Message-ID: <46C00446.7030703@openvz.org>
Date: Mon, 13 Aug 2007 11:12:06 +0400
From: Pavel Emelyanov <xemul@openvz.org>
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To: Christoph Hellwig <hch@infradead.org>
CC: akpm@osdl.org, devel@openvz.org, linux-kernel@vger.kernel.org,
       containers@lists.osdl.org, oleg@tv-sign.ru, sukadev@us.ibm.com
Subject: Re: [PATCH 3/20] Introduce MS_KERNMOUNT flag
References: <46BC506B.mailGIV1AXDXM@openvz.org> <20070811034721.GB22216@infradead.org>
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Christoph Hellwig wrote:
> On Fri, Aug 10, 2007 at 03:47:55PM +0400, xemul@openvz.org wrote:
>> This flag tells the .get_sb callback that this is a kern_mount() call
>> so that it can trust *data pointer to be valid in-kernel one. If this
>> flag is passed from the user process, it is cleared since the *data
>> pointer is not a valid kernel object.
>>
>> Running a few steps forward - this will be needed for proc to create the
>> superblock and store a valid pid namespace on it during the namespace
>> creation. The reason, why the namespace cannot live without proc mount
>> is described in the appropriate patch.
> 
> I don't like this at all.  We should never pass kernel and userspace
> addresses through the same pointer.  Maybe add an additional argument
> to the get_sb prototype instead.  But this whole idea of mounting /proc
> from kernelspace sounds like a really bad idea to me.  /proc should
> never be mounted from the kernel but always normally from userspace.

Why then is it mounted in proc_root_init()?

Thanks,
Pavel
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