | |
1230 | * If a hint addr is less than mmap_min_addr change hint to be as | |
1231 | * low as possible but still greater than mmap_min_addr | |
1232 | */ | |
1233 | static inline unsigned long round_hint_to_min(unsigned long hint) | |
1234 | { | |
1235 | hint &= PAGE_MASK; | |
1236 | if (((void *)hint != NULL) && | |
1237 | (hint < mmap_min_addr)) | |
1238 | return PAGE_ALIGN(mmap_min_addr); | |
1239 | return hint; | |
1240 | } | |
1241 | ||
1242 | static inline int mlock_future_check(struct mm_struct *mm, | |
1243 | unsigned long flags, | |
1244 | unsigned long len) | |
1245 | { | |
1246 | unsigned long locked, lock_limit; | |
1247 | ||
1248 | /* mlock MCL_FUTURE? */ | |
1249 | if (flags & VM_LOCKED) { | |
1250 | locked = len >> PAGE_SHIFT; | |
1251 | locked += mm->locked_vm; | |
1252 | lock_limit = rlimit(RLIMIT_MEMLOCK); | |
1253 | lock_limit >>= PAGE_SHIFT; | |
1254 | if (locked > lock_limit && !capable(CAP_IPC_LOCK)) | |
1255 | return -EAGAIN; | |
1256 | } | |
1257 | return 0; | |
1258 | } | |
1259 | ||
1260 | /* | |
1261 | * The caller must hold down_write(¤t->mm->mmap_sem). | |
1262 | */ | |
1263 | unsigned long do_mmap(struct file *file, unsigned long addr, | |
1264 | unsigned long len, unsigned long prot, | |
1265 | unsigned long flags, vm_flags_t vm_flags, | |
1266 | unsigned long pgoff, unsigned long *populate) | |
1267 | { | |
1268 | struct mm_struct *mm = current->mm; | |
1269 | ||
1270 | *populate = 0; | |
1271 | ||
1272 | if (!len) | |
1273 | return -EINVAL; | |
1274 | ||
1275 | /* | |
1276 | * Does the application expect PROT_READ to imply PROT_EXEC? | |
1277 | * | |
1278 | * (the exception is when the underlying filesystem is noexec | |
1279 | * mounted, in which case we dont add PROT_EXEC.) | |
1280 | */ | |
1281 | if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) | |
1282 | if (!(file && path_noexec(&file->f_path))) | |
1283 | prot |= PROT_EXEC; | |
1284 | ||
1285 | if (!(flags & MAP_FIXED)) | |
1286 | addr = round_hint_to_min(addr); | |
1287 | ||
1288 | /* Careful about overflows.. */ | |
1289 | len = PAGE_ALIGN(len); | |
1290 | if (!len) | |
1291 | return -ENOMEM; | |
1292 | ||
1293 | /* offset overflow? */ | |
1294 | if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) | |
1295 | return -EOVERFLOW; | |
1296 | ||
1297 | /* Too many mappings? */ | |
1298 | if (mm->map_count > sysctl_max_map_count) | |
1299 | return -ENOMEM; | |
1300 | ||
1301 | /* Obtain the address to map to. we verify (or select) it and ensure | |
1302 | * that it represents a valid section of the address space. | |
1303 | */ | |
1304 | addr = get_unmapped_area(file, addr, len, pgoff, flags); | |
1305 | if (offset_in_page(addr)) | |
1306 | return addr; | |
1307 | ||
1308 | /* Do simple checking here so the lower-level routines won't have | |
1309 | * to. we assume access permissions have been handled by the open | |
1310 | * of the memory object, so we don't do any here. | |
1311 | */ | |
1312 | vm_flags |= calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) | | |
1313 | mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; | |
1314 | ||
1315 | if (flags & MAP_LOCKED) | |
1316 | if (!can_do_mlock()) | |
1317 | return -EPERM; | |
1318 | ||
1319 | if (mlock_future_check(mm, vm_flags, len)) | |
1320 | return -EAGAIN; | |
1321 | ||
1322 | if (file) { | |
1323 | struct inode *inode = file_inode(file); | |
1324 | ||
1325 | switch (flags & MAP_TYPE) { | |
1326 | case MAP_SHARED: | |
1327 | if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) | |
1328 | return -EACCES; | |
1329 | ||
1330 | /* | |
1331 | * Make sure we don't allow writing to an append-only | |
1332 | * file.. | |
1333 | */ | |
1334 | if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) | |
1335 | return -EACCES; | |
1336 | ||
1337 | /* | |
1338 | * Make sure there are no mandatory locks on the file. | |
1339 | */ | |
1340 | if (locks_verify_locked(file)) | |
1341 | return -EAGAIN; | |
1342 | ||
1343 | vm_flags |= VM_SHARED | VM_MAYSHARE; | |
1344 | if (!(file->f_mode & FMODE_WRITE)) | |
1345 | vm_flags &= ~(VM_MAYWRITE | VM_SHARED); | |
1346 | ||
1347 | /* fall through */ | |
1348 | case MAP_PRIVATE: | |
1349 | if (!(file->f_mode & FMODE_READ)) | |
1350 | return -EACCES; | |
1351 | if (path_noexec(&file->f_path)) { | |
1352 | if (vm_flags & VM_EXEC) | |
1353 | return -EPERM; | |
1354 | vm_flags &= ~VM_MAYEXEC; | |
1355 | } | |
1356 | ||
1357 | if (!file->f_op->mmap) | |
1358 | return -ENODEV; | |
1359 | if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) | |
1360 | return -EINVAL; | |
1361 | break; | |
1362 | ||
1363 | default: | |
1364 | return -EINVAL; | |
1365 | } | |
1366 | } else { | |
1367 | switch (flags & MAP_TYPE) { | |
1368 | case MAP_SHARED: | |
1369 | if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) | |
1370 | return -EINVAL; | |
1371 | /* | |
1372 | * Ignore pgoff. | |
1373 | */ | |
1374 | pgoff = 0; | |
1375 | vm_flags |= VM_SHARED | VM_MAYSHARE; | |
1376 | break; | |
1377 | case MAP_PRIVATE: | |
1378 | /* | |
1379 | * Set pgoff according to addr for anon_vma. | |
1380 | */ | |
1381 | pgoff = addr >> PAGE_SHIFT; | |
1382 | break; | |
1383 | default: | |
1384 | return -EINVAL; | |
1385 | } | |
1386 | } | |
1387 | ||
1388 | /* | |
1389 | * Set 'VM_NORESERVE' if we should not account for the | |
1390 | * memory use of this mapping. | |
1391 | */ | |
1392 | if (flags & MAP_NORESERVE) { | |
1393 | /* We honor MAP_NORESERVE if allowed to overcommit */ | |
1394 | if (sysctl_overcommit_memory != OVERCOMMIT_NEVER) | |
1395 | vm_flags |= VM_NORESERVE; | |
1396 | ||
1397 | /* hugetlb applies strict overcommit unless MAP_NORESERVE */ | |
1398 | if (file && is_file_hugepages(file)) | |
1399 | vm_flags |= VM_NORESERVE; | |
1400 | } | |
1401 | ||
1402 | addr = mmap_region(file, addr, len, vm_flags, pgoff); | |
1403 | if (!IS_ERR_VALUE(addr) && | |
1404 | ((vm_flags & VM_LOCKED) || | |
1405 | (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE)) | |
1406 | *populate = len; | |
1407 | return addr; | |
1408 | } | |
1409 | ||
1410 | SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, | |
1411 | unsigned long, prot, unsigned long, flags, | |
1412 | unsigned long, fd, unsigned long, pgoff) | |
1413 | { | |
1414 | struct file *file = NULL; | |
1415 | unsigned long retval; | |
1416 | ||
1417 | if (!(flags & MAP_ANONYMOUS)) { | |
1418 | audit_mmap_fd(fd, flags); | |
1419 | file = fget(fd); | |
1420 | if (!file) | |
1421 | return -EBADF; | |
1422 | if (is_file_hugepages(file)) | |
1423 | len = ALIGN(len, huge_page_size(hstate_file(file))); | |
1424 | retval = -EINVAL; | |
1425 | if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file))) | |
1426 | goto out_fput; | |
1427 | } else if (flags & MAP_HUGETLB) { | |
1428 | struct user_struct *user = NULL; | |
1429 | struct hstate *hs; | |
1430 | ||
1431 | hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK); | |
1432 | if (!hs) | |
1433 | return -EINVAL; | |
1434 | ||
1435 | len = ALIGN(len, huge_page_size(hs)); | |
1436 | /* | |
1437 | * VM_NORESERVE is used because the reservations will be | |
1438 | * taken when vm_ops->mmap() is called | |
1439 | * A dummy user value is used because we are not locking | |
1440 | * memory so no accounting is necessary | |
1441 | */ | |
1442 | file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, | |
1443 | VM_NORESERVE, | |
1444 | &user, HUGETLB_ANONHUGE_INODE, | |
1445 | (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK); | |
1446 | if (IS_ERR(file)) | |
1447 | return PTR_ERR(file); | |
1448 | } | |
1449 | ||
1450 | flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); | |
1451 | ||
1452 | retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); | |
1453 | out_fput: | |
1454 | if (file) | |
1455 | fput(file); | |
1456 | return retval; | |
1457 | } | |
1458 | ||
1459 | #ifdef __ARCH_WANT_SYS_OLD_MMAP | |
1460 | struct mmap_arg_struct { | |
1461 | unsigned long addr; | |
1462 | unsigned long len; | |
1463 | unsigned long prot; | |
1464 | unsigned long flags; | |
1465 | unsigned long fd; | |
1466 | unsigned long offset; | |
1467 | }; | |
1468 | ||
1469 | SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) | |
1470 | { | |
1471 | struct mmap_arg_struct a; | |
1472 | ||
1473 | if (copy_from_user(&a, arg, sizeof(a))) | |
1474 | return -EFAULT; | |
1475 | if (offset_in_page(a.offset)) | |
1476 | return -EINVAL; | |
1477 | ||
1478 | return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, | |
1479 | a.offset >> PAGE_SHIFT); | |
1480 | } | |
1481 | #endif /* __ARCH_WANT_SYS_OLD_MMAP */ | |
1482 | ||
1483 | /* | |
1484 | * Some shared mappigns will want the pages marked read-only | |
1485 | * to track write events. If so, we'll downgrade vm_page_prot | |
1486 | * to the private version (using protection_map[] without the | |
1487 | * VM_SHARED bit). | |
1488 | */ | |
1489 | int vma_wants_writenotify(struct vm_area_struct *vma) | |
1490 | { | |
1491 | vm_flags_t vm_flags = vma->vm_flags; | |
1492 | const struct vm_operations_struct *vm_ops = vma->vm_ops; | |
1493 | ||
1494 | /* If it was private or non-writable, the write bit is already clear */ | |
1495 | if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) | |
1496 | return 0; | |
1497 | ||
1498 | /* The backer wishes to know when pages are first written to? */ | |
1499 | if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite)) | |
1500 | return 1; | |
1501 | ||
1502 | /* The open routine did something to the protections that pgprot_modify | |
1503 | * won't preserve? */ | |
1504 | if (pgprot_val(vma->vm_page_prot) != | |
1505 | pgprot_val(vm_pgprot_modify(vma->vm_page_prot, vm_flags))) | |
1506 | return 0; | |
1507 | ||
1508 | /* Do we need to track softdirty? */ | |
1509 | if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY)) | |
1510 | return 1; | |
1511 | ||
1512 | /* Specialty mapping? */ | |
