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; |
Jiri Slaby | 59e99e5 | 2010-03-05 13:41:44 -0800 | [diff] [blame] | 28 | if (rlimit(RLIMIT_MEMLOCK) != 0) |
Alexey Dobriyan | e8edc6e | 2007-05-21 01:22:52 +0400 | [diff] [blame] | 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 | /* |
| 35 | * Mlocked pages are marked with PageMlocked() flag for efficient testing |
| 36 | * in vmscan and, possibly, the fault path; and to support semi-accurate |
| 37 | * statistics. |
| 38 | * |
| 39 | * An mlocked page [PageMlocked(page)] is unevictable. As such, it will |
| 40 | * be placed on the LRU "unevictable" list, rather than the [in]active lists. |
| 41 | * The unevictable list is an LRU sibling list to the [in]active lists. |
| 42 | * PageUnevictable is set to indicate the unevictable state. |
| 43 | * |
| 44 | * When lazy mlocking via vmscan, it is important to ensure that the |
| 45 | * vma's VM_LOCKED status is not concurrently being modified, otherwise we |
| 46 | * may have mlocked a page that is being munlocked. So lazy mlock must take |
| 47 | * the mmap_sem for read, and verify that the vma really is locked |
| 48 | * (see mm/rmap.c). |
| 49 | */ |
| 50 | |
| 51 | /* |
| 52 | * LRU accounting for clear_page_mlock() |
| 53 | */ |
| 54 | void __clear_page_mlock(struct page *page) |
| 55 | { |
| 56 | VM_BUG_ON(!PageLocked(page)); |
| 57 | |
| 58 | if (!page->mapping) { /* truncated ? */ |
| 59 | return; |
| 60 | } |
| 61 | |
Nick Piggin | 5344b7e | 2008-10-18 20:26:51 -0700 | [diff] [blame] | 62 | dec_zone_page_state(page, NR_MLOCK); |
| 63 | count_vm_event(UNEVICTABLE_PGCLEARED); |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 64 | if (!isolate_lru_page(page)) { |
| 65 | putback_lru_page(page); |
| 66 | } else { |
| 67 | /* |
KOSAKI Motohiro | 8891d6d | 2008-11-12 13:26:53 -0800 | [diff] [blame] | 68 | * We lost the race. the page already moved to evictable list. |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 69 | */ |
KOSAKI Motohiro | 8891d6d | 2008-11-12 13:26:53 -0800 | [diff] [blame] | 70 | if (PageUnevictable(page)) |
Nick Piggin | 5344b7e | 2008-10-18 20:26:51 -0700 | [diff] [blame] | 71 | count_vm_event(UNEVICTABLE_PGSTRANDED); |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 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 | |
Nick Piggin | 5344b7e | 2008-10-18 20:26:51 -0700 | [diff] [blame] | 83 | if (!TestSetPageMlocked(page)) { |
| 84 | inc_zone_page_state(page, NR_MLOCK); |
| 85 | count_vm_event(UNEVICTABLE_PGMLOCKED); |
| 86 | if (!isolate_lru_page(page)) |
| 87 | putback_lru_page(page); |
| 88 | } |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 89 | } |
| 90 | |
Lee Schermerhorn | 6927c1d | 2009-12-14 17:59:55 -0800 | [diff] [blame] | 91 | /** |
| 92 | * munlock_vma_page - munlock a vma page |
| 93 | * @page - page to be unlocked |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 94 | * |
Lee Schermerhorn | 6927c1d | 2009-12-14 17:59:55 -0800 | [diff] [blame] | 95 | * called from munlock()/munmap() path with page supposedly on the LRU. |
| 96 | * When we munlock a page, because the vma where we found the page is being |
| 97 | * munlock()ed or munmap()ed, we want to check whether other vmas hold the |
| 98 | * page locked so that we can leave it on the unevictable lru list and not |
| 99 | * bother vmscan with it. However, to walk the page's rmap list in |
