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16d69265 | 1 | #include <linux/mm.h> |
30992c97 MM |
2 | #include <linux/slab.h> |
3 | #include <linux/string.h> | |
3b32123d | 4 | #include <linux/compiler.h> |
b95f1b31 | 5 | #include <linux/export.h> |
96840aa0 | 6 | #include <linux/err.h> |
3b8f14b4 | 7 | #include <linux/sched.h> |
eb36c587 | 8 | #include <linux/security.h> |
9800339b | 9 | #include <linux/swap.h> |
33806f06 | 10 | #include <linux/swapops.h> |
00619bcc JM |
11 | #include <linux/mman.h> |
12 | #include <linux/hugetlb.h> | |
39f1f78d | 13 | #include <linux/vmalloc.h> |
897ab3e0 | 14 | #include <linux/userfaultfd_k.h> |
00619bcc | 15 | |
a4bb1e43 | 16 | #include <asm/sections.h> |
7c0f6ba6 | 17 | #include <linux/uaccess.h> |
30992c97 | 18 | |
6038def0 NK |
19 | #include "internal.h" |
20 | ||
a4bb1e43 AH |
21 | static inline int is_kernel_rodata(unsigned long addr) |
22 | { | |
23 | return addr >= (unsigned long)__start_rodata && | |
24 | addr < (unsigned long)__end_rodata; | |
25 | } | |
26 | ||
27 | /** | |
28 | * kfree_const - conditionally free memory | |
29 | * @x: pointer to the memory | |
30 | * | |
31 | * Function calls kfree only if @x is not in .rodata section. | |
32 | */ | |
33 | void kfree_const(const void *x) | |
34 | { | |
35 | if (!is_kernel_rodata((unsigned long)x)) | |
36 | kfree(x); | |
37 | } | |
38 | EXPORT_SYMBOL(kfree_const); | |
39 | ||
30992c97 | 40 | /** |
30992c97 | 41 | * kstrdup - allocate space for and copy an existing string |
30992c97 MM |
42 | * @s: the string to duplicate |
43 | * @gfp: the GFP mask used in the kmalloc() call when allocating memory | |
44 | */ | |
45 | char *kstrdup(const char *s, gfp_t gfp) | |
46 | { | |
47 | size_t len; | |
48 | char *buf; | |
49 | ||
50 | if (!s) | |
51 | return NULL; | |
52 | ||
53 | len = strlen(s) + 1; | |
1d2c8eea | 54 | buf = kmalloc_track_caller(len, gfp); |
30992c97 MM |
55 | if (buf) |
56 | memcpy(buf, s, len); | |
57 | return buf; | |
58 | } | |
59 | EXPORT_SYMBOL(kstrdup); | |
96840aa0 | 60 | |
a4bb1e43 AH |
61 | /** |
62 | * kstrdup_const - conditionally duplicate an existing const string | |
63 | * @s: the string to duplicate | |
64 | * @gfp: the GFP mask used in the kmalloc() call when allocating memory | |
65 | * | |
66 | * Function returns source string if it is in .rodata section otherwise it | |
67 | * fallbacks to kstrdup. | |
68 | * Strings allocated by kstrdup_const should be freed by kfree_const. | |
69 | */ | |
70 | const char *kstrdup_const(const char *s, gfp_t gfp) | |
71 | { | |
72 | if (is_kernel_rodata((unsigned long)s)) | |
73 | return s; | |
74 | ||
75 | return kstrdup(s, gfp); | |
76 | } | |
77 | EXPORT_SYMBOL(kstrdup_const); | |
78 | ||
1e66df3e JF |
79 | /** |
80 | * kstrndup - allocate space for and copy an existing string | |
81 | * @s: the string to duplicate | |
82 | * @max: read at most @max chars from @s | |
83 | * @gfp: the GFP mask used in the kmalloc() call when allocating memory | |
84 | */ | |
85 | char *kstrndup(const char *s, size_t max, gfp_t gfp) | |
86 | { | |
87 | size_t len; | |
88 | char *buf; | |
89 | ||
90 | if (!s) | |
91 | return NULL; | |
92 | ||
93 | len = strnlen(s, max); | |
94 | buf = kmalloc_track_caller(len+1, gfp); | |
95 | if (buf) { | |
96 | memcpy(buf, s, len); | |
97 | buf[len] = '\0'; | |
