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1 | #include <linux/mm.h> | |
2 | #include <linux/slab.h> | |
3 | #include <linux/string.h> | |
4 | #include <linux/compiler.h> | |
5 | #include <linux/export.h> | |
6 | #include <linux/err.h> | |
7 | #include <linux/sched.h> | |
8 | #include <linux/sched/mm.h> | |
9 | #include <linux/sched/task_stack.h> | |
10 | #include <linux/security.h> | |
11 | #include <linux/swap.h> | |
12 | #include <linux/swapops.h> | |
13 | #include <linux/mman.h> | |
14 | #include <linux/hugetlb.h> | |
15 | #include <linux/vmalloc.h> | |
16 | #include <linux/userfaultfd_k.h> | |
17 | ||
18 | #include <asm/sections.h> | |
19 | #include <linux/uaccess.h> | |
20 | ||
21 | #include "internal.h" | |
22 | ||
23 | static inline int is_kernel_rodata(unsigned long addr) | |
24 | { | |
25 | return addr >= (unsigned long)__start_rodata && | |
26 | addr < (unsigned long)__end_rodata; | |
27 | } | |
28 | ||
29 | /** | |
30 | * kfree_const - conditionally free memory | |
31 | * @x: pointer to the memory | |
32 | * | |
33 | * Function calls kfree only if @x is not in .rodata section. | |
34 | */ | |
35 | void kfree_const(const void *x) | |
36 | { | |
37 | if (!is_kernel_rodata((unsigned long)x)) | |
38 | kfree(x); | |
39 | } | |
40 | EXPORT_SYMBOL(kfree_const); | |
41 | ||
42 | /** | |
43 | * kstrdup - allocate space for and copy an existing string | |
44 | * @s: the string to duplicate | |
45 | * @gfp: the GFP mask used in the kmalloc() call when allocating memory | |
46 | */ | |
47 | char *kstrdup(const char *s, gfp_t gfp) | |
48 | { | |
49 | size_t len; | |
50 | char *buf; | |
51 | ||
52 | if (!s) | |
53 | return NULL; | |
54 | ||
55 | len = strlen(s) + 1; | |
56 | buf = kmalloc_track_caller(len, gfp); | |
57 | if (buf) | |
58 | memcpy(buf, s, len); | |
59 | return buf; | |
60 | } | |
61 | EXPORT_SYMBOL(kstrdup); | |
62 | ||
63 | /** | |
64 | * kstrdup_const - conditionally duplicate an existing const string | |
65 | * @s: the string to duplicate | |
66 | * @gfp: the GFP mask used in the kmalloc() call when allocating memory | |
67 | * | |
68 | * Function returns source string if it is in .rodata section otherwise it | |
69 | * fallbacks to kstrdup. | |
70 | * Strings allocated by kstrdup_const should be freed by kfree_const. | |
71 | */ | |
72 | const char *kstrdup_const(const char *s, gfp_t gfp) | |
73 | { | |
74 | if (is_kernel_rodata((unsigned long)s)) | |
75 | return s; | |
76 | ||
77 | return kstrdup(s, gfp); | |
78 | } | |
79 | EXPORT_SYMBOL(kstrdup_const); | |
80 | ||
81 | /** | |
82 | * kstrndup - allocate space for and copy an existing string | |
83 | * @s: the string to duplicate | |
84 | * @max: read at most @max chars from @s | |
85 | * @gfp: the GFP mask used in the kmalloc() call when allocating memory | |
86 | * | |
87 | * Note: Use kmemdup_nul() instead if the size is known exactly. | |
88 | */ | |
89 | char *kstrndup(const char *s, size_t max, gfp_t gfp) | |
90 | { | |
91 | size_t len; | |
92 | char *buf; | |
93 | ||
94 | if (!s) | |
95 | return NULL; | |
96 | ||
97 | len = strnlen(s, max); | |
98 | buf = kmalloc_track_caller(len+1, gfp); | |
99 | if (buf) { | |
100 | memcpy(buf, s, len); | |
101 | buf[len] = '\0'; | |
102 | } | |
103 | return buf; | |
104 | } | |
105 | EXPORT_SYMBOL(kstrndup); | |
106 | ||
107 | /** | |
108 | * kmemdup - duplicate region of memory | |
109 | * | |
110 | * @src: memory region to duplicate | |
111 | * @len: memory region length | |
112 | * @gfp: GFP mask to use | |
113 | */ | |
114 | void *kmemdup(const void *src, size_t len, gfp_t gfp) | |
