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From: Mathieu Desnoyers on 28 Apr 2010 13:50
* Greg KH (gregkh(a)suse.de) wrote:
> 2.6.32-stable review patch. If anyone has any objections, please let us know.
>
> ------------------
>
> From: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com>
>
> The mainline kernel as of 2.6.34-rc5 is not affected by this problem because
> commit 10fad5e46f6c7bdfb01b1a012380a38e3c6ab346 fixed it by refactoring.
>
> lockdep fix incorrect percpu usage
>
> 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.
>
> It should be applied to stable 2.6.23.x to 2.6.33.x (or whichever of these
> stable branches are still maintained).

Tejun, (same as module.c patch) should this patch be applied to 2.6.32.x, or
will it cause problems on ia64 ?

Thanks,

Mathieu

>
> (tested on 2.6.33.1 x86_64)
>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com>
> CC: Randy Dunlap <randy.dunlap(a)oracle.com>
> CC: Eric Dumazet <dada1(a)cosmosbay.com>
> CC: Rusty Russell <rusty(a)rustcorp.com.au>
> CC: Peter Zijlstra <a.p.zijlstra(a)chello.nl>
> CC: Tejun Heo <tj(a)kernel.org>
> CC: Ingo Molnar <mingo(a)elte.hu>
> CC: Andrew Morton <akpm(a)linux-foundation.org>
> CC: Linus Torvalds <torvalds(a)linux-foundation.org>
> CC: Greg Kroah-Hartman <gregkh(a)suse.de>
> CC: Steven Rostedt <rostedt(a)goodmis.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de>
>
> ---
> kernel/lockdep.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> --- a/kernel/lockdep.c
> +++ b/kernel/lockdep.c
> @@ -591,9 +591,9 @@ static int static_obj(void *obj)
> * percpu var?
> */
> for_each_possible_cpu(i) {
> - start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
> - end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
> - + per_cpu_offset(i);
> + start = (unsigned long) per_cpu_ptr(&__per_cpu_start, i);
> + end = (unsigned long) per_cpu_ptr(&__per_cpu_start
> + + PERCPU_ENOUGH_ROOM, i);
>
> if ((addr >= start) && (addr < end))
> return 1;
>
>

--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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