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Subject: Re: Analyzed/Solved: Booting 2.6.30-rc2-git7 very slow
From: Mike Galbraith <efault@gmx.de>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>,
       Martin Knoblauch <knobi@knobisoft.de>,
       "Rafael J. Wysocki" <rjw@sisk.pl>, linux-kernel@vger.kernel.org,
       tigran aivazian <tigran@aivazian.fsnet.co.uk>
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Date: Wed, 29 Apr 2009 16:18:45 +0200
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On Wed, 2009-04-29 at 13:08 +0100, Al Viro wrote:
> On Wed, Apr 29, 2009 at 01:17:55AM -0700, Andrew Morton wrote:
> 
> > > > > Questions remains: was this intentional? It breaks existing userspace and should therefore be considered a regression - right? On the other hand, it will never be a problem for RHEL-4/5 kernels, unless the change in 2.6.29 gets backported. Any ideas?
> > > > 
> > > > afaik that was unintentional and was probably a mistake.
> > > > 
> > > > I wonder how we did that.
> > > 
> > > <paste>
> > > > [hotplug]# grep sysfs /proc/mounts
> > > > none /sys sysfs rw,relatime 0 0
> > > > /sys /sys sysfs rw,relatime 0 0
> > > 
> > > ___(I wonder how the heck that is accomplished)
> > 
> > Beats me.  I'm not seeing likely changes in fs/proc/base.c or around
> > show_mountinfo().  Maybe sysfs broke in an ingenious way.  (hopefully
> > cc's viro).
> 
> Er...  Somebody mounting sysfs twice?  From some init script and from
> /etc/fstab, perhaps?  That definitely looks like two mount(2) had to
> have been done to cause that...

Yeah, but how does one go about doing that?

Using mount -f, I can convince mount to succeed, but I still have only
one entry in /proc/mounts, despite what my mount binary imagines.

marge:..sys/vm # grep sysfs /proc/mounts
sysfs /sys sysfs rw,relatime 0 0

marge:..sys/vm # mount|grep sysfs
sysfs on /sys type sysfs (rw)
sys on /sys type sysfs (rw)
/sys on /sys type sysfs (rw)

	-Mike

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