98 | } | |
99 | return buf; | |
100 | } | |
101 | EXPORT_SYMBOL(kstrndup); | |
102 | ||
1a2f67b4 AD |
103 | /** |
104 | * kmemdup - duplicate region of memory | |
105 | * | |
106 | * @src: memory region to duplicate | |
107 | * @len: memory region length | |
108 | * @gfp: GFP mask to use | |
109 | */ | |
110 | void *kmemdup(const void *src, size_t len, gfp_t gfp) | |
111 | { | |
112 | void *p; | |
113 | ||
1d2c8eea | 114 | p = kmalloc_track_caller(len, gfp); |
1a2f67b4 AD |
115 | if (p) |
116 | memcpy(p, src, len); | |
117 | return p; | |
118 | } | |
119 | EXPORT_SYMBOL(kmemdup); | |
120 | ||
610a77e0 LZ |
121 | /** |
122 | * memdup_user - duplicate memory region from user space | |
123 | * | |
124 | * @src: source address in user space | |
125 | * @len: number of bytes to copy | |
126 | * | |
127 | * Returns an ERR_PTR() on failure. | |
128 | */ | |
129 | void *memdup_user(const void __user *src, size_t len) | |
130 | { | |
131 | void *p; | |
132 | ||
133 | /* | |
134 | * Always use GFP_KERNEL, since copy_from_user() can sleep and | |
135 | * cause pagefault, which makes it pointless to use GFP_NOFS | |
136 | * or GFP_ATOMIC. | |
137 | */ | |
138 | p = kmalloc_track_caller(len, GFP_KERNEL); | |
139 | if (!p) | |
140 | return ERR_PTR(-ENOMEM); | |
141 | ||
142 | if (copy_from_user(p, src, len)) { | |
143 | kfree(p); | |
144 | return ERR_PTR(-EFAULT); | |
145 | } | |
146 | ||
147 | return p; | |
148 | } | |
149 | EXPORT_SYMBOL(memdup_user); | |
150 | ||
96840aa0 DA |
151 | /* |
152 | * strndup_user - duplicate an existing string from user space | |
96840aa0 DA |
153 | * @s: The string to duplicate |
154 | * @n: Maximum number of bytes to copy, including the trailing NUL. | |
155 | */ | |
156 | char *strndup_user(const char __user *s, long n) | |
157 | { | |
158 | char *p; | |
159 | long length; | |
160 | ||
161 | length = strnlen_user(s, n); | |
162 | ||
163 | if (!length) | |
164 | return ERR_PTR(-EFAULT); | |
165 | ||
166 | if (length > n) | |
167 | return ERR_PTR(-EINVAL); | |
168 | ||
90d74045 | 169 | p = memdup_user(s, length); |
96840aa0 | 170 | |
90d74045 JL |
171 | if (IS_ERR(p)) |
172 | return p; | |
96840aa0 DA |
173 | |
174 | p[length - 1] = '\0'; | |
175 | ||
176 | return p; | |
177 | } | |
178 | EXPORT_SYMBOL(strndup_user); | |
16d69265 | 179 | |
e9d408e1 AV |
180 | /** |
181 | * memdup_user_nul - duplicate memory region from user space and NUL-terminate | |
182 | * | |
183 | * @src: source address in user space | |
184 | * @len: number of bytes to copy | |
185 | * | |
186 | * Returns an ERR_PTR() on failure. | |
187 | */ | |
188 | void *memdup_user_nul(const void __user *src, size_t len) | |
189 | { | |
190 | char *p; | |
191 | ||
192 | /* | |
193 | * Always use GFP_KERNEL, since copy_from_user() can sleep and | |
194 | * cause pagefault, which makes it pointless to use GFP_NOFS | |
195 | * or GFP_ATOMIC. | |
196 | */ | |
197 | p = kmalloc_track_caller(len + 1, GFP_KERNEL); | |
198 | if (!p) | |
199 | return ERR_PTR(-ENOMEM); | |
200 | ||
201 | if (copy_from_user(p, src, len)) { | |
202 | kfree(p); | |
203 | return ERR_PTR(-EFAULT); | |
204 | } | |
205 | p[len] = '\0'; | |
206 | ||
207 | return p; | |
208 | } | |
209 | EXPORT_SYMBOL(memdup_user_nul); | |
210 | ||
6038def0 NK |
211 | void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, |