115 | { | |
116 | void *p; | |
117 | ||
118 | p = kmalloc_track_caller(len, gfp); | |
119 | if (p) | |
120 | memcpy(p, src, len); | |
121 | return p; | |
122 | } | |
123 | EXPORT_SYMBOL(kmemdup); | |
124 | ||
125 | /** | |
126 | * kmemdup_nul - Create a NUL-terminated string from unterminated data | |
127 | * @s: The data to stringify | |
128 | * @len: The size of the data | |
129 | * @gfp: the GFP mask used in the kmalloc() call when allocating memory | |
130 | */ | |
131 | char *kmemdup_nul(const char *s, size_t len, gfp_t gfp) | |
132 | { | |
133 | char *buf; | |
134 | ||
135 | if (!s) | |
136 | return NULL; | |
137 | ||
138 | buf = kmalloc_track_caller(len + 1, gfp); | |
139 | if (buf) { | |
140 | memcpy(buf, s, len); | |
141 | buf[len] = '\0'; | |
142 | } | |
143 | return buf; | |
144 | } | |
145 | EXPORT_SYMBOL(kmemdup_nul); | |
146 | ||
147 | /** | |
148 | * memdup_user - duplicate memory region from user space | |
149 | * | |
150 | * @src: source address in user space | |
151 | * @len: number of bytes to copy | |
152 | * | |
153 | * Returns an ERR_PTR() on failure. | |
154 | */ | |
155 | void *memdup_user(const void __user *src, size_t len) | |
156 | { | |
157 | void *p; | |
158 | ||
159 | /* | |
160 | * Always use GFP_KERNEL, since copy_from_user() can sleep and | |
161 | * cause pagefault, which makes it pointless to use GFP_NOFS | |
162 | * or GFP_ATOMIC. | |
163 | */ | |
164 | p = kmalloc_track_caller(len, GFP_KERNEL); | |
165 | if (!p) | |
166 | return ERR_PTR(-ENOMEM); | |
167 | ||
168 | if (copy_from_user(p, src, len)) { | |
169 | kfree(p); | |
170 | return ERR_PTR(-EFAULT); | |
171 | } | |
172 | ||
173 | return p; | |
174 | } | |
175 | EXPORT_SYMBOL(memdup_user); | |
176 | ||
177 | /* | |
178 | * strndup_user - duplicate an existing string from user space | |
179 | * @s: The string to duplicate | |
180 | * @n: Maximum number of bytes to copy, including the trailing NUL. | |
181 | */ | |
182 | char *strndup_user(const char __user *s, long n) | |
183 | { | |
184 | char *p; | |
185 | long length; | |
186 | ||
187 | length = strnlen_user(s, n); | |
188 | ||
189 | if (!length) | |
190 | return ERR_PTR(-EFAULT); | |
191 | ||
192 | if (length > n) | |
193 | return ERR_PTR(-EINVAL); | |
194 | ||
195 | p = memdup_user(s, length); | |
196 | ||
197 | if (IS_ERR(p)) | |
198 | return p; | |
199 | ||
200 | p[length - 1] = '\0'; | |
201 | ||
202 | return p; | |
203 | } | |
204 | EXPORT_SYMBOL(strndup_user); | |
205 | ||
206 | /** | |
207 | * memdup_user_nul - duplicate memory region from user space and NUL-terminate | |
208 | * | |
209 | * @src: source address in user space | |
210 | * @len: number of bytes to copy | |
211 | * | |
212 | * Returns an ERR_PTR() on failure. | |
213 | */ | |
214 | void *memdup_user_nul(const void __user *src, size_t len) | |
215 | { | |
216 | char *p; | |
217 | ||
218 | /* | |
219 | * Always use GFP_KERNEL, since copy_from_user() can sleep and | |
220 | * cause pagefault, which makes it pointless to use GFP_NOFS | |
221 | * or GFP_ATOMIC. | |
222 | */ | |
223 | p = kmalloc_track_caller(len + 1, GFP_KERNEL); | |
224 | if (!p) | |
225 | return ERR_PTR(-ENOMEM); | |
226 | ||
227 | if (copy_from_user(p, src, len)) { | |
228 | kfree(p); | |
229 | return ERR_PTR(-EFAULT); | |
230 | } | |
231 | p[len] = '\0'; | |
232 | ||
233 | return p; | |
234 | } | |
235 | EXPORT_SYMBOL(memdup_user_nul); | |
236 | ||
237 | void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, | |
238 | struct vm_area_struct *prev, struct rb_node *rb_parent) | |
239 | { | |
240 | struct vm_area_struct *next; | |
241 | ||