1513 | if (vm_flags & VM_PFNMAP) | |
1514 | return 0; | |
1515 | ||
1516 | /* Can the mapping track the dirty pages? */ | |
1517 | return vma->vm_file && vma->vm_file->f_mapping && | |
1518 | mapping_cap_account_dirty(vma->vm_file->f_mapping); | |
1519 | } | |
1520 | ||
1521 | /* | |
1522 | * We account for memory if it's a private writeable mapping, | |
1523 | * not hugepages and VM_NORESERVE wasn't set. | |
1524 | */ | |
1525 | static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags) | |
1526 | { | |
1527 | /* | |
1528 | * hugetlb has its own accounting separate from the core VM | |
1529 | * VM_HUGETLB may not be set yet so we cannot check for that flag. | |
1530 | */ | |
1531 | if (file && is_file_hugepages(file)) | |
1532 | return 0; | |
1533 | ||
1534 | return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE; | |
1535 | } | |
1536 | ||
1537 | unsigned long mmap_region(struct file *file, unsigned long addr, | |
1538 | unsigned long len, vm_flags_t vm_flags, unsigned long pgoff) | |
1539 | { | |
1540 | struct mm_struct *mm = current->mm; | |
1541 | struct vm_area_struct *vma, *prev; | |
1542 | int error; | |
1543 | struct rb_node **rb_link, *rb_parent; | |
1544 | unsigned long charged = 0; | |
1545 | ||
1546 | /* Check against address space limit. */ | |
1547 | if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) { | |
1548 | unsigned long nr_pages; | |
1549 | ||
1550 | /* | |
1551 | * MAP_FIXED may remove pages of mappings that intersects with | |
1552 | * requested mapping. Account for the pages it would unmap. | |
1553 | */ | |
1554 | nr_pages = count_vma_pages_range(mm, addr, addr + len); | |
1555 | ||
1556 | if (!may_expand_vm(mm, vm_flags, | |
1557 | (len >> PAGE_SHIFT) - nr_pages)) | |
1558 | return -ENOMEM; | |
1559 | } | |
1560 | ||
1561 | /* Clear old maps */ | |
1562 | while (find_vma_links(mm, addr, addr + len, &prev, &rb_link, | |
1563 | &rb_parent)) { | |
1564 | if (do_munmap(mm, addr, len)) | |
1565 | return -ENOMEM; | |
1566 | } | |
1567 | ||
1568 | /* | |
1569 | * Private writable mapping: check memory availability | |
1570 | */ | |
1571 | if (accountable_mapping(file, vm_flags)) { | |
1572 | charged = len >> PAGE_SHIFT; | |
1573 | if (security_vm_enough_memory_mm(mm, charged)) | |
1574 | return -ENOMEM; | |
1575 | vm_flags |= VM_ACCOUNT; | |
1576 | } | |
1577 | ||
1578 | /* | |
1579 | * Can we just expand an old mapping? | |
1580 | */ | |
1581 | vma = vma_merge(mm, prev, addr, addr + len, vm_flags, | |
1582 | NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX); | |
1583 | if (vma) | |
1584 | goto out; | |
1585 | ||
1586 | /* | |
1587 | * Determine the object being mapped and call the appropriate | |
1588 | * specific mapper. the address has already been validated, but | |
1589 | * not unmapped, but the maps are removed from the list. | |
1590 | */ | |
1591 | vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); | |
1592 | if (!vma) { | |
1593 | error = -ENOMEM; | |
1594 | goto unacct_error; | |
1595 | } | |
1596 | ||
1597 | vma->vm_mm = mm; | |
1598 | vma->vm_start = addr; | |
1599 | vma->vm_end = addr + len; | |
1600 | vma->vm_flags = vm_flags; | |
1601 | vma->vm_page_prot = vm_get_page_prot(vm_flags); | |
1602 | vma->vm_pgoff = pgoff; | |
1603 | INIT_LIST_HEAD(&vma->anon_vma_chain); | |
1604 | ||
1605 | if (file) { | |
1606 | if (vm_flags & VM_DENYWRITE) { | |
1607 | error = deny_write_access(file); | |
1608 | if (error) | |
1609 | goto free_vma; | |
1610 | } | |
1611 | if (vm_flags & VM_SHARED) { | |
1612 | error = mapping_map_writable(file->f_mapping); | |
1613 | if (error) | |
1614 | goto allow_write_and_free_vma; | |
1615 | } | |
1616 | ||
1617 | /* ->mmap() can change vma->vm_file, but must guarantee that | |
1618 | * vma_link() below can deny write-access if VM_DENYWRITE is set | |
1619 | * and map writably if VM_SHARED is set. This usually means the | |
1620 | * new file must not have been exposed to user-space, yet. | |
1621 | */ | |
1622 | vma->vm_file = get_file(file); | |
1623 | error = file->f_op->mmap(file, vma); | |
1624 | if (error) | |
1625 | goto unmap_and_free_vma; | |
1626 | ||
1627 | /* Can addr have changed?? | |
1628 | * | |
1629 | * Answer: Yes, several device drivers can do it in their | |
1630 | * f_op->mmap method. -DaveM | |
1631 | * Bug: If addr is changed, prev, rb_link, rb_parent should | |
1632 | * be updated for vma_link() | |
1633 | */ | |
1634 | WARN_ON_ONCE(addr != vma->vm_start); | |
1635 | ||
1636 | addr = vma->vm_start; | |
1637 | vm_flags = vma->vm_flags; | |
1638 | } else if (vm_flags & VM_SHARED) { | |
1639 | error = shmem_zero_setup(vma); | |
1640 | if (error) | |
1641 | goto free_vma; | |
1642 | } | |
1643 | ||
1644 | vma_link(mm, vma, prev, rb_link, rb_parent); | |
1645 | /* Once vma denies write, undo our temporary denial count */ | |
1646 | if (file) { | |
1647 | if (vm_flags & VM_SHARED) | |
1648 | mapping_unmap_writable(file->f_mapping); | |
1649 | if (vm_flags & VM_DENYWRITE) | |
1650 | allow_write_access(file); | |
1651 | } | |
1652 | file = vma->vm_file; | |
1653 | out: | |
1654 | perf_event_mmap(vma); | |
1655 | ||
1656 | vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT); | |
1657 | if (vm_flags & VM_LOCKED) { | |
1658 | if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) || | |
1659 | vma == get_gate_vma(current->mm))) | |
1660 | mm->locked_vm += (len >> PAGE_SHIFT); | |
1661 | else | |
1662 | vma->vm_flags &= VM_LOCKED_CLEAR_MASK; | |
1663 | } | |
1664 | ||
1665 | if (file) | |
1666 | uprobe_mmap(vma); | |
1667 | ||
1668 | /* | |
1669 | * New (or expanded) vma always get soft dirty status. | |
1670 | * Otherwise user-space soft-dirty page tracker won't | |
1671 | * be able to distinguish situation when vma area unmapped, | |
1672 | * then new mapped in-place (which must be aimed as | |
1673 | * a completely new data area). | |
1674 | */ | |
1675 | vma->vm_flags |= VM_SOFTDIRTY; | |
1676 | ||
1677 | vma_set_page_prot(vma); | |
1678 | ||
1679 | return addr; | |
1680 | ||
1681 | unmap_and_free_vma: | |
1682 | vma->vm_file = NULL; | |
1683 | fput(file); | |
1684 | ||
1685 | /* Undo any partial mapping done by a device driver. */ | |
1686 | unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); | |
1687 | charged = 0; | |
1688 | if (vm_flags & VM_SHARED) | |
1689 | mapping_unmap_writable(file->f_mapping); | |
1690 | allow_write_and_free_vma: | |
1691 | if (vm_flags & VM_DENYWRITE) | |
1692 | allow_write_access(file); | |
1693 | free_vma: | |
1694 | kmem_cache_free(vm_area_cachep, vma); | |
1695 | unacct_error: | |
1696 | if (charged) | |
1697 | vm_unacct_memory(charged); | |
1698 | return error; | |
1699 | } | |
1700 | ||
1701 | unsigned long unmapped_area(struct vm_unmapped_area_info *info) | |
1702 | { | |
1703 | /* | |
1704 | * We implement the search by looking for an rbtree node that | |
1705 | * immediately follows a suitable gap. That is, | |
1706 | * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length; | |
1707 | * - gap_end = vma->vm_start >= info->low_limit + length; | |
1708 | * - gap_end - gap_start >= length | |
1709 | */ | |
1710 | ||
1711 | struct mm_struct *mm = current->mm; | |
1712 | struct vm_area_struct *vma; | |
1713 | unsigned long length, low_limit, high_limit, gap_start, gap_end; | |
1714 | ||
1715 | /* Adjust search length to account for worst case alignment overhead */ | |
1716 | length = info->length + info->align_mask; | |
1717 | if (length < info->length) | |
1718 | return -ENOMEM; | |
1719 | ||
1720 | /* Adjust search limits by the desired length */ | |
1721 | if (info->high_limit < length) | |
1722 | return -ENOMEM; | |
1723 | high_limit = info->high_limit - length; | |
1724 | ||
1725 | if (info->low_limit > high_limit) | |
1726 | return -ENOMEM; | |
1727 | low_limit = info->low_limit + length; | |
1728 | ||
1729 | /* Check if rbtree root looks promising */ | |
1730 | if (RB_EMPTY_ROOT(&mm->mm_rb)) | |
1731 | goto check_highest; | |
1732 | vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); | |
1733 | if (vma->rb_subtree_gap < length) | |
1734 | goto check_highest; | |
1735 | ||
1736 | while (true) { | |
1737 | /* Visit left subtree if it looks promising */ | |
1738 | gap_end = vma->vm_start; | |
1739 | if (gap_end >= low_limit && vma->vm_rb.rb_left) { | |
1740 | struct vm_area_struct *left = | |
1741 | rb_entry(vma->vm_rb.rb_left, | |
1742 | struct vm_area_struct, vm_rb); | |
1743 | if (left->rb_subtree_gap >= length) { | |
1744 | vma = left; | |
1745 | continue; | |
1746 | } | |
1747 | } | |
1748 | ||
1749 | gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0; | |
1750 | check_current: | |
1751 | /* Check if current node has a suitable gap */ | |
1752 | if (gap_start > high_limit) | |
1753 | return -ENOMEM; | |
1754 | if (gap_end >= low_limit && gap_end - gap_start >= length) | |
1755 | goto found; | |
1756 | ||
1757 | /* Visit right subtree if it looks promising */ | |
1758 | if (vma->vm_rb.rb_right) { | |
1759 | struct vm_area_struct *right = | |
1760 | rb_entry(vma->vm_rb.rb_right, | |
1761 | struct vm_area_struct, vm_rb); | |
1762 | if (right->rb_subtree_gap >= length) { | |
1763 | vma = right; | |
1764 | continue; | |
1765 | } | |
1766 | } | |
1767 | ||
1768 | /* Go back up the rbtree to find next candidate node */ | |
1769 | while (true) { | |
1770 | struct rb_node *prev = &vma->vm_rb; | |
1771 | if (!rb_parent(prev)) | |
1772 | goto check_highest; | |
1773 | vma = rb_entry(rb_parent(prev), | |
1774 | struct vm_area_struct, vm_rb); | |
1775 | if (prev == vma->vm_rb.rb_left) { | |
1776 | gap_start = vma->vm_prev->vm_end; | |
1777 | gap_end = vma->vm_start; | |
1778 | goto check_current; | |
1779 | } | |
1780 | } | |
1781 | } | |
1782 | ||
1783 | check_highest: | |
1784 | /* Check highest gap, which does not precede any rbtree node */ | |
1785 | gap_start = mm->highest_vm_end; | |