| 100 | * try_to_munlock() we must isolate the page from the LRU. If some other |
| 101 | * task has removed the page from the LRU, we won't be able to do that. |
| 102 | * So we clear the PageMlocked as we might not get another chance. If we |
| 103 | * can't isolate the page, we leave it for putback_lru_page() and vmscan |
| 104 | * [page_referenced()/try_to_unmap()] to deal with. |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 105 | */ |
Hugh Dickins | 73848b4 | 2009-12-14 17:59:22 -0800 | [diff] [blame] | 106 | void munlock_vma_page(struct page *page) |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 107 | { |
| 108 | BUG_ON(!PageLocked(page)); |
| 109 | |
Nick Piggin | 5344b7e | 2008-10-18 20:26:51 -0700 | [diff] [blame] | 110 | if (TestClearPageMlocked(page)) { |
| 111 | dec_zone_page_state(page, NR_MLOCK); |
| 112 | if (!isolate_lru_page(page)) { |
| 113 | int ret = try_to_munlock(page); |
| 114 | /* |
| 115 | * did try_to_unlock() succeed or punt? |
| 116 | */ |
Hugh Dickins | 53f79ac | 2009-12-14 17:58:58 -0800 | [diff] [blame] | 117 | if (ret != SWAP_MLOCK) |
Nick Piggin | 5344b7e | 2008-10-18 20:26:51 -0700 | [diff] [blame] | 118 | count_vm_event(UNEVICTABLE_PGMUNLOCKED); |
| 119 | |
| 120 | putback_lru_page(page); |
| 121 | } else { |
| 122 | /* |
Lee Schermerhorn | 6927c1d | 2009-12-14 17:59:55 -0800 | [diff] [blame] | 123 | * Some other task has removed the page from the LRU. |
| 124 | * putback_lru_page() will take care of removing the |
| 125 | * page from the unevictable list, if necessary. |
| 126 | * vmscan [page_referenced()] will move the page back |
| 127 | * to the unevictable list if some other vma has it |
| 128 | * mlocked. |
Nick Piggin | 5344b7e | 2008-10-18 20:26:51 -0700 | [diff] [blame] | 129 | */ |
| 130 | if (PageUnevictable(page)) |
| 131 | count_vm_event(UNEVICTABLE_PGSTRANDED); |
| 132 | else |
| 133 | count_vm_event(UNEVICTABLE_PGMUNLOCKED); |
| 134 | } |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 135 | } |
| 136 | } |
| 137 | |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 138 | /** |
Hugh Dickins | 408e82b | 2009-09-21 17:03:23 -0700 | [diff] [blame] | 139 | * __mlock_vma_pages_range() - mlock a range of pages in the vma. |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 140 | * @vma: target vma |
| 141 | * @start: start address |
| 142 | * @end: end address |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 143 | * |
Hugh Dickins | 408e82b | 2009-09-21 17:03:23 -0700 | [diff] [blame] | 144 | * This takes care of making the pages present too. |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 145 | * |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 146 | * return 0 on success, negative error code on error. |
| 147 | * |
| 148 | * vma->vm_mm->mmap_sem must be held for at least read. |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 149 | */ |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 150 | static long __mlock_vma_pages_range(struct vm_area_struct *vma, |
Hugh Dickins | 408e82b | 2009-09-21 17:03:23 -0700 | [diff] [blame] | 151 | unsigned long start, unsigned long end) |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 152 | { |
| 153 | struct mm_struct *mm = vma->vm_mm; |
| 154 | unsigned long addr = start; |
| 155 | struct page *pages[16]; /* 16 gives a reasonable batch */ |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 156 | int nr_pages = (end - start) / PAGE_SIZE; |