242 | vma->vm_prev = prev; | |
243 | if (prev) { | |
244 | next = prev->vm_next; | |
245 | prev->vm_next = vma; | |
246 | } else { | |
247 | mm->mmap = vma; | |
248 | if (rb_parent) | |
249 | next = rb_entry(rb_parent, | |
250 | struct vm_area_struct, vm_rb); | |
251 | else | |
252 | next = NULL; | |
253 | } | |
254 | vma->vm_next = next; | |
255 | if (next) | |
256 | next->vm_prev = vma; | |
257 | } | |
258 | ||
259 | /* Check if the vma is being used as a stack by this task */ | |
260 | int vma_is_stack_for_current(struct vm_area_struct *vma) | |
261 | { | |
262 | struct task_struct * __maybe_unused t = current; | |
263 | ||
264 | return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t)); | |
265 | } | |
266 | ||
267 | #if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT) | |
268 | void arch_pick_mmap_layout(struct mm_struct *mm) | |
269 | { | |
270 | mm->mmap_base = TASK_UNMAPPED_BASE; | |
271 | mm->get_unmapped_area = arch_get_unmapped_area; | |
272 | } | |
273 | #endif | |
274 | ||
275 | /* | |
276 | * Like get_user_pages_fast() except its IRQ-safe in that it won't fall | |
277 | * back to the regular GUP. | |
278 | * If the architecture not support this function, simply return with no | |
279 | * page pinned | |
280 | */ | |
281 | int __weak __get_user_pages_fast(unsigned long start, | |
282 | int nr_pages, int write, struct page **pages) | |
283 | { | |
284 | return 0; | |
285 | } | |
286 | EXPORT_SYMBOL_GPL(__get_user_pages_fast); | |
287 | ||
288 | /** | |
289 | * get_user_pages_fast() - pin user pages in memory | |
290 | * @start: starting user address | |
291 | * @nr_pages: number of pages from start to pin | |
292 | * @write: whether pages will be written to | |
293 | * @pages: array that receives pointers to the pages pinned. | |
294 | * Should be at least nr_pages long. | |
295 | * | |
296 | * Returns number of pages pinned. This may be fewer than the number | |
297 | * requested. If nr_pages is 0 or negative, returns 0. If no pages | |
298 | * were pinned, returns -errno. | |
299 | * | |
300 | * get_user_pages_fast provides equivalent functionality to get_user_pages, | |
301 | * operating on current and current->mm, with force=0 and vma=NULL. However | |
302 | * unlike get_user_pages, it must be called without mmap_sem held. | |
303 | * | |
304 | * get_user_pages_fast may take mmap_sem and page table locks, so no | |
305 | * assumptions can be made about lack of locking. get_user_pages_fast is to be | |
306 | * implemented in a way that is advantageous (vs get_user_pages()) when the | |
307 | * user memory area is already faulted in and present in ptes. However if the | |
308 | * pages have to be faulted in, it may turn out to be slightly slower so | |
309 | * callers need to carefully consider what to use. On many architectures, | |
310 | * get_user_pages_fast simply falls back to get_user_pages. | |
311 | */ | |
312 | int __weak get_user_pages_fast(unsigned long start, | |
313 | int nr_pages, int write, struct page **pages) | |
314 | { | |
315 | return get_user_pages_unlocked(start, nr_pages, pages, | |
316 | write ? FOLL_WRITE : 0); | |
317 | } | |
318 | EXPORT_SYMBOL_GPL(get_user_pages_fast); | |
319 | ||
320 | unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr, | |
321 | unsigned long len, unsigned long prot, | |
322 | unsigned long flag, unsigned long pgoff) | |
323 | { | |
324 | unsigned long ret; | |
325 | struct mm_struct *mm = current->mm; | |
326 | unsigned long populate; | |
327 | LIST_HEAD(uf); | |
328 | ||
329 | ret = security_mmap_file(file, prot, flag); | |