1786 | gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */ | |
1787 | if (gap_start > high_limit) | |
1788 | return -ENOMEM; | |
1789 | ||
1790 | found: | |
1791 | /* We found a suitable gap. Clip it with the original low_limit. */ | |
1792 | if (gap_start < info->low_limit) | |
1793 | gap_start = info->low_limit; | |
1794 | ||
1795 | /* Adjust gap address to the desired alignment */ | |
1796 | gap_start += (info->align_offset - gap_start) & info->align_mask; | |
1797 | ||
1798 | VM_BUG_ON(gap_start + info->length > info->high_limit); | |
1799 | VM_BUG_ON(gap_start + info->length > gap_end); | |
1800 | return gap_start; | |
1801 | } | |
1802 | ||
1803 | unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info) | |
1804 | { | |
1805 | struct mm_struct *mm = current->mm; | |
1806 | struct vm_area_struct *vma; | |
1807 | unsigned long length, low_limit, high_limit, gap_start, gap_end; | |
1808 | ||
1809 | /* Adjust search length to account for worst case alignment overhead */ | |
1810 | length = info->length + info->align_mask; | |
1811 | if (length < info->length) | |
1812 | return -ENOMEM; | |
1813 | ||
1814 | /* | |
1815 | * Adjust search limits by the desired length. | |
1816 | * See implementation comment at top of unmapped_area(). | |
1817 | */ | |
1818 | gap_end = info->high_limit; | |
1819 | if (gap_end < length) | |
1820 | return -ENOMEM; | |
1821 | high_limit = gap_end - length; | |
1822 | ||
1823 | if (info->low_limit > high_limit) | |
1824 | return -ENOMEM; | |
1825 | low_limit = info->low_limit + length; | |
1826 | ||
1827 | /* Check highest gap, which does not precede any rbtree node */ | |
1828 | gap_start = mm->highest_vm_end; | |
1829 | if (gap_start <= high_limit) | |
1830 | goto found_highest; | |
1831 | ||
1832 | /* Check if rbtree root looks promising */ | |
1833 | if (RB_EMPTY_ROOT(&mm->mm_rb)) | |
1834 | return -ENOMEM; | |
1835 | vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); | |
1836 | if (vma->rb_subtree_gap < length) | |
1837 | return -ENOMEM; | |
1838 | ||
1839 | while (true) { | |
1840 | /* Visit right subtree if it looks promising */ | |
1841 | gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0; | |
1842 | if (gap_start <= high_limit && vma->vm_rb.rb_right) { | |
1843 | struct vm_area_struct *right = | |
1844 | rb_entry(vma->vm_rb.rb_right, | |
1845 | struct vm_area_struct, vm_rb); | |
1846 | if (right->rb_subtree_gap >= length) { | |
1847 | vma = right; | |
1848 | continue; | |
1849 | } | |
1850 | } | |
1851 | ||
1852 | check_current: | |
1853 | /* Check if current node has a suitable gap */ | |
1854 | gap_end = vma->vm_start; | |
1855 | if (gap_end < low_limit) | |
1856 | return -ENOMEM; | |
1857 | if (gap_start <= high_limit && gap_end - gap_start >= length) | |
1858 | goto found; | |
1859 | ||
1860 | /* Visit left subtree if it looks promising */ | |
1861 | if (vma->vm_rb.rb_left) { | |
1862 | struct vm_area_struct *left = | |
1863 | rb_entry(vma->vm_rb.rb_left, | |
1864 | struct vm_area_struct, vm_rb); | |
1865 | if (left->rb_subtree_gap >= length) { | |
1866 | vma = left; | |
1867 | continue; | |
1868 | } | |
1869 | } | |
1870 | ||
1871 | /* Go back up the rbtree to find next candidate node */ | |
1872 | while (true) { | |
1873 | struct rb_node *prev = &vma->vm_rb; | |
1874 | if (!rb_parent(prev)) | |
1875 | return -ENOMEM; | |
1876 | vma = rb_entry(rb_parent(prev), | |
1877 | struct vm_area_struct, vm_rb); | |
1878 | if (prev == vma->vm_rb.rb_right) { | |
1879 | gap_start = vma->vm_prev ? | |
1880 | vma->vm_prev->vm_end : 0; | |
1881 | goto check_current; | |
1882 | } | |
1883 | } | |
1884 | } | |
1885 | ||
1886 | found: | |
1887 | /* We found a suitable gap. Clip it with the original high_limit. */ | |
1888 | if (gap_end > info->high_limit) | |
1889 | gap_end = info->high_limit; | |
1890 | ||
1891 | found_highest: | |
1892 | /* Compute highest gap address at the desired alignment */ | |
1893 | gap_end -= info->length; | |
1894 | gap_end -= (gap_end - info->align_offset) & info->align_mask; | |
1895 | ||
1896 | VM_BUG_ON(gap_end < info->low_limit); | |
1897 | VM_BUG_ON(gap_end < gap_start); | |
1898 | return gap_end; | |
1899 | } | |
1900 | ||
1901 | /* Get an address range which is currently unmapped. | |
1902 | * For shmat() with addr=0. | |
1903 | * | |
1904 | * Ugly calling convention alert: | |
1905 | * Return value with the low bits set means error value, | |
1906 | * ie | |
1907 | * if (ret & ~PAGE_MASK) | |
1908 | * error = ret; | |
1909 | * | |
1910 | * This function "knows" that -ENOMEM has the bits set. | |
1911 | */ | |
1912 | #ifndef HAVE_ARCH_UNMAPPED_AREA | |
1913 | unsigned long | |
1914 | arch_get_unmapped_area(struct file *filp, unsigned long addr, | |
1915 | unsigned long len, unsigned long pgoff, unsigned long flags) | |
1916 | { | |
1917 | struct mm_struct *mm = current->mm; | |
1918 | struct vm_area_struct *vma; | |
1919 | struct vm_unmapped_area_info info; | |
1920 | ||
1921 | if (len > TASK_SIZE - mmap_min_addr) | |
1922 | return -ENOMEM; | |
1923 | ||
1924 | if (flags & MAP_FIXED) | |
1925 | return addr; | |
1926 | ||
1927 | if (addr) { | |
1928 | addr = PAGE_ALIGN(addr); | |
1929 | vma = find_vma(mm, addr); | |
1930 | if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && | |
1931 | (!vma || addr + len <= vma->vm_start)) | |
1932 | return addr; | |
1933 | } | |
1934 | ||
1935 | info.flags = 0; | |
1936 | info.length = len; | |
1937 | info.low_limit = mm->mmap_base; | |
1938 | info.high_limit = TASK_SIZE; | |
1939 | info.align_mask = 0; | |
1940 | return vm_unmapped_area(&info); | |
1941 | } | |
1942 | #endif | |
1943 | ||
1944 | /* | |
1945 | * This mmap-allocator allocates new areas top-down from below the | |
1946 | * stack's low limit (the base): | |
1947 | */ | |
1948 | #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN | |
1949 | unsigned long | |
1950 | arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, | |
1951 | const unsigned long len, const unsigned long pgoff, | |
1952 | const unsigned long flags) | |
1953 | { | |
1954 | struct vm_area_struct *vma; | |
1955 | struct mm_struct *mm = current->mm; | |
1956 | unsigned long addr = addr0; | |
1957 | struct vm_unmapped_area_info info; | |
1958 | ||
1959 | /* requested length too big for entire address space */ | |
1960 | if (len > TASK_SIZE - mmap_min_addr) | |
1961 | return -ENOMEM; | |
1962 | ||
1963 | if (flags & MAP_FIXED) | |
1964 | return addr; | |
1965 | ||
1966 | /* requesting a specific address */ | |
1967 | if (addr) { | |
1968 | addr = PAGE_ALIGN(addr); | |
1969 | vma = find_vma(mm, addr); | |
1970 | if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && | |
1971 | (!vma || addr + len <= vma->vm_start)) | |
1972 | return addr; | |
1973 | } | |
1974 | ||
1975 | info.flags = VM_UNMAPPED_AREA_TOPDOWN; | |
1976 | info.length = len; | |
1977 | info.low_limit = max(PAGE_SIZE, mmap_min_addr); | |
1978 | info.high_limit = mm->mmap_base; | |
1979 | info.align_mask = 0; | |
1980 | addr = vm_unmapped_area(&info); | |
1981 | ||
1982 | /* | |
1983 | * A failed mmap() very likely causes application failure, | |
1984 | * so fall back to the bottom-up function here. This scenario | |
1985 | * can happen with large stack limits and large mmap() | |
1986 | * allocations. | |
1987 | */ | |
1988 | if (offset_in_page(addr)) { | |
1989 | VM_BUG_ON(addr != -ENOMEM); | |
1990 | info.flags = 0; | |
1991 | info.low_limit = TASK_UNMAPPED_BASE; | |
1992 | info.high_limit = TASK_SIZE; | |
1993 | addr = vm_unmapped_area(&info); | |
1994 | } | |
1995 | ||
1996 | return addr; | |
1997 | } | |
1998 | #endif | |
1999 | ||
2000 | unsigned long | |
2001 | get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, | |
2002 | unsigned long pgoff, unsigned long flags) | |
2003 | { | |
2004 | unsigned long (*get_area)(struct file *, unsigned long, | |
2005 | unsigned long, unsigned long, unsigned long); | |
2006 | ||
2007 | unsigned long error = arch_mmap_check(addr, len, flags); | |
2008 | if (error) | |
2009 | return error; | |
2010 | ||
2011 | /* Careful about overflows.. */ | |
2012 | if (len > TASK_SIZE) | |
2013 | return -ENOMEM; | |
2014 | ||
2015 | get_area = current->mm->get_unmapped_area; | |
2016 | if (file && file->f_op->get_unmapped_area) | |
2017 | get_area = file->f_op->get_unmapped_area; | |
2018 | addr = get_area(file, addr, len, pgoff, flags); | |
2019 | if (IS_ERR_VALUE(addr)) | |
2020 | return addr; | |
2021 | ||
2022 | if (addr > TASK_SIZE - len) | |
2023 | return -ENOMEM; | |
2024 | if (offset_in_page(addr)) | |
2025 | return -EINVAL; | |
2026 | ||
2027 | addr = arch_rebalance_pgtables(addr, len); | |
2028 | error = security_mmap_addr(addr); | |
2029 | return error ? error : addr; | |
2030 | } | |
2031 | ||
2032 | EXPORT_SYMBOL(get_unmapped_area); | |
2033 | ||
2034 | /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ | |
2035 | struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) | |
2036 | { | |
2037 | struct rb_node *rb_node; | |
2038 | struct vm_area_struct *vma; | |
2039 | ||
2040 | /* Check the cache first. */ | |
2041 | vma = vmacache_find(mm, addr); | |
2042 | if (likely(vma)) | |
2043 | return vma; | |
2044 | ||
2045 | rb_node = mm->mm_rb.rb_node; | |
2046 | ||
2047 | while (rb_node) { | |
2048 | struct vm_area_struct *tmp; | |
2049 | ||
2050 | tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); | |
2051 | ||
2052 | if (tmp->vm_end > addr) { | |
2053 | vma = tmp; | |
2054 | if (tmp->vm_start <= addr) | |
2055 | break; | |
2056 | rb_node = rb_node->rb_left; | |
2057 | } else | |
2058 | rb_node = rb_node->rb_right; | |
2059 | } | |
2060 | ||
2061 | if (vma) | |
2062 | vmacache_update(addr, vma); | |
2063 | return vma; | |
2064 | } | |
2065 | ||
2066 | EXPORT_SYMBOL(find_vma); | |
2067 | ||
2068 | /* | |
2069 | * Same as find_vma, but also return a pointer to the previous VMA in *pprev. | |
2070 | */ | |