212 | struct vm_area_struct *prev, struct rb_node *rb_parent) | |
213 | { | |
214 | struct vm_area_struct *next; | |
215 | ||
216 | vma->vm_prev = prev; | |
217 | if (prev) { | |
218 | next = prev->vm_next; | |
219 | prev->vm_next = vma; | |
220 | } else { | |
221 | mm->mmap = vma; | |
222 | if (rb_parent) | |
223 | next = rb_entry(rb_parent, | |
224 | struct vm_area_struct, vm_rb); | |
225 | else | |
226 | next = NULL; | |
227 | } | |
228 | vma->vm_next = next; | |
229 | if (next) | |
230 | next->vm_prev = vma; | |
231 | } | |
232 | ||
b7643757 | 233 | /* Check if the vma is being used as a stack by this task */ |
d17af505 | 234 | int vma_is_stack_for_current(struct vm_area_struct *vma) |
b7643757 | 235 | { |
d17af505 AL |
236 | struct task_struct * __maybe_unused t = current; |
237 | ||
b7643757 SP |
238 | return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t)); |
239 | } | |
240 | ||
efc1a3b1 | 241 | #if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT) |
16d69265 AM |
242 | void arch_pick_mmap_layout(struct mm_struct *mm) |
243 | { | |
244 | mm->mmap_base = TASK_UNMAPPED_BASE; | |
245 | mm->get_unmapped_area = arch_get_unmapped_area; | |
16d69265 AM |
246 | } |
247 | #endif | |
912985dc | 248 | |
45888a0c XG |
249 | /* |
250 | * Like get_user_pages_fast() except its IRQ-safe in that it won't fall | |
251 | * back to the regular GUP. | |
25985edc | 252 | * If the architecture not support this function, simply return with no |
45888a0c XG |
253 | * page pinned |
254 | */ | |
3b32123d | 255 | int __weak __get_user_pages_fast(unsigned long start, |
45888a0c XG |
256 | int nr_pages, int write, struct page **pages) |
257 | { | |
258 | return 0; | |
259 | } | |
260 | EXPORT_SYMBOL_GPL(__get_user_pages_fast); | |
261 | ||
9de100d0 AG |
262 | /** |
263 | * get_user_pages_fast() - pin user pages in memory | |
264 | * @start: starting user address | |
265 | * @nr_pages: number of pages from start to pin | |
266 | * @write: whether pages will be written to | |
267 | * @pages: array that receives pointers to the pages pinned. | |
268 | * Should be at least nr_pages long. | |
269 | * | |
9de100d0 AG |
270 | * Returns number of pages pinned. This may be fewer than the number |
271 | * requested. If nr_pages is 0 or negative, returns 0. If no pages | |
272 | * were pinned, returns -errno. | |
d2bf6be8 NP |
273 | * |
274 | * get_user_pages_fast provides equivalent functionality to get_user_pages, | |
275 | * operating on current and current->mm, with force=0 and vma=NULL. However | |
276 | * unlike get_user_pages, it must be called without mmap_sem held. | |
277 | * | |
278 | * get_user_pages_fast may take mmap_sem and page table locks, so no | |
279 | * assumptions can be made about lack of locking. get_user_pages_fast is to be | |
280 | * implemented in a way that is advantageous (vs get_user_pages()) when the | |
281 | * user memory area is already faulted in and present in ptes. However if the | |
282 | * pages have to be faulted in, it may turn out to be slightly slower so | |
283 | * callers need to carefully consider what to use. On many architectures, | |
284 | * get_user_pages_fast simply falls back to get_user_pages. | |
9de100d0 | 285 | */ |
3b32123d | 286 | int __weak get_user_pages_fast(unsigned long start, |
912985dc RR |