Helge Deller | 72eb8c6 | 2008-11-17 00:30:57 +0100 | [diff] [blame] | 157 | int ret = 0; |
Hugh Dickins | 408e82b | 2009-09-21 17:03:23 -0700 | [diff] [blame] | 158 | int gup_flags; |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 159 | |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 160 | VM_BUG_ON(start & ~PAGE_MASK); |
| 161 | VM_BUG_ON(end & ~PAGE_MASK); |
| 162 | VM_BUG_ON(start < vma->vm_start); |
| 163 | VM_BUG_ON(end > vma->vm_end); |
Hugh Dickins | 408e82b | 2009-09-21 17:03:23 -0700 | [diff] [blame] | 164 | VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem)); |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 165 | |
Hugh Dickins | 58fa879 | 2009-09-21 17:03:31 -0700 | [diff] [blame] | 166 | gup_flags = FOLL_TOUCH | FOLL_GET; |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 167 | if (vma->vm_flags & VM_WRITE) |
Hugh Dickins | 58fa879 | 2009-09-21 17:03:31 -0700 | [diff] [blame] | 168 | gup_flags |= FOLL_WRITE; |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 169 | |
Linus Torvalds | d782437 | 2010-08-15 11:35:52 -0700 | [diff] [blame] | 170 | /* We don't try to access the guard page of a stack vma */ |
| 171 | if (vma->vm_flags & VM_GROWSDOWN) { |
| 172 | if (start == vma->vm_start) { |
| 173 | start += PAGE_SIZE; |
| 174 | nr_pages--; |
| 175 | } |
| 176 | } |
| 177 | |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 178 | while (nr_pages > 0) { |
| 179 | int i; |
| 180 | |
| 181 | cond_resched(); |
| 182 | |
| 183 | /* |
| 184 | * get_user_pages makes pages present if we are |
| 185 | * setting mlock. and this extra reference count will |
| 186 | * disable migration of this page. However, page may |
| 187 | * still be truncated out from under us. |
| 188 | */ |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 189 | ret = __get_user_pages(current, mm, addr, |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 190 | min_t(int, nr_pages, ARRAY_SIZE(pages)), |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 191 | gup_flags, pages, NULL); |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 192 | /* |
| 193 | * This can happen for, e.g., VM_NONLINEAR regions before |
| 194 | * a page has been allocated and mapped at a given offset, |
| 195 | * or for addresses that map beyond end of a file. |
Hugh Dickins | 408e82b | 2009-09-21 17:03:23 -0700 | [diff] [blame] | 196 | * We'll mlock the pages if/when they get faulted in. |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 197 | */ |
| 198 | if (ret < 0) |
| 199 | break; |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 200 | |
| 201 | lru_add_drain(); /* push cached pages to LRU */ |
| 202 | |
| 203 | for (i = 0; i < ret; i++) { |
| 204 | struct page *page = pages[i]; |
| 205 | |
Hugh Dickins | 6e91971 | 2009-09-21 17:03:32 -0700 | [diff] [blame] | 206 | if (page->mapping) { |
| 207 | /* |
| 208 | * That preliminary check is mainly to avoid |
| 209 | * the pointless overhead of lock_page on the |
| 210 | * ZERO_PAGE: which might bounce very badly if |
| 211 | * there is contention. However, we're still |
| 212 | * dirtying its cacheline with get/put_page: |
| 213 | * we'll add another __get_user_pages flag to |
| 214 | * avoid it if that case turns out to matter. |
| 215 | */ |
| 216 | lock_page(page); |
| 217 | /* |
| 218 | * Because we lock page here and migration is |
| 219 | * blocked by the elevated reference, we need |
| 220 | * only check for file-cache page truncation. |
