Re: [PATCH] tracing: add trace event for memory-failure

From: Steven Rostedt
Date: Wed Mar 18 2015 - 23:22:12 EST


On Thu, 19 Mar 2015 11:04:30 +0800
Xie XiuQi <xiexiuqi@xxxxxxxxxx> wrote:

> Memory-failure as the high level machine check handler, it's necessary
> to report memory page recovery action result to user space by ftrace.
>
> This patch add a event at ras group for memory-failure.
>
> The output like below:
> # tracer: nop
> #
> # entries-in-buffer/entries-written: 2/2 #P:24
> #
> # _-----=> irqs-off
> # / _----=> need-resched
> # | / _---=> hardirq/softirq
> # || / _--=> preempt-depth
> # ||| / delay
> # TASK-PID CPU# |||| TIMESTAMP FUNCTION
> # | | | |||| | |
> mce-inject-13150 [001] .... 277.019359: memory_failure_event: pfn 0x19869: free buddy page recovery: Delayed
>
> ---
> v1->v2:
> - Comment update
> - Just passing 'result' instead of 'action_name[result]',
> suggested by Steve. And hard coded there because trace-cmd
> and perf do not have a way to process enums.
>

I'll try to fix that issue soon, such that enums will work.

> Cc: Tony Luck <tony.luck@xxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Signed-off-by: Xie XiuQi <xiexiuqi@xxxxxxxxxx>
> ---
> include/ras/ras_event.h | 38 ++++++++++++++++++++++++++++++++++++++
> mm/memory-failure.c | 3 +++
> 2 files changed, 41 insertions(+)
>
> diff --git a/include/ras/ras_event.h b/include/ras/ras_event.h
> index 79abb9c..ebb05f3 100644
> --- a/include/ras/ras_event.h
> +++ b/include/ras/ras_event.h
> @@ -232,6 +232,44 @@ TRACE_EVENT(aer_event,
> __print_flags(__entry->status, "|", aer_uncorrectable_errors))
> );
>
> +/*
> + * memory-failure recovery action result event
> + *
> + * unsigned long pfn - Page Number of the corrupted page
> + * char * action - Recovery action for various type of pages
> + * int result - Action result
> + *
> + * NOTE: 'action' and 'result' are defined at mm/memory-failure.c
> + */
> +TRACE_EVENT(memory_failure_event,
> + TP_PROTO(const unsigned long pfn,
> + const char *action,
> + const int result),

"const unsigned long" and "const int" is that really needed? These are
passed by value parameters. There's no need to make them const. The
"const char *" is required though.

-- Steve

> +
> + TP_ARGS(pfn, action, result),
> +
> + TP_STRUCT__entry(
> + __field(unsigned long, pfn)
> + __string(action, action)
> + __field(int, result)
> + ),
> +
> + TP_fast_assign(
> + __entry->pfn = pfn;
> + __assign_str(action, action);
> + __entry->result = result;
> + ),
> +
> + TP_printk("pfn %#lx: %s page recovery: %s",
> + __entry->pfn,
> + __get_str(action),
> + __print_symbolic(__entry->result,
> + {0, "Ignored"},
> + {1, "Failed"},
> + {2, "Delayed"},
> + {3, "Recovered"})
> + )
> +);
> #endif /* _TRACE_HW_EVENT_MC_H */
>
> /* This part must be outside protection */
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index feb803b..3a71668 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -56,6 +56,7 @@
> #include <linux/mm_inline.h>
> #include <linux/kfifo.h>
> #include "internal.h"
> +#include <ras/ras_event.h>
>
> int sysctl_memory_failure_early_kill __read_mostly = 0;
>
> @@ -844,6 +845,8 @@ static struct page_state {
> */
> static void action_result(unsigned long pfn, char *msg, int result)
> {
> + trace_memory_failure_event(pfn, msg, result);
> +
> pr_err("MCE %#lx: %s page recovery: %s\n",
> pfn, msg, action_name[result]);
> }

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