linux-kernel - Re: [PATCH 0/4] futex: get_user_pages

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 30 Sep 2008 17:21:51 +1000
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Eric Dumazet <dada1@...mosbay.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 0/4] futex: get_user_pages_fast() for shared futexes

On Sunday 28 September 2008 02:17, Ingo Molnar wrote:
> * Peter Zijlstra <a.p.zijlstra@...llo.nl> wrote:
> > Since get_user_pages_fast() made it in, I thought to give this another
> > try. Lightly tested by disabling the private futexes and running some
> > java proglets.
>
> hm, very interesting. Since this is an important futex usecase i started
> testing it in tip/core/futexes:
>
>  cd33272: futex: cleanup fshared
>  a135356: futex: use fast_gup()
>  39ce77b: futex: reduce mmap_sem usage
>  0d7a336: futex: rely on get_user_pages() for shared futexes
>
> Nick, it would be nice to get an Acked-by/Reviewed-by from you, before
> we think about whether it should go upstream.

Yeah, these all look pretty good. It's nice to get rid of mmap sem here.

Which reminds me, we need to put a might_lock mmap_sem into
get_user_pages_fast...

But these patches look good to me (last time we discussed them I thought
there was a race with page truncate, but it looks like you've closed that
by holding page lock over the whole operation...)

Nice work, Peter.

BTW. what kinds of things use inter-process futexes as of now?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/