Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/mm/mlock.c |
| 3 | * |
| 4 | * (C) Copyright 1995 Linus Torvalds |
| 5 | * (C) Copyright 2002 Christoph Hellwig |
| 6 | */ |
| 7 | |
Randy.Dunlap | c59ede7 | 2006-01-11 12:17:46 -0800 | [diff] [blame] | 8 | #include <linux/capability.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 9 | #include <linux/mman.h> |
| 10 | #include <linux/mm.h> |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 11 | #include <linux/swap.h> |
| 12 | #include <linux/swapops.h> |
| 13 | #include <linux/pagemap.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 14 | #include <linux/mempolicy.h> |
| 15 | #include <linux/syscalls.h> |
Alexey Dobriyan | e8edc6e | 2007-05-21 01:22:52 +0400 | [diff] [blame] | 16 | #include <linux/sched.h> |
| 17 | #include <linux/module.h> |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 18 | #include <linux/rmap.h> |
| 19 | #include <linux/mmzone.h> |
| 20 | #include <linux/hugetlb.h> |
| 21 | |
| 22 | #include "internal.h" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 23 | |
Alexey Dobriyan | e8edc6e | 2007-05-21 01:22:52 +0400 | [diff] [blame] | 24 | int can_do_mlock(void) |
| 25 | { |
| 26 | if (capable(CAP_IPC_LOCK)) |
| 27 | return 1; |
| 28 | if (current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur != 0) |
| 29 | return 1; |
| 30 | return 0; |
| 31 | } |
| 32 | EXPORT_SYMBOL(can_do_mlock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 33 | |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 34 | #ifdef CONFIG_UNEVICTABLE_LRU |
| 35 | /* |
| 36 | * Mlocked pages are marked with PageMlocked() flag for efficient testing |
| 37 | * in vmscan and, possibly, the fault path; and to support semi-accurate |
| 38 | * statistics. |
| 39 | * |
| 40 | * An mlocked page [PageMlocked(page)] is unevictable. As such, it will |
| 41 | * be placed on the LRU "unevictable" list, rather than the [in]active lists. |
| 42 | * The unevictable list is an LRU sibling list to the [in]active lists. |
| 43 | * PageUnevictable is set to indicate the unevictable state. |
| 44 | * |
| 45 | * When lazy mlocking via vmscan, it is important to ensure that the |
| 46 | * vma's VM_LOCKED status is not concurrently being modified, otherwise we |
| 47 | * may have mlocked a page that is being munlocked. So lazy mlock must take |
| 48 | * the mmap_sem for read, and verify that the vma really is locked |
| 49 | * (see mm/rmap.c). |
| 50 | */ |
| 51 | |
| 52 | /* |
| 53 | * LRU accounting for clear_page_mlock() |
| 54 | */ |
| 55 | void __clear_page_mlock(struct page *page) |
| 56 | { |
| 57 | VM_BUG_ON(!PageLocked(page)); |
| 58 | |
| 59 | if (!page->mapping) { /* truncated ? */ |
| 60 | return; |
| 61 | } |
| 62 | |
| 63 | if (!isolate_lru_page(page)) { |
| 64 | putback_lru_page(page); |
| 65 | } else { |
| 66 | /* |
| 67 | * Page not on the LRU yet. Flush all pagevecs and retry. |
| 68 | */ |
| 69 | lru_add_drain_all(); |
| 70 | if (!isolate_lru_page(page)) |
| 71 | putback_lru_page(page); |
| 72 | } |
| 73 | } |
| 74 | |
| 75 | /* |
| 76 | * Mark page as mlocked if not already. |
| 77 | * If page on LRU, isolate and putback to move to unevictable list. |
| 78 | */ |
| 79 | void mlock_vma_page(struct page *page) |
| 80 | { |
| 81 | BUG_ON(!PageLocked(page)); |
| 82 | |
| 83 | if (!TestSetPageMlocked(page) && !isolate_lru_page(page)) |
| 84 | putback_lru_page(page); |
| 85 | } |
| 86 | |
| 87 | /* |
| 88 | * called from munlock()/munmap() path with page supposedly on the LRU. |
