Re: [PATCH] trace: don't call page_to_pfn() if page is NULL

[Steven Rostedt]

Mel,

As you were the original author of this code, can I get your Acked-by?

Thanks,

-- Steve


On Thu, 2012-09-20 at 14:04 +0800, Wen Congyang wrote:
> When allocating memory fails, page is NULL. page_to_pfn() will
> cause the kernel panicked if we don't use sparsemem vmemmap.
> 
> Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
> 
> ---
>  include/trace/events/kmem.h |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h
> index 5f889f1..08fa272 100644
> --- a/include/trace/events/kmem.h
> +++ b/include/trace/events/kmem.h
> @@ -214,7 +214,7 @@ TRACE_EVENT(mm_page_alloc,
>  
>  	TP_printk("page=%p pfn=%lu order=%d migratetype=%d gfp_flags=%s",
>  		__entry->page,
> -		page_to_pfn(__entry->page),
> +		__entry->page ? page_to_pfn(__entry->page) : 0,
>  		__entry->order,
>  		__entry->migratetype,
>  		show_gfp_flags(__entry->gfp_flags))
> @@ -240,7 +240,7 @@ DECLARE_EVENT_CLASS(mm_page,
>  
>  	TP_printk("page=%p pfn=%lu order=%u migratetype=%d percpu_refill=%d",
>  		__entry->page,
> -		page_to_pfn(__entry->page),
> +		__entry->page ? page_to_pfn(__entry->page) : 0,
>  		__entry->order,
>  		__entry->migratetype,
>  		__entry->order == 0)


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