2071 | struct vm_area_struct * | |
2072 | find_vma_prev(struct mm_struct *mm, unsigned long addr, | |
2073 | struct vm_area_struct **pprev) | |
2074 | { | |
2075 | struct vm_area_struct *vma; | |
2076 | ||
2077 | vma = find_vma(mm, addr); | |
2078 | if (vma) { | |
2079 | *pprev = vma->vm_prev; | |
2080 | } else { | |
2081 | struct rb_node *rb_node = mm->mm_rb.rb_node; | |
2082 | *pprev = NULL; | |
2083 | while (rb_node) { | |
2084 | *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb); | |
2085 | rb_node = rb_node->rb_right; | |
2086 | } | |
2087 | } | |
2088 | return vma; | |
2089 | } | |
2090 | ||
2091 | /* | |
2092 | * Verify that the stack growth is acceptable and | |
2093 | * update accounting. This is shared with both the | |
2094 | * grow-up and grow-down cases. | |
2095 | */ | |
2096 | static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow) | |
2097 | { | |
2098 | struct mm_struct *mm = vma->vm_mm; | |
2099 | struct rlimit *rlim = current->signal->rlim; | |
2100 | unsigned long new_start, actual_size; | |
2101 | ||
2102 | /* address space limit tests */ | |
2103 | if (!may_expand_vm(mm, vma->vm_flags, grow)) | |
2104 | return -ENOMEM; | |
2105 | ||
2106 | /* Stack limit test */ | |
2107 | actual_size = size; | |
2108 | if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN))) | |
2109 | actual_size -= PAGE_SIZE; | |
2110 | if (actual_size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur)) | |
2111 | return -ENOMEM; | |
2112 | ||
2113 | /* mlock limit tests */ | |
2114 | if (vma->vm_flags & VM_LOCKED) { | |
2115 | unsigned long locked; | |
2116 | unsigned long limit; | |
2117 | locked = mm->locked_vm + grow; | |
2118 | limit = READ_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur); | |
2119 | limit >>= PAGE_SHIFT; | |
2120 | if (locked > limit && !capable(CAP_IPC_LOCK)) | |
2121 | return -ENOMEM; | |
2122 | } | |
2123 | ||
2124 | /* Check to ensure the stack will not grow into a hugetlb-only region */ | |
2125 | new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : | |
2126 | vma->vm_end - size; | |
2127 | if (is_hugepage_only_range(vma->vm_mm, new_start, size)) | |
2128 | return -EFAULT; | |
2129 | ||
2130 | /* | |
2131 | * Overcommit.. This must be the final test, as it will | |
2132 | * update security statistics. | |
2133 | */ | |
2134 | if (security_vm_enough_memory_mm(mm, grow)) | |
2135 | return -ENOMEM; | |
2136 | ||
2137 | return 0; | |
2138 | } | |
2139 | ||
2140 | #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) | |
2141 | /* | |
2142 | * PA-RISC uses this for its stack; IA64 for its Register Backing Store. | |
2143 | * vma is the last one with address > vma->vm_end. Have to extend vma. | |
2144 | */ | |
2145 | int expand_upwards(struct vm_area_struct *vma, unsigned long address) | |
2146 | { | |
2147 | struct mm_struct *mm = vma->vm_mm; | |
2148 | int error; | |
2149 | ||
2150 | if (!(vma->vm_flags & VM_GROWSUP)) | |
2151 | return -EFAULT; | |
2152 | ||
2153 | /* | |
2154 | * We must make sure the anon_vma is allocated | |
2155 | * so that the anon_vma locking is not a noop. | |
2156 | */ | |
2157 | if (unlikely(anon_vma_prepare(vma))) | |
2158 | return -ENOMEM; | |
2159 | vma_lock_anon_vma(vma); | |
2160 | ||
2161 | /* | |
2162 | * vma->vm_start/vm_end cannot change under us because the caller | |
2163 | * is required to hold the mmap_sem in read mode. We need the | |
2164 | * anon_vma lock to serialize against concurrent expand_stacks. | |
2165 | * Also guard against wrapping around to address 0. | |
2166 | */ | |
2167 | if (address < PAGE_ALIGN(address+4)) | |
2168 | address = PAGE_ALIGN(address+4); | |
2169 | else { | |
2170 | vma_unlock_anon_vma(vma); | |
2171 | return -ENOMEM; | |
2172 | } | |
2173 | error = 0; | |
2174 | ||
2175 | /* Somebody else might have raced and expanded it already */ | |
2176 | if (address > vma->vm_end) { | |
2177 | unsigned long size, grow; | |
2178 | ||
2179 | size = address - vma->vm_start; | |
2180 | grow = (address - vma->vm_end) >> PAGE_SHIFT; | |
2181 | ||
2182 | error = -ENOMEM; | |
2183 | if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) { | |
2184 | error = acct_stack_growth(vma, size, grow); | |
2185 | if (!error) { | |
2186 | /* | |
2187 | * vma_gap_update() doesn't support concurrent | |
2188 | * updates, but we only hold a shared mmap_sem | |
2189 | * lock here, so we need to protect against | |
2190 | * concurrent vma expansions. | |
2191 | * vma_lock_anon_vma() doesn't help here, as | |
2192 | * we don't guarantee that all growable vmas | |
2193 | * in a mm share the same root anon vma. | |
2194 | * So, we reuse mm->page_table_lock to guard | |
2195 | * against concurrent vma expansions. | |
2196 | */ | |
2197 | spin_lock(&mm->page_table_lock); | |
2198 | if (vma->vm_flags & VM_LOCKED) | |
2199 | mm->locked_vm += grow; | |
2200 | vm_stat_account(mm, vma->vm_flags, grow); | |
2201 | anon_vma_interval_tree_pre_update_vma(vma); | |
2202 | vma->vm_end = address; | |
2203 | anon_vma_interval_tree_post_update_vma(vma); | |
2204 | if (vma->vm_next) | |
2205 | vma_gap_update(vma->vm_next); | |
2206 | else | |
2207 | mm->highest_vm_end = address; | |
2208 | spin_unlock(&mm->page_table_lock); | |
2209 | ||
2210 | perf_event_mmap(vma); | |
2211 | } | |
2212 | } | |
2213 | } | |
2214 | vma_unlock_anon_vma(vma); | |
2215 | khugepaged_enter_vma_merge(vma, vma->vm_flags); | |
2216 | validate_mm(mm); | |
2217 | return error; | |
2218 | } | |
2219 | #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ | |
2220 | ||
2221 | /* | |
2222 | * vma is the first one with address < vma->vm_start. Have to extend vma. | |
2223 | */ | |
2224 | int expand_downwards(struct vm_area_struct *vma, | |
2225 | unsigned long address) | |
2226 | { | |
2227 | struct mm_struct *mm = vma->vm_mm; | |
2228 | int error; | |
2229 | ||
2230 | /* | |
2231 | * We must make sure the anon_vma is allocated | |
2232 | * so that the anon_vma locking is not a noop. | |
2233 | */ | |
2234 | if (unlikely(anon_vma_prepare(vma))) | |
2235 | return -ENOMEM; | |
2236 | ||
2237 | address &= PAGE_MASK; | |
2238 | error = security_mmap_addr(address); | |
2239 | if (error) | |
2240 | return error; | |
2241 | ||
2242 | vma_lock_anon_vma(vma); | |
2243 | ||
2244 | /* | |
2245 | * vma->vm_start/vm_end cannot change under us because the caller | |
2246 | * is required to hold the mmap_sem in read mode. We need the | |
2247 | * anon_vma lock to serialize against concurrent expand_stacks. | |
2248 | */ | |
2249 | ||
2250 | /* Somebody else might have raced and expanded it already */ | |
2251 | if (address < vma->vm_start) { | |
2252 | unsigned long size, grow; | |
2253 | ||
2254 | size = vma->vm_end - address; | |
2255 | grow = (vma->vm_start - address) >> PAGE_SHIFT; | |
2256 | ||
2257 | error = -ENOMEM; | |
2258 | if (grow <= vma->vm_pgoff) { | |
2259 | error = acct_stack_growth(vma, size, grow); | |
2260 | if (!error) { | |
2261 | /* | |
2262 | * vma_gap_update() doesn't support concurrent | |
2263 | * updates, but we only hold a shared mmap_sem | |
2264 | * lock here, so we need to protect against | |
2265 | * concurrent vma expansions. | |
2266 | * vma_lock_anon_vma() doesn't help here, as | |
2267 | * we don't guarantee that all growable vmas | |
2268 | * in a mm share the same root anon vma. | |
2269 | * So, we reuse mm->page_table_lock to guard | |
2270 | * against concurrent vma expansions. | |
2271 | */ | |
2272 | spin_lock(&mm->page_table_lock); | |
2273 | if (vma->vm_flags & VM_LOCKED) | |
2274 | mm->locked_vm += grow; | |
2275 | vm_stat_account(mm, vma->vm_flags, grow); | |
2276 | anon_vma_interval_tree_pre_update_vma(vma); | |
2277 | vma->vm_start = address; | |
2278 | vma->vm_pgoff -= grow; | |
2279 | anon_vma_interval_tree_post_update_vma(vma); | |
2280 | vma_gap_update(vma); | |
2281 | spin_unlock(&mm->page_table_lock); | |
2282 | ||
2283 | perf_event_mmap(vma); | |
2284 | } | |
2285 | } | |
2286 | } | |
2287 | vma_unlock_anon_vma(vma); | |
2288 | khugepaged_enter_vma_merge(vma, vma->vm_flags); | |
2289 | validate_mm(mm); | |
2290 | return error; | |
2291 | } | |
2292 | ||
2293 | /* | |
2294 | * Note how expand_stack() refuses to expand the stack all the way to | |
2295 | * abut the next virtual mapping, *unless* that mapping itself is also | |
2296 | * a stack mapping. We want to leave room for a guard page, after all | |
2297 | * (the guard page itself is not added here, that is done by the | |
2298 | * actual page faulting logic) | |
2299 | * | |
2300 | * This matches the behavior of the guard page logic (see mm/memory.c: | |
2301 | * check_stack_guard_page()), which only allows the guard page to be | |
2302 | * removed under these circumstances. | |
2303 | */ | |
2304 | #ifdef CONFIG_STACK_GROWSUP | |
2305 | int expand_stack(struct vm_area_struct *vma, unsigned long address) | |
2306 | { | |
2307 | struct vm_area_struct *next; | |
2308 | ||
2309 | address &= PAGE_MASK; | |
2310 | next = vma->vm_next; | |
2311 | if (next && next->vm_start == address + PAGE_SIZE) { | |
2312 | if (!(next->vm_flags & VM_GROWSUP)) | |
2313 | return -ENOMEM; | |
2314 | } | |
2315 | return expand_upwards(vma, address); | |
2316 | } | |
2317 | ||
2318 | struct vm_area_struct * | |
2319 | find_extend_vma(struct mm_struct *mm, unsigned long addr) | |
2320 | { | |
2321 | struct vm_area_struct *vma, *prev; | |
2322 | ||
2323 | addr &= PAGE_MASK; | |
2324 | vma = find_vma_prev(mm, addr, &prev); | |
2325 | if (vma && (vma->vm_start <= addr)) | |
2326 | return vma; | |
2327 | if (!prev || expand_stack(prev, addr)) | |
2328 | return NULL; | |
2329 | if (prev->vm_flags & VM_LOCKED) | |
2330 | populate_vma_page_range(prev, addr, prev->vm_end, NULL); | |
2331 | return prev; | |
2332 | } | |
2333 | #else | |
2334 | int expand_stack(struct vm_area_struct *vma, unsigned long address) | |
2335 | { | |
2336 | struct vm_area_struct *prev; | |
2337 | ||