| 89 | * |
| 90 | * Note: unlike mlock_vma_page(), we can't just clear the PageMlocked |
| 91 | * [in try_to_munlock()] and then attempt to isolate the page. We must |
| 92 | * isolate the page to keep others from messing with its unevictable |
| 93 | * and mlocked state while trying to munlock. However, we pre-clear the |
| 94 | * mlocked state anyway as we might lose the isolation race and we might |
| 95 | * not get another chance to clear PageMlocked. If we successfully |
| 96 | * isolate the page and try_to_munlock() detects other VM_LOCKED vmas |
| 97 | * mapping the page, it will restore the PageMlocked state, unless the page |
| 98 | * is mapped in a non-linear vma. So, we go ahead and SetPageMlocked(), |
| 99 | * perhaps redundantly. |
| 100 | * If we lose the isolation race, and the page is mapped by other VM_LOCKED |
| 101 | * vmas, we'll detect this in vmscan--via try_to_munlock() or try_to_unmap() |
| 102 | * either of which will restore the PageMlocked state by calling |
| 103 | * mlock_vma_page() above, if it can grab the vma's mmap sem. |
| 104 | */ |
| 105 | static void munlock_vma_page(struct page *page) |
| 106 | { |
| 107 | BUG_ON(!PageLocked(page)); |
| 108 | |
| 109 | if (TestClearPageMlocked(page) && !isolate_lru_page(page)) { |
| 110 | try_to_munlock(page); |
| 111 | putback_lru_page(page); |
| 112 | } |
| 113 | } |
| 114 | |
| 115 | /* |
| 116 | * mlock a range of pages in the vma. |
| 117 | * |
| 118 | * This takes care of making the pages present too. |
| 119 | * |
| 120 | * vma->vm_mm->mmap_sem must be held for write. |
| 121 | */ |
| 122 | static int __mlock_vma_pages_range(struct vm_area_struct *vma, |
| 123 | unsigned long start, unsigned long end) |
| 124 | { |
| 125 | struct mm_struct *mm = vma->vm_mm; |
| 126 | unsigned long addr = start; |
| 127 | struct page *pages[16]; /* 16 gives a reasonable batch */ |
| 128 | int write = !!(vma->vm_flags & VM_WRITE); |
| 129 | int nr_pages = (end - start) / PAGE_SIZE; |
| 130 | int ret; |
| 131 | |
| 132 | VM_BUG_ON(start & ~PAGE_MASK || end & ~PAGE_MASK); |
| 133 | VM_BUG_ON(start < vma->vm_start || end > vma->vm_end); |
| 134 | VM_BUG_ON(!rwsem_is_locked(&vma->vm_mm->mmap_sem)); |
| 135 | |
| 136 | lru_add_drain_all(); /* push cached pages to LRU */ |
| 137 | |
| 138 | while (nr_pages > 0) { |
| 139 | int i; |
| 140 | |
| 141 | cond_resched(); |
| 142 | |
| 143 | /* |
| 144 | * get_user_pages makes pages present if we are |
| 145 | * setting mlock. and this extra reference count will |
| 146 | * disable migration of this page. However, page may |
| 147 | * still be truncated out from under us. |
| 148 | */ |
| 149 | ret = get_user_pages(current, mm, addr, |
| 150 | min_t(int, nr_pages, ARRAY_SIZE(pages)), |
| 151 | write, 0, pages, NULL); |
| 152 | /* |
| 153 | * This can happen for, e.g., VM_NONLINEAR regions before |
| 154 | * a page has been allocated and mapped at a given offset, |
| 155 | * or for addresses that map beyond end of a file. |
| 156 | * We'll mlock the the pages if/when they get faulted in. |
| 157 | */ |
| 158 | if (ret < 0) |
| 159 | break; |
| 160 | if (ret == 0) { |
| 161 | /* |
| 162 | * We know the vma is there, so the only time |
| 163 | * we cannot get a single page should be an |
| 164 | * error (ret < 0) case. |
| 165 | */ |
| 166 | WARN_ON(1); |
| 167 | break; |
| 168 | } |
| 169 | |
| 170 | lru_add_drain(); /* push cached pages to LRU */ |
| 171 | |
| 172 | for (i = 0; i < ret; i++) { |
