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    SubjectRe: [BUG] percpu misaligned allocation
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    From: Frederic Weisbecker <fweisbec@gmail.com>
    Date: Thu, 18 Mar 2010 05:49:33 +0100

    > While using the lock events through perf in a sparc box, I can see
    > the following message repeated many times:
    >
    > Kernel unaligned access at TPC[49357c] perf_trace_lock_acquire+0xb4/0x180
    >
    > It actually hangs the box as the messages are sent to a serial console.
    >
    > When used with perf, the trace events use a per cpu buffer allocated
    > in kernel/trace/trace_event_perf.c, and the allocation appears to return
    > a misaligned percpu pointer. It is aligned to 4 while it seems it
    > requires to be aligned to 8.

    Thanks I'll take a look at this.

    RAW locks (both rwlocks and spinlocks) on sparc64 are 4-bytes
    in size, maybe some piece of code is assuming that locks
    are cpu word sized.

    Where is perf_trace_lock_acquire() I can't find it in Linus's
    tree? Does it get created by some crazy macro expansion?



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