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Date: Mon, 11 Aug 2014 08:11:53 -0700
From: Guenter Roeck <linux@roeck-us.net>
To: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Kees Cook <keescook@chromium.org>, Linux-MIPS <linux-mips@linux-mips.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: MIPS: hang in kmalloc with seccomp writer locks
Message-ID: <20140811151153.GA14365@roeck-us.net>
References: <CAOLZvyFuDqi4+pEae=n7+ZJoAx-vca-pRS8ZAQqvTk-tSyPiwg@mail.gmail.com>
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On Mon, Aug 11, 2014 at 01:35:28PM +0200, Manuel Lauss wrote:
> Hi Kees,
> 
> My MIPS32 toys hang early during bootup at the first kmalloc() with
> seccomp enabled.
> I've bisected it to commit dbd952127d11bb44a4ea30b08cc60531b6a23d71
> ("seccomp: introduce writer locking").  And indeed, reverting this
> commit fixes the hang.
> 
> I'm not sure if seccomp is even working on MIPS, but I've never had
> problems with
> it before so I thought I let you know.
> 

Also see [1] and [2], the latter providing a patch to fix the problem.
The problem is only seen in unicore systems with lock debugging disabled.

Guenter

---
[1] https://lkml.org/lkml/2014/8/9/163
[2] https://lkml.org/lkml/2014/8/10/184