2.6.23-rc1: known regressions with patches

2.6.23-rc1: known regressions with patches

[Michal Piotrowski]

Hi all,

Here is a list of some known regressions in 2.6.23-rc1
with patches available.

Feel free to add new regressions/remove fixed etc.
http://kernelnewbies.org/known_regressions

List of Aces

Name                    Regressions fixed since 21-Jun-2007
Andi Kleen                             4
Linus Torvalds                         4
Adrian Bunk                            3
Andrew Morton                          3
Jens Axboe                             3
Al Viro                                2
David Woodhouse                        2
Hugh Dickins                           2
Tejun Heo                              2



Unclassified

Subject         : Regression with sys_time() speedup patch
References      : http://lkml.org/lkml/2007/7/20/205
Last known good : ?
Submitter       : Takashi Iwai <tiwai@suse.de>
Caused-By       : ?
Handled-By      : Ingo Molnar <mingo@elte.hu>
Patch           : http://lkml.org/lkml/2007/7/20/219
Status          : patch available

Subject         : kobject link failure
References      : http://lkml.org/lkml/2007/7/19/495
Last known good : ?
Submitter       : Jan Engelhardt <jengelh@linux01.gwdg.de>
Caused-By       : ?
Handled-By      : Cornelia Huck <cornelia.huck@de.ibm.com>
                  Greg Kroah-Hartman <gregkh@suse.de>
Patch           : http://lkml.org/lkml/2007/7/20/143
Status          : patch available

Subject         : Kconfig prompts without help text
References      : http://lkml.org/lkml/2007/7/16/326
Last known good : ?
Submitter       : Stefan Richter <stefanr@s5r6.in-berlin.de>
Caused-By       : ?
Handled-By      : Jan Engelhardt <jengelh@linux01.gwdg.de>
Patch           : http://lkml.org/lkml/2007/7/18/236
Status          : patch available

Subject         : Oops while modprobing phy fixed module
References      : http://lkml.org/lkml/2007/7/14/63
Last known good : ?
Submitter       : Gabriel C <nix.or.die@googlemail.com>
Caused-By       : Tejun Heo <htejun@gmail.com>
                  commit 3007e997de91ec59af39a3f9c91595b31ae6e08b
Handled-By      : Satyam Sharma <satyam.sharma@gmail.com>
                  Tejun Heo <htejun@gmail.com>
                  Vitaly Bordug <vitb@kernel.crashing.org>
Patch1          : http://lkml.org/lkml/2007/7/18/506
Status          : patch available



FS

Subject         : ia64 build failure from recent diskquota patch
References      : http://lkml.org/lkml/2007/7/18/407
Last known good : ?
Submitter       : Doug Chapman <doug.chapman@hp.com>
Caused-By       : Vasily Tarasov <vtaras@openvz.org>
                  commit b716395e2b8e450e294537de0c91476ded2f0395
Handled-By      : Luck, Tony <tony.luck@intel.com>
Patch1          : http://lkml.org/lkml/2007/7/20/255
Patch2          : http://lkml.org/lkml/2007/7/20/272
Status          : patch available



Media

Subject         : usbvision: don't return an uninitialized value
References      : http://lkml.org/lkml/2007/7/23/65
Last known good : ?
Submitter       : Adrian Bunk <bunk@stusta.de>
Caused-By       : ?
Handled-By      : Adrian Bunk <bunk@stusta.de>
Patch           : http://lkml.org/lkml/2007/7/23/65
Status          : patch available



Regards,
Michal

--
LOG
http://www.stardust.webpages.pl/log/

Re: 2.6.23-rc1: known regressions with patches

[Ingo Molnar]

* Michal Piotrowski <michal.k.k.piotrowski@gmail.com> wrote:

> Subject         : Regression with sys_time() speedup patch
> References      : http://lkml.org/lkml/2007/7/20/205
> Last known good : ?
> Submitter       : Takashi Iwai <tiwai@suse.de>
> Caused-By       : ?
> Handled-By      : Ingo Molnar <mingo@elte.hu>
> Patch           : http://lkml.org/lkml/2007/7/20/219
> Status          : patch available

this has been resolved in -rc1 already, by:

commit 2008220879af095d00ca27eb168a55c8595fbc0b

	Ingo 

Re: 2.6.23-rc1: known regressions with patches

[Greg KH]

On Mon, Jul 23, 2007 at 11:47:44AM +0200, Michal Piotrowski wrote:
> Unclassified
> 
> Subject         : kobject link failure
> References      : http://lkml.org/lkml/2007/7/19/495
> Last known good : ?

This is caused by a patch that happened after 2.6.22 was released, so it
is a regression.

