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Date:   Mon, 1 Aug 2011 17:39:54 +0400
From:   Vasiliy Kulikov <segoon@openwall.com>
To:     Manuel Lauss <manuel.lauss@googlemail.com>
Cc:     linux-kernel@vger.kernel.org,
        Linux-MIPS <linux-mips@linux-mips.org>
Subject: Re: shm broken on MIPS in current -git
Message-ID: <20110801133954.GA11452@albatros>
References: <CAOLZvyEQNS3dwQ+6bh2o6kADp7Gd3xOpah8y1_AhqJ2FWSP9VA@mail.gmail.com>
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Manuel,

On Mon, Aug 01, 2011 at 14:51 +0200, Manuel Lauss wrote:
> CPU 0 Unable to handle kernel paging request at virtual address
> 00000000, epc == 80527c64, ra == 8024afb8
> Oops[#1]:
[...]
> epc   : 80527c64 __down_write_nested+0x68/0xf0

Could you post the asm code of __down_write_nested() of your image?
What pointer is NULL?  Looks like MIPS handles namespaces in usermode
helpers other way.

> ra    : 8024afb8 exit_shm+0x30/0x64
> Status: 10003c02    KERNEL EXL
> Cause : 0080800c
> BadVA : 00000000
> PrId  : 800c8000 (Au1300)
> Process kworker/u:0 (pid: 9, threadinfo=8fc44000, task=8fc3f520, tls=00000000)
> Stack : 14200972 d3054429 00000000 56b8e493 8060d118 00000000 8fc3f520 00000002
>         8fc2c000 8060d114 00000000 8024afb8 00000000 00000000 00000000 00000000
>         8060d0c0 00000000 8fc3f520 80128ae8 30480023 0b309f84 34ffeedb ef9e65d6
>         38019941 af430015 f6d9ebeb 00000000 00000000 00000000 8fc29ce0 8fc15300
>         00000000 00000000 00000000 00000000 00000000 00000000 00000000 80139578
>         ...
> Call Trace:
> [<80527c64>] __down_write_nested+0x68/0xf0
> [<8024afb8>] exit_shm+0x30/0x64
> [<80128ae8>] do_exit+0x50c/0x664
> [<80139578>] ____call_usermodehelper+0xfc/0x118
> [<801061bc>] kernel_thread_helper+0x10/0x18

Thanks,

-- 
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments