Re: [Bug #32982] Kernel locks up a few minutes after boot

[NeilBrown <neilb-l3A5Bk7waGM@public.gmane.org>]

On Mon, 18 Apr 2011 07:07:11 +1000 NeilBrown <neilb-l3A5Bk7waGM@public.gmane.org> wrote:

> On Sun, 17 Apr 2011 20:37:39 +0200 Bart Van Assche <bvanassche-y/PYEvSCHaw@public.gmane.orgg> wrote:
> 
> > On Sun, Apr 17, 2011 at 7:03 PM, Linus Torvalds
> > <torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org> wrote:
> > > On Sun, Apr 17, 2011 at 5:57 AM, Rafael J. Wysocki <rjw-KKrjLPT3xs0@public.gmane.org> wrote:
> > > > This message has been generated automatically as a part of a summary report
> > > > of recent regressions.
> > > >
> > > > The following bug entry is on the current list of known regressions
> > > > from 2.6.38.  Please verify if it still should be listed and let the tracking team
> > > > know (either way).
> > > >
> > > >
> > > > Bug-Entry       : http://bugzilla.kernel.org/show_bug.cgi?id=32982
> > > > Subject         : Kernel locks up a few minutes after boot
> > > > Submitter       : Bart Van Assche <bart.vanassche@gmail.com>
> > > > Date            : 2011-04-10 19:55 (8 days old)
> > >
> > > Is this machine running a RAID5 setup or something like that?
> > >
> > > There is a known interaction with the new block layer plugging code
> > > and MD. The "hung task" report in that bugzilla looks very much like
> > > that issue. And you do have "root=/dev/md0", so clearly there's some
> > > md thing going on.
> > >
> > > And bisecting might not work all that well for it, because I suspect
> > > it ends up being very much a matter of IO patterns how it triggers.
> > >
> > > Neil supposedly has a patch for it, but I haven't seen it yet. Neil, Jens?
> > 
> > (converted top-posting into bottom-posting)
> > 
> > Hello Linus,
> > 
> > On the system on which bug #32982 has been triggered md0, md1 and md2
> > have been configured as two-disk RAID1 (mirroring).
> 
> If any of those have write-intent bitmaps then I definitely know what the
> problem is and I'll be posting patches later today (probably not much later).
> 

Actually it won't be today.  The new block device plugging is still unusable
for MD - so I won't be able to fix this until that gets sorted out.

NeilBrown