Re: [PATCH] lockdep fix incorrect percpu usage

Mathieu Desnoyers
2010-03-30T15:05:56Z

* Peter Zijlstra (peterz@infradead.org) wrote:
> On Tue, 2010-03-30 at 09:45 -0400, Mathieu Desnoyers wrote:
> > * Peter Zijlstra (peterz@infradead.org) wrote:
> > > On Mon, 2010-03-29 at 23:34 -0400, Mathieu Desnoyers wrote:
> > > > Should use per_cpu_ptr() to obfuscate the per cpu pointers (RELOC_HIDE is needed
> > > > for per cpu pointers).
> > > >
> > > > git blame points to commit:
> > > >
> > > > lockdep.c: commit 8e18257d29238311e82085152741f0c3aa18b74d
> > > >
> > > > But it's really just moving the code around. But it's enough to say that the
> > > > problems appeared before Jul 19 01:48:54 2007, which brings us back to 2.6.23.
> > > >
> > > > So it should be applied to stable 2.6.23.x to 2.6.33.x (or whichever of these
> > > > stable branches are still maintained) and to mainline 2.6.34-rc2.
> > >
> > > well, definately not to mainline, since that code is utterly busted in
> > > mainline due to recent per-cpu changes.
> >
> > How recent ? I'm based on
> >
> > commit f57d4e859a8acd63f878cd0534ec4b990b1710dc
> > Merge: 0528faa... eed6351...
> > Author: Ingo Molnar <mingo@elte.hu>
> > Date: Mon Mar 29 18:56:00 2010 +0200
> >
> > from -tip and I see the problem there, both in module.c and lockdep.c.
>
> Yeah, its basically been busted since the early merge window period,
> hopefully Tejun's patches will make it in soon:
>
> http://lkml.org/lkml/2010/3/10/79

I see. These patches are "on their way" to mainline, so it's better not to
create conflicts. So the lockdep patch should only be applied to -stable, but
separate module.c patch should apply to both -stable and mainline. Am I
correct ?

Thanks,

Mathieu

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--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.