| 173 | struct page *page = pages[i]; |
| 174 | |
| 175 | lock_page(page); |
| 176 | /* |
| 177 | * Because we lock page here and migration is blocked |
| 178 | * by the elevated reference, we need only check for |
| 179 | * page truncation (file-cache only). |
| 180 | */ |
| 181 | if (page->mapping) |
| 182 | mlock_vma_page(page); |
| 183 | unlock_page(page); |
| 184 | put_page(page); /* ref from get_user_pages() */ |
| 185 | |
| 186 | /* |
| 187 | * here we assume that get_user_pages() has given us |
| 188 | * a list of virtually contiguous pages. |
| 189 | */ |
| 190 | addr += PAGE_SIZE; /* for next get_user_pages() */ |
| 191 | nr_pages--; |
| 192 | } |
| 193 | } |
| 194 | |
| 195 | lru_add_drain_all(); /* to update stats */ |
| 196 | |
| 197 | return 0; /* count entire vma as locked_vm */ |
| 198 | } |
| 199 | |
| 200 | /* |
| 201 | * private structure for munlock page table walk |
| 202 | */ |
| 203 | struct munlock_page_walk { |
| 204 | struct vm_area_struct *vma; |
| 205 | pmd_t *pmd; /* for migration_entry_wait() */ |
| 206 | }; |
| 207 | |
| 208 | /* |
| 209 | * munlock normal pages for present ptes |
| 210 | */ |
| 211 | static int __munlock_pte_handler(pte_t *ptep, unsigned long addr, |
| 212 | unsigned long end, struct mm_walk *walk) |
| 213 | { |
| 214 | struct munlock_page_walk *mpw = walk->private; |
| 215 | swp_entry_t entry; |
| 216 | struct page *page; |
| 217 | pte_t pte; |
| 218 | |
| 219 | retry: |
| 220 | pte = *ptep; |
| 221 | /* |
| 222 | * If it's a swap pte, we might be racing with page migration. |
| 223 | */ |
| 224 | if (unlikely(!pte_present(pte))) { |
| 225 | if (!is_swap_pte(pte)) |
| 226 | goto out; |
| 227 | entry = pte_to_swp_entry(pte); |
| 228 | if (is_migration_entry(entry)) { |
| 229 | migration_entry_wait(mpw->vma->vm_mm, mpw->pmd, addr); |
| 230 | goto retry; |
| 231 | } |
| 232 | goto out; |
| 233 | } |
| 234 | |
| 235 | page = vm_normal_page(mpw->vma, addr, pte); |
| 236 | if (!page) |
| 237 | goto out; |
| 238 | |
| 239 | lock_page(page); |
| 240 | if (!page->mapping) { |
| 241 | unlock_page(page); |
| 242 | goto retry; |
| 243 | } |
| 244 | munlock_vma_page(page); |
| 245 | unlock_page(page); |
| 246 | |
| 247 | out: |
| 248 | return 0; |
| 249 | } |
| 250 | |
| 251 | /* |
| 252 | * Save pmd for pte handler for waiting on migration entries |
| 253 | */ |
| 254 | static int __munlock_pmd_handler(pmd_t *pmd, unsigned long addr, |
| 255 | unsigned long end, struct mm_walk *walk) |
| 256 | { |
| 257 | struct munlock_page_walk *mpw = walk->private; |
| 258 | |
| 259 | mpw->pmd = pmd; |
| 260 | return 0; |
| 261 | } |
| 262 | |
| 263 | |
| 264 | /* |
| 265 | * munlock a range of pages in the vma using standard page table walk. |
| 266 | * |
| 267 | * vma->vm_mm->mmap_sem must be held for write. |
| 268 | */ |
| 269 | static void __munlock_vma_pages_range(struct vm_area_struct *vma, |
| 270 | unsigned long start, unsigned long end) |
| 271 | { |
| 272 | struct mm_struct *mm = vma->vm_mm; |
| 273 | struct munlock_page_walk mpw = { |
| 274 | .vma = vma, |
| 275 | }; |
| 276 | struct mm_walk munlock_page_walk = { |
| 277 | .pmd_entry = __munlock_pmd_handler, |
| 278 | .pte_entry = __munlock_pte_handler, |
| 279 | .private = &mpw, |
| 280 | .mm = mm, |
| 281 | }; |
| 282 | |
| 283 | VM_BUG_ON(start & ~PAGE_MASK || end & ~PAGE_MASK); |
| 284 | VM_BUG_ON(!rwsem_is_locked(&vma->vm_mm->mmap_sem)); |
| 285 | VM_BUG_ON(start < vma->vm_start); |
| 286 | VM_BUG_ON(end > vma->vm_end); |
