+
+/*
+ * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB
+ * shm segments) get accounted against the user_struct instead.
+ */
+static spinlock_t shmlock_user_lock = SPIN_LOCK_UNLOCKED;
+
+int user_shm_lock(size_t size, struct user_struct *user)
+{
+ unsigned long lock_limit, locked;
+ int allowed = 0;
+
+ spin_lock(&shmlock_user_lock);
+ locked = size >> PAGE_SHIFT;
+ lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
+ lock_limit >>= PAGE_SHIFT;
+ if (locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK))
+ goto out;
+ get_uid(user);
+ user->locked_shm += locked;
+ allowed = 1;
+out:
+ spin_unlock(&shmlock_user_lock);
+ return allowed;
+}
+
+void user_shm_unlock(size_t size, struct user_struct *user)
+{
+ spin_lock(&shmlock_user_lock);
+ user->locked_shm -= (size >> PAGE_SHIFT);
+ spin_unlock(&shmlock_user_lock);
+ free_uid(user);
+}