linux-kernel - Re: [RFC 02/11] mm: debug: deal with a new family of MM pointers

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Date:	Thu, 30 Apr 2015 19:17:28 +0300
From:	"Kirill A. Shutemov" <kirill@...temov.name>
To:	Sasha Levin <sasha.levin@...cle.com>
Cc:	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	linux-mm@...ck.org
Subject: Re: [RFC 02/11] mm: debug: deal with a new family of MM pointers

On Tue, Apr 14, 2015 at 04:56:24PM -0400, Sasha Levin wrote:
> This teaches our printing functions about a new family of MM pointer that it
> could now print.
> 
> I've picked %pZ because %pm and %pM were already taken, so I figured it
> doesn't really matter what we go with. We also have the option of stealing
> one of those two...
> 
> Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
> ---
>  lib/vsprintf.c |   13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index 8243e2f..809d19d 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -1375,6 +1375,16 @@ char *comm_name(char *buf, char *end, struct task_struct *tsk,
>  	return string(buf, end, name, spec);
>  }
>  
> +static noinline_for_stack
> +char *mm_pointer(char *buf, char *end, struct task_struct *tsk,
> +		struct printf_spec spec, const char *fmt)
> +{
> +	switch (fmt[1]) {

shouldn't we printout at least pointer address for unknown suffixes?

> +	}
> +
> +	return buf;
> +}
> +
>  int kptr_restrict __read_mostly;
>  
>  /*
> @@ -1463,6 +1473,7 @@ int kptr_restrict __read_mostly;
>   *        (legacy clock framework) of the clock
>   * - 'Cr' For a clock, it prints the current rate of the clock
>   * - 'T' task_struct->comm
> + * - 'Z' Outputs a readable version of a type of memory management struct.
>   *
>   * Note: The difference between 'S' and 'F' is that on ia64 and ppc64
>   * function pointers are really function descriptors, which contain a
> @@ -1615,6 +1626,8 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
>  				   spec, fmt);
>  	case 'T':
>  		return comm_name(buf, end, ptr, spec, fmt);
> +	case 'Z':
> +		return mm_pointer(buf, end, ptr, spec, fmt);
>  	}
>  	spec.flags |= SMALL;
>  	if (spec.field_width == -1) {
> -- 
> 1.7.10.4
> 
> --
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-- 
 Kirill A. Shutemov
--
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