| 221 | */ |
| 222 | if (page->mapping) |
| 223 | mlock_vma_page(page); |
| 224 | unlock_page(page); |
| 225 | } |
Hugh Dickins | 408e82b | 2009-09-21 17:03:23 -0700 | [diff] [blame] | 226 | put_page(page); /* ref from get_user_pages() */ |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 227 | } |
Hugh Dickins | 408e82b | 2009-09-21 17:03:23 -0700 | [diff] [blame] | 228 | |
| 229 | addr += ret * PAGE_SIZE; |
| 230 | nr_pages -= ret; |
Lee Schermerhorn | 9978ad5 | 2008-10-18 20:26:56 -0700 | [diff] [blame] | 231 | ret = 0; |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 232 | } |
| 233 | |
Hugh Dickins | 408e82b | 2009-09-21 17:03:23 -0700 | [diff] [blame] | 234 | return ret; /* 0 or negative error code */ |
Lee Schermerhorn | 9978ad5 | 2008-10-18 20:26:56 -0700 | [diff] [blame] | 235 | } |
| 236 | |
| 237 | /* |
| 238 | * convert get_user_pages() return value to posix mlock() error |
| 239 | */ |
| 240 | static int __mlock_posix_error_return(long retval) |
| 241 | { |
| 242 | if (retval == -EFAULT) |
| 243 | retval = -ENOMEM; |
| 244 | else if (retval == -ENOMEM) |
| 245 | retval = -EAGAIN; |
| 246 | return retval; |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 247 | } |
| 248 | |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 249 | /** |
| 250 | * mlock_vma_pages_range() - mlock pages in specified vma range. |
| 251 | * @vma - the vma containing the specfied address range |
| 252 | * @start - starting address in @vma to mlock |
| 253 | * @end - end address [+1] in @vma to mlock |
| 254 | * |
| 255 | * For mmap()/mremap()/expansion of mlocked vma. |
| 256 | * |
| 257 | * return 0 on success for "normal" vmas. |
| 258 | * |
| 259 | * return number of pages [> 0] to be removed from locked_vm on success |
| 260 | * of "special" vmas. |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 261 | */ |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 262 | long mlock_vma_pages_range(struct vm_area_struct *vma, |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 263 | unsigned long start, unsigned long end) |
| 264 | { |
| 265 | int nr_pages = (end - start) / PAGE_SIZE; |
| 266 | BUG_ON(!(vma->vm_flags & VM_LOCKED)); |
| 267 | |
| 268 | /* |
| 269 | * filter unlockable vmas |
| 270 | */ |
| 271 | if (vma->vm_flags & (VM_IO | VM_PFNMAP)) |
| 272 | goto no_mlock; |
| 273 | |
| 274 | if (!((vma->vm_flags & (VM_DONTEXPAND | VM_RESERVED)) || |
| 275 | is_vm_hugetlb_page(vma) || |
Lee Schermerhorn | 8edb08c | 2008-10-18 20:26:49 -0700 | [diff] [blame] | 276 | vma == get_gate_vma(current))) { |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 277 | |
Hugh Dickins | 408e82b | 2009-09-21 17:03:23 -0700 | [diff] [blame] | 278 | __mlock_vma_pages_range(vma, start, end); |
Hugh Dickins | d5b5623 | 2009-02-08 20:56:58 +0000 | [diff] [blame] | 279 | |
| 280 | /* Hide errors from mmap() and other callers */ |
| 281 | return 0; |
Lee Schermerhorn | 8edb08c | 2008-10-18 20:26:49 -0700 | [diff] [blame] | 282 | } |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 283 | |
| 284 | /* |
| 285 | * User mapped kernel pages or huge pages: |
| 286 | * make these pages present to populate the ptes, but |
| 287 | * fall thru' to reset VM_LOCKED--no need to unlock, and |
| 288 | * return nr_pages so these don't get counted against task's |
| 289 | * locked limit. huge pages are already counted against |
| 290 | * locked vm limit. |