287 | int nr_pages, int write, struct page **pages) |
288 | { | |
c164154f LS |
289 | return get_user_pages_unlocked(start, nr_pages, pages, |
290 | write ? FOLL_WRITE : 0); | |
912985dc RR |
291 | } |
292 | EXPORT_SYMBOL_GPL(get_user_pages_fast); | |
ca2b84cb | 293 | |
eb36c587 AV |
294 | unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr, |
295 | unsigned long len, unsigned long prot, | |
9fbeb5ab | 296 | unsigned long flag, unsigned long pgoff) |
eb36c587 AV |
297 | { |
298 | unsigned long ret; | |
299 | struct mm_struct *mm = current->mm; | |
41badc15 | 300 | unsigned long populate; |
897ab3e0 | 301 | LIST_HEAD(uf); |
eb36c587 AV |
302 | |
303 | ret = security_mmap_file(file, prot, flag); | |
304 | if (!ret) { | |
9fbeb5ab MH |
305 | if (down_write_killable(&mm->mmap_sem)) |
306 | return -EINTR; | |
bebeb3d6 | 307 | ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff, |
897ab3e0 | 308 | &populate, &uf); |
eb36c587 | 309 | up_write(&mm->mmap_sem); |
897ab3e0 | 310 | userfaultfd_unmap_complete(mm, &uf); |
41badc15 ML |
311 | if (populate) |
312 | mm_populate(ret, populate); | |
eb36c587 AV |
313 | } |
314 | return ret; | |
315 | } | |
316 | ||
317 | unsigned long vm_mmap(struct file *file, unsigned long addr, | |
318 | unsigned long len, unsigned long prot, | |
319 | unsigned long flag, unsigned long offset) | |
320 | { | |
321 | if (unlikely(offset + PAGE_ALIGN(len) < offset)) | |
322 | return -EINVAL; | |
ea53cde0 | 323 | if (unlikely(offset_in_page(offset))) |
eb36c587 AV |
324 | return -EINVAL; |
325 | ||
9fbeb5ab | 326 | return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT); |
eb36c587 AV |
327 | } |
328 | EXPORT_SYMBOL(vm_mmap); | |
329 | ||
39f1f78d AV |
330 | void kvfree(const void *addr) |
331 | { | |
332 | if (is_vmalloc_addr(addr)) | |
333 | vfree(addr); | |
334 | else | |
335 | kfree(addr); | |
336 | } | |
337 | EXPORT_SYMBOL(kvfree); | |
338 | ||
e39155ea KS |
339 | static inline void *__page_rmapping(struct page *page) |
340 | { | |
341 | unsigned long mapping; | |
342 | ||
343 | mapping = (unsigned long)page->mapping; | |
344 | mapping &= ~PAGE_MAPPING_FLAGS; | |
345 | ||
346 | return (void *)mapping; | |
347 | } | |
348 | ||
349 | /* Neutral page->mapping pointer to address_space or anon_vma or other */ | |
350 | void *page_rmapping(struct page *page) | |
351 | { | |
352 | page = compound_head(page); | |
353 | return __page_rmapping(page); | |
354 | } | |
355 | ||
1aa8aea5 AM |
356 | /* |
357 | * Return true if this page is mapped into pagetables. | |
358 | * For compound page it returns true if any subpage of compound page is mapped. | |
359 | */ | |
360 | bool page_mapped(struct page *page) | |
361 | { | |
362 | int i; | |
363 | ||
364 | if (likely(!PageCompound(page))) | |
365 | return atomic_read(&page->_mapcount) >= 0; | |
366 | page = compound_head(page); | |
367 | if (atomic_read(compound_mapcount_ptr(page)) >= 0) | |
368 | return true; | |
369 | if (PageHuge(page)) | |
370 | return false; | |
371 | for (i = 0; i < hpage_nr_pages(page); i++) { | |
372 | if (atomic_read(&page[i]._mapcount) >= 0) | |
373 | return true; | |
374 | } | |
375 | return false; | |
376 | } | |
377 | EXPORT_SYMBOL(page_mapped); | |
378 | ||
e39155ea KS |
379 | struct anon_vma *page_anon_vma(struct page *page) |
380 | { | |
381 | unsigned long mapping; | |
