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Date: Tue, 2 Apr 2013 10:52:15 -0700
Message-ID: <CA+55aFz-0J3uhJC-00AJ0R-4TVOYqFGJk0h5x0HmaX+JR6_MYQ@mail.gmail.com>
Subject: Re: ipc,sem: sysv semaphore scalability
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Sasha Levin <sasha.levin@oracle.com>
Cc: Peter Hurley <peter@hurleysoftware.com>, Dave Jones <davej@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Rik van Riel <riel@surriel.com>,
        Davidlohr Bueso <davidlohr.bueso@hp.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        hhuang@redhat.com, "Low, Jason" <jason.low2@hp.com>,
        Michel Lespinasse <walken@google.com>,
        Larry Woodman <lwoodman@redhat.com>,
        "Vinod, Chegu" <chegu_vinod@hp.com>,
        Stanislav Kinsbursky <skinsbursky@parallels.com>
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On Tue, Apr 2, 2013 at 9:08 AM, Sasha Levin <sasha.levin@oracle.com> wrote:
>
> By just playing with the 'msgsz' parameter with MSG_COPY set.

Hmm. Looking closer, I suspect you're testing without commit
88b9e456b164 ("ipc: don't allocate a copy larger than max"). That
should limit the size passed in to prepare_copy -> load_copy to
msg_ctlmax.

Now, I think it's possibly still a good idea to limit bufsz to INT_MAX
regardless, but as far as I can see that prepare_copy -> load_copy
path is the only place that can get confused. Everybody else uses
size_t (or "long" in the case of r_maxsize) as far as I can tell.

        Linus
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