Comment 2 for bug 381920

OK, I've found the problem:

mount helper locks it's memory using mlockall(MCL_FUTURE) to prevent memory
containing secret data being swapped out. But non-privileged user is limited to
how much memory he/she can lock at most. man mlockall:

"If MCL_FUTURE has been specified, then a later system call (e.g., mmap(2),
sbrk(2), malloc(3)), may fail if it would cause the number of locked bytes to
exceed the permitted maximum."

Without locking memory, it works