Re: [patch] futex API cleanups, futex-api-cleanup-2.5.69-A2

From: Jamie Lokier (jamie@shareable.org)
Date: Mon May 19 2003 - 18:33:53 EST


Ingo Molnar wrote:
> > > - start the phasing out of FUTEX_FD. This i believe is quite unclean and
> > > unrobust, [...]
>
> FUTEX_FD is an instant DoS, it allows the pinning of one page per file
> descriptor, per thread. With a default limit of 1024 open files per
> thread, and 256 threads (on a sane/conservative setup), this means 1 GB of
> RAM can be pinned down by a normal unprivileged user.

The correct solution [;)] is EP_FUTEX - allow a futex to be specified
as the source of an epoll event.

-- Jamie
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