382 | ||
383 | page = compound_head(page); | |
384 | mapping = (unsigned long)page->mapping; | |
385 | if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) | |
386 | return NULL; | |
387 | return __page_rmapping(page); | |
388 | } | |
389 | ||
9800339b SL |
390 | struct address_space *page_mapping(struct page *page) |
391 | { | |
1c290f64 KS |
392 | struct address_space *mapping; |
393 | ||
394 | page = compound_head(page); | |
9800339b | 395 | |
03e5ac2f MP |
396 | /* This happens if someone calls flush_dcache_page on slab page */ |
397 | if (unlikely(PageSlab(page))) | |
398 | return NULL; | |
399 | ||
33806f06 SL |
400 | if (unlikely(PageSwapCache(page))) { |
401 | swp_entry_t entry; | |
402 | ||
403 | entry.val = page_private(page); | |
e39155ea KS |
404 | return swap_address_space(entry); |
405 | } | |
406 | ||
1c290f64 | 407 | mapping = page->mapping; |
bda807d4 | 408 | if ((unsigned long)mapping & PAGE_MAPPING_ANON) |
e39155ea | 409 | return NULL; |
bda807d4 MK |
410 | |
411 | return (void *)((unsigned long)mapping & ~PAGE_MAPPING_FLAGS); | |
9800339b | 412 | } |
bda807d4 | 413 | EXPORT_SYMBOL(page_mapping); |
9800339b | 414 | |
b20ce5e0 KS |
415 | /* Slow path of page_mapcount() for compound pages */ |
416 | int __page_mapcount(struct page *page) | |
417 | { | |
418 | int ret; | |
419 | ||
420 | ret = atomic_read(&page->_mapcount) + 1; | |
dd78fedd KS |
421 | /* |
422 | * For file THP page->_mapcount contains total number of mapping | |
423 | * of the page: no need to look into compound_mapcount. | |
424 | */ | |
425 | if (!PageAnon(page) && !PageHuge(page)) | |
426 | return ret; | |
b20ce5e0 KS |
427 | page = compound_head(page); |
428 | ret += atomic_read(compound_mapcount_ptr(page)) + 1; | |
429 | if (PageDoubleMap(page)) | |
430 | ret--; | |
431 | return ret; | |
432 | } | |
433 | EXPORT_SYMBOL_GPL(__page_mapcount); | |
434 | ||
39a1aa8e AR |
435 | int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; |
436 | int sysctl_overcommit_ratio __read_mostly = 50; | |
437 | unsigned long sysctl_overcommit_kbytes __read_mostly; | |
438 | int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; | |
439 | unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */ | |
440 | unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */ | |
441 | ||
49f0ce5f JM |
442 | int overcommit_ratio_handler(struct ctl_table *table, int write, |
443 | void __user *buffer, size_t *lenp, | |
444 | loff_t *ppos) | |
445 | { | |
446 | int ret; | |
447 | ||
448 | ret = proc_dointvec(table, write, buffer, lenp, ppos); | |
449 | if (ret == 0 && write) | |
450 | sysctl_overcommit_kbytes = 0; | |
451 | return ret; | |
452 | } | |
453 | ||
454 | int overcommit_kbytes_handler(struct ctl_table *table, int write, | |
455 | void __user *buffer, size_t *lenp, | |
456 | loff_t *ppos) | |
457 | { | |
458 | int ret; | |
459 | ||
460 | ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos); | |
461 | if (ret == 0 && write) | |
462 | sysctl_overcommit_ratio = 0; | |
463 | return ret; | |
464 | } | |
465 | ||
00619bcc JM |
466 | /* |
467 | * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used | |
468 | */ | |
469 | unsigned long vm_commit_limit(void) | |
470 | { | |
49f0ce5f JM |
471 | unsigned long allowed; |
472 | ||
473 | if (sysctl_overcommit_kbytes) | |