> Submitter       : Jan Engelhardt <jengelh@linux01.gwdg.de>
> Caused-By       : ?
> Handled-By      : Cornelia Huck <cornelia.huck@de.ibm.com>
>                   Greg Kroah-Hartman <gregkh@suse.de>
> Patch           : http://lkml.org/lkml/2007/7/20/143
> Status          : patch available

I'll be sending Cornelia's patch to Linus within the week to fix this.

thanks,

greg k-h

Re: 2.6.23-rc1: known regressions with patches

[Tejun Heo]

Michal Piotrowski wrote:
> Subject         : Oops while modprobing phy fixed module
> References      : http://lkml.org/lkml/2007/7/14/63
> Last known good : ?
> Submitter       : Gabriel C <nix.or.die@googlemail.com>
> Caused-By       : Tejun Heo <htejun@gmail.com>
>                   commit 3007e997de91ec59af39a3f9c91595b31ae6e08b
> Handled-By      : Satyam Sharma <satyam.sharma@gmail.com>
>                   Tejun Heo <htejun@gmail.com>
>                   Vitaly Bordug <vitb@kernel.crashing.org>
> Patch1          : http://lkml.org/lkml/2007/7/18/506
> Status          : patch available

Patch is in mainline.  Commit a1da4dfe35bc36c3bc9716d995c85b7983c38a76.

Thanks.

-- 
tejun

Re: 2.6.23-rc1: known regressions with patches

[Michal Piotrowski]

On 24/07/07, Greg KH <gregkh@suse.de> wrote:
> On Mon, Jul 23, 2007 at 11:47:44AM +0200, Michal Piotrowski wrote:
> > Unclassified
> >
> > Subject         : kobject link failure
> > References      : http://lkml.org/lkml/2007/7/19/495
> > Last known good : ?
>
> This is caused by a patch that happened after 2.6.22 was released, so it
> is a regression.

Yes, I know. "?" is a default value. When someone says that bug
appeared after 2.6.22-git7 I'm adding this information to "Last known
good".

>
> > Submitter       : Jan Engelhardt <jengelh@linux01.gwdg.de>
> > Caused-By       : ?
> > Handled-By      : Cornelia Huck <cornelia.huck@de.ibm.com>
> >                   Greg Kroah-Hartman <gregkh@suse.de>
> > Patch           : http://lkml.org/lkml/2007/7/20/143
> > Status          : patch available
>
> I'll be sending Cornelia's patch to Linus within the week to fix this.
>
> thanks,
>
> greg k-h
>

Regards,
Michal

-- 
LOG
http://www.stardust.webpages.pl/log/

[bug] SLUB & freeing locks [was: Re: 2.6.23-rc1: known regressions with patches]

[Ingo Molnar]

there's a new regression:

SLUB does not seem to call debug_check_no_locks_freed() - hence on SLUB 
we will not notice certain types of freeing races. (such as freeing an 
object still locked and used on another CPU.) SLAB does this corretly.

	Ingo

Re: [bug] SLUB & freeing locks [was: Re: 2.6.23-rc1: known regressions with patches]

[Peter Zijlstra]

On Thu, 2007-07-26 at 11:10 +0200, Ingo Molnar wrote:
> there's a new regression:
> 
> SLUB does not seem to call debug_check_no_locks_freed() - hence on SLUB 
> we will not notice certain types of freeing races. (such as freeing an 
> object still locked and used on another CPU.) SLAB does this corretly.

Does this help?

---
 mm/slub.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c
+++ linux-2.6/mm/slub.c
@@ -1131,6 +1131,7 @@ static void __free_slab(struct kmem_cach
 		slab_pad_check(s, page);
 		for_each_object(p, s, page_address(page))
 			check_object(s, page, p, 0);
+		ClearSlabDebug(page);
 	}
 
 	mod_zone_page_state(page_zone(page),
@@ -1169,7 +1170,6 @@ static void discard_slab(struct kmem_cac
 
 	atomic_long_dec(&n->nr_slabs);
 	reset_page_mapcount(page);
-	ClearSlabDebug(page);
 	__ClearPageSlab(page);
 	free_slab(s, page);
 }

Re: [bug] SLUB & freeing locks [was: Re: 2.6.23-rc1: known regressions with patches]

[Peter Zijlstra]

On Thu, 2007-07-26 at 11:26 +0200, Peter Zijlstra wrote:
> On Thu, 2007-07-26 at 11:10 +0200, Ingo Molnar wrote:
> > there's a new regression:
> > 
> > SLUB does not seem to call debug_check_no_locks_freed() - hence on SLUB 
> > we will not notice certain types of freeing races. (such as freeing an 
> > object still locked and used on another CPU.) SLAB does this corretly.

Oh, nm, it doesn't call debug_check_no_locks_freed() at all.

