Re: [RFC v3 3/4] mm, printk: introduce new format %pGt for page_type

[Randy Dunlap <rdunlap@infradead.org>]

On 12/19/22 01:44, Andy Shevchenko wrote:
> On Sun, Dec 18, 2022 at 07:19:00PM +0900, Hyeonggon Yoo wrote:
>> %pGp format is used to print 'flags' field of struct page.
>> As some page flags (e.g. PG_buddy, see page-flags.h for more details)
>> are set in page_type field, introduce %pGt format which provides
>> human readable output of page_type.
>>
>> Note that the sense of bits are different in page_type. if page_type is
>> 0xffffffff, no flags are set. if PG_slab (0x00100000) flag is set,
>> page_type is 0xffefffff. Clearing a bit means we set the bit.
>>
>> Bits in page_type are inverted when printing page type names.
> 
> ...
> 
>> +#define __def_pagetype_names						\
>> +	{PG_slab,			"slab"		},		\
>> +	{PG_offline,			"offline"	},		\
>> +	{PG_guard,			"guard"		},		\
>> +	{PG_table,			"table"		},		\
>> +	{PG_buddy,			"buddy"		}
> 
> Wondering if it will be more robust to define a helper macro
> 
> #define DEF_PAGETYPE_NAME(_name)	{ PG_##_name, __stringify(_name) }
> ...
> #undef DEF_PAGETYPE_MASK
> 
> In this case it decreases the chances of typo in the strings and flags.

I'd say Yes.  (and #undef DEF_PAGETYPE_NAME methinks; or change both to _MASK)

-- 
~Randy