474 | allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10); | |
475 | else | |
476 | allowed = ((totalram_pages - hugetlb_total_pages()) | |
477 | * sysctl_overcommit_ratio / 100); | |
478 | allowed += total_swap_pages; | |
479 | ||
480 | return allowed; | |
00619bcc JM |
481 | } |
482 | ||
39a1aa8e AR |
483 | /* |
484 | * Make sure vm_committed_as in one cacheline and not cacheline shared with | |
485 | * other variables. It can be updated by several CPUs frequently. | |
486 | */ | |
487 | struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp; | |
488 | ||
489 | /* | |
490 | * The global memory commitment made in the system can be a metric | |
491 | * that can be used to drive ballooning decisions when Linux is hosted | |
492 | * as a guest. On Hyper-V, the host implements a policy engine for dynamically | |
493 | * balancing memory across competing virtual machines that are hosted. | |
494 | * Several metrics drive this policy engine including the guest reported | |
495 | * memory commitment. | |
496 | */ | |
497 | unsigned long vm_memory_committed(void) | |
498 | { | |
499 | return percpu_counter_read_positive(&vm_committed_as); | |
500 | } | |
501 | EXPORT_SYMBOL_GPL(vm_memory_committed); | |
502 | ||
503 | /* | |
504 | * Check that a process has enough memory to allocate a new virtual | |
505 | * mapping. 0 means there is enough memory for the allocation to | |
506 | * succeed and -ENOMEM implies there is not. | |
507 | * | |
508 | * We currently support three overcommit policies, which are set via the | |
509 | * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting | |
510 | * | |
511 | * Strict overcommit modes added 2002 Feb 26 by Alan Cox. | |
512 | * Additional code 2002 Jul 20 by Robert Love. | |
513 | * | |
514 | * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. | |
515 | * | |
516 | * Note this is a helper function intended to be used by LSMs which | |
517 | * wish to use this logic. | |
518 | */ | |
519 | int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) | |
520 | { | |
521 | long free, allowed, reserve; | |
522 | ||
523 | VM_WARN_ONCE(percpu_counter_read(&vm_committed_as) < | |
524 | -(s64)vm_committed_as_batch * num_online_cpus(), | |
525 | "memory commitment underflow"); | |
526 | ||
527 | vm_acct_memory(pages); | |
528 | ||
529 | /* | |
530 | * Sometimes we want to use more memory than we have | |
531 | */ | |
532 | if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) | |
533 | return 0; | |
534 | ||
535 | if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { | |
536 | free = global_page_state(NR_FREE_PAGES); | |
11fb9989 | 537 | free += global_node_page_state(NR_FILE_PAGES); |
39a1aa8e AR |
538 | |
539 | /* | |
540 | * shmem pages shouldn't be counted as free in this | |
541 | * case, they can't be purged, only swapped out, and | |
542 | * that won't affect the overall amount of available | |
543 | * memory in the system. | |
544 | */ | |
11fb9989 | 545 | free -= global_node_page_state(NR_SHMEM); |
39a1aa8e AR |
546 | |
547 | free += get_nr_swap_pages(); | |
548 | ||
549 | /* | |
550 | * Any slabs which are created with the | |
551 | * SLAB_RECLAIM_ACCOUNT flag claim to have contents | |
552 | * which are reclaimable, under pressure. The dentry | |
553 | * cache and most inode caches should fall into this | |