2338 | address &= PAGE_MASK; | |
2339 | prev = vma->vm_prev; | |
2340 | if (prev && prev->vm_end == address) { | |
2341 | if (!(prev->vm_flags & VM_GROWSDOWN)) | |
2342 | return -ENOMEM; | |
2343 | } | |
2344 | return expand_downwards(vma, address); | |
2345 | } | |
2346 | ||
2347 | struct vm_area_struct * | |
2348 | find_extend_vma(struct mm_struct *mm, unsigned long addr) | |
2349 | { | |
2350 | struct vm_area_struct *vma; | |
2351 | unsigned long start; | |
2352 | ||
2353 | addr &= PAGE_MASK; | |
2354 | vma = find_vma(mm, addr); | |
2355 | if (!vma) | |
2356 | return NULL; | |
2357 | if (vma->vm_start <= addr) | |
2358 | return vma; | |
2359 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
2360 | return NULL; | |
2361 | start = vma->vm_start; | |
2362 | if (expand_stack(vma, addr)) | |
2363 | return NULL; | |
2364 | if (vma->vm_flags & VM_LOCKED) | |
2365 | populate_vma_page_range(vma, addr, start, NULL); | |
2366 | return vma; | |
2367 | } | |
2368 | #endif | |
2369 | ||
2370 | EXPORT_SYMBOL_GPL(find_extend_vma); | |
2371 | ||
2372 | /* | |
2373 | * Ok - we have the memory areas we should free on the vma list, | |
2374 | * so release them, and do the vma updates. | |
2375 | * | |
2376 | * Called with the mm semaphore held. | |
2377 | */ | |
2378 | static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) | |
2379 | { | |
2380 | unsigned long nr_accounted = 0; | |
2381 | ||
2382 | /* Update high watermark before we lower total_vm */ | |
2383 | update_hiwater_vm(mm); | |
2384 | do { | |
2385 | long nrpages = vma_pages(vma); | |
2386 | ||
2387 | if (vma->vm_flags & VM_ACCOUNT) | |
2388 | nr_accounted += nrpages; | |
2389 | vm_stat_account(mm, vma->vm_flags, -nrpages); | |
2390 | vma = remove_vma(vma); | |
2391 | } while (vma); | |
2392 | vm_unacct_memory(nr_accounted); | |
2393 | validate_mm(mm); | |
2394 | } | |
2395 | ||
2396 | /* | |
2397 | * Get rid of page table information in the indicated region. | |
2398 | * | |
2399 | * Called with the mm semaphore held. | |
2400 | */ | |
2401 | static void unmap_region(struct mm_struct *mm, | |
2402 | struct vm_area_struct *vma, struct vm_area_struct *prev, | |
2403 | unsigned long start, unsigned long end) | |
2404 | { | |
2405 | struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap; | |
2406 | struct mmu_gather tlb; | |
2407 | ||
2408 | lru_add_drain(); | |
2409 | tlb_gather_mmu(&tlb, mm, start, end); | |
2410 | update_hiwater_rss(mm); | |
2411 | unmap_vmas(&tlb, vma, start, end); | |
2412 | free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, | |
2413 | next ? next->vm_start : USER_PGTABLES_CEILING); | |
2414 | tlb_finish_mmu(&tlb, start, end); | |
2415 | } | |
2416 | ||
2417 | /* | |
2418 | * Create a list of vma's touched by the unmap, removing them from the mm's | |
2419 | * vma list as we go.. | |
2420 | */ | |
2421 | static void | |
2422 | detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, | |
2423 | struct vm_area_struct *prev, unsigned long end) | |
2424 | { | |
2425 | struct vm_area_struct **insertion_point; | |
2426 | struct vm_area_struct *tail_vma = NULL; | |
2427 | ||
2428 | insertion_point = (prev ? &prev->vm_next : &mm->mmap); | |
2429 | vma->vm_prev = NULL; | |
2430 | do { | |
2431 | vma_rb_erase(vma, &mm->mm_rb); | |
2432 | mm->map_count--; | |
2433 | tail_vma = vma; | |
2434 | vma = vma->vm_next; | |
2435 | } while (vma && vma->vm_start < end); | |
2436 | *insertion_point = vma; | |
2437 | if (vma) { | |
2438 | vma->vm_prev = prev; | |
2439 | vma_gap_update(vma); | |
2440 | } else | |
2441 | mm->highest_vm_end = prev ? prev->vm_end : 0; | |
2442 | tail_vma->vm_next = NULL; | |
2443 | ||
2444 | /* Kill the cache */ | |
2445 | vmacache_invalidate(mm); | |
2446 | } | |
2447 | ||
2448 | /* | |
2449 | * __split_vma() bypasses sysctl_max_map_count checking. We use this on the | |
2450 | * munmap path where it doesn't make sense to fail. | |
2451 | */ | |
2452 | static int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma, | |
2453 | unsigned long addr, int new_below) | |
2454 | { | |
2455 | struct vm_area_struct *new; | |
2456 | int err; | |
2457 | ||
2458 | if (is_vm_hugetlb_page(vma) && (addr & | |
2459 | ~(huge_page_mask(hstate_vma(vma))))) | |
2460 | return -EINVAL; | |
2461 | ||
2462 | new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); | |
2463 | if (!new) | |
2464 | return -ENOMEM; | |
2465 | ||
2466 | /* most fields are the same, copy all, and then fixup */ | |
2467 | *new = *vma; | |
2468 | ||
2469 | INIT_LIST_HEAD(&new->anon_vma_chain); | |
2470 | ||
2471 | if (new_below) | |
2472 | new->vm_end = addr; | |
2473 | else { | |
2474 | new->vm_start = addr; | |
2475 | new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); | |
2476 | } | |
2477 | ||
2478 | err = vma_dup_policy(vma, new); | |
2479 | if (err) | |
2480 | goto out_free_vma; | |
2481 | ||
2482 | err = anon_vma_clone(new, vma); | |
2483 | if (err) | |
2484 | goto out_free_mpol; | |
2485 | ||
2486 | if (new->vm_file) | |
2487 | get_file(new->vm_file); | |
2488 | ||
2489 | if (new->vm_ops && new->vm_ops->open) | |
2490 | new->vm_ops->open(new); | |
2491 | ||
2492 | if (new_below) | |
2493 | err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + | |
2494 | ((addr - new->vm_start) >> PAGE_SHIFT), new); | |
2495 | else | |
2496 | err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); | |
2497 | ||
2498 | /* Success. */ | |
2499 | if (!err) | |
2500 | return 0; | |
2501 | ||
2502 | /* Clean everything up if vma_adjust failed. */ | |
2503 | if (new->vm_ops && new->vm_ops->close) | |
2504 | new->vm_ops->close(new); | |
2505 | if (new->vm_file) | |
2506 | fput(new->vm_file); | |
2507 | unlink_anon_vmas(new); | |
2508 | out_free_mpol: | |
2509 | mpol_put(vma_policy(new)); | |
2510 | out_free_vma: | |
2511 | kmem_cache_free(vm_area_cachep, new); | |
2512 | return err; | |
2513 | } | |
2514 | ||
2515 | /* | |
2516 | * Split a vma into two pieces at address 'addr', a new vma is allocated | |
2517 | * either for the first part or the tail. | |
2518 | */ | |
2519 | int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, | |
2520 | unsigned long addr, int new_below) | |
2521 | { | |
2522 | if (mm->map_count >= sysctl_max_map_count) | |
2523 | return -ENOMEM; | |
2524 | ||
2525 | return __split_vma(mm, vma, addr, new_below); | |
2526 | } | |
2527 | ||
2528 | /* Munmap is split into 2 main parts -- this part which finds | |
2529 | * what needs doing, and the areas themselves, which do the | |
2530 | * work. This now handles partial unmappings. | |
2531 | * Jeremy Fitzhardinge <jeremy@goop.org> | |
2532 | */ | |
2533 | int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) | |
2534 | { | |
2535 | unsigned long end; | |
2536 | struct vm_area_struct *vma, *prev, *last; | |
2537 | ||
2538 | if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start) | |
2539 | return -EINVAL; | |
2540 | ||
2541 | len = PAGE_ALIGN(len); | |
2542 | if (len == 0) | |
2543 | return -EINVAL; | |
2544 | ||
2545 | /* Find the first overlapping VMA */ | |
2546 | vma = find_vma(mm, start); | |
2547 | if (!vma) | |
2548 | return 0; | |
2549 | prev = vma->vm_prev; | |
2550 | /* we have start < vma->vm_end */ | |
2551 | ||
2552 | /* if it doesn't overlap, we have nothing.. */ | |
2553 | end = start + len; | |
2554 | if (vma->vm_start >= end) | |
2555 | return 0; | |
2556 | ||
2557 | /* | |
2558 | * If we need to split any vma, do it now to save pain later. | |
2559 | * | |
2560 | * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially | |
2561 | * unmapped vm_area_struct will remain in use: so lower split_vma | |
2562 | * places tmp vma above, and higher split_vma places tmp vma below. | |
2563 | */ | |
2564 | if (start > vma->vm_start) { | |
2565 | int error; | |
2566 | ||
2567 | /* | |
2568 | * Make sure that map_count on return from munmap() will | |
2569 | * not exceed its limit; but let map_count go just above | |
2570 | * its limit temporarily, to help free resources as expected. | |
2571 | */ | |
2572 | if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) | |
2573 | return -ENOMEM; | |
2574 | ||
2575 | error = __split_vma(mm, vma, start, 0); | |
2576 | if (error) | |
2577 | return error; | |
2578 | prev = vma; | |
2579 | } | |
2580 | ||
2581 | /* Does it split the last one? */ | |
2582 | last = find_vma(mm, end); | |
2583 | if (last && end > last->vm_start) { | |
2584 | int error = __split_vma(mm, last, end, 1); | |
2585 | if (error) | |
2586 | return error; | |
2587 | } | |
2588 | vma = prev ? prev->vm_next : mm->mmap; | |
2589 | ||
2590 | /* | |
2591 | * unlock any mlock()ed ranges before detaching vmas | |
2592 | */ | |
2593 | if (mm->locked_vm) { | |
2594 | struct vm_area_struct *tmp = vma; | |
2595 | while (tmp && tmp->vm_start < end) { | |
2596 | if (tmp->vm_flags & VM_LOCKED) { | |
2597 | mm->locked_vm -= vma_pages(tmp); | |
2598 | munlock_vma_pages_all(tmp); | |
2599 | } | |
2600 | tmp = tmp->vm_next; | |
2601 | } | |
2602 | } | |
2603 | ||
2604 | /* | |
2605 | * Remove the vma's, and unmap the actual pages | |
2606 | */ | |
2607 | detach_vmas_to_be_unmapped(mm, vma, prev, end); | |
2608 | unmap_region(mm, vma, prev, start, end); | |
2609 | ||
2610 | arch_unmap(mm, vma, start, end); | |
2611 | ||
2612 | /* Fix up all other VM information */ | |
2613 | remove_vma_list(mm, vma); | |
2614 | ||
2615 | return 0; | |
2616 | } | |
2617 | ||
2618 | int vm_munmap(unsigned long start, size_t len) | |
2619 | { | |
2620 | int ret; | |
2621 | struct mm_struct *mm = current->mm; | |
2622 | ||
2623 | down_write(&mm->mmap_sem); | |
2624 | ret = do_munmap(mm, start, len); | |
2625 | up_write(&mm->mmap_sem); | |
2626 | return ret; | |
2627 | } | |
2628 | EXPORT_SYMBOL(vm_munmap); | |
2629 | ||
2630 | SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) | |
2631 | { | |
2632 | profile_munmap(addr); | |
2633 | return vm_munmap(addr, len); | |
