Re: system gets stuck in a lock during boot

From: Steven Rostedt
Date: Mon Oct 05 2009 - 21:26:49 EST


On Fri, 2009-10-02 at 17:12 -0400, Jason Baron wrote:

> hi Justin,
>
> I've been playing around with gcc '4.5' as well and hit a panic that
> looks very similar to what you've seen with stock 2.6.31 - I haven't
> seen it anywhere else. Anyways, it seems to be some sort of alignment
> issue with the 'struct ftrace_event_call'. I'm not sure yet if this is a
> compiler or kernel issue. But the following kernel patch fixes the issue
> for me. It would be interesting to verify if the patch also resolves the
> issue for you.
>
> thanks,
>
> -Jason
>
>
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index 6ad76bf..0029af4 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -164,6 +164,7 @@
> LIKELY_PROFILE() \
> BRANCH_PROFILE() \
> TRACE_PRINTKS() \
> + . = ALIGN(32); \
> FTRACE_EVENTS() \
> TRACE_SYSCALLS()
>
> diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
> index a81170d..43f9f1e 100644
> --- a/include/linux/ftrace_event.h
> +++ b/include/linux/ftrace_event.h
> @@ -124,7 +124,7 @@ struct ftrace_event_call {
> atomic_t profile_count;
> int (*profile_enable)(struct ftrace_event_call *);
> void (*profile_disable)(struct ftrace_event_call *);
> -};
> +} __attribute__((aligned(32)));
>
> #define MAX_FILTER_PRED 32
> #define MAX_FILTER_STR_VAL 128
> diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
> index f64fbaa..4697fb6 100644
> --- a/include/trace/ftrace.h
> +++ b/include/trace/ftrace.h
> @@ -600,7 +600,7 @@ static int ftrace_raw_init_event_##call(void) \
> } \
> \
> static struct ftrace_event_call __used \
> -__attribute__((__aligned__(4))) \
> +__attribute__((__aligned__(32))) \
> __attribute__((section("_ftrace_events"))) event_##call = { \
> .name = #call, \
> .system = __stringify(TRACE_SYSTEM), \

Are all alignments needed? Or just adding one might help. Or removing
the one directly above?

-- Steve


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