linux-kernel - Re: [bug] /etc/profile: line 30: /dev/null: Permission denied (Was: Re: [PATCH] Remove broken by design and by implementation devtmpfs maintenance disaster)

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Message-ID: <20090917203113.GA9530@elte.hu>
Date:	Thu, 17 Sep 2009 22:31:13 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Kay Sievers <kay.sievers@...y.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Greg KH <greg@...ah.com>, linux-kernel@...r.kernel.org
Subject: Re: [bug] /etc/profile: line 30: /dev/null: Permission denied
	(Was: Re: [PATCH] Remove broken by design and by implementation
	devtmpfs maintenance disaster)


* Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> On Thu, 17 Sep 2009, Kay Sievers wrote:
> 
> > On Thu, Sep 17, 2009 at 20:53, Ingo Molnar <mingo@...e.hu> wrote:
> > > I've reproduced a bug with the following .config options:
> > >
> > > ??CONFIG_DEVTMPFS=y
> > > ??CONFIG_DEVTMPFS_MOUNT=y
> > >
> > > /dev/null and /dev/zero are not read/writable to ordinary users, 
> > > breaking normal bootup and login:
> > 
> > Udev should run long before some ordinary/non-root user can login, 
> > and apply the permissions as it always does. It's known to work on 
> > Fedora, SUSE, Ubuntu. What kind of system/environment/setup is that 
> > where you see this?
> 
> I don't know if this is what Ingo does, but I have a few machines 
> where I don't run the distro-supplied 'initrd' at all, because it's 
> easier to boot without it. The Fedora initrd doesn't allow me to 
> sanely set root filesystem parameters without totally rewriting the 
> initrd image, which I'm not interested in, for example (they'll take 
> effect for the root initrd, not the final root).

Correct: i'm booting raw bzImages, with /dev copied to the real /dev. To 
this box udev is mostly an annoyance that slows down my bootup ;-)

Furthermore, this is a really old image, Fedora Core 6, where udev does 
not get updated anymore. I still boot new kernels on it though, and it 
worked fine up to now.

	Ingo
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