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    SubjectRe: [170/197] lockdep: fix incorrect percpu usage
    * Greg KH (gregkh@suse.de) wrote:
    > 2.6.32-stable review patch. If anyone has any objections, please let us know.
    >
    > ------------------
    >
    > From: Mathieu Desnoyers <mathieu.desnoyers@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@efficios.com>
    > CC: Randy Dunlap <randy.dunlap@oracle.com>
    > CC: Eric Dumazet <dada1@cosmosbay.com>
    > CC: Rusty Russell <rusty@rustcorp.com.au>
    > CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
    > CC: Tejun Heo <tj@kernel.org>
    > CC: Ingo Molnar <mingo@elte.hu>
    > CC: Andrew Morton <akpm@linux-foundation.org>
    > CC: Linus Torvalds <torvalds@linux-foundation.org>
    > CC: Greg Kroah-Hartman <gregkh@suse.de>
    > CC: Steven Rostedt <rostedt@goodmis.org>
    > Signed-off-by: Greg Kroah-Hartman <gregkh@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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