| 291 | */ |
| 292 | make_pages_present(start, end); |
| 293 | |
| 294 | no_mlock: |
| 295 | vma->vm_flags &= ~VM_LOCKED; /* and don't come back! */ |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 296 | return nr_pages; /* error or pages NOT mlocked */ |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 297 | } |
| 298 | |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 299 | /* |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 300 | * munlock_vma_pages_range() - munlock all pages in the vma range.' |
| 301 | * @vma - vma containing range to be munlock()ed. |
| 302 | * @start - start address in @vma of the range |
| 303 | * @end - end of range in @vma. |
| 304 | * |
| 305 | * For mremap(), munmap() and exit(). |
| 306 | * |
| 307 | * Called with @vma VM_LOCKED. |
| 308 | * |
| 309 | * Returns with VM_LOCKED cleared. Callers must be prepared to |
| 310 | * deal with this. |
| 311 | * |
| 312 | * We don't save and restore VM_LOCKED here because pages are |
| 313 | * still on lru. In unmap path, pages might be scanned by reclaim |
| 314 | * and re-mlocked by try_to_{munlock|unmap} before we unmap and |
| 315 | * free them. This will result in freeing mlocked pages. |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 316 | */ |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 317 | void munlock_vma_pages_range(struct vm_area_struct *vma, |
Hugh Dickins | 408e82b | 2009-09-21 17:03:23 -0700 | [diff] [blame] | 318 | unsigned long start, unsigned long end) |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 319 | { |
Hugh Dickins | 408e82b | 2009-09-21 17:03:23 -0700 | [diff] [blame] | 320 | unsigned long addr; |
| 321 | |
| 322 | lru_add_drain(); |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 323 | vma->vm_flags &= ~VM_LOCKED; |
Hugh Dickins | 408e82b | 2009-09-21 17:03:23 -0700 | [diff] [blame] | 324 | |
| 325 | for (addr = start; addr < end; addr += PAGE_SIZE) { |
Hugh Dickins | 6e91971 | 2009-09-21 17:03:32 -0700 | [diff] [blame] | 326 | struct page *page; |
| 327 | /* |
| 328 | * Although FOLL_DUMP is intended for get_dump_page(), |
| 329 | * it just so happens that its special treatment of the |
| 330 | * ZERO_PAGE (returning an error instead of doing get_page) |
| 331 | * suits munlock very well (and if somehow an abnormal page |
| 332 | * has sneaked into the range, we won't oops here: great). |
| 333 | */ |
| 334 | page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); |
| 335 | if (page && !IS_ERR(page)) { |
Hugh Dickins | 408e82b | 2009-09-21 17:03:23 -0700 | [diff] [blame] | 336 | lock_page(page); |
Hugh Dickins | 6e91971 | 2009-09-21 17:03:32 -0700 | [diff] [blame] | 337 | /* |
| 338 | * Like in __mlock_vma_pages_range(), |
| 339 | * because we lock page here and migration is |
| 340 | * blocked by the elevated reference, we need |
| 341 | * only check for file-cache page truncation. |
| 342 | */ |
Hugh Dickins | 408e82b | 2009-09-21 17:03:23 -0700 | [diff] [blame] | 343 | if (page->mapping) |
| 344 | munlock_vma_page(page); |
| 345 | unlock_page(page); |
| 346 | put_page(page); |
| 347 | } |
| 348 | cond_resched(); |
| 349 | } |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 350 | } |
| 351 | |
| 352 | /* |
| 353 | * mlock_fixup - handle mlock[all]/munlock[all] requests. |
| 354 | * |
| 355 | * Filters out "special" vmas -- VM_LOCKED never gets set for these, and |