554 | */ | |
555 | free += global_page_state(NR_SLAB_RECLAIMABLE); | |
556 | ||
557 | /* | |
558 | * Leave reserved pages. The pages are not for anonymous pages. | |
559 | */ | |
560 | if (free <= totalreserve_pages) | |
561 | goto error; | |
562 | else | |
563 | free -= totalreserve_pages; | |
564 | ||
565 | /* | |
566 | * Reserve some for root | |
567 | */ | |
568 | if (!cap_sys_admin) | |
569 | free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); | |
570 | ||
571 | if (free > pages) | |
572 | return 0; | |
573 | ||
574 | goto error; | |
575 | } | |
576 | ||
577 | allowed = vm_commit_limit(); | |
578 | /* | |
579 | * Reserve some for root | |
580 | */ | |
581 | if (!cap_sys_admin) | |
582 | allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); | |
583 | ||
584 | /* | |
585 | * Don't let a single process grow so big a user can't recover | |
586 | */ | |
587 | if (mm) { | |
588 | reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10); | |
589 | allowed -= min_t(long, mm->total_vm / 32, reserve); | |
590 | } | |
591 | ||
592 | if (percpu_counter_read_positive(&vm_committed_as) < allowed) | |
593 | return 0; | |
594 | error: | |
595 | vm_unacct_memory(pages); | |
596 | ||
597 | return -ENOMEM; | |
598 | } | |
599 | ||
a9090253 WR |
600 | /** |
601 | * get_cmdline() - copy the cmdline value to a buffer. | |
602 | * @task: the task whose cmdline value to copy. | |
603 | * @buffer: the buffer to copy to. | |
604 | * @buflen: the length of the buffer. Larger cmdline values are truncated | |
605 | * to this length. | |
606 | * Returns the size of the cmdline field copied. Note that the copy does | |
607 | * not guarantee an ending NULL byte. | |
608 | */ | |
609 | int get_cmdline(struct task_struct *task, char *buffer, int buflen) | |
610 | { | |
611 | int res = 0; | |
612 | unsigned int len; | |
613 | struct mm_struct *mm = get_task_mm(task); | |
a3b609ef | 614 | unsigned long arg_start, arg_end, env_start, env_end; |
a9090253 WR |
615 | if (!mm) |
616 | goto out; | |
617 | if (!mm->arg_end) | |
618 | goto out_mm; /* Shh! No looking before we're done */ | |
619 | ||
a3b609ef MG |
620 | down_read(&mm->mmap_sem); |
621 | arg_start = mm->arg_start; | |
622 | arg_end = mm->arg_end; | |
623 | env_start = mm->env_start; | |
624 | env_end = mm->env_end; | |
625 | up_read(&mm->mmap_sem); | |
626 | ||
627 | len = arg_end - arg_start; | |
a9090253 WR |
628 | |
629 | if (len > buflen) | |
630 | len = buflen; | |
631 | ||
f307ab6d | 632 | res = access_process_vm(task, arg_start, buffer, len, FOLL_FORCE); |
a9090253 WR |
633 | |
634 | /* | |
635 | * If the nul at the end of args has been overwritten, then | |
636 | * assume application is using setproctitle(3). | |
637 | */ | |
638 | if (res > 0 && buffer[res-1] != '\0' && len < buflen) { | |
639 | len = strnlen(buffer, res); | |
640 | if (len < res) { | |
641 | res = len; | |
642 | } else { | |
a3b609ef | 643 | len = env_end - env_start; |
a9090253 WR |
644 | if (len > buflen - res) |
645 | len = buflen - res; | |
a3b609ef | 646 | res += access_process_vm(task, env_start, |
f307ab6d LS |
647 | buffer+res, len, |
648 | FOLL_FORCE); | |
a9090253 WR |
649 | res = strnlen(buffer, res); |
650 | } | |
651 | } | |
652 | out_mm: | |
653 | mmput(mm); | |
654 | out: | |
655 | return res; | |
656 | } |