330 | if (!ret) { | |
331 | if (down_write_killable(&mm->mmap_sem)) | |
332 | return -EINTR; | |
333 | ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff, | |
334 | &populate, &uf); | |
335 | up_write(&mm->mmap_sem); | |
336 | userfaultfd_unmap_complete(mm, &uf); | |
337 | if (populate) | |
338 | mm_populate(ret, populate); | |
339 | } | |
340 | return ret; | |
341 | } | |
342 | ||
343 | unsigned long vm_mmap(struct file *file, unsigned long addr, | |
344 | unsigned long len, unsigned long prot, | |
345 | unsigned long flag, unsigned long offset) | |
346 | { | |
347 | if (unlikely(offset + PAGE_ALIGN(len) < offset)) | |
348 | return -EINVAL; | |
349 | if (unlikely(offset_in_page(offset))) | |
350 | return -EINVAL; | |
351 | ||
352 | return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT); | |
353 | } | |
354 | EXPORT_SYMBOL(vm_mmap); | |
355 | ||
356 | /** | |
357 | * kvmalloc_node - attempt to allocate physically contiguous memory, but upon | |
358 | * failure, fall back to non-contiguous (vmalloc) allocation. | |
359 | * @size: size of the request. | |
360 | * @flags: gfp mask for the allocation - must be compatible (superset) with GFP_KERNEL. | |
361 | * @node: numa node to allocate from | |
362 | * | |
363 | * Uses kmalloc to get the memory but if the allocation fails then falls back | |
364 | * to the vmalloc allocator. Use kvfree for freeing the memory. | |
365 | * | |
366 | * Reclaim modifiers - __GFP_NORETRY and __GFP_NOFAIL are not supported. | |
367 | * __GFP_RETRY_MAYFAIL is supported, and it should be used only if kmalloc is | |
368 | * preferable to the vmalloc fallback, due to visible performance drawbacks. | |
369 | * | |
370 | * Any use of gfp flags outside of GFP_KERNEL should be consulted with mm people. | |
371 | */ | |
372 | void *kvmalloc_node(size_t size, gfp_t flags, int node) | |
373 | { | |
374 | gfp_t kmalloc_flags = flags; | |
375 | void *ret; | |
376 | ||
377 | /* | |
378 | * vmalloc uses GFP_KERNEL for some internal allocations (e.g page tables) | |
379 | * so the given set of flags has to be compatible. | |
380 | */ | |
381 | WARN_ON_ONCE((flags & GFP_KERNEL) != GFP_KERNEL); | |
382 | ||
383 | /* | |
384 | * We want to attempt a large physically contiguous block first because | |
385 | * it is less likely to fragment multiple larger blocks and therefore | |
386 | * contribute to a long term fragmentation less than vmalloc fallback. | |
387 | * However make sure that larger requests are not too disruptive - no | |
388 | * OOM killer and no allocation failure warnings as we have a fallback. | |
389 | */ | |
390 | if (size > PAGE_SIZE) { | |
391 | kmalloc_flags |= __GFP_NOWARN; | |
392 | ||
393 | if (!(kmalloc_flags & __GFP_RETRY_MAYFAIL)) | |
394 | kmalloc_flags |= __GFP_NORETRY; | |
395 | } | |
396 | ||
397 | ret = kmalloc_node(size, kmalloc_flags, node); | |
398 | ||
399 | /* | |
400 | * It doesn't really make sense to fallback to vmalloc for sub page | |
401 | * requests | |
402 | */ | |
403 | if (ret || size <= PAGE_SIZE) | |
404 | return ret; | |
405 | ||
406 | return __vmalloc_node_flags_caller(size, node, flags, | |
407 | __builtin_return_address(0)); | |
408 | } | |
409 | EXPORT_SYMBOL(kvmalloc_node); | |
410 | ||
411 | void kvfree(const void *addr) | |
412 | { | |
413 | if (is_vmalloc_addr(addr)) | |
414 | vfree(addr); | |
415 | else | |
416 | kfree(addr); | |
417 | } | |
418 | EXPORT_SYMBOL(kvfree); | |
419 | ||
420 | static inline void *__page_rmapping(struct page *page) | |
421 | { | |
422 | unsigned long mapping; | |
423 | ||
424 | mapping = (unsigned long)page->mapping; | |
