Re: linux-next: Tree for March 7: slab corruptions

[Laurent Riffard]

Le 09.03.2008 04:05, Greg KH a écrit :
> On Sun, Mar 09, 2008 at 12:29:48AM +0530, Balaji Rao wrote:
> > On Saturday 08 March 2008 04:15:22 pm Laurent Riffard wrote:
> > > Le 07.03.2008 04:18, Stephen Rothwell a ??crit :
> > > > Hi all,
> > > >
> > > > I have created today's linux-next tree at
> > > > git://git.kernel.org/pub/scm/linux/kernel/git/sfr/linux-next.git
> > > I've got a lot of "Slab corruption" with next-20060307 (actually a
> > > continuous flow of warnings) whereas next-20060306 is fine.
[snip]
> > > I did a bisection:
> > >
> > > 5a428808720b31026890d3ff71fbd891d9a94fd6 is first bad commit
> > > commit 5a428808720b31026890d3ff71fbd891d9a94fd6
> > > Author: Balaji Rao <balajirrao@xxxxxxxxx>
> > > Date:   Thu Mar 6 22:23:18 2008 +0530
> > >
> > >     kobjects: mark cleaned up kobjects as unitialized
> > >
> > >     When I remove only the kvm-intel module without removing the kvm module
> > >     itself, I get an error saying that a kobject is trying to be
> > >     reinitialized. Its because of the fact that kvm reuses a kobject in
> > >     kvm_init when calling sysdev_register.
> > >
> > >     This patch fixes kobject_cleanup by marking the kobject as
> > > uninitialized when we cleanup to allow kobjects to be reused.
> > >
> > >     Signed-off-by: Balaji Rao <balajirrao@xxxxxxxxx>
> > >     Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
> > >
> > > :040000 040000 c15d08d966391dec783d137558fad66d9c2da57b
> > > : eddea2ec69c014370cf98cc2fc7e24a8dc301e70 M     lib
> > >
> > > .config attached
> > > ~~
> > > laurent
> > Hi greg,
> >
> > Apparently, its the wrong place to mark the kobject as uninitialized as the 
> > kobject could be freed by then. I've now moved it to the top of 
> > kobject_cleanup(). This fixes the problem for me.
> >
> > laurent, can you please revert the above commit , and apply this patch ? Does 
> > it help ?
> >
> > Signed-off-by: Balaji Rao <balajirrao@xxxxxxxxx>

Yes, it does help, all the "Slab corruptions" warnings are gone.
Thanks.

Tested-by: Laurent Riffard <laurent.riffard@xxxxxxx>

> > diff --git a/lib/kobject.c b/lib/kobject.c
> > index d784dae..a1f87bd 100644
> > --- a/lib/kobject.c
> > +++ b/lib/kobject.c
> > @@ -548,6 +548,9 @@ static void kobject_cleanup(struct kobject *kobj)
> >         pr_debug("kobject: '%s' (%p): %s\n",
> >                  kobject_name(kobj), kobj, __FUNCTION__);
> >  
> > +       /* Set the state to uninitialized */
> > +       kobj->state_initialized = 0;
> > +
> >         if (t && !t->release)
> >                 pr_debug("kobject: '%s' (%p): does not have a release() "
> >                          "function, it is broken and must be fixed.\n",
>
> Doh, this is correct, sorry about that, I'll fix this up properly...
>
> thanks,
>
> greg k-h
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