| 356 | * munlock is a no-op. However, for some special vmas, we go ahead and |
| 357 | * populate the ptes via make_pages_present(). |
| 358 | * |
| 359 | * For vmas that pass the filters, merge/split as appropriate. |
| 360 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 361 | static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev, |
| 362 | unsigned long start, unsigned long end, unsigned int newflags) |
| 363 | { |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 364 | struct mm_struct *mm = vma->vm_mm; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 365 | pgoff_t pgoff; |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 366 | int nr_pages; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 367 | int ret = 0; |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 368 | int lock = newflags & VM_LOCKED; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 369 | |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 370 | if (newflags == vma->vm_flags || |
| 371 | (vma->vm_flags & (VM_IO | VM_PFNMAP))) |
| 372 | goto out; /* don't set VM_LOCKED, don't count */ |
| 373 | |
| 374 | if ((vma->vm_flags & (VM_DONTEXPAND | VM_RESERVED)) || |
| 375 | is_vm_hugetlb_page(vma) || |
| 376 | vma == get_gate_vma(current)) { |
| 377 | if (lock) |
| 378 | make_pages_present(start, end); |
| 379 | goto out; /* don't set VM_LOCKED, don't count */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 380 | } |
| 381 | |
| 382 | pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); |
| 383 | *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma, |
| 384 | vma->vm_file, pgoff, vma_policy(vma)); |
| 385 | if (*prev) { |
| 386 | vma = *prev; |
| 387 | goto success; |
| 388 | } |
| 389 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 390 | if (start != vma->vm_start) { |
| 391 | ret = split_vma(mm, vma, start, 1); |
| 392 | if (ret) |
| 393 | goto out; |
| 394 | } |
| 395 | |
| 396 | if (end != vma->vm_end) { |
| 397 | ret = split_vma(mm, vma, end, 0); |
| 398 | if (ret) |
| 399 | goto out; |
| 400 | } |
| 401 | |
| 402 | success: |
| 403 | /* |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 404 | * Keep track of amount of locked VM. |
| 405 | */ |
| 406 | nr_pages = (end - start) >> PAGE_SHIFT; |
| 407 | if (!lock) |
| 408 | nr_pages = -nr_pages; |
| 409 | mm->locked_vm += nr_pages; |
| 410 | |
| 411 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 412 | * vm_flags is protected by the mmap_sem held in write mode. |
| 413 | * 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] | 414 | * set VM_LOCKED, __mlock_vma_pages_range will bring it back. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 415 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 416 | |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 417 | if (lock) { |
Hugh Dickins | 408e82b | 2009-09-21 17:03:23 -0700 | [diff] [blame] | 418 | vma->vm_flags = newflags; |
| 419 | ret = __mlock_vma_pages_range(vma, start, end); |
| 420 | if (ret < 0) |
| 421 | ret = __mlock_posix_error_return(ret); |
Lee Schermerhorn | 8edb08c | 2008-10-18 20:26:49 -0700 | [diff] [blame] | 422 | } else { |
Hugh Dickins | 408e82b | 2009-09-21 17:03:23 -0700 | [diff] [blame] | 423 | munlock_vma_pages_range(vma, start, end); |
Lee Schermerhorn | 8edb08c | 2008-10-18 20:26:49 -0700 | [diff] [blame] | 424 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 425 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 426 | out: |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 427 | *prev = vma; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 428 | return ret; |
