Re: 3.0-git15 Atomic scheduling in pidmap_init

[Paul E. McKenney]

On Thu, Aug 18, 2011 at 02:00:34PM -0700, Andrew Morton wrote:
> On Thu, 18 Aug 2011 11:35:23 -0700
> "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
> 
> > On Wed, Aug 17, 2011 at 07:17:50PM -0400, Josh Boyer wrote:
> > > On Thu, Aug 18, 2011 at 01:06:44AM +0200, Frederic Weisbecker wrote:
> > > > On Wed, Aug 17, 2011 at 07:02:19PM -0400, Josh Boyer wrote:
> > > > > On Wed, Aug 17, 2011 at 03:49:16PM -0700, Paul E. McKenney wrote:
> > > > > > On Wed, Aug 17, 2011 at 06:37:35PM -0400, Josh Boyer wrote:
> > > > > > > On Mon, Aug 15, 2011 at 08:20:52AM -0700, Paul E. McKenney wrote:
> > > > > > > > On Mon, Aug 15, 2011 at 10:04:17AM -0400, Josh Boyer wrote:
> > > > > > > > > > Please see the attached.
> > > > > > > > > 
> > > > > > > > > Fixed it up quickly to apply on top of -rc2 and it seems to solve the
> > > > > > > > > problem nicely.  Thanks for the patch.
> > > > > > > > 
> > > > > > > > Good to hear!  I guess I should keep it, then.  ;-)
> > > > > > > 
> > > > > > > Hey Paul, were you going to send this to Linus for -rc3?  I haven't seen
> > > > > > > it come across LKML yet.
> > > > > > 
> > > > > > I might...  But does it qualify as a regression?  That part of the
> > > > > > code hasn't changed for some time now.
> > > > > 
> > > > > It's a fix for a problem that is newly surfaced in 3.1.  A regression,
> > > > > likely not since it's been there forever, but new debugging options
> > > > > uncovered it.  I'm pretty sure the -rc stage takes fixes even if they
> > > > > aren't regressions.
> > > > 
> > > > Nope, after -rc1 only regressions fixes are taken (most of the time).
> > > 
> > > Sigh.
> > > 
> > > Look, either way I'm carrying this patch in Fedora because it fixes
> > > a bug that is actually being reported by users (and by abrtd as well).
> > > If you both want to wait until 3.2 to actually submit it to Linus,
> > > then OK.
> > > 
> > > Honestly, I'm just glad we actually run with the debug options enabled
> > > (which seems to be a rare thing) so bugs like this are actually found.
> > > Thanks for the fix.
> > 
> > I am sorry, but I didn't make the rules!  And I must carry the fix
> > longer as well, if that makes you feel any better.
> 
> bah, we're not that anal.  The patch fixes a bug and prevents a nasty
> warning spew.  Please, send it to Linus.

Given your Acked-by and Josh's Tested-by I might consider it.  ;-)

Speaking of which, Josh, does this patch help Nicolas and Michal?

> We appear to be referring to the patch "rcu: Avoid having just-onlined
> CPU resched itself when RCU is idle"?  If so, the changelog doesn't
> even mention that the patch fixes a scheduling-while-atomic warning and
> the changelog fails to refer to the redhat bug report.  These omissions
> should be repaired, please.

OK...  But I cannot bring myself to believe that my fix does more than
hide some other bug.  Which is OK, I will just say that in the changelog.

							Thanx, Paul
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