| 287 | |
| 288 | lru_add_drain_all(); /* push cached pages to LRU */ |
| 289 | walk_page_range(start, end, &munlock_page_walk); |
| 290 | lru_add_drain_all(); /* to update stats */ |
| 291 | } |
| 292 | |
| 293 | #else /* CONFIG_UNEVICTABLE_LRU */ |
| 294 | |
| 295 | /* |
| 296 | * Just make pages present if VM_LOCKED. No-op if unlocking. |
| 297 | */ |
| 298 | static int __mlock_vma_pages_range(struct vm_area_struct *vma, |
| 299 | unsigned long start, unsigned long end) |
| 300 | { |
| 301 | if (vma->vm_flags & VM_LOCKED) |
| 302 | make_pages_present(start, end); |
| 303 | return 0; |
| 304 | } |
| 305 | |
| 306 | /* |
| 307 | * munlock a range of pages in the vma -- no-op. |
| 308 | */ |
| 309 | static void __munlock_vma_pages_range(struct vm_area_struct *vma, |
| 310 | unsigned long start, unsigned long end) |
| 311 | { |
| 312 | } |
| 313 | #endif /* CONFIG_UNEVICTABLE_LRU */ |
| 314 | |
| 315 | /* |
| 316 | * mlock all pages in this vma range. For mmap()/mremap()/... |
| 317 | */ |
| 318 | int mlock_vma_pages_range(struct vm_area_struct *vma, |
| 319 | unsigned long start, unsigned long end) |
| 320 | { |
Lee Schermerhorn | 8edb08c | 2008-10-18 20:26:49 -0700 | [diff] [blame^] | 321 | struct mm_struct *mm = vma->vm_mm; |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 322 | int nr_pages = (end - start) / PAGE_SIZE; |
| 323 | BUG_ON(!(vma->vm_flags & VM_LOCKED)); |
| 324 | |
| 325 | /* |
| 326 | * filter unlockable vmas |
| 327 | */ |
| 328 | if (vma->vm_flags & (VM_IO | VM_PFNMAP)) |
| 329 | goto no_mlock; |
| 330 | |
| 331 | if (!((vma->vm_flags & (VM_DONTEXPAND | VM_RESERVED)) || |
| 332 | is_vm_hugetlb_page(vma) || |
Lee Schermerhorn | 8edb08c | 2008-10-18 20:26:49 -0700 | [diff] [blame^] | 333 | vma == get_gate_vma(current))) { |
| 334 | downgrade_write(&mm->mmap_sem); |
| 335 | nr_pages = __mlock_vma_pages_range(vma, start, end); |
| 336 | |
| 337 | up_read(&mm->mmap_sem); |
| 338 | /* vma can change or disappear */ |
| 339 | down_write(&mm->mmap_sem); |
| 340 | vma = find_vma(mm, start); |
| 341 | /* non-NULL vma must contain @start, but need to check @end */ |
| 342 | if (!vma || end > vma->vm_end) |
| 343 | return -EAGAIN; |
| 344 | return nr_pages; |
| 345 | } |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 346 | |
| 347 | /* |
| 348 | * User mapped kernel pages or huge pages: |
| 349 | * make these pages present to populate the ptes, but |
| 350 | * fall thru' to reset VM_LOCKED--no need to unlock, and |
| 351 | * return nr_pages so these don't get counted against task's |
| 352 | * locked limit. huge pages are already counted against |
| 353 | * locked vm limit. |
| 354 | */ |
| 355 | make_pages_present(start, end); |
| 356 | |
| 357 | no_mlock: |
| 358 | vma->vm_flags &= ~VM_LOCKED; /* and don't come back! */ |
| 359 | return nr_pages; /* pages NOT mlocked */ |
| 360 | } |
| 361 | |
| 362 | |
| 363 | /* |
| 364 | * munlock all pages in vma. For munmap() and exit(). |
| 365 | */ |
| 366 | void munlock_vma_pages_all(struct vm_area_struct *vma) |
| 367 | { |
| 368 | vma->vm_flags &= ~VM_LOCKED; |
| 369 | __munlock_vma_pages_range(vma, vma->vm_start, vma->vm_end); |
| 370 | } |
| 371 | |
| 372 | /* |
| 373 | * mlock_fixup - handle mlock[all]/munlock[all] requests. |
| 374 | * |
| 375 | * Filters out "special" vmas -- VM_LOCKED never gets set for these, and |
| 376 | * munlock is a no-op. However, for some special vmas, we go ahead and |
| 377 | * populate the ptes via make_pages_present(). |
