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Date: Sat, 10 Mar 2018 03:06:34 +0300
From: Alexey Dobriyan <adobriyan@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] proc: register filesystem last
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References: <20180309222709.GA3843@avx2>
 <20180309144938.d308e0bf98fb6b5bbcb82189@linux-foundation.org>
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On Fri, Mar 09, 2018 at 02:49:38PM -0800, Andrew Morton wrote:
> On Sat, 10 Mar 2018 01:27:09 +0300 Alexey Dobriyan <adobriyan@gmail.com> wrote:
> 
> > As soon as register_filesystem() exits, filesystem can be mounted.
> > It is better to present fully operational /proc.
> > 
> > Of course it doesn't matter because /proc is not modular
> > but do it anyway.
> > 
> > Drop error check, it should be handled by panicking.
> 
> So... shouldn't we add a call to panic()?

via FS_PANIC flag, yes. I have a patch somewhere.
There are 104 filesystems ATM, some internal, some not.
Some modular, some not.