Re: T400 suspend/resume regression -- bisected to a mystery merge commit

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Friday 02 October 2009, Magnus Damm wrote:
> On Mon, Sep 28, 2009 at 10:51 PM, Theodore Tso <tytso@mit.edu> wrote:
> > On Sun, Sep 27, 2009 at 06:13:42PM +0200, Rafael J. Wysocki wrote:
> >>
> >> commit c7121843685de2bf7f3afd3ae1d6a146010bf1fc
> >> Author: Magnus Damm <magnus.damm@gmail.com>
> >> Date:   Tue Jul 28 14:09:55 2009 -0700
> >>
> >>     clocksource: Save mult_orig in clocksource_disable()
> >>
> >> Please try to revert it and retest.
> >
> > Using Linus's suggested technique, I bisected it down to this commit:
> >
> > Author: Martin Schwidefsky <schwidefsky@de.ibm.com>
> > Date:   Fri Aug 14 15:47:30 2009 +0200
> >
> >    timekeeping: Update clocksource with stop_machine
> >
> >    update_wall_time calls change_clocksource HZ times per second to check
> >    if a new clock source is available. In close to 100% of all calls
> >    there is no new clock. Replace the tick based check by an update done
> >    with stop_machine.
> >
> >    Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
> >    Cc: Ingo Molnar <mingo@elte.hu>
> >    Acked-by: John Stultz <johnstul@us.ibm.com>
> >    Cc: Daniel Walker <dwalker@fifo99.com>
> >    LKML-Reference: <20090814134810.711836357@de.ibm.com>
> >    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> >
> > Unfortunately there are a bunch of patches I'm trying to get in shape
> > to push to Linus (the merge window coincided unfortunately with
> > LinuxCon/Plumbeer's so I'm a bit behind) so I haven't had a chance to
> > take it further.  I'll try reverting each of the above two patches,
> > and report back in a day or two.
> 
> Just checking, did need to revert
> c7121843685de2bf7f3afd3ae1d6a146010bf1fc? I hope not. =)

But someone else did, as mentioned above.  It is on the regression list as
http://bugzilla.kernel.org/show_bug.cgi?id=14222

Thanks,
Rafael