2634 | } | |
2635 | ||
2636 | ||
2637 | /* | |
2638 | * Emulation of deprecated remap_file_pages() syscall. | |
2639 | */ | |
2640 | SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size, | |
2641 | unsigned long, prot, unsigned long, pgoff, unsigned long, flags) | |
2642 | { | |
2643 | ||
2644 | struct mm_struct *mm = current->mm; | |
2645 | struct vm_area_struct *vma; | |
2646 | unsigned long populate = 0; | |
2647 | unsigned long ret = -EINVAL; | |
2648 | struct file *file; | |
2649 | ||
2650 | pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. " | |
2651 | "See Documentation/vm/remap_file_pages.txt.\n", | |
2652 | current->comm, current->pid); | |
2653 | ||
2654 | if (prot) | |
2655 | return ret; | |
2656 | start = start & PAGE_MASK; | |
2657 | size = size & PAGE_MASK; | |
2658 | ||
2659 | if (start + size <= start) | |
2660 | return ret; | |
2661 | ||
2662 | /* Does pgoff wrap? */ | |
2663 | if (pgoff + (size >> PAGE_SHIFT) < pgoff) | |
2664 | return ret; | |
2665 | ||
2666 | down_write(&mm->mmap_sem); | |
2667 | vma = find_vma(mm, start); | |
2668 | ||
2669 | if (!vma || !(vma->vm_flags & VM_SHARED)) | |
2670 | goto out; | |
2671 | ||
2672 | if (start < vma->vm_start || start + size > vma->vm_end) | |
2673 | goto out; | |
2674 | ||
2675 | if (pgoff == linear_page_index(vma, start)) { | |
2676 | ret = 0; | |
2677 | goto out; | |
2678 | } | |
2679 | ||
2680 | prot |= vma->vm_flags & VM_READ ? PROT_READ : 0; | |
2681 | prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0; | |
2682 | prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0; | |
2683 | ||
2684 | flags &= MAP_NONBLOCK; | |
2685 | flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE; | |
2686 | if (vma->vm_flags & VM_LOCKED) { | |
2687 | flags |= MAP_LOCKED; | |
2688 | /* drop PG_Mlocked flag for over-mapped range */ | |
2689 | munlock_vma_pages_range(vma, start, start + size); | |
2690 | } | |
2691 | ||
2692 | file = get_file(vma->vm_file); | |
2693 | ret = do_mmap_pgoff(vma->vm_file, start, size, | |
2694 | prot, flags, pgoff, &populate); | |
2695 | fput(file); | |
2696 | out: | |
2697 | up_write(&mm->mmap_sem); | |
2698 | if (populate) | |
2699 | mm_populate(ret, populate); | |
2700 | if (!IS_ERR_VALUE(ret)) | |
2701 | ret = 0; | |
2702 | return ret; | |
2703 | } | |
2704 | ||
2705 | static inline void verify_mm_writelocked(struct mm_struct *mm) | |
2706 | { | |
2707 | #ifdef CONFIG_DEBUG_VM | |
2708 | if (unlikely(down_read_trylock(&mm->mmap_sem))) { | |
2709 | WARN_ON(1); | |
2710 | up_read(&mm->mmap_sem); | |
2711 | } | |
2712 | #endif | |
2713 | } | |
2714 | ||
2715 | /* | |
2716 | * this is really a simplified "do_mmap". it only handles | |
2717 | * anonymous maps. eventually we may be able to do some | |
2718 | * brk-specific accounting here. | |
2719 | */ | |
2720 | static unsigned long do_brk(unsigned long addr, unsigned long len) | |
2721 | { | |
2722 | struct mm_struct *mm = current->mm; | |
2723 | struct vm_area_struct *vma, *prev; | |
2724 | unsigned long flags; | |
2725 | struct rb_node **rb_link, *rb_parent; | |
2726 | pgoff_t pgoff = addr >> PAGE_SHIFT; | |
2727 | int error; | |
2728 | ||
2729 | len = PAGE_ALIGN(len); | |
2730 | if (!len) | |
2731 | return addr; | |
2732 | ||
2733 | flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; | |
2734 | ||
2735 | error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED); | |
2736 | if (offset_in_page(error)) | |
2737 | return error; | |
2738 | ||
2739 | error = mlock_future_check(mm, mm->def_flags, len); | |
2740 | if (error) | |
2741 | return error; | |
2742 | ||
2743 | /* | |
2744 | * mm->mmap_sem is required to protect against another thread | |
2745 | * changing the mappings in case we sleep. | |
2746 | */ | |
2747 | verify_mm_writelocked(mm); | |
2748 | ||
2749 | /* | |
2750 | * Clear old maps. this also does some error checking for us | |
2751 | */ | |
2752 | while (find_vma_links(mm, addr, addr + len, &prev, &rb_link, | |
2753 | &rb_parent)) { | |
2754 | if (do_munmap(mm, addr, len)) | |
2755 | return -ENOMEM; | |
2756 | } | |
2757 | ||
2758 | /* Check against address space limits *after* clearing old maps... */ | |
2759 | if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT)) | |
2760 | return -ENOMEM; | |
2761 | ||
2762 | if (mm->map_count > sysctl_max_map_count) | |
2763 | return -ENOMEM; | |
2764 | ||
2765 | if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT)) | |
2766 | return -ENOMEM; | |
2767 | ||
2768 | /* Can we just expand an old private anonymous mapping? */ | |
2769 | vma = vma_merge(mm, prev, addr, addr + len, flags, | |
2770 | NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX); | |
2771 | if (vma) | |
2772 | goto out; | |
2773 | ||
2774 | /* | |
2775 | * create a vma struct for an anonymous mapping | |
2776 | */ | |
2777 | vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); | |
2778 | if (!vma) { | |
2779 | vm_unacct_memory(len >> PAGE_SHIFT); | |
2780 | return -ENOMEM; | |
2781 | } | |
2782 | ||
2783 | INIT_LIST_HEAD(&vma->anon_vma_chain); | |
2784 | vma->vm_mm = mm; | |
2785 | vma->vm_start = addr; | |
2786 | vma->vm_end = addr + len; | |
2787 | vma->vm_pgoff = pgoff; | |
2788 | vma->vm_flags = flags; | |
2789 | vma->vm_page_prot = vm_get_page_prot(flags); | |
2790 | vma_link(mm, vma, prev, rb_link, rb_parent); | |
2791 | out: | |
2792 | perf_event_mmap(vma); | |
2793 | mm->total_vm += len >> PAGE_SHIFT; | |
2794 | mm->data_vm += len >> PAGE_SHIFT; | |
2795 | if (flags & VM_LOCKED) | |
2796 | mm->locked_vm += (len >> PAGE_SHIFT); | |
2797 | vma->vm_flags |= VM_SOFTDIRTY; | |
2798 | return addr; | |
2799 | } | |
2800 | ||
2801 | unsigned long vm_brk(unsigned long addr, unsigned long len) | |
2802 | { | |
2803 | struct mm_struct *mm = current->mm; | |
2804 | unsigned long ret; | |
2805 | bool populate; | |
2806 | ||
2807 | down_write(&mm->mmap_sem); | |
2808 | ret = do_brk(addr, len); | |
2809 | populate = ((mm->def_flags & VM_LOCKED) != 0); | |
2810 | up_write(&mm->mmap_sem); | |
2811 | if (populate) | |
2812 | mm_populate(addr, len); | |
2813 | return ret; | |
2814 | } | |
2815 | EXPORT_SYMBOL(vm_brk); | |
2816 | ||
2817 | /* Release all mmaps. */ | |
2818 | void exit_mmap(struct mm_struct *mm) | |
2819 | { | |
2820 | struct mmu_gather tlb; | |
2821 | struct vm_area_struct *vma; | |
2822 | unsigned long nr_accounted = 0; | |
2823 | ||
2824 | /* mm's last user has gone, and its about to be pulled down */ | |
2825 | mmu_notifier_release(mm); | |
2826 | ||
2827 | if (mm->locked_vm) { | |
2828 | vma = mm->mmap; | |
2829 | while (vma) { | |
2830 | if (vma->vm_flags & VM_LOCKED) | |
2831 | munlock_vma_pages_all(vma); | |
2832 | vma = vma->vm_next; | |
2833 | } | |
2834 | } | |
2835 | ||
2836 | arch_exit_mmap(mm); | |
2837 | ||
2838 | vma = mm->mmap; | |
2839 | if (!vma) /* Can happen if dup_mmap() received an OOM */ | |
2840 | return; | |
2841 | ||
2842 | lru_add_drain(); | |
2843 | flush_cache_mm(mm); | |
2844 | tlb_gather_mmu(&tlb, mm, 0, -1); | |
2845 | /* update_hiwater_rss(mm) here? but nobody should be looking */ | |
2846 | /* Use -1 here to ensure all VMAs in the mm are unmapped */ | |
2847 | unmap_vmas(&tlb, vma, 0, -1); | |
2848 | ||
2849 | free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING); | |
2850 | tlb_finish_mmu(&tlb, 0, -1); | |
2851 | ||
2852 | /* | |
2853 | * Walk the list again, actually closing and freeing it, | |
2854 | * with preemption enabled, without holding any MM locks. | |
2855 | */ | |
2856 | while (vma) { | |
2857 | if (vma->vm_flags & VM_ACCOUNT) | |
2858 | nr_accounted += vma_pages(vma); | |
2859 | vma = remove_vma(vma); | |
2860 | } | |
2861 | vm_unacct_memory(nr_accounted); | |
2862 | } | |
2863 | ||
2864 | /* Insert vm structure into process list sorted by address | |
2865 | * and into the inode's i_mmap tree. If vm_file is non-NULL | |
2866 | * then i_mmap_rwsem is taken here. | |
2867 | */ | |
2868 | int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) | |
2869 | { | |
2870 | struct vm_area_struct *prev; | |
2871 | struct rb_node **rb_link, *rb_parent; | |
2872 | ||
2873 | if (find_vma_links(mm, vma->vm_start, vma->vm_end, | |
2874 | &prev, &rb_link, &rb_parent)) | |
2875 | return -ENOMEM; | |
2876 | if ((vma->vm_flags & VM_ACCOUNT) && | |
2877 | security_vm_enough_memory_mm(mm, vma_pages(vma))) | |
2878 | return -ENOMEM; | |
2879 | ||
2880 | /* | |
2881 | * The vm_pgoff of a purely anonymous vma should be irrelevant | |
2882 | * until its first write fault, when page's anon_vma and index | |
2883 | * are set. But now set the vm_pgoff it will almost certainly | |
2884 | * end up with (unless mremap moves it elsewhere before that | |
2885 | * first wfault), so /proc/pid/maps tells a consistent story. | |
2886 | * | |
2887 | * By setting it to reflect the virtual start address of the | |
2888 | * vma, merges and splits can happen in a seamless way, just | |
2889 | * using the existing file pgoff checks and manipulations. | |
2890 | * Similarly in do_mmap_pgoff and in do_brk. | |
2891 | */ | |
2892 | if (vma_is_anonymous(vma)) { | |
2893 | BUG_ON(vma->anon_vma); | |
2894 | vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; | |
2895 | } | |
2896 | ||
2897 | vma_link(mm, vma, prev, rb_link, rb_parent); | |
2898 | return 0; | |
2899 | } | |
2900 | ||
2901 | /* | |
2902 | * Copy the vma structure to a new location in the same mm, | |
2903 | * prior to moving page table entries, to effect an mremap move. | |
2904 | */ | |
2905 | struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, | |
2906 | unsigned long addr, unsigned long len, pgoff_t pgoff, | |
2907 | bool *need_rmap_locks) | |
2908 | { | |
2909 | struct vm_area_struct *vma = *vmap; | |
2910 | unsigned long vma_start = vma->vm_start; | |
2911 | struct mm_struct *mm = vma->vm_mm; | |
2912 | struct vm_area_struct *new_vma, *prev; | |
