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Date: Mon, 1 Dec 2014 09:53:16 -0800
Message-ID: <CA+55aFwooh31=GMVUoriev+t92=roye_ck+czqr48M1sQ3UOMg@mail.gmail.com>
Subject: Re: frequent lockups in 3.18rc4
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Will Deacon <will.deacon@arm.com>, Tejun Heo <tj@kernel.org>
Cc: Dave Jones <davej@redhat.com>, Andy Lutomirski <luto@amacapital.net>,
        Don Zickus <dzickus@redhat.com>, Thomas Gleixner <tglx@linutronix.de>,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>
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Sender: linux-kernel-owner@vger.kernel.org

On Mon, Dec 1, 2014 at 9:10 AM, Will Deacon <will.deacon@arm.com> wrote:
>
> So I don't even have binfmt-misc compiled in. The two handlers I have are
> BINFMT_ELF and BINFMT_SCRIPT, but they both check for headers that we won't
> get back from oom_score afaict.

Hmm. So I can't even get that "oom_score" file to be executable in the
first place, which should mean that execve() should terminate very
quickly with an EACCES error.

The fact that you have a "flush_work()" that is waiting for completion
is interesting. Maybe the odd new thread is a worker thread for some
modprobe or similar, and we .  There's that whole

   request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2))

which ends up creating a new work. Maybe the flush_work() is waiting
for that whole mess. Adding Tejun to the cc, since there *were*
changes to workqueues etc since 3.16..

Tejun, full thread on lkml, I'm assuming you can find it in your mail archives..

                      Linus
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