Re: Analyzed/Solved: Booting 2.6.30-rc2-git7 very slow

[Martin Knoblauch <knobi@knobisoft.de>]

----- Original Message ----

> From: Andrew Morton <akpm@linux-foundation.org>
> To: Mike Galbraith <efault@gmx.de>
> Cc: Martin Knoblauch <knobi@knobisoft.de>; Rafael J. Wysocki <rjw@sisk.pl>; linux-kernel@vger.kernel.org; tigran aivazian <tigran@aivazian.fsnet.co.uk>; Al Viro <viro@zeniv.linux.org.uk>
> Sent: Wednesday, April 29, 2009 10:17:55 AM
> Subject: Re: Analyzed/Solved: Booting 2.6.30-rc2-git7 very slow
> 
> On Wed, 29 Apr 2009 05:51:36 +0200 Mike Galbraith wrote:
> 
> > On Tue, 2009-04-28 at 18:28 -0700, Andrew Morton wrote: 
> > > On Fri, 24 Apr 2009 05:45:19 -0700 (PDT) Martin Knoblauch 
> wrote:
> > > 
> > > > 
> > > > 
> > > >  OK, I just found the reason for both intel-ucode and tg3 failures. 
> Apparently between 2.6.28 and 2.6.29 the mount of sysfs has subtely changed 
> from:
> > > > 
> > > > /sys /sys sysfs rw 0 0
> > > > 
> > > > to:
> > > > 
> > > > none /sys sysfs rw,relatime 0 0
> > > 
> > > I assume that you're referring to the contents of /proc/mounts?
> > > 
> > > >  The "none" breaks the RHEL-4 provided hotplug script "firmware.agent" 
> when it tries to parse the mount point for "/sys". As a result, the firmware 
> loading is never properly finished and the driver(s) just timeout on the value  
> in /sys/class/firmware/timeout. Bingo. Simple fix in user-pace possible - cool 
> down Martin :-)
> > > > 
> > > > 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.
> > 
> > 
> > > [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).
> 
> Displaying relatime seems a bit pointless too.

 Hmm. I actually believe the "none" line comes out of /etc/fstab, but was never before displayed in /proc/mount.

This is from 2.6.19:

[root@lpsdm60 ~]# grep sysfs /etc/fstab
none    /sys    sysfs   defaults        0       0
[root@lpsdm60 ~]# mount | grep sysfs
none on /sys type sysfs (rw)
[root@lpsdm60 ~]# grep sysfs /proc/mounts
/sys /sys sysfs rw 0 0


And this is from 2.6.30:

[root@lpsdm52 linux-2.6.30-rc3-git2]# grep sysfs /etc/fstab
none    /sys    sysfs   defaults        0       0
[root@lpsdm52 linux-2.6.30-rc3-git2]# mount | grep sysfs
none on /sys type sysfs (rw)
[root@lpsdm52 linux-2.6.30-rc3-git2]# grep sysfs /proc/mounts
none /sys sysfs rw,relatime 0 0
/sys /sys sysfs rw,relatime 0 0


 Any changes to mount-handling in 2.6.29?

Cheers
Martin