2913 | struct rb_node **rb_link, *rb_parent; | |
2914 | bool faulted_in_anon_vma = true; | |
2915 | ||
2916 | /* | |
2917 | * If anonymous vma has not yet been faulted, update new pgoff | |
2918 | * to match new location, to increase its chance of merging. | |
2919 | */ | |
2920 | if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) { | |
2921 | pgoff = addr >> PAGE_SHIFT; | |
2922 | faulted_in_anon_vma = false; | |
2923 | } | |
2924 | ||
2925 | if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) | |
2926 | return NULL; /* should never get here */ | |
2927 | new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, | |
2928 | vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma), | |
2929 | vma->vm_userfaultfd_ctx); | |
2930 | if (new_vma) { | |
2931 | /* | |
2932 | * Source vma may have been merged into new_vma | |
2933 | */ | |
2934 | if (unlikely(vma_start >= new_vma->vm_start && | |
2935 | vma_start < new_vma->vm_end)) { | |
2936 | /* | |
2937 | * The only way we can get a vma_merge with | |
2938 | * self during an mremap is if the vma hasn't | |
2939 | * been faulted in yet and we were allowed to | |
2940 | * reset the dst vma->vm_pgoff to the | |
2941 | * destination address of the mremap to allow | |
2942 | * the merge to happen. mremap must change the | |
2943 | * vm_pgoff linearity between src and dst vmas | |
2944 | * (in turn preventing a vma_merge) to be | |
2945 | * safe. It is only safe to keep the vm_pgoff | |
2946 | * linear if there are no pages mapped yet. | |
2947 | */ | |
2948 | VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma); | |
2949 | *vmap = vma = new_vma; | |
2950 | } | |
2951 | *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff); | |
2952 | } else { | |
2953 | new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); | |
2954 | if (!new_vma) | |
2955 | goto out; | |
2956 | *new_vma = *vma; | |
2957 | new_vma->vm_start = addr; | |
2958 | new_vma->vm_end = addr + len; | |
2959 | new_vma->vm_pgoff = pgoff; | |
2960 | if (vma_dup_policy(vma, new_vma)) | |
2961 | goto out_free_vma; | |
2962 | INIT_LIST_HEAD(&new_vma->anon_vma_chain); | |
2963 | if (anon_vma_clone(new_vma, vma)) | |
2964 | goto out_free_mempol; | |
2965 | if (new_vma->vm_file) | |
2966 | get_file(new_vma->vm_file); | |
2967 | if (new_vma->vm_ops && new_vma->vm_ops->open) | |
2968 | new_vma->vm_ops->open(new_vma); | |
2969 | vma_link(mm, new_vma, prev, rb_link, rb_parent); | |
2970 | *need_rmap_locks = false; | |
2971 | } | |
2972 | return new_vma; | |
2973 | ||
2974 | out_free_mempol: | |
2975 | mpol_put(vma_policy(new_vma)); | |
2976 | out_free_vma: | |
2977 | kmem_cache_free(vm_area_cachep, new_vma); | |
2978 | out: | |
2979 | return NULL; | |
2980 | } | |
2981 | ||
2982 | /* | |
2983 | * Return true if the calling process may expand its vm space by the passed | |
2984 | * number of pages | |
2985 | */ | |
2986 | bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages) | |
2987 | { | |
2988 | if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT) | |
2989 | return false; | |
2990 | ||
2991 | if (is_data_mapping(flags) && | |
2992 | mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) { | |
2993 | if (ignore_rlimit_data) | |
2994 | pr_warn_once("%s (%d): VmData %lu exceed data ulimit " | |
2995 | "%lu. Will be forbidden soon.\n", | |
2996 | current->comm, current->pid, | |
2997 | (mm->data_vm + npages) << PAGE_SHIFT, | |
2998 | rlimit(RLIMIT_DATA)); | |
2999 | else | |
3000 | return false; | |
3001 | } | |
3002 | ||
3003 | return true; | |
3004 | } | |
3005 | ||
3006 | void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages) | |
3007 | { | |
3008 | mm->total_vm += npages; | |
3009 | ||
3010 | if (is_exec_mapping(flags)) | |
3011 | mm->exec_vm += npages; | |
3012 | else if (is_stack_mapping(flags)) | |
3013 | mm->stack_vm += npages; | |
3014 | else if (is_data_mapping(flags)) | |
3015 | mm->data_vm += npages; | |
3016 | } | |
3017 | ||
3018 | static int special_mapping_fault(struct vm_area_struct *vma, | |
3019 | struct vm_fault *vmf); | |
3020 | ||
3021 | /* | |
3022 | * Having a close hook prevents vma merging regardless of flags. | |
3023 | */ | |
3024 | static void special_mapping_close(struct vm_area_struct *vma) | |
3025 | { | |
3026 | } | |
3027 | ||
3028 | static const char *special_mapping_name(struct vm_area_struct *vma) | |
3029 | { | |
3030 | return ((struct vm_special_mapping *)vma->vm_private_data)->name; | |
3031 | } | |
3032 | ||
3033 | static const struct vm_operations_struct special_mapping_vmops = { | |
3034 | .close = special_mapping_close, | |
3035 | .fault = special_mapping_fault, | |
3036 | .name = special_mapping_name, | |
3037 | }; | |
3038 | ||
3039 | static const struct vm_operations_struct legacy_special_mapping_vmops = { | |
3040 | .close = special_mapping_close, | |
3041 | .fault = special_mapping_fault, | |
3042 | }; | |
3043 | ||
3044 | static int special_mapping_fault(struct vm_area_struct *vma, | |
3045 | struct vm_fault *vmf) | |
3046 | { | |
3047 | pgoff_t pgoff; | |
3048 | struct page **pages; | |
3049 | ||
3050 | if (vma->vm_ops == &legacy_special_mapping_vmops) | |
3051 | pages = vma->vm_private_data; | |
3052 | else | |
3053 | pages = ((struct vm_special_mapping *)vma->vm_private_data)-> | |
3054 | pages; | |
3055 | ||
3056 | for (pgoff = vmf->pgoff; pgoff && *pages; ++pages) | |
3057 | pgoff--; | |
3058 | ||
3059 | if (*pages) { | |
3060 | struct page *page = *pages; | |
3061 | get_page(page); | |
3062 | vmf->page = page; | |
3063 | return 0; | |
3064 | } | |
3065 | ||
3066 | return VM_FAULT_SIGBUS; | |
3067 | } | |
3068 | ||
3069 | static struct vm_area_struct *__install_special_mapping( | |
3070 | struct mm_struct *mm, | |
3071 | unsigned long addr, unsigned long len, | |
3072 | unsigned long vm_flags, void *priv, | |
3073 | const struct vm_operations_struct *ops) | |
3074 | { | |
3075 | int ret; | |
3076 | struct vm_area_struct *vma; | |
3077 | ||
3078 | vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); | |
3079 | if (unlikely(vma == NULL)) | |
3080 | return ERR_PTR(-ENOMEM); | |
3081 | ||
3082 | INIT_LIST_HEAD(&vma->anon_vma_chain); | |
3083 | vma->vm_mm = mm; | |
3084 | vma->vm_start = addr; | |
3085 | vma->vm_end = addr + len; | |
3086 | ||
3087 | vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY; | |
3088 | vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); | |
3089 | ||
3090 | vma->vm_ops = ops; | |
3091 | vma->vm_private_data = priv; | |
3092 | ||
3093 | ret = insert_vm_struct(mm, vma); | |
3094 | if (ret) | |
3095 | goto out; | |
3096 | ||
3097 | vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT); | |
3098 | ||
3099 | perf_event_mmap(vma); | |
3100 | ||
3101 | return vma; | |
3102 | ||
3103 | out: | |
3104 | kmem_cache_free(vm_area_cachep, vma); | |
3105 | return ERR_PTR(ret); | |
3106 | } | |
3107 | ||
3108 | /* | |
3109 | * Called with mm->mmap_sem held for writing. | |
3110 | * Insert a new vma covering the given region, with the given flags. | |
3111 | * Its pages are supplied by the given array of struct page *. | |
3112 | * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. | |
3113 | * The region past the last page supplied will always produce SIGBUS. | |
3114 | * The array pointer and the pages it points to are assumed to stay alive | |
3115 | * for as long as this mapping might exist. | |
3116 | */ | |
3117 | struct vm_area_struct *_install_special_mapping( | |
3118 | struct mm_struct *mm, | |
3119 | unsigned long addr, unsigned long len, | |
3120 | unsigned long vm_flags, const struct vm_special_mapping *spec) | |
3121 | { | |
3122 | return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec, | |
3123 | &special_mapping_vmops); | |
3124 | } | |
3125 | ||
3126 | int install_special_mapping(struct mm_struct *mm, | |
3127 | unsigned long addr, unsigned long len, | |
3128 | unsigned long vm_flags, struct page **pages) | |
3129 | { | |
3130 | struct vm_area_struct *vma = __install_special_mapping( | |
3131 | mm, addr, len, vm_flags, (void *)pages, | |
3132 | &legacy_special_mapping_vmops); | |
3133 | ||
3134 | return PTR_ERR_OR_ZERO(vma); | |
3135 | } | |
3136 | ||
3137 | static DEFINE_MUTEX(mm_all_locks_mutex); | |
3138 | ||
3139 | static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) | |
3140 | { | |
3141 | if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) { | |
3142 | /* | |
3143 | * The LSB of head.next can't change from under us | |
3144 | * because we hold the mm_all_locks_mutex. | |
3145 | */ | |
3146 | down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem); | |
3147 | /* | |
3148 | * We can safely modify head.next after taking the | |
3149 | * anon_vma->root->rwsem. If some other vma in this mm shares | |
3150 | * the same anon_vma we won't take it again. | |
3151 | * | |
3152 | * No need of atomic instructions here, head.next | |
3153 | * can't change from under us thanks to the | |
3154 | * anon_vma->root->rwsem. | |
3155 | */ | |
3156 | if (__test_and_set_bit(0, (unsigned long *) | |
3157 | &anon_vma->root->rb_root.rb_node)) | |
3158 | BUG(); | |
3159 | } | |
3160 | } | |
3161 | ||
3162 | static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) | |
3163 | { | |
3164 | if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { | |
3165 | /* | |
3166 | * AS_MM_ALL_LOCKS can't change from under us because | |
3167 | * we hold the mm_all_locks_mutex. | |
3168 | * | |
3169 | * Operations on ->flags have to be atomic because | |
3170 | * even if AS_MM_ALL_LOCKS is stable thanks to the | |
3171 | * mm_all_locks_mutex, there may be other cpus | |
3172 | * changing other bitflags in parallel to us. | |
3173 | */ | |
3174 | if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) | |
3175 | BUG(); | |
3176 | down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem); | |
3177 | } | |
3178 | } | |
3179 | ||
3180 | /* | |