This should do I guess.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 mm/slub.c |    1 +
 1 file changed, 1 insertion(+)

Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c
+++ linux-2.6/mm/slub.c
@@ -1656,6 +1656,7 @@ static void __always_inline slab_free(st
 	unsigned long flags;
 
 	local_irq_save(flags);
+	debug_check_no_locks_freed(object, s->size);
 	if (likely(page == s->cpu_slab[smp_processor_id()] &&
 						!SlabDebug(page))) {
 		object[page->offset] = page->lockless_freelist;

Re: [bug] SLUB & freeing locks [was: Re: 2.6.23-rc1: known regressions with patches]

[Ingo Molnar]

* Peter Zijlstra <peterz@infradead.org> wrote:

> On Thu, 2007-07-26 at 11:26 +0200, Peter Zijlstra wrote:
> > On Thu, 2007-07-26 at 11:10 +0200, Ingo Molnar wrote:
> > > there's a new regression:
> > > 
> > > SLUB does not seem to call debug_check_no_locks_freed() - hence on SLUB 
> > > we will not notice certain types of freeing races. (such as freeing an 
> > > object still locked and used on another CPU.) SLAB does this corretly.
> 
> Oh, nm, it doesn't call debug_check_no_locks_freed() at all.
> 
> This should do I guess.
> 
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

yeah.

Acked-by: Ingo Molnar <mingo@elte.hu>

	Ingo

Re: [bug] SLUB & freeing locks [was: Re: 2.6.23-rc1: known regressions with patches]

[Pekka Enberg]

On 7/26/07, Peter Zijlstra <peterz@infradead.org> wrote:
> --- linux-2.6.orig/mm/slub.c
> +++ linux-2.6/mm/slub.c
> @@ -1656,6 +1656,7 @@ static void __always_inline slab_free(st
>         unsigned long flags;
>
>         local_irq_save(flags);
> +       debug_check_no_locks_freed(object, s->size);

Although it doesn't matter much, I think this should be s->objsize. Christoph?

                                         Pekka

Re: [bug] SLUB & freeing locks [was: Re: 2.6.23-rc1: known regressions with patches]

[Peter Zijlstra]

On Thu, 2007-07-26 at 14:08 +0300, Pekka Enberg wrote:
> On 7/26/07, Peter Zijlstra <peterz@infradead.org> wrote:
> > --- linux-2.6.orig/mm/slub.c
> > +++ linux-2.6/mm/slub.c
> > @@ -1656,6 +1656,7 @@ static void __always_inline slab_free(st
> >         unsigned long flags;
> >
> >         local_irq_save(flags);
> > +       debug_check_no_locks_freed(object, s->size);
> 
> Although it doesn't matter much, I think this should be s->objsize. Christoph?

Ah, I think you are right, s->size includes all the padding and
redzones.

Re: [bug] SLUB & freeing locks [was: Re: 2.6.23-rc1: known regressions with patches]

[Christoph Lameter]

On Thu, 26 Jul 2007, Pekka Enberg wrote:

> On 7/26/07, Peter Zijlstra <peterz@infradead.org> wrote:
> > --- linux-2.6.orig/mm/slub.c
> > +++ linux-2.6/mm/slub.c
> > @@ -1656,6 +1656,7 @@ static void __always_inline slab_free(st
> >         unsigned long flags;
> > 
> >         local_irq_save(flags);
> > +       debug_check_no_locks_freed(object, s->size);
> 
> Although it doesn't matter much, I think this should be s->objsize. Christoph?

Correct. Locks can only be in the first objsize range of bytes.

Re: [bug] SLUB & freeing locks [was: Re: 2.6.23-rc1: known regressions with patches]

[Christoph Lameter]

Re: [bug] SLUB & freeing locks [was: Re: 2.6.23-rc1: known regressions with patches]

[Christoph Lameter]

Note that debug_check... adds more code to the slab_free hotpath which 
will have a significant performance impact if lockdep is enabled.

Acked-by: Christoph Lameter <clameter@sgi.com>

[PATCH] slub: add lock debugging check

[Peter Zijlstra]

Ingo noticed that the SLUB code does include the lock debugging free
check.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Christoph Lameter <clameter@sgi.com>
---
 mm/slub.c |    1 +
 1 file changed, 1 insertion(+)

Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c
+++ linux-2.6/mm/slub.c
@@ -1656,6 +1656,7 @@ static void __always_inline slab_free(st
 	unsigned long flags;
 
 	local_irq_save(flags);
+	debug_check_no_locks_freed(object, s->objsize);
 	if (likely(page == s->cpu_slab[smp_processor_id()] &&
 						!SlabDebug(page))) {
 		object[page->offset] = page->lockless_freelist;

Re: [bug] SLUB & freeing locks [was: Re: 2.6.23-rc1: known regressions with patches]

[Peter Zijlstra]

On Thu, 2007-07-26 at 11:26 +0200, Peter Zijlstra wrote:

