Users locking memory using futexes

[Jamie Lokier]

Perez-Gonzalez, Inaky wrote:
> [...] each time you lock a futex you are pinning the containing page
> into physical memory, that would cause that if you have, for
> example, 4000 futexes locked in 4000 different pages, there is going
> to be 4 MB of memory locked in [...]

Ouch!  It looks to me like userspace can use FUTEX_FD to lock many
pages of memory, achieving the same as mlock() but without the
resource checks.

Denial of service attack?

-- Jamie