3181 | * This operation locks against the VM for all pte/vma/mm related | |
3182 | * operations that could ever happen on a certain mm. This includes | |
3183 | * vmtruncate, try_to_unmap, and all page faults. | |
3184 | * | |
3185 | * The caller must take the mmap_sem in write mode before calling | |
3186 | * mm_take_all_locks(). The caller isn't allowed to release the | |
3187 | * mmap_sem until mm_drop_all_locks() returns. | |
3188 | * | |
3189 | * mmap_sem in write mode is required in order to block all operations | |
3190 | * that could modify pagetables and free pages without need of | |
3191 | * altering the vma layout. It's also needed in write mode to avoid new | |
3192 | * anon_vmas to be associated with existing vmas. | |
3193 | * | |
3194 | * A single task can't take more than one mm_take_all_locks() in a row | |
3195 | * or it would deadlock. | |
3196 | * | |
3197 | * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in | |
3198 | * mapping->flags avoid to take the same lock twice, if more than one | |
3199 | * vma in this mm is backed by the same anon_vma or address_space. | |
3200 | * | |
3201 | * We take locks in following order, accordingly to comment at beginning | |
3202 | * of mm/rmap.c: | |
3203 | * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for | |
3204 | * hugetlb mapping); | |
3205 | * - all i_mmap_rwsem locks; | |
3206 | * - all anon_vma->rwseml | |
3207 | * | |
3208 | * We can take all locks within these types randomly because the VM code | |
3209 | * doesn't nest them and we protected from parallel mm_take_all_locks() by | |
3210 | * mm_all_locks_mutex. | |
3211 | * | |
3212 | * mm_take_all_locks() and mm_drop_all_locks are expensive operations | |
3213 | * that may have to take thousand of locks. | |
3214 | * | |
3215 | * mm_take_all_locks() can fail if it's interrupted by signals. | |
3216 | */ | |
3217 | int mm_take_all_locks(struct mm_struct *mm) | |
3218 | { | |
3219 | struct vm_area_struct *vma; | |
3220 | struct anon_vma_chain *avc; | |
3221 | ||
3222 | BUG_ON(down_read_trylock(&mm->mmap_sem)); | |
3223 | ||
3224 | mutex_lock(&mm_all_locks_mutex); | |
3225 | ||
3226 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
3227 | if (signal_pending(current)) | |
3228 | goto out_unlock; | |
3229 | if (vma->vm_file && vma->vm_file->f_mapping && | |
3230 | is_vm_hugetlb_page(vma)) | |
3231 | vm_lock_mapping(mm, vma->vm_file->f_mapping); | |
3232 | } | |
3233 | ||
3234 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
3235 | if (signal_pending(current)) | |
3236 | goto out_unlock; | |
3237 | if (vma->vm_file && vma->vm_file->f_mapping && | |
3238 | !is_vm_hugetlb_page(vma)) | |
3239 | vm_lock_mapping(mm, vma->vm_file->f_mapping); | |
3240 | } | |
3241 | ||
3242 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
3243 | if (signal_pending(current)) | |
3244 | goto out_unlock; | |
3245 | if (vma->anon_vma) | |
3246 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) | |
3247 | vm_lock_anon_vma(mm, avc->anon_vma); | |
3248 | } | |
3249 | ||
3250 | return 0; | |
3251 | ||
3252 | out_unlock: | |
3253 | mm_drop_all_locks(mm); | |
3254 | return -EINTR; | |
3255 | } | |
3256 | ||
3257 | static void vm_unlock_anon_vma(struct anon_vma *anon_vma) | |
3258 | { | |
3259 | if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) { | |
3260 | /* | |
3261 | * The LSB of head.next can't change to 0 from under | |
3262 | * us because we hold the mm_all_locks_mutex. | |
3263 | * | |
3264 | * We must however clear the bitflag before unlocking | |
3265 | * the vma so the users using the anon_vma->rb_root will | |
3266 | * never see our bitflag. | |
3267 | * | |
3268 | * No need of atomic instructions here, head.next | |
3269 | * can't change from under us until we release the | |
3270 | * anon_vma->root->rwsem. | |
3271 | */ | |
3272 | if (!__test_and_clear_bit(0, (unsigned long *) | |
3273 | &anon_vma->root->rb_root.rb_node)) | |
3274 | BUG(); | |
3275 | anon_vma_unlock_write(anon_vma); | |
3276 | } | |
3277 | } | |
3278 | ||
3279 | static void vm_unlock_mapping(struct address_space *mapping) | |
3280 | { | |
3281 | if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { | |
3282 | /* | |
3283 | * AS_MM_ALL_LOCKS can't change to 0 from under us | |
3284 | * because we hold the mm_all_locks_mutex. | |
3285 | */ | |
3286 | i_mmap_unlock_write(mapping); | |
3287 | if (!test_and_clear_bit(AS_MM_ALL_LOCKS, | |
3288 | &mapping->flags)) | |
3289 | BUG(); | |
3290 | } | |
3291 | } | |
3292 | ||
3293 | /* | |
3294 | * The mmap_sem cannot be released by the caller until | |
3295 | * mm_drop_all_locks() returns. | |
3296 | */ | |
3297 | void mm_drop_all_locks(struct mm_struct *mm) | |
3298 | { | |
3299 | struct vm_area_struct *vma; | |
3300 | struct anon_vma_chain *avc; | |
3301 | ||
3302 | BUG_ON(down_read_trylock(&mm->mmap_sem)); | |
3303 | BUG_ON(!mutex_is_locked(&mm_all_locks_mutex)); | |
3304 | ||
3305 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
3306 | if (vma->anon_vma) | |
3307 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) | |
3308 | vm_unlock_anon_vma(avc->anon_vma); | |
3309 | if (vma->vm_file && vma->vm_file->f_mapping) | |
3310 | vm_unlock_mapping(vma->vm_file->f_mapping); | |
3311 | } | |
3312 | ||
3313 | mutex_unlock(&mm_all_locks_mutex); | |
3314 | } | |
3315 | ||
3316 | /* | |
3317 | * initialise the VMA slab | |
3318 | */ | |
3319 | void __init mmap_init(void) | |
3320 | { | |
3321 | int ret; | |
3322 | ||
3323 | ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL); | |
3324 | VM_BUG_ON(ret); | |
3325 | } | |
3326 | ||
3327 | /* | |
3328 | * Initialise sysctl_user_reserve_kbytes. | |
3329 | * | |
3330 | * This is intended to prevent a user from starting a single memory hogging | |
3331 | * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER | |
3332 | * mode. | |
3333 | * | |
3334 | * The default value is min(3% of free memory, 128MB) | |
3335 | * 128MB is enough to recover with sshd/login, bash, and top/kill. | |
3336 | */ | |
3337 | static int init_user_reserve(void) | |
3338 | { | |
3339 | unsigned long free_kbytes; | |
3340 | ||
3341 | free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); | |
3342 | ||
3343 | sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17); | |
3344 | return 0; | |
3345 | } | |
3346 | subsys_initcall(init_user_reserve); | |
3347 | ||
3348 | /* | |
3349 | * Initialise sysctl_admin_reserve_kbytes. | |
3350 | * | |
3351 | * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin | |
3352 | * to log in and kill a memory hogging process. | |
3353 | * | |
3354 | * Systems with more than 256MB will reserve 8MB, enough to recover | |
3355 | * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will | |
3356 | * only reserve 3% of free pages by default. | |
3357 | */ | |
3358 | static int init_admin_reserve(void) | |
3359 | { | |
3360 | unsigned long free_kbytes; | |
3361 | ||
3362 | free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); | |
3363 | ||
3364 | sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13); | |
3365 | return 0; | |
3366 | } | |
3367 | subsys_initcall(init_admin_reserve); | |
3368 | ||
3369 | /* | |
3370 | * Reinititalise user and admin reserves if memory is added or removed. | |
3371 | * | |
3372 | * The default user reserve max is 128MB, and the default max for the | |
3373 | * admin reserve is 8MB. These are usually, but not always, enough to | |
3374 | * enable recovery from a memory hogging process using login/sshd, a shell, | |
3375 | * and tools like top. It may make sense to increase or even disable the | |
3376 | * reserve depending on the existence of swap or variations in the recovery | |
3377 | * tools. So, the admin may have changed them. | |
3378 | * | |
3379 | * If memory is added and the reserves have been eliminated or increased above | |
3380 | * the default max, then we'll trust the admin. | |
3381 | * | |
3382 | * If memory is removed and there isn't enough free memory, then we | |
3383 | * need to reset the reserves. | |
3384 | * | |
3385 | * Otherwise keep the reserve set by the admin. | |
3386 | */ | |
3387 | static int reserve_mem_notifier(struct notifier_block *nb, | |
3388 | unsigned long action, void *data) | |
3389 | { | |
3390 | unsigned long tmp, free_kbytes; | |
3391 | ||
3392 | switch (action) { | |
3393 | case MEM_ONLINE: | |
3394 | /* Default max is 128MB. Leave alone if modified by operator. */ | |
3395 | tmp = sysctl_user_reserve_kbytes; | |
3396 | if (0 < tmp && tmp < (1UL << 17)) | |
3397 | init_user_reserve(); | |
3398 | ||
3399 | /* Default max is 8MB. Leave alone if modified by operator. */ | |
3400 | tmp = sysctl_admin_reserve_kbytes; | |
3401 | if (0 < tmp && tmp < (1UL << 13)) | |
3402 | init_admin_reserve(); | |
3403 | ||
3404 | break; | |
3405 | case MEM_OFFLINE: | |
3406 | free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); | |
3407 | ||
3408 | if (sysctl_user_reserve_kbytes > free_kbytes) { | |
3409 | init_user_reserve(); | |
3410 | pr_info("vm.user_reserve_kbytes reset to %lu\n", | |
3411 | sysctl_user_reserve_kbytes); | |
3412 | } | |
3413 | ||
3414 | if (sysctl_admin_reserve_kbytes > free_kbytes) { | |
3415 | init_admin_reserve(); | |
3416 | pr_info("vm.admin_reserve_kbytes reset to %lu\n", | |
3417 | sysctl_admin_reserve_kbytes); | |
3418 | } | |
3419 | break; | |
3420 | default: | |
3421 | break; | |
3422 | } | |
3423 | return NOTIFY_OK; | |
3424 | } | |
3425 | ||
3426 | static struct notifier_block reserve_mem_nb = { | |
3427 | .notifier_call = reserve_mem_notifier, | |
3428 | }; | |
3429 | ||
3430 | static int __meminit init_reserve_notifier(void) | |
3431 | { | |
3432 | if (register_hotmemory_notifier(&reserve_mem_nb)) | |
3433 | pr_err("Failed registering memory add/remove notifier for admin reserve\n"); | |
3434 | ||
3435 | return 0; | |
3436 | } | |
3437 | subsys_initcall(init_reserve_notifier); |