Messages in this thread | | | From | Rusty Russell <> | Subject | Re: [patch] futex API cleanups, futex-api-cleanup-2.5.69-A2 | Date | Tue, 20 May 2003 10:15:23 +1000 |
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In message <Pine.LNX.4.44.0305191752130.13233-100000@localhost.localdomain> you write: > > > > - 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.
Yes. There was a patch which limited it, never got applied.
The real solution is not to pin the page: I pinned the page originally to prevent dealing with addresses changing due to swap out, but you found the COW bug and that blew away that theory anyway 8)
I think the vcache callbacks or similar could be extended to cover the swap out/swap in case.
Cheers, Rusty. -- Anyone who quotes me in their sig is an idiot. -- Rusty Russell. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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