| 429 | } |
| 430 | |
| 431 | static int do_mlock(unsigned long start, size_t len, int on) |
| 432 | { |
| 433 | unsigned long nstart, end, tmp; |
| 434 | struct vm_area_struct * vma, * prev; |
| 435 | int error; |
| 436 | |
| 437 | len = PAGE_ALIGN(len); |
| 438 | end = start + len; |
| 439 | if (end < start) |
| 440 | return -EINVAL; |
| 441 | if (end == start) |
| 442 | return 0; |
| 443 | vma = find_vma_prev(current->mm, start, &prev); |
| 444 | if (!vma || vma->vm_start > start) |
| 445 | return -ENOMEM; |
| 446 | |
| 447 | if (start > vma->vm_start) |
| 448 | prev = vma; |
| 449 | |
| 450 | for (nstart = start ; ; ) { |
| 451 | unsigned int newflags; |
| 452 | |
| 453 | /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ |
| 454 | |
| 455 | newflags = vma->vm_flags | VM_LOCKED; |
| 456 | if (!on) |
| 457 | newflags &= ~VM_LOCKED; |
| 458 | |
| 459 | tmp = vma->vm_end; |
| 460 | if (tmp > end) |
| 461 | tmp = end; |
| 462 | error = mlock_fixup(vma, &prev, nstart, tmp, newflags); |
| 463 | if (error) |
| 464 | break; |
| 465 | nstart = tmp; |
| 466 | if (nstart < prev->vm_end) |
| 467 | nstart = prev->vm_end; |
| 468 | if (nstart >= end) |
| 469 | break; |
| 470 | |
| 471 | vma = prev->vm_next; |
| 472 | if (!vma || vma->vm_start != nstart) { |
| 473 | error = -ENOMEM; |
| 474 | break; |
| 475 | } |
| 476 | } |
| 477 | return error; |
| 478 | } |
| 479 | |
Heiko Carstens | 6a6160a | 2009-01-14 14:14:15 +0100 | [diff] [blame] | 480 | SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 481 | { |
| 482 | unsigned long locked; |
| 483 | unsigned long lock_limit; |
| 484 | int error = -ENOMEM; |
| 485 | |
| 486 | if (!can_do_mlock()) |
| 487 | return -EPERM; |
| 488 | |
KOSAKI Motohiro | 8891d6d | 2008-11-12 13:26:53 -0800 | [diff] [blame] | 489 | lru_add_drain_all(); /* flush pagevec */ |
| 490 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 491 | down_write(¤t->mm->mmap_sem); |
| 492 | len = PAGE_ALIGN(len + (start & ~PAGE_MASK)); |
| 493 | start &= PAGE_MASK; |
| 494 | |
| 495 | locked = len >> PAGE_SHIFT; |
| 496 | locked += current->mm->locked_vm; |
| 497 | |
Jiri Slaby | 59e99e5 | 2010-03-05 13:41:44 -0800 | [diff] [blame] | 498 | lock_limit = rlimit(RLIMIT_MEMLOCK); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 499 | lock_limit >>= PAGE_SHIFT; |
| 500 | |
| 501 | /* check against resource limits */ |
| 502 | if ((locked <= lock_limit) || capable(CAP_IPC_LOCK)) |
| 503 | error = do_mlock(start, len, 1); |
| 504 | up_write(¤t->mm->mmap_sem); |
| 505 | return error; |
| 506 | } |
| 507 | |
Heiko Carstens | 6a6160a | 2009-01-14 14:14:15 +0100 | [diff] [blame] | 508 | SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 509 | { |
| 510 | int ret; |
| 511 | |
| 512 | down_write(¤t->mm->mmap_sem); |
| 513 | len = PAGE_ALIGN(len + (start & ~PAGE_MASK)); |
| 514 | start &= PAGE_MASK; |
| 515 | ret = do_mlock(start, len, 0); |
| 516 | up_write(¤t->mm->mmap_sem); |
| 517 | return ret; |
| 518 | } |
| 519 | |
| 520 | static int do_mlockall(int flags) |
| 521 | { |
| 522 | struct vm_area_struct * vma, * prev = NULL; |
| 523 | unsigned int def_flags = 0; |
| 524 | |
| 525 | if (flags & MCL_FUTURE) |
| 526 | def_flags = VM_LOCKED; |
| 527 | current->mm->def_flags = def_flags; |
| 528 | if (flags == MCL_FUTURE) |