425 | mapping &= ~PAGE_MAPPING_FLAGS; | |
426 | ||
427 | return (void *)mapping; | |
428 | } | |
429 | ||
430 | /* Neutral page->mapping pointer to address_space or anon_vma or other */ | |
431 | void *page_rmapping(struct page *page) | |
432 | { | |
433 | page = compound_head(page); | |
434 | return __page_rmapping(page); | |
435 | } | |
436 | ||
437 | /* | |
438 | * Return true if this page is mapped into pagetables. | |
439 | * For compound page it returns true if any subpage of compound page is mapped. | |
440 | */ | |
441 | bool page_mapped(struct page *page) | |
442 | { | |
443 | int i; | |
444 | ||
445 | if (likely(!PageCompound(page))) | |
446 | return atomic_read(&page->_mapcount) >= 0; | |
447 | page = compound_head(page); | |
448 | if (atomic_read(compound_mapcount_ptr(page)) >= 0) | |
449 | return true; | |
450 | if (PageHuge(page)) | |
451 | return false; | |
452 | for (i = 0; i < hpage_nr_pages(page); i++) { | |
453 | if (atomic_read(&page[i]._mapcount) >= 0) | |
454 | return true; | |
455 | } | |
456 | return false; | |
457 | } | |
458 | EXPORT_SYMBOL(page_mapped); | |
459 | ||
460 | struct anon_vma *page_anon_vma(struct page *page) | |
461 | { | |
462 | unsigned long mapping; | |
463 | ||
464 | page = compound_head(page); | |
465 | mapping = (unsigned long)page->mapping; | |
466 | if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) | |
467 | return NULL; | |
468 | return __page_rmapping(page); | |
469 | } | |
470 | ||
471 | struct address_space *page_mapping(struct page *page) | |
472 | { | |
473 | struct address_space *mapping; | |
474 | ||
475 | page = compound_head(page); | |
476 | ||
477 | /* This happens if someone calls flush_dcache_page on slab page */ | |
478 | if (unlikely(PageSlab(page))) | |
479 | return NULL; | |
480 | ||
481 | if (unlikely(PageSwapCache(page))) { | |
482 | swp_entry_t entry; | |
483 | ||
484 | entry.val = page_private(page); | |
485 | return swap_address_space(entry); | |
486 | } | |
487 | ||
488 | mapping = page->mapping; | |
489 | if ((unsigned long)mapping & PAGE_MAPPING_ANON) | |
490 | return NULL; | |
491 | ||
492 | return (void *)((unsigned long)mapping & ~PAGE_MAPPING_FLAGS); | |
493 | } | |
494 | EXPORT_SYMBOL(page_mapping); | |
495 | ||
496 | /* Slow path of page_mapcount() for compound pages */ | |
497 | int __page_mapcount(struct page *page) | |
498 | { | |
499 | int ret; | |
500 | ||
501 | ret = atomic_read(&page->_mapcount) + 1; | |
502 | /* | |
503 | * For file THP page->_mapcount contains total number of mapping | |
504 | * of the page: no need to look into compound_mapcount. | |
505 | */ | |
506 | if (!PageAnon(page) && !PageHuge(page)) | |
507 | return ret; | |
508 | page = compound_head(page); | |
509 | ret += atomic_read(compound_mapcount_ptr(page)) + 1; | |
510 | if (PageDoubleMap(page)) | |
511 | ret--; | |
512 | return ret; | |
513 | } | |
514 | EXPORT_SYMBOL_GPL(__page_mapcount); | |
515 | ||
516 | int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; | |
517 | int sysctl_overcommit_ratio __read_mostly = 50; | |
518 | unsigned long sysctl_overcommit_kbytes __read_mostly; | |
519 | int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; | |
520 | unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */ | |
521 | unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */ | |
522 | ||
523 | int overcommit_ratio_handler(struct ctl_table *table, int write, | |
524 | void __user *buffer, size_t *lenp, | |
525 | loff_t *ppos) | |
526 | { | |
527 | int ret; | |
528 | ||
529 | ret = proc_dointvec(table, write, buffer, lenp, ppos); | |
