4 * (C) Copyright 1995 Linus Torvalds
5 * (C) Copyright 2002 Christoph Hellwig
8 #include <linux/capability.h>
9 #include <linux/mman.h>
11 #include <linux/mempolicy.h>
12 #include <linux/syscalls.h>
13 #include <linux/sched.h>
14 #include <linux/module.h>
16 int can_do_mlock(void)
18 if (capable(CAP_IPC_LOCK))
20 if (current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur != 0)
24 EXPORT_SYMBOL(can_do_mlock);
26 static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
27 unsigned long start, unsigned long end, unsigned int newflags)
29 struct mm_struct * mm = vma->vm_mm;
34 if (newflags == vma->vm_flags) {
39 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
40 *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
41 vma->vm_file, pgoff, vma_policy(vma));
49 if (start != vma->vm_start) {
50 ret = split_vma(mm, vma, start, 1);
55 if (end != vma->vm_end) {
56 ret = split_vma(mm, vma, end, 0);
63 * vm_flags is protected by the mmap_sem held in write mode.
64 * It's okay if try_to_unmap_one unmaps a page just after we
65 * set VM_LOCKED, make_pages_present below will bring it back.
67 vma->vm_flags = newflags;
70 * Keep track of amount of locked VM.
72 pages = (end - start) >> PAGE_SHIFT;
73 if (newflags & VM_LOCKED) {
75 if (!(newflags & VM_IO))
76 ret = make_pages_present(start, end);
79 mm->locked_vm -= pages;
84 static int do_mlock(unsigned long start, size_t len, int on)
86 unsigned long nstart, end, tmp;
87 struct vm_area_struct * vma, * prev;
90 len = PAGE_ALIGN(len);
96 vma = find_vma_prev(current->mm, start, &prev);
97 if (!vma || vma->vm_start > start)
100 if (start > vma->vm_start)
103 for (nstart = start ; ; ) {
104 unsigned int newflags;
106 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
108 newflags = vma->vm_flags | VM_LOCKED;
110 newflags &= ~VM_LOCKED;
115 error = mlock_fixup(vma, &prev, nstart, tmp, newflags);
119 if (nstart < prev->vm_end)
120 nstart = prev->vm_end;
125 if (!vma || vma->vm_start != nstart) {
133 asmlinkage long sys_mlock(unsigned long start, size_t len)
135 unsigned long locked;
136 unsigned long lock_limit;
142 down_write(¤t->mm->mmap_sem);
143 len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
146 locked = len >> PAGE_SHIFT;
147 locked += current->mm->locked_vm;
149 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
150 lock_limit >>= PAGE_SHIFT;
152 /* check against resource limits */
153 if ((locked <= lock_limit) || capable(CAP_IPC_LOCK))
154 error = do_mlock(start, len, 1);
155 up_write(¤t->mm->mmap_sem);
159 asmlinkage long sys_munlock(unsigned long start, size_t len)
163 down_write(¤t->mm->mmap_sem);
164 len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
166 ret = do_mlock(start, len, 0);
167 up_write(¤t->mm->mmap_sem);
171 static int do_mlockall(int flags)
173 struct vm_area_struct * vma, * prev = NULL;
174 unsigned int def_flags = 0;
176 if (flags & MCL_FUTURE)
177 def_flags = VM_LOCKED;
178 current->mm->def_flags = def_flags;
179 if (flags == MCL_FUTURE)
182 for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
183 unsigned int newflags;
185 newflags = vma->vm_flags | VM_LOCKED;
186 if (!(flags & MCL_CURRENT))
187 newflags &= ~VM_LOCKED;
190 mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
196 asmlinkage long sys_mlockall(int flags)
198 unsigned long lock_limit;
201 if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
208 down_write(¤t->mm->mmap_sem);
210 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
211 lock_limit >>= PAGE_SHIFT;
214 if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) ||
215 capable(CAP_IPC_LOCK))
216 ret = do_mlockall(flags);
217 up_write(¤t->mm->mmap_sem);
222 asmlinkage long sys_munlockall(void)
226 down_write(¤t->mm->mmap_sem);
227 ret = do_mlockall(0);
228 up_write(¤t->mm->mmap_sem);
233 * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB
234 * shm segments) get accounted against the user_struct instead.
236 static DEFINE_SPINLOCK(shmlock_user_lock);
238 int user_shm_lock(size_t size, struct user_struct *user)
240 unsigned long lock_limit, locked;
243 locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
244 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
245 if (lock_limit == RLIM_INFINITY)
247 lock_limit >>= PAGE_SHIFT;
248 spin_lock(&shmlock_user_lock);
250 locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK))
253 user->locked_shm += locked;
256 spin_unlock(&shmlock_user_lock);
260 void user_shm_unlock(size_t size, struct user_struct *user)
262 spin_lock(&shmlock_user_lock);
263 user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
264 spin_unlock(&shmlock_user_lock);