| 529 | goto out; |
| 530 | |
| 531 | for (vma = current->mm->mmap; vma ; vma = prev->vm_next) { |
| 532 | unsigned int newflags; |
| 533 | |
| 534 | newflags = vma->vm_flags | VM_LOCKED; |
| 535 | if (!(flags & MCL_CURRENT)) |
| 536 | newflags &= ~VM_LOCKED; |
| 537 | |
| 538 | /* Ignore errors */ |
| 539 | mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags); |
| 540 | } |
| 541 | out: |
| 542 | return 0; |
| 543 | } |
| 544 | |
Heiko Carstens | 3480b25 | 2009-01-14 14:14:16 +0100 | [diff] [blame] | 545 | SYSCALL_DEFINE1(mlockall, int, flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 546 | { |
| 547 | unsigned long lock_limit; |
| 548 | int ret = -EINVAL; |
| 549 | |
| 550 | if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE))) |
| 551 | goto out; |
| 552 | |
| 553 | ret = -EPERM; |
| 554 | if (!can_do_mlock()) |
| 555 | goto out; |
| 556 | |
KOSAKI Motohiro | 8891d6d | 2008-11-12 13:26:53 -0800 | [diff] [blame] | 557 | lru_add_drain_all(); /* flush pagevec */ |
| 558 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 559 | down_write(¤t->mm->mmap_sem); |
| 560 | |
Jiri Slaby | 59e99e5 | 2010-03-05 13:41:44 -0800 | [diff] [blame] | 561 | lock_limit = rlimit(RLIMIT_MEMLOCK); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 562 | lock_limit >>= PAGE_SHIFT; |
| 563 | |
| 564 | ret = -ENOMEM; |
| 565 | if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) || |
| 566 | capable(CAP_IPC_LOCK)) |
| 567 | ret = do_mlockall(flags); |
| 568 | up_write(¤t->mm->mmap_sem); |
| 569 | out: |
| 570 | return ret; |
| 571 | } |
| 572 | |
Heiko Carstens | 3480b25 | 2009-01-14 14:14:16 +0100 | [diff] [blame] | 573 | SYSCALL_DEFINE0(munlockall) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 574 | { |
| 575 | int ret; |
| 576 | |
| 577 | down_write(¤t->mm->mmap_sem); |
| 578 | ret = do_mlockall(0); |
| 579 | up_write(¤t->mm->mmap_sem); |
| 580 | return ret; |
| 581 | } |
| 582 | |
| 583 | /* |
| 584 | * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB |
| 585 | * shm segments) get accounted against the user_struct instead. |
| 586 | */ |
| 587 | static DEFINE_SPINLOCK(shmlock_user_lock); |
| 588 | |
| 589 | int user_shm_lock(size_t size, struct user_struct *user) |
| 590 | { |
| 591 | unsigned long lock_limit, locked; |
| 592 | int allowed = 0; |
| 593 | |
| 594 | locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; |
Jiri Slaby | 59e99e5 | 2010-03-05 13:41:44 -0800 | [diff] [blame] | 595 | lock_limit = rlimit(RLIMIT_MEMLOCK); |
Herbert van den Bergh | 5ed44a4 | 2007-07-15 23:38:25 -0700 | [diff] [blame] | 596 | if (lock_limit == RLIM_INFINITY) |
| 597 | allowed = 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 598 | lock_limit >>= PAGE_SHIFT; |
| 599 | spin_lock(&shmlock_user_lock); |
Herbert van den Bergh | 5ed44a4 | 2007-07-15 23:38:25 -0700 | [diff] [blame] | 600 | if (!allowed && |
| 601 | locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 602 | goto out; |
| 603 | get_uid(user); |
| 604 | user->locked_shm += locked; |
| 605 | allowed = 1; |
| 606 | out: |
| 607 | spin_unlock(&shmlock_user_lock); |
| 608 | return allowed; |
| 609 | } |
| 610 | |
| 611 | void user_shm_unlock(size_t size, struct user_struct *user) |
| 612 | { |
| 613 | spin_lock(&shmlock_user_lock); |
| 614 | user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| 615 | spin_unlock(&shmlock_user_lock); |
| 616 | free_uid(user); |
| 617 | } |