| 378 | * |
| 379 | * For vmas that pass the filters, merge/split as appropriate. |
| 380 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 381 | static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev, |
| 382 | unsigned long start, unsigned long end, unsigned int newflags) |
| 383 | { |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 384 | struct mm_struct *mm = vma->vm_mm; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 385 | pgoff_t pgoff; |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 386 | int nr_pages; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 387 | int ret = 0; |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 388 | int lock = newflags & VM_LOCKED; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 389 | |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 390 | if (newflags == vma->vm_flags || |
| 391 | (vma->vm_flags & (VM_IO | VM_PFNMAP))) |
| 392 | goto out; /* don't set VM_LOCKED, don't count */ |
| 393 | |
| 394 | if ((vma->vm_flags & (VM_DONTEXPAND | VM_RESERVED)) || |
| 395 | is_vm_hugetlb_page(vma) || |
| 396 | vma == get_gate_vma(current)) { |
| 397 | if (lock) |
| 398 | make_pages_present(start, end); |
| 399 | goto out; /* don't set VM_LOCKED, don't count */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 400 | } |
| 401 | |
| 402 | pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); |
| 403 | *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma, |
| 404 | vma->vm_file, pgoff, vma_policy(vma)); |
| 405 | if (*prev) { |
| 406 | vma = *prev; |
| 407 | goto success; |
| 408 | } |
| 409 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 410 | if (start != vma->vm_start) { |
| 411 | ret = split_vma(mm, vma, start, 1); |
| 412 | if (ret) |
| 413 | goto out; |
| 414 | } |
| 415 | |
| 416 | if (end != vma->vm_end) { |
| 417 | ret = split_vma(mm, vma, end, 0); |
| 418 | if (ret) |
| 419 | goto out; |
| 420 | } |
| 421 | |
| 422 | success: |
| 423 | /* |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 424 | * Keep track of amount of locked VM. |
| 425 | */ |
| 426 | nr_pages = (end - start) >> PAGE_SHIFT; |
| 427 | if (!lock) |
| 428 | nr_pages = -nr_pages; |
| 429 | mm->locked_vm += nr_pages; |
| 430 | |
| 431 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 432 | * vm_flags is protected by the mmap_sem held in write mode. |
| 433 | * It's okay if try_to_unmap_one unmaps a page just after we |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 434 | * set VM_LOCKED, __mlock_vma_pages_range will bring it back. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 435 | */ |
| 436 | vma->vm_flags = newflags; |
| 437 | |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 438 | if (lock) { |
Lee Schermerhorn | 8edb08c | 2008-10-18 20:26:49 -0700 | [diff] [blame^] | 439 | /* |
| 440 | * mmap_sem is currently held for write. Downgrade the write |
| 441 | * lock to a read lock so that other faults, mmap scans, ... |
| 442 | * while we fault in all pages. |
| 443 | */ |
| 444 | downgrade_write(&mm->mmap_sem); |
| 445 | |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 446 | ret = __mlock_vma_pages_range(vma, start, end); |
| 447 | if (ret > 0) { |
| 448 | mm->locked_vm -= ret; |
| 449 | ret = 0; |
| 450 | } |
Lee Schermerhorn | 8edb08c | 2008-10-18 20:26:49 -0700 | [diff] [blame^] | 451 | /* |
| 452 | * Need to reacquire mmap sem in write mode, as our callers |
| 453 | * expect this. We have no support for atomically upgrading |