> ---
>  mm/slub.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Index: linux-2.6/mm/slub.c
> ===================================================================
> --- linux-2.6.orig/mm/slub.c
> +++ linux-2.6/mm/slub.c
> @@ -1131,6 +1131,7 @@ static void __free_slab(struct kmem_cach
>  		slab_pad_check(s, page);
>  		for_each_object(p, s, page_address(page))
>  			check_object(s, page, p, 0);
> +		ClearSlabDebug(page);
>  	}
>  
>  	mod_zone_page_state(page_zone(page),
> @@ -1169,7 +1170,6 @@ static void discard_slab(struct kmem_cac
>  
>  	atomic_long_dec(&n->nr_slabs);
>  	reset_page_mapcount(page);
> -	ClearSlabDebug(page);
>  	__ClearPageSlab(page);
>  	free_slab(s, page);
>  }
> 

Christoph, how about this bit, it looks to me like we clear SlabDebug()
before we hit the last check in __free_slab().

Re: [bug] SLUB & freeing locks [was: Re: 2.6.23-rc1: known regressions with patches]

[Christoph Lameter]

On Thu, 26 Jul 2007, Peter Zijlstra wrote:

> > Index: linux-2.6/mm/slub.c
> > ===================================================================
> > --- linux-2.6.orig/mm/slub.c
> > +++ linux-2.6/mm/slub.c
> > @@ -1131,6 +1131,7 @@ static void __free_slab(struct kmem_cach
> >  		slab_pad_check(s, page);
> >  		for_each_object(p, s, page_address(page))
> >  			check_object(s, page, p, 0);
> > +		ClearSlabDebug(page);
> >  	}
> >  
> >  	mod_zone_page_state(page_zone(page),
> > @@ -1169,7 +1170,6 @@ static void discard_slab(struct kmem_cac
> >  
> >  	atomic_long_dec(&n->nr_slabs);
> >  	reset_page_mapcount(page);
> > -	ClearSlabDebug(page);
> >  	__ClearPageSlab(page);
> >  	free_slab(s, page);
> >  }
> > 
> 
> Christoph, how about this bit, it looks to me like we clear SlabDebug()
> before we hit the last check in __free_slab().

Looks right. Have you tried to run a kernel with this change and 
"slub_debug"?

Acked-by: Christoph Lameter <clameter@sgi.com>

Re: [bug] SLUB & freeing locks [was: Re: 2.6.23-rc1: known regressions with patches]

[Peter Zijlstra]

On Thu, 2007-07-26 at 11:10 -0700, Christoph Lameter wrote:
> On Thu, 26 Jul 2007, Peter Zijlstra wrote:
> 
> > > Index: linux-2.6/mm/slub.c
> > > ===================================================================
> > > --- linux-2.6.orig/mm/slub.c
> > > +++ linux-2.6/mm/slub.c
> > > @@ -1131,6 +1131,7 @@ static void __free_slab(struct kmem_cach
> > >  		slab_pad_check(s, page);
> > >  		for_each_object(p, s, page_address(page))
> > >  			check_object(s, page, p, 0);
> > > +		ClearSlabDebug(page);
> > >  	}
> > >  
> > >  	mod_zone_page_state(page_zone(page),
> > > @@ -1169,7 +1170,6 @@ static void discard_slab(struct kmem_cac
> > >  
> > >  	atomic_long_dec(&n->nr_slabs);
> > >  	reset_page_mapcount(page);
> > > -	ClearSlabDebug(page);
> > >  	__ClearPageSlab(page);
> > >  	free_slab(s, page);
> > >  }
> > > 
> > 
> > Christoph, how about this bit, it looks to me like we clear SlabDebug()
> > before we hit the last check in __free_slab().
> 
> Looks right. Have you tried to run a kernel with this change and 
> "slub_debug"?
> 
> Acked-by: Christoph Lameter <clameter@sgi.com>

Not something this clean, only my WIP slub-rt. I'll run this and do a
proper post of this fix.

[PATCH] slub: fix bug in slub debug support

[Peter Zijlstra]

Seems to properly boot

---
We ClearSlabDebug() before the last SlabDebug() check. Clear it later.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Christoph Lameter <clameter@sgi.com>
---
 mm/slub.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c
+++ linux-2.6/mm/slub.c
@@ -1131,6 +1131,7 @@ static void __free_slab(struct kmem_cach
 		slab_pad_check(s, page);
 		for_each_object(p, s, page_address(page))
 			check_object(s, page, p, 0);
+		ClearSlabDebug(page);
 	}
 
 	mod_zone_page_state(page_zone(page),
@@ -1169,7 +1170,6 @@ static void discard_slab(struct kmem_cac
 
 	atomic_long_dec(&n->nr_slabs);
 	reset_page_mapcount(page);
-	ClearSlabDebug(page);
 	__ClearPageSlab(page);
 	free_slab(s, page);
 }