1 files changed, 45 insertions, 0 deletions

diff --git a/mm/mlock.c b/mm/mlock.c
index 1ada366570cb..3035a56e7616 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -667,3 +667,48 @@ void user_shm_unlock(size_t size, struct user_struct *user)
         spin_unlock(&shmlock_user_lock);
         free_uid(user);
 }
+
+void *alloc_locked_buffer(size_t size)
+{
+        unsigned long rlim, vm, pgsz;
+        void *buffer = NULL;
+
+        pgsz = PAGE_ALIGN(size) >> PAGE_SHIFT;
+
+        down_write(&current->mm->mmap_sem);
+
+        rlim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
+        vm   = current->mm->total_vm + pgsz;
+        if (rlim < vm)
+                goto out;
+
+        rlim = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
+        vm   = current->mm->locked_vm + pgsz;
+        if (rlim < vm)
+                goto out;
+
+        buffer = kzalloc(size, GFP_KERNEL);
+        if (!buffer)
+                goto out;
+
+        current->mm->total_vm  += pgsz;
+        current->mm->locked_vm += pgsz;
+
+ out:
+        up_write(&current->mm->mmap_sem);
+        return buffer;
+}
+
+void free_locked_buffer(void *buffer, size_t size)
+{
+        unsigned long pgsz = PAGE_ALIGN(size) >> PAGE_SHIFT;
+
+        down_write(&current->mm->mmap_sem);
+
+        current->mm->total_vm  -= pgsz;
+        current->mm->locked_vm -= pgsz;
+
+        up_write(&current->mm->mmap_sem);
+
+        kfree(buffer);
+}