| 454 | * a sem to write, so we need to check for ranges while sem |
| 455 | * is unlocked. |
| 456 | */ |
| 457 | up_read(&mm->mmap_sem); |
| 458 | /* vma can change or disappear */ |
| 459 | down_write(&mm->mmap_sem); |
| 460 | *prev = find_vma(mm, start); |
| 461 | /* non-NULL *prev must contain @start, but need to check @end */ |
| 462 | if (!(*prev) || end > (*prev)->vm_end) |
| 463 | ret = -EAGAIN; |
| 464 | } else { |
| 465 | /* |
| 466 | * TODO: for unlocking, pages will already be resident, so |
| 467 | * we don't need to wait for allocations/reclaim/pagein, ... |
| 468 | * However, unlocking a very large region can still take a |
| 469 | * while. Should we downgrade the semaphore for both lock |
| 470 | * AND unlock ? |
| 471 | */ |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 472 | __munlock_vma_pages_range(vma, start, end); |
Lee Schermerhorn | 8edb08c | 2008-10-18 20:26:49 -0700 | [diff] [blame^] | 473 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 474 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 475 | out: |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 476 | *prev = vma; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 477 | return ret; |
| 478 | } |
| 479 | |
| 480 | static int do_mlock(unsigned long start, size_t len, int on) |
| 481 | { |
| 482 | unsigned long nstart, end, tmp; |
| 483 | struct vm_area_struct * vma, * prev; |
| 484 | int error; |
| 485 | |
| 486 | len = PAGE_ALIGN(len); |
| 487 | end = start + len; |
| 488 | if (end < start) |
| 489 | return -EINVAL; |
| 490 | if (end == start) |
| 491 | return 0; |
| 492 | vma = find_vma_prev(current->mm, start, &prev); |
| 493 | if (!vma || vma->vm_start > start) |
| 494 | return -ENOMEM; |
| 495 | |
| 496 | if (start > vma->vm_start) |
| 497 | prev = vma; |
| 498 | |
| 499 | for (nstart = start ; ; ) { |
| 500 | unsigned int newflags; |
| 501 | |
| 502 | /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ |
| 503 | |
| 504 | newflags = vma->vm_flags | VM_LOCKED; |
| 505 | if (!on) |
| 506 | newflags &= ~VM_LOCKED; |
| 507 | |
| 508 | tmp = vma->vm_end; |
| 509 | if (tmp > end) |
| 510 | tmp = end; |
| 511 | error = mlock_fixup(vma, &prev, nstart, tmp, newflags); |
| 512 | if (error) |
| 513 | break; |
| 514 | nstart = tmp; |
| 515 | if (nstart < prev->vm_end) |
| 516 | nstart = prev->vm_end; |
| 517 | if (nstart >= end) |
| 518 | break; |
| 519 | |
| 520 | vma = prev->vm_next; |
| 521 | if (!vma || vma->vm_start != nstart) { |
| 522 | error = -ENOMEM; |
| 523 | break; |
| 524 | } |
| 525 | } |
| 526 | return error; |
| 527 | } |
| 528 | |
| 529 | asmlinkage long sys_mlock(unsigned long start, size_t len) |
| 530 | { |
| 531 | unsigned long locked; |
| 532 | unsigned long lock_limit; |
| 533 | int error = -ENOMEM; |
| 534 | |
| 535 | if (!can_do_mlock()) |
| 536 | return -EPERM; |
| 537 | |
| 538 | down_write(¤t->mm->mmap_sem); |
| 539 | len = PAGE_ALIGN(len + (start & ~PAGE_MASK)); |
| 540 | start &= PAGE_MASK; |
| 541 | |
| 542 | locked = len >> PAGE_SHIFT; |
| 543 | locked += current->mm->locked_vm; |
| 544 | |
| 545 | lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; |
| 546 | lock_limit >>= PAGE_SHIFT; |
| 547 | |
| 548 | /* check against resource limits */ |
| 549 | if ((locked <= lock_limit) || capable(CAP_IPC_LOCK)) |
| 550 | error = do_mlock(start, len, 1); |
| 551 | up_write(¤t->mm->mmap_sem); |
| 552 | return error; |
| 553 | } |
| 554 | |
| 555 | asmlinkage long sys_munlock(unsigned long start, size_t len) |
