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

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Date:	Mon, 16 Mar 2015 21:04:58 +0800
From:	Xie XiuQi <xiexiuqi@...wei.com>
To:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
CC:	"gong.chen@...ux.intel.com" <gong.chen@...ux.intel.com>,
	"bhelgaas@...gle.com" <bhelgaas@...gle.com>,
	"bp@...e.de" <bp@...e.de>,
	"tony.luck@...el.com" <tony.luck@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"jingle.chen@...wei.com" <jingle.chen@...wei.com>
Subject: Re: [PATCH] tracing: add trace event for memory-failure

On 2015/3/16 17:27, Naoya Horiguchi wrote:
> On Fri, Mar 13, 2015 at 06:10:51PM +0800, Xie XiuQi 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
>>
>> Signed-off-by: Xie XiuQi <xiexiuqi@...wei.com>
>> ---
>>  include/ras/ras_event.h |   36 ++++++++++++++++++++++++++++++++++++
>>  mm/memory-failure.c     |    3 +++
>>  2 files changed, 39 insertions(+), 0 deletions(-)
>>
>> diff --git a/include/ras/ras_event.h b/include/ras/ras_event.h
>> index 79abb9c..0a6c8f3 100644
>> --- a/include/ras/ras_event.h
>> +++ b/include/ras/ras_event.h
>> @@ -232,6 +232,42 @@ 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: "free buddy", "free huge", "high
>> + *			order kernel", "free buddy, 2nd try", "different
>> + *			compound page after locking", "hugepage already
>> + *			hardware poisoned", "unmapping failed", "already
>> + *			truncated LRU", etc.
> 
> Listing all possible values here might be prone to become out of date when
> someone try to add/remove/change action_result() call sites.
> So I'd like to have some enumerator to bundle these strings in one place
> in mm/memory-failure.c.
> # I feel like doing this later.

Good, we need this.

> 
>> + * char * result -	Action result: Ignored, Failed, Delayed, Recovered.
> 
> mm/memory-failure.c has good explanation:
> 
>   /*
>    * Error handlers for various types of pages.
>    */
>   enum outcome {
>           IGNORED,        /* Error: cannot be handled */
>           FAILED,         /* Error: handling failed */
>           DELAYED,        /* Will be handled later */
>           RECOVERED,      /* Successfully recovered */
>   };
> 
> So adding a reference to here looks better to me.

Thanks for you comments. I'll change it.

> 
> Thanks,
> Naoya Horiguchi
> 
>> + */
>> +TRACE_EVENT(memory_failure_event,
>> +	TP_PROTO(const unsigned long pfn,
>> +		 const char *action,
>> +		 const char *result),
>> +
>> +	TP_ARGS(pfn, action, result),
>> +
>> +	TP_STRUCT__entry(
>> +		__field(unsigned long, pfn)
>> +		__string(action, action)
>> +		__string(result, result)
>> +	),
>> +
>> +	TP_fast_assign(
>> +		__entry->pfn = pfn;
>> +		__assign_str(action, action);
>> +		__assign_str(result, result);
>> +	),
>> +
>> +	TP_printk("pfn %#lx: %s page recovery: %s",
>> +		__entry->pfn,
>> +		__get_str(action),
>> +		__get_str(result)
>> +	)
>> +);
>>  #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 d487f8d..86a9cce 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;
>>  
>> @@ -837,6 +838,8 @@ static struct page_state {
>>   */
>>  static void action_result(unsigned long pfn, char *msg, int result)
>>  {
>> +	trace_memory_failure_event(pfn, msg, action_name[result]);
>> +
>>  	pr_err("MCE %#lx: %s page recovery: %s\n",
>>  		pfn, msg, action_name[result]);
>>  }
>> -- 
>> 1.7.1
>>
> .
> 


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