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    SubjectRe: Random scheduler/unaligned accesses crashes with perf lock events on sparc 64
    On Mon, Apr 05, 2010 at 12:22:33PM -0700, David Miller wrote:
    > From: Frederic Weisbecker <fweisbec@gmail.com>
    > Date: Mon, 5 Apr 2010 08:57:04 +0200
    >
    > > It seems to happen after an unaligned access fixup.
    >
    > You shouldn't be getting the unaligned fixup in the first place,
    > especially in the locations where you see them. I suspect that
    > once you see first fixup, all of the registers in the cpu have
    > been corrupted in one way or another.
    >
    > I suspect something fundamental gets corrupted, for example the
    > current register window (%cwp) is corrupted and that screws up all of
    > the registers so every single function starts accessing garbage.
    >
    > My suspicions lie in three places, the ftrace mcount()
    > stubs, stack_trace_flush(), or the new perf_arch_save_caller_regs()
    > since those are the three places offhand that could make
    > us potentially make us return to function in the wrong
    > register window.


    It happens without CONFIG_FUNCTION_TRACER as well (but it happens
    when the function tracer runs). And I hadn't your perf_arch_save_caller_regs()
    when I triggered this.



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