530 | if (ret == 0 && write) | |
531 | sysctl_overcommit_kbytes = 0; | |
532 | return ret; | |
533 | } | |
534 | ||
535 | int overcommit_kbytes_handler(struct ctl_table *table, int write, | |
536 | void __user *buffer, size_t *lenp, | |
537 | loff_t *ppos) | |
538 | { | |
539 | int ret; | |
540 | ||
541 | ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos); | |
542 | if (ret == 0 && write) | |
543 | sysctl_overcommit_ratio = 0; | |
544 | return ret; | |
545 | } | |
546 | ||
547 | /* | |
548 | * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used | |
549 | */ | |
550 | unsigned long vm_commit_limit(void) | |
551 | { | |
552 | unsigned long allowed; | |
553 | ||
554 | if (sysctl_overcommit_kbytes) | |
555 | allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10); | |
556 | else | |
557 | allowed = ((totalram_pages - hugetlb_total_pages()) | |
558 | * sysctl_overcommit_ratio / 100); | |
559 | allowed += total_swap_pages; | |
560 | ||
561 | return allowed; | |
562 | } | |
563 | ||
564 | /* | |
565 | * Make sure vm_committed_as in one cacheline and not cacheline shared with | |
566 | * other variables. It can be updated by several CPUs frequently. | |
567 | */ | |
568 | struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp; | |
569 | ||
570 | /* | |
571 | * The global memory commitment made in the system can be a metric | |
572 | * that can be used to drive ballooning decisions when Linux is hosted | |
573 | * as a guest. On Hyper-V, the host implements a policy engine for dynamically | |
574 | * balancing memory across competing virtual machines that are hosted. | |
575 | * Several metrics drive this policy engine including the guest reported | |
576 | * memory commitment. | |
577 | */ | |
578 | unsigned long vm_memory_committed(void) | |
579 | { | |
580 | return percpu_counter_read_positive(&vm_committed_as); | |
581 | } | |
582 | EXPORT_SYMBOL_GPL(vm_memory_committed); | |
583 | ||
584 | /* | |
585 | * Check that a process has enough memory to allocate a new virtual | |
586 | * mapping. 0 means there is enough memory for the allocation to | |
587 | * succeed and -ENOMEM implies there is not. | |
588 | * | |
589 | * We currently support three overcommit policies, which are set via the | |
590 | * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting | |
591 | * | |
592 | * Strict overcommit modes added 2002 Feb 26 by Alan Cox. | |
593 | * Additional code 2002 Jul 20 by Robert Love. | |
594 | * | |
595 | * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. | |
596 | * | |
597 | * Note this is a helper function intended to be used by LSMs which | |
598 | * wish to use this logic. | |
599 | */ | |
600 | int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) | |
601 | { | |
602 | long free, allowed, reserve; | |
603 | ||
604 | VM_WARN_ONCE(percpu_counter_read(&vm_committed_as) < | |
605 | -(s64)vm_committed_as_batch * num_online_cpus(), | |
606 | "memory commitment underflow"); | |
607 | ||
608 | vm_acct_memory(pages); | |
609 | ||
610 | /* | |
611 | * Sometimes we want to use more memory than we have | |
612 | */ | |
613 | if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) | |
614 | return 0; | |
615 | ||
616 | if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { | |
617 | free = global_page_state(NR_FREE_PAGES); | |
618 | free += global_node_page_state(NR_FILE_PAGES); | |
619 | ||
620 | /* | |
621 | * shmem pages shouldn't be counted as free in this | |
622 | * case, they can't be purged, only swapped out, and | |
623 | * that won't affect the overall amount of available | |
