Message-ID: <20100204073643.GA31291@elte.hu>
Date:	Thu, 4 Feb 2010 08:36:43 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Dave Airlie <airlied@...il.com>
Cc:	Dave Airlie <airlied@...ux.ie>, torvalds@...ux-foundation.org,
	linux-kernel@...r.kernel.org, dri-devel@...ts.sf.net
Subject: Re: [crash, PATCH] Revert "drm/radeon/kms: move radeon KMS on/off
 switch out of staging."


* Dave Airlie <airlied@...il.com> wrote:

> >> On Wed, Feb 3, 2010 at 1:46 AM, Ingo Molnar <mingo@...e.hu> wrote:
> >> >
> >> > * Dave Airlie <airlied@...il.com> wrote:
> >> >
> >> >> On Tue, Feb 2, 2010 at 6:17 PM, Ingo Molnar <mingo@...e.hu> wrote:
> >> >> >
> >> >> > * Dave Airlie <airlied@...ux.ie> wrote:
> >> >> >
> >> >> >> > Hi Linus,
> >> >> >> >
> >> >> >> > Please pull the 'drm-linus' branch from
> >> >> >> > ssh://master.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6.git drm-linus
> >> >> >> >
> >> >> >>
> >> >> >> I've also added an oops fix I seem to lose off my radar to this tree.
> >> >> >>
> >> >> >> commit 17aafccab4352b422aa01fa6ebf82daff693a5b3
> >> >> >> Author: Michel D??nzer <daenzer@...are.com>
> >> >> >> Date: ? Fri Jan 22 09:20:00 2010 +0100
> >> >> >>
> >> >> >> ? ? drm/radeon/kms: Fix oops after radeon_cs_parser_init() failure.
> >> >> >
> >> >>
> >> >> Wierd this suggests something else is wrong on that machine can you get me
> >> >> the whole dmesg? I'm guessing some iommu or swiotlb issue.
> >> >
> >> > This box has no known hardware or software problems, just this week it booted
> >> > in excess of 1000 kernels so i'd exclude that angle for now.
> >> >
> >> > I have bisected the crash back to the DRM tree and the crash went away with
> >> > the Kconfig revert i applied - and it got fixed by Jerome's patch. I posted
> >> > my config and i posted the relevant boot log as well. Find below the full
> >> > bootlog as well with vanilla -git (ab65832) and the config. (i dont think it
> >> > matters)
> >> >
> >> >> I've asked Jerome to fix the oops, but really anyone with an old .config
> >> >> won't get hit by this, and we've booted this on quite a lot of machines at
> >> >> this point.
> >> >
> >> > I dont see the commit in yesterday's linux-next. It has very fresh
> >> > timestamps:
> >> >
> >> > ?commit f71d0187987e691516cd10c2702f002c0e2f0edc
> >> > ?Author: ? ? Dave Airlie <airlied@...hat.com>
> >> > ?AuthorDate: Mon Feb 1 11:35:47 2010 +1000
> >> > ?Commit: ? ? Dave Airlie <airlied@...hat.com>
> >> > ?CommitDate: Mon Feb 1 11:35:47 2010 +1000
> >> >
> >> > What kind of widespread testing could this commit have gotten in the less
> >> > than 24 hours before it hit mainline?
> >> >
> >>
> >> Its shipping in a major distro by default, its planned to be shipped in an
> >> even more major distro. Its been boot tested on 1000s of machines by 1000s
> >> of ppl.
> >
> > Well but that's not the precise tree you sent to Linus, is it?
> 
> It pretty much is. If I could blame your crash on any of the recent patches 
> I would but its something new and unfun. [...]

You dont seem to realize the plain and simple fact that the bug (and some 
other bug) was obscure before because this particular KMS aspect of the 
radeon driver was in drivers/staging/, and it became more prominent via this 
post-rc6 commit:

 | From f71d0187987e691516cd10c2702f002c0e2f0edc Mon Sep 17 00:00:00 2001
 | From: Dave Airlie <airlied@...hat.com>
 | Date: Mon, 1 Feb 2010 11:35:47 +1000
 | Subject: [PATCH] drm/radeon/kms: move radeon KMS on/off switch out of staging.
 |
 | We are happy enough that the KMS driver is stable enough for enough people
 | for the kms enable/disable to leave staging. Distros can now contemplate
 | turning this on.
 |
 | Signed-off-by: Dave Airlie <airlied@...hat.com>
 | ---
 |  drivers/gpu/drm/Kconfig |    2 ++
 |  drivers/staging/Kconfig |    2 --
 |  2 files changed, 2 insertions(+), 2 deletions(-)

I never claimed (and still dont claim) that the bug is 'new' per se, so why 
do you keep beating down on that straw man argument? I said it in my very 
first mail that this bug got brought upon us by the Kconfig commit above:

> > It's the moving of radeom KMS out of staging after -rc6 that causes it, 
> > because it brought it into the scope of my testing:
> >
> >   f71d018: drm/radeon/kms: move radeon KMS on/off switch out of staging.
> > 
> > So at least on this box it's clearly not ready for mainline enablement 
> > yet.

I dont mind reporting bugs and testing patches (as i did), all i said is that 
from a QA angle it's somewhat late to do that in -rc7. (It's not even a 
completely new driver either, which people would know to stay away from - 
it's a new config option of an existing driver, so i'd expect many people to 
turn it on when they see it in the oldconfig - even though it's default-off.)

You made the bug more prominent by moving it into the driver proper, after 
-rc6, and while i dont mind reporting and working on bugs, your constant 
denial is somewhat counter-productive, as (beyond the waste of time on these 
emails) it suggests that we might see repeat incidents of this kind in the 
future.

Anyway, with two bugs in a row this commit is clearly too problematic for me 
so i have reverted f71d018 from -tip.

Thanks,

	Ingo
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