Re: 3.1-rc1-git9: Reported regressions 2.6.39 -> 3.0

Paul E. McKenney
2011-08-15T15:38:13Z

On Sun, Aug 14, 2011 at 09:02:27PM +0200, Rafael J. Wysocki wrote:
> [NOTE:
> We already have a bug entry for tracking regressions from 3.0:
>
> http://bugzilla.kernel.org/show_bug.cgi?id=40982
>
> but there are no reports linked to it, mostly because Maciej is on vacation,
> but also because the frequency of reporting regressions has been low
> recently. So, if you're seeing a regression from 3.0, please let us know.]
>
> This message contains a list of some post-2.6.39 regressions introduced before
> 3.0, for which there are no fixes in the mainline known to the tracking team.
> If any of them have been fixed already, please let us know.
>
> If you know of any other unresolved post-2.6.39 regressions, please let us know
> either and we'll add them to the list. Also, please let us know if any
> of the entries below are invalid.
>
> Each entry from the list will be sent additionally in an automatic reply to
> this message with CCs to the people involved in reporting and handling the
> issue.
>
>
> Listed regressions statistics:
>
> Date Total Pending Unresolved
> ----------------------------------------
> 2011-08-14 63 22 19
>
>
> Unresolved regressions
> ----------------------
>
> Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=40282
> Subject : IP forwarding regression since 3.0-rc6
> Submitter : Stephan Seitz <stse+lkml@fsing.rootsland.net>
> Date : 2011-07-25 12:51 (21 days old)
> Message-ID : <20110725T141145.GA.2ae38.stse@fsing.rootsland.net>
> References : http://marc.info/?l=linux-kernel&m=131159880004908&w=2
>
>
> Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=40172
> Subject : lockdep trace from post 3.0.
> Submitter : Dave Jones <davej@redhat.com>
> Date : 2011-07-24 1:32 (22 days old)
> Message-ID : <20110724013257.GA6777@redhat.com>
> References : http://marc.info/?l=linux-kernel&m=131147120206819&w=2
>
>
> Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=40092
> Subject : RCU stall in linux-3.0.0
> Submitter : Philip Armstrong <phil@kantaka.co.uk>
> Date : 2011-07-25 21:44 (21 days old)

This one was due the the CPU's idea of the current time getting way
out of sync (as in more than a minute's worth of disagreement, which is
pretty impressive when you think about it). So what happened is that
one CPU decided that the current grace period was a full minute old
immediately, and thus started screaming piteously. John Stultz provided
a configuration workaround, and he and Thomas Gleixner would be working
out the long-term fix.

Thanx, Paul