624 | * memory in the system. | |
625 | */ | |
626 | free -= global_node_page_state(NR_SHMEM); | |
627 | ||
628 | free += get_nr_swap_pages(); | |
629 | ||
630 | /* | |
631 | * Any slabs which are created with the | |
632 | * SLAB_RECLAIM_ACCOUNT flag claim to have contents | |
633 | * which are reclaimable, under pressure. The dentry | |
634 | * cache and most inode caches should fall into this | |
635 | */ | |
636 | free += global_node_page_state(NR_SLAB_RECLAIMABLE); | |
637 | ||
638 | /* | |
639 | * Leave reserved pages. The pages are not for anonymous pages. | |
640 | */ | |
641 | if (free <= totalreserve_pages) | |
642 | goto error; | |
643 | else | |
644 | free -= totalreserve_pages; | |
645 | ||
646 | /* | |
647 | * Reserve some for root | |
648 | */ | |
649 | if (!cap_sys_admin) | |
650 | free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); | |
651 | ||
652 | if (free > pages) | |
653 | return 0; | |
654 | ||
655 | goto error; | |
656 | } | |
657 | ||
658 | allowed = vm_commit_limit(); | |
659 | /* | |
660 | * Reserve some for root | |
661 | */ | |
662 | if (!cap_sys_admin) | |
663 | allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); | |
664 | ||
665 | /* | |
666 | * Don't let a single process grow so big a user can't recover | |
667 | */ | |
668 | if (mm) { | |
669 | reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10); | |
670 | allowed -= min_t(long, mm->total_vm / 32, reserve); | |
671 | } | |
672 | ||
673 | if (percpu_counter_read_positive(&vm_committed_as) < allowed) | |
674 | return 0; | |
675 | error: | |
676 | vm_unacct_memory(pages); | |
677 | ||
678 | return -ENOMEM; | |
679 | } | |
680 | ||
681 | /** | |
682 | * get_cmdline() - copy the cmdline value to a buffer. | |
683 | * @task: the task whose cmdline value to copy. | |
684 | * @buffer: the buffer to copy to. | |
685 | * @buflen: the length of the buffer. Larger cmdline values are truncated | |
686 | * to this length. | |
687 | * Returns the size of the cmdline field copied. Note that the copy does | |
688 | * not guarantee an ending NULL byte. | |
689 | */ | |
690 | int get_cmdline(struct task_struct *task, char *buffer, int buflen) | |
691 | { | |
692 | int res = 0; | |
693 | unsigned int len; | |
694 | struct mm_struct *mm = get_task_mm(task); | |
695 | unsigned long arg_start, arg_end, env_start, env_end; | |
696 | if (!mm) | |
697 | goto out; | |
698 | if (!mm->arg_end) | |
699 | goto out_mm; /* Shh! No looking before we're done */ | |
700 | ||
701 | down_read(&mm->mmap_sem); | |
702 | arg_start = mm->arg_start; | |
703 | arg_end = mm->arg_end; | |
704 | env_start = mm->env_start; | |
705 | env_end = mm->env_end; | |
706 | up_read(&mm->mmap_sem); | |
707 | ||
708 | len = arg_end - arg_start; | |
709 | ||
710 | if (len > buflen) | |
711 | len = buflen; | |
712 | ||
713 | res = access_process_vm(task, arg_start, buffer, len, FOLL_FORCE); | |
714 | ||
715 | /* | |
716 | * If the nul at the end of args has been overwritten, then | |
717 | * assume application is using setproctitle(3). | |
718 | */ | |
719 | if (res > 0 && buffer[res-1] != '\0' && len < buflen) { | |
720 | len = strnlen(buffer, res); | |
721 | if (len < res) { | |
722 | res = len; | |
723 | } else { | |
724 | len = env_end - env_start; | |
725 | if (len > buflen - res) | |
726 | len = buflen - res; | |
727 | res += access_process_vm(task, env_start, | |
728 | buffer+res, len, | |
729 | FOLL_FORCE); | |
730 | res = strnlen(buffer, res); | |
731 | } | |
732 | } | |
733 | out_mm: | |
734 | mmput(mm); | |
735 | out: | |
736 | return res; | |
737 | } |