| 556 | { |
| 557 | int ret; |
| 558 | |
| 559 | down_write(¤t->mm->mmap_sem); |
| 560 | len = PAGE_ALIGN(len + (start & ~PAGE_MASK)); |
| 561 | start &= PAGE_MASK; |
| 562 | ret = do_mlock(start, len, 0); |
| 563 | up_write(¤t->mm->mmap_sem); |
| 564 | return ret; |
| 565 | } |
| 566 | |
| 567 | static int do_mlockall(int flags) |
| 568 | { |
| 569 | struct vm_area_struct * vma, * prev = NULL; |
| 570 | unsigned int def_flags = 0; |
| 571 | |
| 572 | if (flags & MCL_FUTURE) |
| 573 | def_flags = VM_LOCKED; |
| 574 | current->mm->def_flags = def_flags; |
| 575 | if (flags == MCL_FUTURE) |
| 576 | goto out; |
| 577 | |
| 578 | for (vma = current->mm->mmap; vma ; vma = prev->vm_next) { |
| 579 | unsigned int newflags; |
| 580 | |
| 581 | newflags = vma->vm_flags | VM_LOCKED; |
| 582 | if (!(flags & MCL_CURRENT)) |
| 583 | newflags &= ~VM_LOCKED; |
| 584 | |
| 585 | /* Ignore errors */ |
| 586 | mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags); |
| 587 | } |
| 588 | out: |
| 589 | return 0; |
| 590 | } |
| 591 | |
| 592 | asmlinkage long sys_mlockall(int flags) |
| 593 | { |
| 594 | unsigned long lock_limit; |
| 595 | int ret = -EINVAL; |
| 596 | |
| 597 | if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE))) |
| 598 | goto out; |
| 599 | |
| 600 | ret = -EPERM; |
| 601 | if (!can_do_mlock()) |
| 602 | goto out; |
| 603 | |
| 604 | down_write(¤t->mm->mmap_sem); |
| 605 | |
| 606 | lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; |
| 607 | lock_limit >>= PAGE_SHIFT; |
| 608 | |
| 609 | ret = -ENOMEM; |
| 610 | if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) || |
| 611 | capable(CAP_IPC_LOCK)) |
| 612 | ret = do_mlockall(flags); |
| 613 | up_write(¤t->mm->mmap_sem); |
| 614 | out: |
| 615 | return ret; |
| 616 | } |
| 617 | |
| 618 | asmlinkage long sys_munlockall(void) |
| 619 | { |
| 620 | int ret; |
| 621 | |
| 622 | down_write(¤t->mm->mmap_sem); |
| 623 | ret = do_mlockall(0); |
| 624 | up_write(¤t->mm->mmap_sem); |
| 625 | return ret; |
| 626 | } |
| 627 | |
| 628 | /* |
| 629 | * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB |
| 630 | * shm segments) get accounted against the user_struct instead. |
| 631 | */ |
| 632 | static DEFINE_SPINLOCK(shmlock_user_lock); |
| 633 | |
| 634 | int user_shm_lock(size_t size, struct user_struct *user) |
| 635 | { |
| 636 | unsigned long lock_limit, locked; |
| 637 | int allowed = 0; |
| 638 | |
| 639 | locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| 640 | lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; |
Herbert van den Bergh | 5ed44a4 | 2007-07-15 23:38:25 -0700 | [diff] [blame] | 641 | if (lock_limit == RLIM_INFINITY) |
| 642 | allowed = 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 643 | lock_limit >>= PAGE_SHIFT; |
| 644 | spin_lock(&shmlock_user_lock); |
Herbert van den Bergh | 5ed44a4 | 2007-07-15 23:38:25 -0700 | [diff] [blame] | 645 | if (!allowed && |
| 646 | locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 647 | goto out; |
| 648 | get_uid(user); |
| 649 | user->locked_shm += locked; |
| 650 | allowed = 1; |
| 651 | out: |
| 652 | spin_unlock(&shmlock_user_lock); |
| 653 | return allowed; |
| 654 | } |
| 655 | |
| 656 | void user_shm_unlock(size_t size, struct user_struct *user) |
| 657 | { |
| 658 | spin_lock(&shmlock_user_lock); |
| 659 | user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| 660 | spin_unlock(&shmlock_user_lock); |
| 661 | free_uid(user); |
| 662 | } |